WO2010011090A2 - Optical sheet with enhanced scratch resistance, filter including the same, and image display device including the optical sheet or the filter - Google Patents
Optical sheet with enhanced scratch resistance, filter including the same, and image display device including the optical sheet or the filter Download PDFInfo
- Publication number
- WO2010011090A2 WO2010011090A2 PCT/KR2009/004101 KR2009004101W WO2010011090A2 WO 2010011090 A2 WO2010011090 A2 WO 2010011090A2 KR 2009004101 W KR2009004101 W KR 2009004101W WO 2010011090 A2 WO2010011090 A2 WO 2010011090A2
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- optical sheet
- light absorption
- external light
- transmission portion
- light transmission
- Prior art date
Links
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- 230000031700 light absorption Effects 0.000 claims abstract description 114
- 230000005540 biological transmission Effects 0.000 claims abstract description 95
- 239000012748 slip agent Substances 0.000 claims abstract description 53
- 239000011347 resin Substances 0.000 claims description 22
- 229920005989 resin Polymers 0.000 claims description 22
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- 239000000463 material Substances 0.000 claims description 17
- RKTYLMNFRDHKIL-UHFFFAOYSA-N copper;5,10,15,20-tetraphenylporphyrin-22,24-diide Chemical compound [Cu+2].C1=CC(C(=C2C=CC([N-]2)=C(C=2C=CC=CC=2)C=2C=CC(N=2)=C(C=2C=CC=CC=2)C2=CC=C3[N-]2)C=2C=CC=CC=2)=NC1=C3C1=CC=CC=C1 RKTYLMNFRDHKIL-UHFFFAOYSA-N 0.000 claims description 5
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- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 6
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- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 2
- 239000004697 Polyetherimide Substances 0.000 description 2
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Images
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/20—Filters
- G02B5/201—Filters in the form of arrays
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/003—Light absorbing elements
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/20—Filters
- G02B5/22—Absorbing filters
- G02B5/223—Absorbing filters containing organic substances, e.g. dyes, inks or pigments
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
- G02F1/133509—Filters, e.g. light shielding masks
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2307/00—Properties of the layers or laminate
- B32B2307/50—Properties of the layers or laminate having particular mechanical properties
- B32B2307/584—Scratch resistance
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J2211/00—Plasma display panels with alternate current induction of the discharge, e.g. AC-PDPs
- H01J2211/20—Constructional details
- H01J2211/34—Vessels, containers or parts thereof, e.g. substrates
- H01J2211/44—Optical arrangements or shielding arrangements, e.g. filters or lenses
- H01J2211/448—Near infrared shielding means
Definitions
- the present invention relates to an optical sheet, a filter including the same, and an image display device including the optical sheet or the filter. More particularly, the present invention relates to an optical sheet with reduced surface spots and enhanced scratch resistance, a filter including the same, and an image display device having a high image quality and including the optical sheet or the filter.
- image display devices include liquid crystal displays (LCDs), plasma display panels (PDPs), field emission displays (FEDs), cathode ray tubes (CRTs), vacuum fluorescence displays, and field emission display panels.
- LCDs liquid crystal displays
- PDPs plasma display panels
- FEDs field emission displays
- CRTs cathode ray tubes
- vacuum fluorescence displays and field emission display panels.
- These image display devices display color images by realizing emission of the three primary lights such as red, blue, and green.
- Such image display devices generally includes a panel assembly that forms images; and a filter that shields electromagnetic waves, near-infrared rays, and/or orange light emitted from the panel assembly and has functions such as surface reflection prevention and/or color adjustment.
- the filter should meet the requirement for light transmittance because it is disposed on a front side of the panel assembly.
- the filter absorbs and/or reflects lights emitted from the panel assembly and thus decreases brightness of the image display device.
- external environmental light passes through the filter of the image display device and may enter the panel assembly.
- the external environmental light that passes through the filter from the outside may interfere with the lights emitted from the panel assembly, thereby decreasing the contrast ratio in bright room and reducing the image display capability of the image display device.
- a conventional optical sheet includes a transparent light transmission portion, and wedge-shaped external light absorption portions which include a light absorbable material and are disposed at predetermined intervals in the light transmission portion. Since the external light absorption portions absorb external environmental light, a contrast ratio of an image is improved.
- External light absorption portions may be prepared according to the following method.
- a composition including a light absorption material is prepared in the form of a dispersion, and then the light absorption material dispersion is scattered on the surface of a light transmission portion having grooves. Then, wiping is performed thereon using a Dr. Blade to fill the grooves of the light transmission portion with the light absorption material dispersion, thereby forming external light absorption portions.
- the light absorption material dispersion is not uniformly dispersed on the surface of the light transmission portion and thus, thickness variations may occur locally.
- spots may be formed on the surface of the light transmission portion.
- the hardness of the light transmission portion and/or external light absorption portions is low, and thus, when brought into contact with external materials, the light transmission portion and/or the external light absorption portions may be easily scratched.
- the present invention provides an optical sheet with reduced surface spots.
- the present invention also provides an optical sheet with enhanced scratch resistance.
- the present invention also provides an optical sheet capable of increasing a contrast ratio in a bright environment and reducing formation of a double image when used in an image display device.
- the present invention also provides a filter including the optical sheet.
- the present invention also provides an image display device having a high image quality and including the optical sheet or the filter.
- an optical sheet including: a light transmission portion including a plurality of grooves spaced apart from each other; and a plurality of external light absorption portions which fill the grooves, wherein at least one selected from the group consisting of the light transmission portion and the external light absorption portions includes a slip agent.
- the external light absorption portions may be formed by filling the grooves with an external light absorption portion forming composition including a curable resin, a light absorbable material, and a slip agent, and curing the curable resin of the external light absorption portion forming composition.
- the curable resin may be an ultraviolet (UV)-ray curable resin.
- the external light absorption portions may include the slip agent and the amount of the slip agent is in the range of 0.05 to 30 parts by weight based on 100 parts by weight of the total weight of the external light absorption portions.
- the light transmission portion may include the slip agent and the amount of the slip agent is in the range of 0.05 to 30 parts by weight based on 100 parts by weight of the total weight of the light transmission portion.
- the slip agent may include at least one selected from the group consisting of a silicon compound and a fluorine compound.
- the optical sheet may further include a base film which is disposed on one surface of the light transmission portion, wherein the one surface is opposite to the other surface in which the grooves are formed and supports the light transmission portion .
- a pitch of the optical sheet may be in the range of 40 to 150 ⁇ m
- the width of the external light absorption portion may be in the range of 10 to 40 ⁇ m
- the height of the external light absorption portion may be in the range of 50 to 200 ⁇ m .
- the thickness-wise cross sections of the external light absorption portions may be triangular, tetragonal, or trapezoidal .
- the external light absorption portions may be disposed in a stripe form, a matrix form, or a wave form .
- the optical sheet may be a sheet for enhancing a contrast ratio .
- a filter for an image display device including the optical sheet and a filter base.
- an image display device including the optical sheet.
- FIG. 1 is an exploded perspective schematic view of an image display device equipped with a filter including an optical sheet according to an embodiment of the present invention
- FIG. 2A is an exploded cross-sectional view of a filter including an optical sheet according to an embodiment of the present invention
- FIG. 2B is an exploded cross-sectional view of a filter including an optical sheet according to another embodiment of the present invention.
- FIG. 3 is a partially enlarged view of the optical sheet of FIG. 2A before the optical sheet is mounted on the filter .
- FIG. 1 is an exploded perspective view of an image display device 1 equipped with a filter 40 including an optical sheet according to an embodiment of the present invention
- FIG. 2A is an exploded cross-sectional view of the filter 40 including an optical sheet 200 according to an embodiment of the present invention
- FIG. 2B is an exploded cross-sectional view of the filter 40 including an optical sheet 200 according to another embodiment of the present invention .
- the image display device 1 includes a case 10, a cover 50 covering a top portion of the case 10, a driving circuit substrate 20 accommodated in the case 10, a panel assembly 30 that forms images, and the filter 40 .
- Visible images are formed in the panel assembly 30 in response to an electrical signal applied from the driving circuit substrate 20 and are displayed to the outside via the filter 40 .
- the filter 40 includes a color adjustment film 100, the optical sheet 200, and a filter base (FB) including an electromagnetic wave shielding film 300, a hard coating layer 400, and a reflection prevention film 500.
- FB filter base
- the color adjustment film 100 may include, for example, a neon light blocking colorant, and may further include a near-infrared ray absorption compound or a colorant.
- a neon light denotes useless light having a wavelength of about 585 nm that is generated when a neon gas is excited.
- a near-infrared ray causes malfunction of surrounding electronic devices, and thus, needs to be shielded.
- the optical sheet 200 includes a base film 230, a light transmission portion 210, and a plurality of external light absorption portions 220.
- the optical sheet 200 may be disposed under the color adjustment film 100.
- the optical sheet 200 described above may be, for example, a sheet for enhancing a contrast ratio, but is not limited thereto.
- the sheet for enhancing a contrast ratio may be interpreted in a broad sense, for example, as a sheet for increasing mainly the contrast ratio of the image display device 1.
- the light transmission portion 210 transmits light emitted from the panel assembly 30 illustrated in FIG. 1.
- the light transmission portion 210 may include a curable resin.
- the light transmission portion 210 may include an acrylate resin that may be cured when exposed to UV rays or heat energy.
- the light transmission portion 210 may be transparent, but not necessarily completely transparent. In the latter case, the light transmission portion 210 may have a transparency level that is generally acceptable in the art as corresponding to a transparent portion.
- the shape of the light transmission portion 210 may be complementary to the shape of the external light absorption portions 220, which will be described later, but the shape of the light transmission portion 210 is not limited thereto. That is, the light transmission portion 210 may have a plurality of grooves g 210 disposed at predetermined intervals, and the grooves g 210 are filled with an external light absorption portion forming composition including a light absorbable material and a curable resin to form the external light absorption portions 220 which will be described later.
- the refractive index of the light transmission portion 210 may be in a range of 1.3 to 1.8. It is difficult to manufacture the light transmission portion 210 to have a refractive index less than 1.3. On the other hand, when the refractive index of the light transmission portion 210 is greater than 1.8, the transmittance of the light transmission portion 210 is significantly decreased and the contrast ratio is also decreased, resulting in a decrease in the overall resolution of the image display device 1.
- the light transmission portion 210 may include a slip agent. Due to inclusion of the slip agent, the surface friction of the light transmission portion 210 is reduced, and thus, when the external light absorption portions 220 are formed later, a dispersion including an external light absorption portion forming composition smoothly flows along the surface of the light transmission portion 210 and is dispersed thereon in a uniform thickness. Thus, when the external light absorption portions 220 are formed by wiping the dispersion dispersed in the uniform thickness on the surface of the light transmission portion 210 using, for example, a Dr. Blade, to fill the grooves g 210 of the light transmission portion 210, spots may not be formed on the surface of the external light absorption portions 220.
- the decrease in the surface friction of the light transmission portion 210 results in an increase in a scratch resistance of the light transmission portion 210.
- the present invention is not limited thereto.
- the slip agent may be included only in the external light absorption portions 220, not in the light transmission portion 210.
- the amount of the slip agent included in the light transmission portion 210 may be, for example, in the range of 0.05 to 30 parts by weight based on 100 parts by weight of the total weight of the light transmission portion 210. If the amount of the slip agent is less than 0.05 parts by weight based on 100 parts by weight of the total weight of the light transmission portion 210, effects of adding the slip agent are negligible. On the other hand, if the amount of the slip agent is greater than 30 parts by weight based on 100 parts by weight of the total weight of the light transmission portion 210, when the light transmission portion forming composition including the slip agent is preserved, an interlayer separation may occur and a light transmittance is thus reduced.
- the slip agent may include at least one selected from the group consisting of a silicon compound and a fluorine compound.
- silicon and/or fluorine compound are used, due to their characteristic immiscibility, silicon and/or fluorine element are arranged toward the surface of the light transmission portion 210, thereby reducing the surface energy of the light transmission portion 210 and improving adhesive characteristics and friction resistance characteristics of the light transmission portion 210.
- the slip agent used in the optical sheet 200 may be, for example, a silicon compound that is cross-linked when exposed to UV rays.
- the silicon compound include silicon diacrylate, silicon polyether acrylate, polyether modified dimethylpolysiloxane etc.
- the slip agent is not limited to these compounds.
- the external light absorption portions 220 are formed by filling the grooves g 210 disposed in the light transmission portion 210 with an external light absorption portion forming composition that includes a light absorbable material and either a thermosetting or UV-ray curable resin, to absorb external light and enhance a contrast ratio in a bright environment in order to obtain high resolution.
- an external light absorption portion forming composition that includes a light absorbable material and either a thermosetting or UV-ray curable resin, to absorb external light and enhance a contrast ratio in a bright environment in order to obtain high resolution.
- each of the external light absorption portions 220 has a tetragonal cross section
- FIG. 2B each of the external light absorption portions 220 has a trapezoidal cross section.
- thermosetting and UV-ray curable resin may be the same as or similar to a compound that is used to form the light transmission portion 210.
- Examples of the light absorbable material may include a black inorganic material, a black organic material, a black-oxidized metal, and mixtures thereof.
- the external light absorption portions 220 include a black-oxidized metal, since the black-oxidized metal has low electric resistance, the electric resistance may be controlled by adjusting the amount of black-oxidized metal power or the thickness of black-oxidized metal film.
- the external light absorption portions 220 can shield electromagnetic waves.
- the external light absorption portions 220 may include a carbon-containing UV- ray curable resin.
- the refractive index of the external light absorption portions 220 may be similar to the refractive index of the light transmission portion 210, specifically in a range of 1.3 to 1.8.
- the external light absorption portion forming composition may further include a slip agent. Due to the inclusion of the slip agent, when the external light absorption portion forming composition is prepared in the form of a dispersion, the flowability of the dispersion is improved. Thus, when the external light absorption portions 220 are formed, the dispersion including the external light absorption portion forming composition flows smoothly along the surface of the light transmission portion 210 and is dispersed in a uniform thickness on the surface the light transmission portion 210. Thus, when the external light absorption portions 220 are formed by wiping the dispersion dispersed in a uniform thickness on the surface of the light transmission portion 210 by using, for example, a Dr. blade, spots may not be formed on the surface of the external light absorption portions 220.
- the decrease in the surface friction of the external light absorption portions 220 results in an increase in scratch resistance of the external light absorption portions 220.
- the slip agent may be included only in the light transmission portion 210, not in the external light absorption portions 220.
- the slip agent may be included in both the light transmission portion 210 and the external light absorption portions 220.
- spots are not formed on the surface of the external light absorption portions 220, and the light transmission portion 210 and external light absorption portions 220 have all a high scratch resistance.
- the amount of the slip agent is in the range of 0.05 to 30 parts by weight based on 100 parts by weight of the total weight of the external light absorption portions 220, that is, the total weight of the external light absorption portion forming composition. If the amount of the slip agent is less than 0.05 parts by weight based on 100 parts by weight of the total weight of the external light absorption portions 220, addition effects of the slip agent are negligible.
- the amount of the slip agent is greater than 30 parts by weight based on 100 parts by weight of the total weight of the external light absorption portions 220, when the external light absorption portion forming composition including the slip agent is preserved, an interlayer separation may occur and an external light absorption rate may be thus lowered.
- the slip agent used in the external light absorption portions 220 may be the same as that used in the light transmission portion 210.
- the base film 230 is disposed on one surface of the light transmission portion 210, that is, the surface opposite to that in which the recess portions 220a are formed.
- the base film 230 supports the light transmission portion 210 in which the external light absorption portions 220 are formed.
- the base film 230 may include at least one material selected from the group consisting of polyethersulphone (PES), polyacrylate (PAR), polyetherimide (PEI), polyethylene naphthalate (PEN), polyethyleneterephthalate (PET), polyphenylene sulfide (PPS), polyallylate, polyimide, polycarbonate (PC), cellulose triacetate (TAC), and cellulose acetate propionate (CAP).
- the base film 230 may include polycarbonate (PC), polyethyleneterephthalate (PET), cellulose triacetate (TAC), or polyethylene naphthalate (PEN).
- the base film 230 may include a material having a refractive index equal or similar to the refractive index of the light transmission portion 210.
- the optical sheet 200 according to the present embodiment of the present invention may further include a protection film 240 (see FIGS. 3 through 5) that will be described later, disposed on one surface of the light transmission portion 210, that is, the surface opposite to that on which the base film 230 is disposed.
- the protection film 240 protects the optical sheet 200 until the optical sheet 200 is mounted on the filter 40, and when the optical sheet 200 is mounted on the filter 40, the protection film 240 is separated from the optical sheet 200; however, the present invention is not limited thereto.
- the filter base is disposed on a surface of the optical sheet 200, and includes an electromagnetic wave shielding film 300, a hard coating layer 400, and a reflection prevention film 500 disposed in this order.
- the structure of the FB is not limited thereto. That is, the electromagnetic wave shielding film 300, the hard coating layer 400, and the reflection prevention film 500 may be disposed in any order in the FB.
- the FB may also include a layer including at least two types of materials having different functions.
- the electromagnetic wave shielding film 300 shields electromagnetic waves.
- the electromagnetic wave shielding film 300 may include a conductive mesh layer, a metal thin layer, a high-refractive-index transparent thin layer, or at least two of the previous layers.
- the electromagnetic wave shielding film 300 is a single layer.
- the structure of the electromagnetic wave shielding film 300 is not limited thereto.
- the electromagnetic wave shielding film 300 may have a multi-layer structure including at least two layers.
- the hard coating layer 400 has a scratch resistance and prevents the electromagnetic wave shielding film 300 or the reflection prevention film 500 that will be described later from being damaged by, for example, contact with external materials.
- the hard coating layer 400 may include reinforced glass alone, or reinforced glass including polymer as a binder.
- the hard coating layer 400 may include an acryl-based polymer, a urethane-based polymer, an epoxy-based polymer, a siloxane-based polymer, or an UV-setting resin such as oligomer.
- the hard coating layer 400 may further include a silica-based filler to increase the hardness thereof.
- the reflection prevention film 500 adjusts the level of transmittance of visible light so as to minimize eye fatigue of users watching the image display device for a long period of time. By disposing the reflection prevention film 500 to adjust the transmittance of visible light, visible light may be selectively absorbed and also, a color reproduction range such as a contrast ratio may be widened.
- the reflection prevention film 500 is a single layer.
- the structure of the reflection prevention film 500 is not limited thereto.
- the reflection prevention film 500 may have a multi-layer structure including at least two layers.
- the reflection prevention film 500 has a reflection prevention effect because visible light that enters from the outside and is reflected from the surface of the reflection prevention film 500 and visible light reflected from an interface between the reflection prevention film 500 and the hard coating layer 400 are out of phase with each other and destructive interference occurs.
- the reflection prevention film 500 may be formed by curing and fixing a mixture of indium tin oxide (ITO) and silicon oxide (SiO 2 ), a mixture of nickel chromate (NiCr) and silicon oxide (SiO 2 ), or the like.
- the reflection prevention film 500 may include a titanium oxide or a specific fluorine resin having a low refractive index.
- FIG. 3 is a partially enlarged view of the optical sheet 200 of FIG. 2A before the optical sheet 200 is mounted on the filter 40. It should be noted that the protective film 240 is not yet removed.
- FIGS. 1 through 3 like reference numerals denote like elements.
- the external light absorption portions 220 may be formed by performing a roll molding process, or an injection molding process wherein the grooves g 210 of the light transmission portion 210 having a shape opposite to the pattern of the external light absorption portions 220 are filled with a thermosetting resin.
- the optical sheet 200 may additionally perform these functions.
- the optical sheet 200 includes the light transmission portion 210, the external light absorption portions 220, the base film 230, and the protection film 240.
- the protection film 240 may be optionally omitted.
- the filter 40 illustrated in FIG. 2A includes the optical sheet 200 from which the protection film 240 is removed .
- the configuration of the light transmission portion 210, the external light absorption portion 220, the base film 230, and the protection film 240 is the same as described above.
- the external light absorption portions 220 may be disposed in various forms, such as a stripe form, a matrix form, a wave form, etc. In addition, the external light absorption portions 220 may be disposed at predetermined intervals to allow light to pass through areas between adjacent external light absorption portions 220. In FIG. 3, the external light absorption portions 220 have tetragonal cross sections. However, the cross-sectional shape of the external light absorption portions 220 is not limited thereto. For example, the external light absorption portions 220 may have triangular, trapezoidal, or pentagonal cross sections.
- a pitch P200 of the optical sheet 200 may be in the range of 40 to 150 ⁇ m
- a width W 220 of the external light absorption portions 220 may be in the range of 10 to 40 ⁇ m
- a height h 220 of the external light absorption portions 220 may be in the range of 50 to 200 ⁇ m
- the width W 220 of the external light absorption portion 220 denotes the width of an end of the external light absorption portion 220 on an image light source side. If the external light absorption portions 220 have a trapezoidal cross section , the width W 220 of the external light absorption portion 220 denotes the width of an end of the external light absorption portion 220 on the image light source side, that is, the maximum width.
- the optical sheet 200 may further include a prism portion (not shown) disposed on one surface of the base film 230, that is, the surface opposite to that on which the light transmission portion 210 is disposed.
- a material for forming the prism portion may be identical or similar to the material for forming the light transmission portion 210.
- the optical sheet 200 may have a high external light absorption rate, an enhanced contrast ratio, and a high resolution, without a large change in transmittance .
- An optical sheet or filter having the structure as described above may be included in an image display device, and thus, in regard to the image display device, the quality of an image is improved and a contrast ratio is increased, and thus, high-resolution images may be obtained.
- Example 1 Manufacture of an optical sheet including a light transmission portion and external light absorption portions, wherein the light transmission portion does not include a slip agent and the external light absorption portions include a slip agent
- a molding roll having a surface on which a plurality of protrusions each having a tetragonal side cross-section were formed was manufactured. Then, by using a pattern roll apparatus (manufactured by Hirano Co., Ltd) equipped with an UV ray generation device, a mixed solution (Sartomer, CN-981) (refractive index: 1.51) containing 100 g of acryl-based curable resin having a low refractive index was slowly added between the molding roll and an optical PET film (manufactured by Toyobo Co., Ltd) having a thickness of 188 ⁇ m and cured, thereby forming a light transmission portion having grooves with a pattern opposite to the pattern of the protrusions of the molding roll.
- a pattern roll apparatus manufactured by Hirano Co., Ltd
- an UV ray generation device a mixed solution (Sartomer, CN-981) (refractive index: 1.51) containing 100 g of acryl-based curable resin having a low refr
- the optical PET film constituted a base film.
- a dispersion (refractive index:1.52) prepared by mixing 5 g of silicon polyether acrylate (Rad 2200, Tego Co., Ltd) as a slip agent, 2 g of carbon black, and 100 g of an acryl-based curable resin mixed solution (Sartomer, CN-985) was scattered over the grooves and then, wiping was performed thereon using a Dr. Blade formed of a soft plastic to uniformly fill the grooves, thereby forming a plurality of external light absorption portions in the grooves. Then, the acryl-based curable resin of the carbon dispersion was cured using UV-rays, thereby obtaining an optical sheet as illustrated in FIG. 3.
- the pitch of the light transmission portion was 73.4 ⁇ m
- the width and height of the external light absorption portions were 22 ⁇ m and 102 ⁇ m , respectively
- the thickness of the light transmission portions was 150 ⁇ m .
- the pitch of the light transmission portion refers to a distance between corresponding sites of adjacent portions of the light transmission portion which are divided by an external light absorption portion.
- Example 2 Manufacture of an optical sheet including a light transmission portion and external light absorption portions, wherein the light transmission portion and the external light absorption portions include a slip agent
- An optical sheet was manufactured in the same manner as in Example 1, except that the light transmission portion was formed including, in addition to the mixed solution including 100 g of acryl-based curable resin having a low refractive index, 5 g of silicon polyether acrylate (Rad 2200, Tego Co., Ltd) as a slip agent.
- Example 3 Manufacture of an optical sheet including a light transmission portion and external light absorption portions, wherein the light transmission portion includes a slip agent and the external light absorption portions do not include a slip agent
- An optical sheet was manufactured in the same manner as in Example 1, except that the external light absorption portion was formed without the slip agent and the light transmission portion was formed including, in addition to the mixed solution including 100 g of acryl-based curable resin having a low refractive index, 5 g of silicon polyether acrylate (Rad 2200, Tego Co., Ltd) as a slip agent.
- Comparative Example 1 Manufacture of an optical sheet including a light transmission portion and external light absorption portions, wherein neither the light transmission portion nor the external light absorption portions include a slip agent
- An optical sheet was manufactured in the same manner as in Example 1, except that the external light absorption portion was formed without the slip agent.
- a pencil hardness test was performed on the light transmission portion and external light absorption portion according to a measurement method speculated in ASTM D3363-93. According to the measurement method, the surface hardnesses of the light transmission portion and external light absorption portion are measured by scratching the surfaces of the light transmission portion and external light absorption portion with a pencil having a hardness defined as B ⁇ HB ⁇ H and then identifying whether scratches were formed on the surfaces of the light transmission portion and external light absorption portion.
- the part including the slip agent had higher surface hardness and thus, higher scratch resistance than the part without the slip agent,.
- the surface hardness was equal to or lower than that in Examples 1 through 3 and thus, it may be concluded that the light transmission portion and external light absorption portions manufactured according to Comparative Example 1 are easily scratched.
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Abstract
Disclosed are an optical sheet, a filter including the same, and an image display device including the optical sheet or the filter. The optical sheet includes: a light transmission portion including a plurality of grooves spaced apart from each other; and a plurality of external light absorption portions which fill the grooves, wherein at least one selected from the group consisting of the light transmission portion and the external light absorption portions includes a slip agent.
Description
The present invention relates to an optical sheet, a filter including the same, and an image display device including the optical sheet or the filter. More particularly, the present invention relates to an optical sheet with reduced surface spots and enhanced scratch resistance, a filter including the same, and an image display device having a high image quality and including the optical sheet or the filter.
Recently, various types of image display devices have been developed. Examples of such image display devices include liquid crystal displays (LCDs), plasma display panels (PDPs), field emission displays (FEDs), cathode ray tubes (CRTs), vacuum fluorescence displays, and field emission display panels. These image display devices display color images by realizing emission of the three primary lights such as red, blue, and green.
Such image display devices generally includes a panel assembly that forms images; and a filter that shields electromagnetic waves, near-infrared rays, and/or orange light emitted from the panel assembly and has functions such as surface reflection prevention and/or color adjustment. The filter should meet the requirement for light transmittance because it is disposed on a front side of the panel assembly.
The filter, however, absorbs and/or reflects lights emitted from the panel assembly and thus decreases brightness of the image display device. In addition, in a bright environment, for example, in a bright room, external environmental light passes through the filter of the image display device and may enter the panel assembly. In this regard, the external environmental light that passes through the filter from the outside may interfere with the lights emitted from the panel assembly, thereby decreasing the contrast ratio in bright room and reducing the image display capability of the image display device.
To address these problems, an optical sheet may be used. In general, a conventional optical sheet includes a transparent light transmission portion, and wedge-shaped external light absorption portions which include a light absorbable material and are disposed at predetermined intervals in the light transmission portion. Since the external light absorption portions absorb external environmental light, a contrast ratio of an image is improved.
External light absorption portions may be prepared according to the following method. A composition including a light absorption material is prepared in the form of a dispersion, and then the light absorption material dispersion is scattered on the surface of a light transmission portion having grooves. Then, wiping is performed thereon using a Dr. Blade to fill the grooves of the light transmission portion with the light absorption material dispersion, thereby forming external light absorption portions.
However, during the filling of the grooves, the light absorption material dispersion is not uniformly dispersed on the surface of the light transmission portion and thus, thickness variations may occur locally. In this case, after the filling of the grooves, spots may be formed on the surface of the light transmission portion.
In addition, the hardness of the light transmission portion and/or external light absorption portions is low, and thus, when brought into contact with external materials, the light transmission portion and/or the external light absorption portions may be easily scratched.
The present invention provides an optical sheet with reduced surface spots.
The present invention also provides an optical sheet with enhanced scratch resistance.
The present invention also provides an optical sheet capable of increasing a contrast ratio in a bright environment and reducing formation of a double image when used in an image display device.
The present invention also provides a filter including the optical sheet.
The present invention also provides an image display device having a high image quality and including the optical sheet or the filter.
According to an aspect of the present invention, there is provided an optical sheet including: a light transmission portion including a plurality of grooves spaced apart from each other; and a plurality of external light absorption portions which fill the grooves, wherein at least one selected from the group consisting of the light transmission portion and the external light absorption portions includes a slip agent.
The external light absorption portions may be formed by filling the grooves with an external light absorption portion forming composition including a curable resin, a light absorbable material, and a slip agent, and curing the curable resin of the external light absorption portion forming composition.
The curable resin may be an ultraviolet (UV)-ray curable resin.
The external light absorption portions may include the slip agent and the amount of the slip agent is in the range of 0.05 to 30 parts by weight based on 100 parts by weight of the total weight of the external light absorption portions.
The light transmission portion may include the slip agent and the amount of the slip agent is in the range of 0.05 to 30 parts by weight based on 100 parts by weight of the total weight of the light transmission portion.
The slip agent may include at least one selected from the group consisting of a silicon compound and a fluorine compound.
The optical sheet may further include a base film which is disposed on one surface of the light transmission portion, wherein the one surface is opposite to the other surface in which the grooves are formed and supports the light transmission portion .
A pitch of the optical sheet may be in the range of 40 to 150 ㎛ , the width of the external light absorption portion may be in the range of 10 to 40 ㎛ , and the height of the external light absorption portion may be in the range of 50 to 200 ㎛ .
The thickness-wise cross sections of the external light absorption portions may be triangular, tetragonal, or trapezoidal .
The external light absorption portions may be disposed in a stripe form, a matrix form, or a wave form .
The optical sheet may be a sheet for enhancing a contrast ratio .
According to another aspect of the present invention, there is provided a filter for an image display device, the filter including the optical sheet and a filter base.
According to another aspect of the present invention, there is provided an image display device including the optical sheet.
The above and other features and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which:
FIG. 1 is an exploded perspective schematic view of an image display device equipped with a filter including an optical sheet according to an embodiment of the present invention;
FIG. 2A is an exploded cross-sectional view of a filter including an optical sheet according to an embodiment of the present invention;
FIG. 2B is an exploded cross-sectional view of a filter including an optical sheet according to another embodiment of the present invention; and
FIG. 3 is a partially enlarged view of the optical sheet of FIG. 2A before the optical sheet is mounted on the filter .
Hereinafter, an optical sheet, a filter including the optical sheet, and an image display device including the optical sheet or the filter will be described in detail with reference to the accompanying drawings according to embodiments of the present invention.
FIG. 1 is an exploded perspective view of an image display device 1 equipped with a filter 40 including an optical sheet according to an embodiment of the present invention, FIG. 2A is an exploded cross-sectional view of the filter 40 including an optical sheet 200 according to an embodiment of the present invention, and FIG. 2B is an exploded cross-sectional view of the filter 40 including an optical sheet 200 according to another embodiment of the present invention .
Referring to FIG. 1, the image display device 1 according to the present embodiment of the present invention includes a case 10, a cover 50 covering a top portion of the case 10, a driving circuit substrate 20 accommodated in the case 10, a panel assembly 30 that forms images, and the filter 40 .
Visible images are formed in the panel assembly 30 in response to an electrical signal applied from the driving circuit substrate 20 and are displayed to the outside via the filter 40 .
Referring to FIGS. 2A and 2B, the filter 40 includes a color adjustment film 100, the optical sheet 200, and a filter base (FB) including an electromagnetic wave shielding film 300, a hard coating layer 400, and a reflection prevention film 500.
The color adjustment film 100 may include, for example, a neon light blocking colorant, and may further include a near-infrared ray absorption compound or a colorant. A neon light denotes useless light having a wavelength of about 585 nm that is generated when a neon gas is excited. A near-infrared ray causes malfunction of surrounding electronic devices, and thus, needs to be shielded.
The optical sheet 200 includes a base film 230, a light transmission portion 210, and a plurality of external light absorption portions 220. The optical sheet 200 may be disposed under the color adjustment film 100. The optical sheet 200 described above may be, for example, a sheet for enhancing a contrast ratio, but is not limited thereto. The sheet for enhancing a contrast ratio may be interpreted in a broad sense, for example, as a sheet for increasing mainly the contrast ratio of the image display device 1.
The light transmission portion 210 transmits light emitted from the panel assembly 30 illustrated in FIG. 1. The light transmission portion 210 may include a curable resin. In particular, the light transmission portion 210 may include an acrylate resin that may be cured when exposed to UV rays or heat energy.
In addition, the light transmission portion 210 may be transparent, but not necessarily completely transparent. In the latter case, the light transmission portion 210 may have a transparency level that is generally acceptable in the art as corresponding to a transparent portion. In general, the shape of the light transmission portion 210 may be complementary to the shape of the external light absorption portions 220, which will be described later, but the shape of the light transmission portion 210 is not limited thereto. That is, the light transmission portion 210 may have a plurality of grooves g210 disposed at predetermined intervals, and the grooves g210 are filled with an external light absorption portion forming composition including a light absorbable material and a curable resin to form the external light absorption portions 220 which will be described later. The refractive index of the light transmission portion 210 may be in a range of 1.3 to 1.8. It is difficult to manufacture the light transmission portion 210 to have a refractive index less than 1.3. On the other hand, when the refractive index of the light transmission portion 210 is greater than 1.8, the transmittance of the light transmission portion 210 is significantly decreased and the contrast ratio is also decreased, resulting in a decrease in the overall resolution of the image display device 1.
The light transmission portion 210 may include a slip agent. Due to inclusion of the slip agent, the surface friction of the light transmission portion 210 is reduced, and thus, when the external light absorption portions 220 are formed later, a dispersion including an external light absorption portion forming composition smoothly flows along the surface of the light transmission portion 210 and is dispersed thereon in a uniform thickness. Thus, when the external light absorption portions 220 are formed by wiping the dispersion dispersed in the uniform thickness on the surface of the light transmission portion 210 using, for example, a Dr. Blade, to fill the grooves g210 of the light transmission portion 210, spots may not be formed on the surface of the external light absorption portions 220. In addition, in this case, the decrease in the surface friction of the light transmission portion 210 results in an increase in a scratch resistance of the light transmission portion 210. However, the present invention is not limited thereto. For example, the slip agent may be included only in the external light absorption portions 220, not in the light transmission portion 210.
If the light transmission portion 210 is formed including the slip agent, the amount of the slip agent included in the light transmission portion 210 may be, for example, in the range of 0.05 to 30 parts by weight based on 100 parts by weight of the total weight of the light transmission portion 210. If the amount of the slip agent is less than 0.05 parts by weight based on 100 parts by weight of the total weight of the light transmission portion 210, effects of adding the slip agent are negligible. On the other hand, if the amount of the slip agent is greater than 30 parts by weight based on 100 parts by weight of the total weight of the light transmission portion 210, when the light transmission portion forming composition including the slip agent is preserved, an interlayer separation may occur and a light transmittance is thus reduced.
The slip agent may include at least one selected from the group consisting of a silicon compound and a fluorine compound. When the silicon and/or fluorine compound are used, due to their characteristic immiscibility, silicon and/or fluorine element are arranged toward the surface of the light transmission portion 210, thereby reducing the surface energy of the light transmission portion 210 and improving adhesive characteristics and friction resistance characteristics of the light transmission portion 210.
The slip agent used in the optical sheet 200 may be, for example, a silicon compound that is cross-linked when exposed to UV rays. Examples of the silicon compound include silicon diacrylate, silicon polyether acrylate, polyether modified dimethylpolysiloxane etc. However, the slip agent is not limited to these compounds.
The external light absorption portions 220 are formed by filling the grooves g210 disposed in the light transmission portion 210 with an external light absorption portion forming composition that includes a light absorbable material and either a thermosetting or UV-ray curable resin, to absorb external light and enhance a contrast ratio in a bright environment in order to obtain high resolution. Referring to FIG. 2A, each of the external light absorption portions 220 has a tetragonal cross section, and referring to FIG. 2B, each of the external light absorption portions 220 has a trapezoidal cross section.
The thermosetting and UV-ray curable resin may be the same as or similar to a compound that is used to form the light transmission portion 210.
Examples of the light absorbable material may include a black inorganic material, a black organic material, a black-oxidized metal, and mixtures thereof. When the external light absorption portions 220 include a black-oxidized metal, since the black-oxidized metal has low electric resistance, the electric resistance may be controlled by adjusting the amount of black-oxidized metal power or the thickness of black-oxidized metal film. Thus, the external light absorption portions 220 can shield electromagnetic waves. The external light absorption portions 220 may include a carbon-containing UV- ray curable resin. The refractive index of the external light absorption portions 220 may be similar to the refractive index of the light transmission portion 210, specifically in a range of 1.3 to 1.8.
The external light absorption portion forming composition may further include a slip agent. Due to the inclusion of the slip agent, when the external light absorption portion forming composition is prepared in the form of a dispersion, the flowability of the dispersion is improved. Thus, when the external light absorption portions 220 are formed, the dispersion including the external light absorption portion forming composition flows smoothly along the surface of the light transmission portion 210 and is dispersed in a uniform thickness on the surface the light transmission portion 210. Thus, when the external light absorption portions 220 are formed by wiping the dispersion dispersed in a uniform thickness on the surface of the light transmission portion 210 by using, for example, a Dr. blade, spots may not be formed on the surface of the external light absorption portions 220. In addition, in this case, the decrease in the surface friction of the external light absorption portions 220 results in an increase in scratch resistance of the external light absorption portions 220. However, the present invention is not limited thereto. For example, the slip agent may be included only in the light transmission portion 210, not in the external light absorption portions 220.
In some embodiments, the slip agent may be included in both the light transmission portion 210 and the external light absorption portions 220. In this regard, spots are not formed on the surface of the external light absorption portions 220, and the light transmission portion 210 and external light absorption portions 220 have all a high scratch resistance.
When the slip agent is included in the external light absorption portion forming composition, the amount of the slip agent is in the range of 0.05 to 30 parts by weight based on 100 parts by weight of the total weight of the external light absorption portions 220, that is, the total weight of the external light absorption portion forming composition. If the amount of the slip agent is less than 0.05 parts by weight based on 100 parts by weight of the total weight of the external light absorption portions 220, addition effects of the slip agent are negligible. On the other hand, if the amount of the slip agent is greater than 30 parts by weight based on 100 parts by weight of the total weight of the external light absorption portions 220, when the external light absorption portion forming composition including the slip agent is preserved, an interlayer separation may occur and an external light absorption rate may be thus lowered.
The slip agent used in the external light absorption portions 220 may be the same as that used in the light transmission portion 210.
The base film 230 is disposed on one surface of the light transmission portion 210, that is, the surface opposite to that in which the recess portions 220a are formed. The base film 230 supports the light transmission portion 210 in which the external light absorption portions 220 are formed. The base film 230 may include at least one material selected from the group consisting of polyethersulphone (PES), polyacrylate (PAR), polyetherimide (PEI), polyethylene naphthalate (PEN), polyethyleneterephthalate (PET), polyphenylene sulfide (PPS), polyallylate, polyimide, polycarbonate (PC), cellulose triacetate (TAC), and cellulose acetate propionate (CAP). Preferably, the base film 230 may include polycarbonate (PC), polyethyleneterephthalate (PET), cellulose triacetate (TAC), or polyethylene naphthalate (PEN). In addition, the base film 230 may include a material having a refractive index equal or similar to the refractive index of the light transmission portion 210.
In addition, the optical sheet 200 according to the present embodiment of the present invention may further include a protection film 240 (see FIGS. 3 through 5) that will be described later, disposed on one surface of the light transmission portion 210, that is, the surface opposite to that on which the base film 230 is disposed. The protection film 240 protects the optical sheet 200 until the optical sheet 200 is mounted on the filter 40, and when the optical sheet 200 is mounted on the filter 40, the protection film 240 is separated from the optical sheet 200; however, the present invention is not limited thereto.
Referring to FIGS. 2A and 2B, the filter base (FB) is disposed on a surface of the optical sheet 200, and includes an electromagnetic wave shielding film 300, a hard coating layer 400, and a reflection prevention film 500 disposed in this order. However, the structure of the FB is not limited thereto. That is, the electromagnetic wave shielding film 300, the hard coating layer 400, and the reflection prevention film 500 may be disposed in any order in the FB. The FB may also include a layer including at least two types of materials having different functions.
The electromagnetic wave shielding film 300 shields electromagnetic waves. The electromagnetic wave shielding film 300 may include a conductive mesh layer, a metal thin layer, a high-refractive-index transparent thin layer, or at least two of the previous layers. In FIGS. 2A and 2B, the electromagnetic wave shielding film 300 is a single layer. However, the structure of the electromagnetic wave shielding film 300 is not limited thereto. For example, the electromagnetic wave shielding film 300 may have a multi-layer structure including at least two layers.
The hard coating layer 400 has a scratch resistance and prevents the electromagnetic wave shielding film 300 or the reflection prevention film 500 that will be described later from being damaged by, for example, contact with external materials. The hard coating layer 400 may include reinforced glass alone, or reinforced glass including polymer as a binder. In addition, the hard coating layer 400 may include an acryl-based polymer, a urethane-based polymer, an epoxy-based polymer, a siloxane-based polymer, or an UV-setting resin such as oligomer. Furthermore, the hard coating layer 400 may further include a silica-based filler to increase the hardness thereof.
The reflection prevention film 500 adjusts the level of transmittance of visible light so as to minimize eye fatigue of users watching the image display device for a long period of time. By disposing the reflection prevention film 500 to adjust the transmittance of visible light, visible light may be selectively absorbed and also, a color reproduction range such as a contrast ratio may be widened. In FIGS. 2A and 2B, the reflection prevention film 500 is a single layer. However, the structure of the reflection prevention film 500 is not limited thereto. For example, the reflection prevention film 500 may have a multi-layer structure including at least two layers.
The reflection prevention film 500 has a reflection prevention effect because visible light that enters from the outside and is reflected from the surface of the reflection prevention film 500 and visible light reflected from an interface between the reflection prevention film 500 and the hard coating layer 400 are out of phase with each other and destructive interference occurs.
The reflection prevention film 500 may be formed by curing and fixing a mixture of indium tin oxide (ITO) and silicon oxide (SiO2), a mixture of nickel chromate (NiCr) and silicon oxide (SiO2), or the like. In addition, the reflection prevention film 500 may include a titanium oxide or a specific fluorine resin having a low refractive index.
FIG. 3 is a partially enlarged view of the optical sheet 200 of FIG. 2A before the optical sheet 200 is mounted on the filter 40. It should be noted that the protective film 240 is not yet removed.
In FIGS. 1 through 3, like reference numerals denote like elements.
The external light absorption portions 220 may be formed by performing a roll molding process, or an injection molding process wherein the grooves g210 of the light transmission portion 210 having a shape opposite to the pattern of the external light absorption portions 220 are filled with a thermosetting resin.
In addition, when the UV-ray curable resin included in the light transmission portion 210 has a reflection prevention function, an electromagnetic wave shielding function, a color adjustment function, or a combined function thereof, the optical sheet 200 may additionally perform these functions.
Referring to FIG. 3, the optical sheet 200 according to the present embodiment of the present invention includes the light transmission portion 210, the external light absorption portions 220, the base film 230, and the protection film 240. Herein, the protection film 240 may be optionally omitted. The filter 40 illustrated in FIG. 2A includes the optical sheet 200 from which the protection film 240 is removed .
The configuration of the light transmission portion 210, the external light absorption portion 220, the base film 230, and the protection film 240 is the same as described above.
The external light absorption portions 220 may be disposed in various forms, such as a stripe form, a matrix form, a wave form, etc. In addition, the external light absorption portions 220 may be disposed at predetermined intervals to allow light to pass through areas between adjacent external light absorption portions 220. In FIG. 3, the external light absorption portions 220 have tetragonal cross sections. However, the cross-sectional shape of the external light absorption portions 220 is not limited thereto. For example, the external light absorption portions 220 may have triangular, trapezoidal, or pentagonal cross sections.
In addition, a pitch P200 of the optical sheet 200 may be in the range of 40 to 150 ㎛ , a width W220 of the external light absorption portions 220 may be in the range of 10 to 40 ㎛ , and a height h220 of the external light absorption portions 220 may be in the range of 50 to 200 ㎛ . Herein, the width W220 of the external light absorption portion 220 denotes the width of an end of the external light absorption portion 220 on an image light source side. If the external light absorption portions 220 have a trapezoidal cross section , the width W220 of the external light absorption portion 220 denotes the width of an end of the external light absorption portion 220 on the image light source side, that is, the maximum width.
The optical sheet 200 according to the present embodiment of the present invention may further include a prism portion (not shown) disposed on one surface of the base film 230, that is, the surface opposite to that on which the light transmission portion 210 is disposed. A material for forming the prism portion may be identical or similar to the material for forming the light transmission portion 210. By including the prism portion, the optical sheet 200 may have a high external light absorption rate, an enhanced contrast ratio, and a high resolution, without a large change in transmittance .
An optical sheet or filter having the structure as described above may be included in an image display device, and thus, in regard to the image display device, the quality of an image is improved and a contrast ratio is increased, and thus, high-resolution images may be obtained.
Hereinafter, the present invention will now be described in more detail with reference to the following Examples. However, these examples are given for the purpose of illustration and not of limitation.
Example 1: Manufacture of an optical sheet including a light transmission portion and external light absorption portions, wherein the light transmission portion does not include a slip agent and the external light absorption portions include a slip agent
A molding roll having a surface on which a plurality of protrusions each having a tetragonal side cross-section were formed was manufactured. Then, by using a pattern roll apparatus (manufactured by Hirano Co., Ltd) equipped with an UV ray generation device, a mixed solution (Sartomer, CN-981) (refractive index: 1.51) containing 100 g of acryl-based curable resin having a low refractive index was slowly added between the molding roll and an optical PET film (manufactured by Toyobo Co., Ltd) having a thickness of 188 ㎛ and cured, thereby forming a light transmission portion having grooves with a pattern opposite to the pattern of the protrusions of the molding roll. Herein the optical PET film constituted a base film. A dispersion (refractive index:1.52) prepared by mixing 5 g of silicon polyether acrylate (Rad 2200, Tego Co., Ltd) as a slip agent, 2 g of carbon black, and 100 g of an acryl-based curable resin mixed solution (Sartomer, CN-985) was scattered over the grooves and then, wiping was performed thereon using a Dr. Blade formed of a soft plastic to uniformly fill the grooves, thereby forming a plurality of external light absorption portions in the grooves. Then, the acryl-based curable resin of the carbon dispersion was cured using UV-rays, thereby obtaining an optical sheet as illustrated in FIG. 3. Herein, the pitch of the light transmission portion was 73.4 ㎛ , the width and height of the external light absorption portions were 22 ㎛ and 102 ㎛ , respectively, and the thickness of the light transmission portions was 150 ㎛ . The pitch of the light transmission portion refers to a distance between corresponding sites of adjacent portions of the light transmission portion which are divided by an external light absorption portion.
Example 2: Manufacture of an optical sheet including a light transmission portion and external light absorption portions, wherein the light transmission portion and the external light absorption portions include a slip agent
An optical sheet was manufactured in the same manner as in Example 1, except that the light transmission portion was formed including, in addition to the mixed solution including 100 g of acryl-based curable resin having a low refractive index, 5 g of silicon polyether acrylate (Rad 2200, Tego Co., Ltd) as a slip agent.
Example 3: Manufacture of an optical sheet including a light transmission portion and external light absorption portions, wherein the light transmission portion includes a slip agent and the external light absorption portions do not include a slip agent
An optical sheet was manufactured in the same manner as in Example 1, except that the external light absorption portion was formed without the slip agent and the light transmission portion was formed including, in addition to the mixed solution including 100 g of acryl-based curable resin having a low refractive index, 5 g of silicon polyether acrylate (Rad 2200, Tego Co., Ltd) as a slip agent.
Comparative Example 1: Manufacture of an optical sheet including a light transmission portion and external light absorption portions, wherein neither the light transmission portion nor the external light absorption portions include a slip agent
An optical sheet was manufactured in the same manner as in Example 1, except that the external light absorption portion was formed without the slip agent.
Evaluation Example
In regard to the light transmission portions and external light absorption portions of the optical sheets manufactured according to Examples 1 to 3 and Comparative Example 1, surface hardness was measured and formation of surface spots was identified. The results are shown in Table 1.
(Surface Hardness)
A pencil hardness test was performed on the light transmission portion and external light absorption portion according to a measurement method speculated in ASTM D3363-93. According to the measurement method, the surface hardnesses of the light transmission portion and external light absorption portion are measured by scratching the surfaces of the light transmission portion and external light absorption portion with a pencil having a hardness defined as B~HB~H and then identifying whether scratches were formed on the surfaces of the light transmission portion and external light absorption portion.
(Surface Spots)
Whether surface spots were formed on the surface of the external light absorption portions was identified with the naked eye. The results are shown in Table 1 below, wherein '○' indicates that surface spots were identified with the naked eye, and '×' indicates that surface spots were not identified with the naked eye.
[Table 1]
Referring to Table 1, in regard to Examples 1 through 3 in which at least one selected from the group consisting of the light transmission portion and the external light absorption portion included the slip agent, the part including the slip agent had higher surface hardness and thus, higher scratch resistance than the part without the slip agent,. On the other hand, in regard to Comparative Example 1 in which the slip agent was not used, the surface hardness was equal to or lower than that in Examples 1 through 3 and thus, it may be concluded that the light transmission portion and external light absorption portions manufactured according to Comparative Example 1 are easily scratched.
In addition, in the cases of the external light absorption portions manufactured according to Examples 1 through 3, surface spots were not formed. However, in the case of Comparative Example 1, surface spots were formed. By referring to the results, it may be concluded that the dispersion of the external light absorption portion forming composition used in Comparative Example 1 had poor flowability, and thus, when the external light absorption portions were formed, the dispersion was not dispersed on the surface of the light transmission portion in a uniform thickness.
While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims.
Claims (13)
1. An optical sheet comprising:
a light transmission portion comprising a plurality of grooves spaced apart from each other; and
a plurality of external light absorption portions which fill the grooves,
wherein at least one selected from the group consisting of the light transmission portion and the external light absorption portions comprises a slip agent.
2. The optical sheet of claim 1, wherein the external light absorption portions are formed by filling the grooves with an external light absorption portion forming composition comprising a curable resin, a light absorbable material, and a slip agent, and curing the curable resin of the external light absorption portion forming composition.
3. The optical sheet of claim 2, wherein the curable resin is an ultraviolet (UV)-ray curable resin.
4. The optical sheet of claim 1, wherein the external light absorption portions comprise the slip agent and the amount of the slip agent is in the range of 0.05 to 30 parts by weight based on 100 parts by weight of the total weight of the external light absorption portions.
5. The optical sheet of claim 1, wherein the light transmission portion comprises the slip agent and the amount of the slip agent is in the range of 0.05 to 30 parts by weight based on 100 parts by weight of the total weight of the light transmission portion.
6. The optical sheet of claim 1, wherein the slip agent comprises at least one selected from the group consisting of a silicon compound and a fluorine compound.
7. The optical sheet of claim 1, further comprising a base film which is disposed on a surface of the light transmission portion, wherein the surface is opposite to the other surface in which the grooves are formed and supports the light transmission portion .
8. The optical sheet of claim 1, wherein a pitch of the optical sheet is in the range of 40 to 150 ㎛ , the width of the external light absorption portion is in the range of 10 to 40 ㎛ , and the height of the external light absorption portion is in the range of 50 to 200 ㎛ .
9. The optical sheet of claim 1, wherein thickness-wise cross sections of the external light absorption portions are triangular, tetragonal, or trapezoidal .
10. The optical sheet of claim 1, wherein the external light absorption portions are disposed in a stripe form, a matrix form, or a wave form .
11. The optical sheet of any one of claims 1-10, wherein the optical sheet is a sheet for enhancing a contrast ratio .
12. A filter for an image display device, the filter comprising:
the optical sheet of any one of claims 1-10; and
a filter base.
13. An image display device comprising the optical sheet of any one of claims 1-10.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR10-2008-0072937 | 2008-07-25 | ||
| KR1020080072937A KR20100011638A (en) | 2008-07-25 | 2008-07-25 | Optical sheet enhancing scratch resistance and filter comprising the same, and image displaying device having the sheet or the filter |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| WO2010011090A2 true WO2010011090A2 (en) | 2010-01-28 |
| WO2010011090A3 WO2010011090A3 (en) | 2010-04-15 |
Family
ID=41570736
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/KR2009/004101 WO2010011090A2 (en) | 2008-07-25 | 2009-07-23 | Optical sheet with enhanced scratch resistance, filter including the same, and image display device including the optical sheet or the filter |
Country Status (3)
| Country | Link |
|---|---|
| KR (1) | KR20100011638A (en) |
| TW (1) | TW201007227A (en) |
| WO (1) | WO2010011090A2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2016029457A (en) * | 2014-07-18 | 2016-03-03 | 大日本印刷株式会社 | Low reflection sheet |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7297810B2 (en) * | 2004-12-30 | 2007-11-20 | 3M Innovative Properties Company | High refractive index monomers for optical applications |
| KR20080036804A (en) * | 2006-10-24 | 2008-04-29 | 엘지전자 주식회사 | Filter and plasma display device thereof |
| KR20080054911A (en) * | 2006-12-14 | 2008-06-19 | 엘지마이크론 주식회사 | Optic film and method for manufacturing thereof |
-
2008
- 2008-07-25 KR KR1020080072937A patent/KR20100011638A/en not_active Application Discontinuation
-
2009
- 2009-07-23 WO PCT/KR2009/004101 patent/WO2010011090A2/en active Application Filing
- 2009-07-27 TW TW098125236A patent/TW201007227A/en unknown
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2016029457A (en) * | 2014-07-18 | 2016-03-03 | 大日本印刷株式会社 | Low reflection sheet |
Also Published As
| Publication number | Publication date |
|---|---|
| TW201007227A (en) | 2010-02-16 |
| WO2010011090A3 (en) | 2010-04-15 |
| KR20100011638A (en) | 2010-02-03 |
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