KR102296165B1 - Optical film and optical display device comprising the same - Google Patents

Abstract

The present invention relates to an optical film and an optical display device comprising the same, which are capable of forming a plurality of air gap forming pillars on a diffusion sheet, impregnating the plurality of air gap forming pillars in a first attachment layer of a first prism sheet when sheets are attached to each other, forming an air gap between the diffusion sheet and the first prism sheet, and improving optical characteristics such as brightness and reliability. The optical film comprises: a diffusion sheet; and a first prism sheet and a second prism sheet, which are successively laminated and formed on an upper surface of the diffusion sheet. The diffusion sheet can comprise: a diffusion base layer; optical diffusion layers formed on an upper surface and a lower surface, respectively, of the diffusion base layer; and a plurality of air gap forming pillars protruding from a surface of an upper surface in a direction vertical to an upper surface of the diffusion base layer and being apart from each other.

Description

Optical film and optical display device including same {OPTICAL FILM AND OPTICAL DISPLAY DEVICE COMPRISING THE SAME}

The present disclosure relates to an optical film and an optical display device including the same.

Unless otherwise indicated herein, the material described in this section is not prior art to the claims of this application, and inclusion in this section is not an admission that it is prior art.

In general, since an optical display device controls the amount of light by reflecting or transmitting light through an optical film, an optical display device using a backlight unit is greatly affected by the performance of the optical film. Such an optical film includes a prism sheet and a diffusion sheet, and the diffusion sheet is composed of a substrate layer, and a light diffusion layer formed on one surface and the other surface of the substrate layer. The prism sheet and the diffusion sheet can be bonded by a gravure coating method using a UV adhesive. In this case, as shown in FIG. 1 , the optical properties such as transmittance and luminance of the optical sheet are obtained as the light diffusion layer is buried in the adhesive and the air gap is lost. There is a problem of loss.

As a method for improving this problem, Patent Document 1 discloses a technique in which a predetermined bonding pattern is formed on the lower portion of the upper optical sheet to reduce the bonding area with the lower optical sheet so that the area on which light is condensed does not decrease. .

However, in Patent Document 1, the height of the adhesive layer penetrated by the apex is low and has irregularities, so that the apex does not sufficiently penetrate the adhesive layer, thereby reducing adhesive strength.

Republic of Korea Patent Registration No. 10-1268085 (2013.05.21)

It is an object to provide an optical film having excellent adhesion and luminance at the same time and an optical display device including the same.

According to an embodiment of the disclosure, the optical film includes a diffusion sheet and a first prism sheet and a second prism sheet that are sequentially laminated on the upper surface of the diffusion sheet, and the diffusion sheet includes a diffusion substrate layer and the diffusion substrate A light diffusion layer formed on the upper and lower surfaces of the layer, respectively, and a plurality of air gap forming pillars protruding from the surface of the upper surface in a direction perpendicular to the upper surface of the diffusion base layer, and spaced apart from each other.

In addition, the first prism sheet includes a first base layer, a first pattern layer protruding from an upper surface of the first base layer, and a first adhesive layer formed on a lower surface of the first base layer, and forming the plurality of air gaps. A portion of the pillar may be impregnated with the first adhesive layer and coupled thereto.

In addition, an impregnation depth of the air gap forming column may be 20 to 60% of the total height of the air gap forming column.

Also, a distance between adjacent air gap forming pillars among the plurality of air gap forming pillars may be 50 μm to 200 μm.

In addition, the vertex angle θ of the air gap forming pillar may be 20 to 90°.

In addition, the height of the air gap forming pillar may be 2 ~ 30㎛.

In addition, the horizontal cross-sectional area of the air gap forming pillar may increase from the top to the bottom.

In addition, the lower width of the air gap forming pillar may be 3 ~ 20㎛.

In addition, the diffusion sheet and the first prism sheet and the second prism sheet may be integrally formed by a lamination process.

According to another embodiment of the disclosure, the optical display device includes a diffusion sheet and a first prism sheet and a second prism sheet sequentially stacked on an upper surface of the diffusion sheet, wherein the diffusion sheet includes a diffusion base layer and the diffusion sheet A light diffusion layer formed on the upper and lower surfaces of the base layer, respectively, and an optical film interposed with a plurality of air gap forming pillars that are formed to protrude from the surface of the upper surface in a direction perpendicular to the upper surface of the diffusion base layer and are spaced apart from each other. .

According to an embodiment disclosed herein, the optical film forms a plurality of air gap forming pillars in the diffusion sheet, so that the plurality of air gap forming pillars are impregnated in the first adhesive layer of the first prism sheet during adhesion between the sheets to form a diffusion sheet and An air gap may be formed between the first prism sheets, and thus optical properties such as luminance and reliability are improved.

1 is a diagram illustrating an impregnation phenomenon of a light diffusion layer.
2 is a schematic diagram illustrating an optical display device according to an embodiment of the disclosure in the present specification.
3 is a perspective view showing an optical film according to an embodiment of the content disclosed in the present specification.
4 is a cross-sectional view taken along line A-A' of FIG. 3 .
5 is a cross-sectional view illustrating a diffusion sheet according to an embodiment of the disclosure in the present specification.
6 and 7 are cross-sectional views showing a diffusion sheet according to another embodiment of the content disclosed herein.

Advantages and features of the present invention, and a method for achieving them will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms, and only these embodiments allow the disclosure of the present invention to be complete, and common knowledge in the art to which the present invention pertains. It is provided to fully inform the possessor of the scope of the invention, and the present invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout.

In describing the embodiments of the present invention, if it is determined that a detailed description of a well-known function or configuration may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. In addition, the terms to be described later are terms defined in consideration of functions in an embodiment of the present invention, which may vary according to intentions or customs of users and operators. Therefore, the definition should be made based on the content throughout this specification.

2 is a schematic diagram illustrating an optical display device according to an embodiment of the disclosure in the present specification.

The optical display device 1 may include a liquid crystal panel 10 , a backlight unit 20 , a guide panel 30 , a lower cover 40 , and an upper case 50 .

The liquid crystal panel 10 includes a color filter array substrate, a thin film transistor array substrate, and a liquid crystal layer interposed therebetween. can be formed

The backlight unit 20 includes a light source 21 , a light guide plate 23 for guiding light generated from the light source, a reflective sheet 24 disposed under the light guide plate 23 , and an optical device disposed on the light guide plate 23 . The film 100 may be included.

The light source 21 is to generate light, and any one of a beneficiation type lamp, a surface light type lamp, a cold cathode fluorescent lamp, an external electrode fluorescent lamp, and a light emitting diode device can be selected and used. The light source cover 22 may be further provided for the purpose of protecting the light source.

The optical film 100 may be formed by integrating a plurality of sheets, and includes a diffusion sheet 110 , a first prism sheet 120 , and a second prism sheet 130 , and the diffusion sheet 110 is a light guide plate. The light incident from 23 may be diffused and supplied to the first prism sheet 120 and the second prism sheet 130 .

The light guide plate 23 serves to guide the light emitted from the light source 21 to the optical film 100, is not easily deformed or broken due to its high strength, and can be formed of polymethymethacrylate with good transmittance. have.

The reflective sheet 24 serves to reflect the light generated from the light source and supply it in the direction of the optical film 100 .

The guide panel 30 may fix and support the liquid crystal panel 10 and the backlight unit 20 .

The lower cover 40 accommodates the liquid crystal panel 10 and the backlight unit 20 , and may be coupled to the upper case 50 .

3 is a perspective view showing an optical film according to an embodiment of the content disclosed herein, and FIG. 4 is a cross-sectional view taken along line A-A' of FIG. 3 .

Referring to FIG. 3 , the optical film 100 may include a diffusion sheet 110 and a first prism sheet 120 and a second prism sheet 130 that are sequentially stacked on the upper surface of the diffusion sheet 110 . can The optical film 100 can improve reliability while minimizing the final thickness by integrating a plurality of sheets by lamination processing.

The first prism sheet 120 is laminated on the upper surface of the diffusion sheet 110 , and a first base layer 121 , a first pattern layer 122 protruding from the upper surface of the first base layer 121 , and A first adhesive layer 123 formed on a lower surface of the first base layer 121 may be included.

The second prism sheet 130 is laminated on the first prism sheet 120 , and a second base layer 131 , a second pattern layer 132 protruding from the upper surface of the second base layer 131 , and A second adhesive layer 133 formed on a lower surface of the second base layer 131 may be included.

The first base layer 121 and the second base layer 131 may be made of a material that can transmit light, and specifically, a polycarbonate-based, polysulfone-based, polyacrylate ( At least one material selected from the group consisting of polyacrylate) series, polystyrene series, polyvinylchloride series, polyvinylalcohol series, polynorbornene series, and polyester series can be made with

The first pattern layer 122 and the second pattern layer 132 may be formed perpendicular to each other, and at least one pattern selected from the group consisting of a prism pattern, a lens pattern, a pyramid pattern, and an emboss pattern, preferably a prism It can be formed in a pattern.

Meanwhile, in FIG. 4 , a prism pattern having a vertical cross section of the first pattern layer 122 and the second pattern layer 132 is illustrated as an example, but the present invention is not limited thereto. It may be formed in any one shape.

The first adhesive layer 123 and the second adhesive layer 133 may include at least one resin selected from the group consisting of an epoxy acrylate resin and a urethane acrylate resin, and a photoinitiator or It may further include a filler. The photoinitiator is for curing the resin and the photocurable monomer, and may include a conventional photoinitiator. Specifically, one or more selected from the group consisting of phosphine oxide and cyclohexylphenyl ketone may be used, and may be included in an amount of 1 to 10 parts by weight, preferably 3 to 7 parts by weight, based on 100 parts by weight of the resin. have. When the above-mentioned range is satisfied, the first adhesive layer 123 and the second adhesive layer 133 may be completely cured, and a residual amount of the photoinitiator may remain to prevent deterioration of the transparency of the optical film 100 .

5 is a cross-sectional view illustrating a diffusion sheet according to an embodiment of the disclosure in the present specification.

4 and 5, the diffusion sheet 110 includes a diffusion base layer 111, light diffusion layers 112 and 113 respectively formed on the upper and lower surfaces of the diffusion base layer 111, and A plurality of air gap forming pillars 115 formed on the upper surface of the diffusion base layer 111 may be included.

The diffusion base layer 111 is preferably colorless and transparent because it has to transmit light, and may be formed of the same material as the above-mentioned first base layer 121 and second base layer 131 , and specifically Polyethyleneterephthalate, polyethylenenaphthalate, acrylic resin, polycarbonate, polystyrene, polyolefin, cellulose acetate, and waterproof vinyl chloride (weather) -resistant vinyl chloride) may be made of one or more synthetic resins selected from the group consisting of. In addition, the diffusion base layer 111 may be formed to a thickness of 10 to 300 μm, preferably 20 to 200 μm, but is not limited thereto.

The light diffusion layers 112 and 113 diffuse the light transmitted from the bottom and scatter the incident light at the same time to serve as a light shield to dilute the bright and dark areas, and include organic or inorganic particles dispersed in the binder and the binder. can do. Here, the organic particles or inorganic particles may be organic beads or inorganic beads, respectively.

For example, the organic particles may be at least one selected from the group consisting of acrylic particles, olefinic particles, acrylic and olefinic copolymer particles, and multi-layered multicomponent particles, preferably acrylic particles. Here, the acrylic particles include methyl methacrylate, ethyl methacrylate, isobutyl methacrylate, normal butyl methacrylate, normal butyl methyl methacrylate, acrylic acid, methacrylic acid, hydroxyethyl methacrylate, hydroxy At least one selected from the group consisting of propyl methacrylate, hydroxy ethyl acrylate, acrylamide, methylol acrylamide, glycidyl methacrylate, ethyl acrylate, isobutyl acrylate, and normal butyl acrylate, preferably For example, at least one selected from the group consisting of methyl methacrylate, ethyl methacrylate, and ethyl acrylate may be used.

The inorganic particles may be at least one selected from the group consisting of silicon oxide, aluminum oxide, titanium oxide, zirconium oxide and magnesium fluoride, preferably silicon oxide.

The binder is an acrylic resin, polyurethane, polyester, fluorine-based resin, silicon-based resin, polyamide, and epoxy resin. It may be at least one selected from the group consisting of.

The plurality of air gap forming pillars 115 may protrude from the surface of the upper surface in a direction perpendicular to the upper surface of the diffusion base layer 111 , and may be disposed to be spaced apart from each other by a predetermined distance. At least a portion of the air gap forming pillar 115 is impregnated in the first adhesive layer 123 of the first prism sheet 120 , and the air is a space spaced apart between the first prism sheet 120 and the diffusion sheet 110 . While securing a gap, the diffusion sheet 110 and the first prism sheet 120 may be coupled. Accordingly, light diffusion is promoted by securing a sufficient air gap, thereby minimizing a decrease in luminance.

For example, a plurality of air gap forming pillars 115 are disposed to be spaced apart from each other by a predetermined interval on the upper surface of the diffusion base layer 111 , and a distance between adjacent air gap forming pillars 115 among the plurality of air gap forming pillars 115 . (W) may be 50 ~ 200㎛, preferably 80 ~ 150㎛, the impregnation depth (D) of the air gap forming pillar 115 is the total height of the air gap forming pillar 115 (h1, h2) ) of 20 to 60%, preferably 30 to 50%. In this embodiment, the plurality of air gap forming pillars 115 may be formed to have the same height (h1, h2), and the heights (h1, h2) of the air gap forming pillar 115 are 2 to 30 μm, preferably Preferably, it may be 5 to 10 μm, and at this time, the impregnation depth (D) may be 1 to 10 μm, preferably 2 to 5 μm, but an air gap at a line satisfying the conditions of the aforementioned impregnation depth (D). The heights (h1, h2) of the forming pillars 115 are changeable, so it is of course possible to appropriately adjust and apply them according to the situation.

If the distance W between the air gap forming pillars 115 is less than 50 μm, it may be difficult to secure an air gap between the diffusion sheet 110 and the first prism sheet 120, and if it exceeds 200 μm, the diffusion sheet ( 110) and the first prism sheet 120 is not preferable because the diffusion sheet 110 may be easily separated from the first prism sheet 120 due to a weak adhesive force.

If the impregnation depth (D) of the air gap forming pillar 115 is less than 20%, it is difficult to maintain the adhesive force between the diffusion sheet 110 and the first prism sheet 120, and when it exceeds 60%, the light diffusion layer 112 ) is buried in the first adhesive layer 123 and the air gap is lost may occur.

Therefore, when the above-mentioned conditions are satisfied, it is possible to secure a sufficient air gap to prevent a decrease in luminance while improving the reliability of the optical film 100 .

As used herein, impregnation means that at least a portion of the air gap forming pillar 115, specifically, the vertex V, which is an upper region of the air gap forming pillar 115, is present in the first adhesive layer 123, and , the vertex V refers to a point having the highest height among the air gap forming pillars 115 , and the impregnation depth D is the vertex V of the air gap forming pillar 115 is the first adhesive layer 123 . means the vertical length impregnated into the inside of

6 and 7 are cross-sectional views showing a diffusion sheet according to another embodiment of the content disclosed herein.

First, to describe with reference to FIG. 5, a plurality of air gap forming pillars 115 are disposed on the upper surface of the diffusion base layer 111 according to the present embodiment to be spaced apart from each other by a predetermined interval, and the vertex angle θ1 of the air gap forming pillar is 20 to 90° (degrees), preferably 40 to 80°. The horizontal cross-sectional area of the air gap forming column 115 may increase from the upper part L2 to the lower part, and in this case, the lower width L1 of the air gap forming column 115 may be 3-20 μm. For example, as shown in FIGS. 6 and 7 , the lower widths L3 and L4 of the air gap forming pillars 215 and 315 increase in proportion to the increase and the height of the vertex angles θ2 and θ3 of the air gap forming pillars. can be As an example, when the apex angle (θ2) of the air gap forming column is 60° and the height is 5 µm, the lower width (L3) of the air gap forming column 215 may be 5 to 6 µm, preferably 5.77 µm, When the apex angle θ3 of the air gap forming column is 80°, the lower width L4 of the air gap forming column 215 may be 8 to 9 µm, preferably 8.4 µm. Although not shown in the drawing, in addition, when the air gap forming column apex angle θ1 is 40°, the lower width L1 of the air gap forming column 115 may be 3 to 4 µm, preferably 3.64 µm, and the air gap When the forming pillar apex angle θ1 is 50°, the lower width L1 of the air gap forming pillar 115 may be 4-5 μm, preferably 4.66 μm, and the air gap forming pillar apex angle θ1 is 70° In the case of , the lower width L1 of the air gap forming pillar 115 may be 6 to 7 μm, preferably 6.99 μm.

Therefore, when each of the above-mentioned range conditions is satisfied, the luminance is excellent and moiré may not occur. Tilt, more preferably 10° Tilt.

Example 1

After coating an acrylic UV resin, which is a column composition, on one side of a polyethylene terephthalate (PET) film, shape processing with a metal mold to form an air gap forming column at an interval of 140 μm, A diffusion sheet was prepared by coating a mixture of 35 g of acrylic resin, 50 g of methyl ethyl ketone, and 25 g of beads on the other surface, and then drying at 110° C. for 60 seconds to form a light diffusion layer.

Then, an adhesive was applied to two prism sheets, and UV curing was performed in a state in which the prepared diffusion sheet was in contact to prepare an optical film.

Example 2

An optical film was manufactured in the same manner as in Example 1, except that the distance between the air gap forming pillars was formed to be 100 μm.

Example 3

An optical film was manufactured in the same manner as in Example 1, except that the distance between the air gap forming pillars was formed to be 80 μm.

Example 4

An optical film was manufactured in the same manner as in Example 1, except that the distance between the air gap forming pillars was formed to be 150 μm.

Example 5

An optical film was manufactured in the same manner as in Example 1, except that the distance between the air gap forming pillars was formed to be 200 μm.

Comparative Example 1

After laminating two prism sheets, an adhesive was applied, and UV curing was performed while the PET diffusion sheet was in contact to prepare an optical film.

Experimental Example 1. Evaluation of optical properties

The luminance was measured using a radiometer (CS-2000; Minolta) for the optical sheets prepared in Examples and Comparative Examples, and the results are shown in Tables 1 and 2 below.

division Comparative Example 1 Example 1 Example 2 X Y luminance X Y luminance X Y luminance #One 0.2845 0.2864 9601.00 0.2840 0.2863 9628.00 0.2844 0.2866 9407.00 #2 0.2845 0.2864 9601.00 0.2840 0.2863 9628.00 0.2844 0.2866 9407.00 #3 0.2845 0.2865 9601.00 0.2840 0.2863 9628.00 0.2844 0.2865 9403.00 AVE 0.2845 0.2865 9601.00 0.2840 0.2863 9628.00 0.2844 0.2866 9405.67 Deviation STANDARD -0.0005 -0.0002 100.28% -0.0001 -0.0001 97.97% peel force - 60g 89g

division Example 3 Example 4 Example 5 X Y luminance X Y luminance X Y luminance #One 0.2837 0.2851 9300.00 0.2845 0.2865 9697.00 0.2845 0.2865 9797.00 #2 0.2838 0.2850 9300.00 0.2846 0.2866 9697.00 0.2846 0.2866 9797.00 #3 0.2837 0.2851 9300.00 0.2845 0.2865 9697.00 0.2845 0.2865 9797.00 AVE 0.2837 0.2851 9300.00 0.2845 0.2865 9697.00 0.2845 0.2865 9797.00 Deviation -0.0008 -0.0014 96.86% 0.0000 0.0001 101.00% 0.0000 0.0001 102.04% peel force 96g 52g 31g

Referring to Tables 1 and 2, it can be seen that the three-ply bonding sheet may cause a decrease in luminance, and in Examples 1 to 5, it can be seen that the luminance deviation is very high, 95% or more, due to the securing of sufficient air gap. there was.

Although the preferred embodiment of the present invention has been described with reference to the accompanying drawings, the embodiments described in the present specification and the configuration shown in the drawings are only the most preferred embodiment of the present invention and represent all of the technical spirit of the present invention. Therefore, it should be understood that there may be various equivalents and modifications that can be substituted for them at the time of filing the present application. Therefore, the embodiments described above are to be understood as illustrative and not restrictive in all respects, and the scope of the present invention is indicated by the following claims rather than the detailed description, and the meaning and scope of the claims and their All changes or modifications derived from the concept of equivalents should be construed as being included in the scope of the present invention.

1: optical display device 10: liquid crystal panel
20: backlight unit 21: light source
22: light source cover 23: light guide plate
24: reflective sheet 30: guide panel
40: lower cover 50: upper case
100: optical film 110: diffusion sheet
115, 215, 315: air gap forming column 120: first prism sheet
130: second prism sheet

Claims (10)

diffusion sheet; and
A first prism sheet and a second prism sheet are sequentially stacked on the upper surface of the diffusion sheet;
The diffusion sheet is formed to protrude at the same height from the surface of the diffusion substrate layer, the light diffusion layer respectively formed on the upper surface and the lower surface of the diffusion substrate layer, and the upper surface in a direction perpendicular to the upper surface of the diffusion substrate layer, spaced apart from each other comprising a plurality of air gap forming pillars;
The distance between adjacent air gap forming pillars among the plurality of air gap forming pillars is 80 to 150 μm, and the horizontal cross-sectional area of the air gap forming pillar increases from the top to the bottom, but the apex angle θ is 40 to 80°, The lower width is 3~20㎛, and the moiré avoidance angle is 3~45°Tilt,
The optical film, characterized in that the diffusion sheet and the first prism sheet and the second prism sheet are integrally formed by a lamination process.
According to claim 1,
The first prism sheet
a first base layer;
a first pattern layer protruding from an upper surface of the first base layer; and
A first adhesive layer formed on the lower surface of the first base layer,
A portion of the plurality of air gap forming pillars is impregnated with the first adhesive layer and coupled to the optical film.
3. The method of claim 2,
The impregnation depth of the air gap forming pillar is an optical film, characterized in that 20 to 60% of the total height of the air gap forming pillar.
delete delete According to claim 1,
The optical film, characterized in that the height of the air gap forming pillar is 2 ~ 30㎛.
delete delete delete A diffusion sheet and a first prism sheet and a second prism sheet that are sequentially laminated on the upper surface of the diffusion sheet,
The diffusion sheet is formed to protrude at the same height from the surface of the diffusion substrate layer, the light diffusion layer respectively formed on the upper surface and the lower surface of the diffusion substrate layer, and the upper surface in a direction perpendicular to the upper surface of the diffusion substrate layer, spaced apart from each other comprising a plurality of air gap forming pillars;
The distance between adjacent air gap forming pillars among the plurality of air gap forming pillars is 80 to 150 μm, and the horizontal cross-sectional area of the air gap forming pillar increases from the top to the bottom, but the apex angle θ is 40 to 80°, The lower width is 3~20㎛, and the moiré avoidance angle is 3~45°Tilt,
and the diffusion sheet and the first prism sheet and the second prism sheet include an optical film integrally formed by a lamination process.

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