KR20170003273A

KR20170003273A - Integral Type Optical Sheet

Info

Publication number: KR20170003273A
Application number: KR1020150093711A
Authority: KR
Inventors: 김용민
Original assignee: 코오롱인더스트리 주식회사
Priority date: 2015-06-30
Filing date: 2015-06-30
Publication date: 2017-01-09

Abstract

The present invention relates to an integral-type optical sheet, and more particularly, to an integral-type optical sheet which includes a lower plate prism sheet including a prism having a column protruding from a mountain part; and an upper plate prism sheet having a surface roughness of 50nm to 200nm under a sheet bonded to the upper surface of the lower plate prism sheet. An adhesive force between the lower plate prism and the upper plate prism sheet is 25 to 200 g/inch^2. The optical sheet has excellent adhesion between the upper plate prism sheet and the lower plate prism sheet and has a thin thickness. So, the optical sheet can have excellent brightness.

Description

[0002] Integral Type Optical Sheet [0003]

The present invention relates to an integral composite optical sheet.

2. Description of the Related Art In general, a liquid crystal display (LCD) is a display device that uses various changes in liquid crystal transmittance according to an applied voltage to change various electrical information generated in various devices into visual information. Such a liquid crystal display device is an apparatus for displaying various information but can not be visualized without its own light source. Therefore, a liquid crystal display device such as a television, a mobile phone, a monitor, and a notebook computer includes a light source unit such as a backlight unit that provides light uniformly over the entire surface in order to visualize information to be displayed.

The backlight unit includes a light source, a reflection plate, a light guide plate, a diffusion sheet, a first optical sheet, a second optical sheet, a protective sheet, and the like. The light source is a device that generates light upon power application. A light emitting diode (LED) and a cold cathode fluorescent lamp (CCFL) may be selectively used.

The light emitted from the light source is incident on the light guide plate and proceeds to cause total internal reflection within the light guide plate. Light incident on the surface of the light guide plate at an incident angle smaller than the critical angle is transmitted without being totally reflected, and is emitted upward and downward. At this time, the reflection plate reflects the light emitted downward and re-enters the light guide plate to improve the light efficiency.

The diffusion sheet diffuses the light emitted through the upper surface of the light guide plate to make the brightness uniform, thereby widening the viewing angle, and the light passing through the diffusion sheet has a lowered front emission luminance. The first optical sheet is composed of a base portion and a structured pattern, refracts light incident from the diffusing sheet, and primarily condenses the light so as to be incident vertically.

The structured pattern is formed integrally with the upper surface of the substrate portion and is structured to vertically emit light passing through the structured pattern through the substrate portion. The structured pattern is generally formed in a triangular shape, and the vertex angle is usually set to about 90 degrees.

The second optical sheet has the same configuration as that of the first optical sheet, and is secondarily condensed and emitted to enhance the brightness of the first-focused light in the first optical sheet.

Here, the first optical sheet and the second optical sheet are arranged so that the structured pattern of the first optical sheet and the structured patterns of the second optical sheet cross each other at right angles in order to further increase the brightness.

The protective sheet is attached to the upper surface to prevent surface damage of the second optical sheet.

In view of this, Korean Patent Laid-Open Publication No. 2014-0003855 proposes a method of minimizing the area of the prism structure adjacent to the adhesive layer by changing the height of the prism of the second optical sheet when using two or more optical sheets . However, there is a problem that the upper prism sheet includes a base layer composed of a PET film, which increases the thickness and affects the light transmittance.

The conventional structure of the conventional prism sheet is such that a PET film is coated on a substrate such as a PET film for each sheet. As a result, a PET film is often used to increase the thickness and affect the light transmittance.

Accordingly, there is a need to provide an optical sheet having a one-piece structure in which two optical sheets are adhered firmly without thickening the thickness when the two optical sheets are adhered to each other as described above.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a monolithic optical sheet in which the surface roughness of a top surface of a top plate is increased and the shape and size of a bonding portion of the bottom plate prism are adjusted to increase the bonding strength between the top sheet optical sheet and the bottom plate optical sheet.

According to a first aspect of the present invention, there is provided a prism sheet comprising: a structure layer including a prism having a column protruding from a mountain portion; And

And an upper plate prism sheet having a surface roughness of 50 nm to 200 nm under the sheet laminated on the upper surface of the lower plate prism sheet.

The prism of the upper plate prism sheet according to the first embodiment may have a height of 10 to 30 μm in cross section and 20 to 60 μm in the base.

The prism of the lower plate prism sheet according to the first embodiment may have a height h1 of 10 to 30 占 퐉 and a base line w1 of 20 to 60 占 퐉, except for the column at its cross section.

The prism of the lower plate prism sheet according to the first embodiment may have a columnar section having a height h2 of 1 to 3 m and a width w2 of 2 to 4 m.

The upper part of the column of the lower plate prism sheet according to the first embodiment may have fine irregularities and the upper surface roughness may be 50 to 200 nm.

The adhesion between the lower plate prism and the upper plate prism sheet according to the first embodiment may be 25 to 200 g / inch ² .

The integrated optical sheet according to the first embodiment may have a brightness of 90% to 95%.

A second preferred embodiment of the present invention is a backlight unit including the above-described optical topographic type sheet.

The integrated optical sheet of the present invention increases the surface roughness of the upper plate prism sheet and the lower plate prism sheet attachment surface to increase the mutual adhesion force. Thereby, there is an advantage that the luminance can be prevented from dropping due to the pressing in the attachment of the upper plate and the lower plate.

That is, even if the lower plate prism sheet is pushed by the upper plate due to the columnar shape protruding from the mountain portion of the lower plate prism sheet, the brightness can be prevented from being lowered because the prism is not pressed more than the width of the column.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view showing a comparison between structures of a conventional optical sheet and an optical sheet of the present invention.
2 is a cross-sectional view of a top plate prism sheet according to the present invention.
3 is a cross-sectional view of a lower plate prism sheet according to the present invention.
4 is a cross-sectional view of an optical sheet according to the present invention.

The present invention relates to a lower plate prism sheet including a prism having a column protruding from a mountain portion; And an upper plate prism sheet having a surface roughness of 50 nm to 200 nm under the sheet laminated on the upper surface of the lower plate prism sheet.

As shown in FIG. 1, in the conventional invention (upper), the lower part of the upper plate prism pushes the lower plate prism, and the luminance is lowered. However, according to the present invention (below), since the prism sheet is formed on the mountain portion of the lower plate prism sheet, even if the lower plate prism sheet is pressed by the upper plate, the prism is not pressed more than the width of the column, .

Hereinafter, the present invention will be described in more detail.

The present invention provides a light emitting device comprising: a structure layer including a prism having a column protruding from an acid portion; A lower plate prism sheet (Fig. 2) including a base layer; And

And an upper plate prism sheet (FIG. 3) having a surface roughness of 50 nm to 200 nm under the sheet laminated on the upper surface of the lower plate prism sheet (FIG. 4).

That is, in order to prevent the lower plate prism from being pressed when the two sheets of prism sheets are laminated, the surface roughness of the lower surface of the upper plate prism sheet is increased, And fine irregularities are formed on the upper portion of the column. With the above feature, it is possible to prevent the phenomenon that the adhesion between the upper plate prism sheet and the lower plate prism sheet increases and the brightness decreases due to the pressing of the vertex of the prism mountain.

The lower plate prism sheet comprises a substrate layer; And a structure layer formed on one surface of the base layer, wherein a plurality of prisms are formed on the structure layer, and when the prism has a triangular section, a column protruding from a triangular mountain portion is formed do. The interior angle of the triangle is preferably 85 DEG to 95 DEG in order to transmit a greater amount of light in the future.

2, the lower plate prism sheet has a height (h1) of 10 to 25 mu m and a base line (w1) of 20 to 60 mu m excluding the columns of the lower plate prism section. However, the present invention is not limited thereto.

The column has a height (h2) of 1 to 3 占 퐉 and a width (w2) of 2 to 4 占 퐉.

If the height h2 is less than 1 mu m, there may be a problem that the prism mountains are pressed to decrease the brightness. If the height h2 is more than 5 mu m, the columnar shape may lie on the side or may be deformed in the mold. If the thickness is less than 2 μm, the mold may be torn or the column shape may be broken, and if it is more than 4 μm, the brightness may decrease.

The upper part of the column is formed with fine concavities and convexities, which can improve adhesion when attached to the upper plate prism sheet. The method of forming the fine irregularities can form irregularities in prism mold roll processing, and the surface roughness of the upper portion of the column is preferably 100 nm to 200 nm. If the surface roughness is less than 100 nm, the effect of improving the adhesion can not be obtained. If the surface roughness is more than 200 nm, the adhesion effect may not be significant.

The base layer is not limited to a transparent film such as a polyethylene terephthalate film, a polycarbonate film, a polypropylene film, a polyethylene film, a polystyrene film or a polyepoxy film.

The upper plate prism sheet includes only a structure layer without a substrate layer, and a plurality of prisms are formed in the structure layer. The cross-section of the prism may be triangular, and the internal angle of the triangle should be 85 to 95 degrees, which is preferable in that a greater amount of light can be transmitted in the future. The surface roughness of the upper plate prism is adjusted by using a release film during manufacturing. If the surface roughness is less than 50 nm, the adhesion of the desired upper and lower plates can not be ensured. If the surface roughness exceeds 500 nm, haze may become worse and the brightness may be reduced.

By adjusting the surface roughness, the top plate prism sheet of the present invention can overcome the problems such as reduction in brightness caused by thickening of the optical sheet including the base layer in the upper plate prism sheet in the conventional prism sheet.

The upper plate prism sheet is characterized in that the height h1 of the cross section is 10 to 30 mu m and the base w1 is 20 to 60 mu m.

The lower part of the upper plate prism sheet can increase the surface roughness by using a release film. This makes it possible to improve the adhesion force when the lower plate prism sheet is attached to the lower plate prism sheet. The surface roughness under the lower plate prism sheet is preferably 50 to 200 nm. When the surface roughness is less than 50 nm, the adhesion improving effect is insufficient. When the surface roughness is more than 200 nm, the haze becomes worse and the brightness may be reduced.

In the integrated optical sheet according to the present invention, the upper plate prism sheet and the lower plate prism sheet may be laminated so that the angle of intersection of the prisms formed on each sheet is 0 to 90 degrees in consideration of luminance increase.

The integrated optical sheet of the present invention is characterized by having a thickness of 30 占 퐉 to 150 占 퐉. It is possible to reduce the thickness of one PET film by using a prism on the existing PET film rather than placing two PET films on it.

With the above-described structure, the optical sheet of the present invention can have a brightness of 95% or more as compared to two PET sheets, and the thickness can be reduced by one PET sheet.

Further, the present invention can provide a backlight unit including the optical sheet.

In the integral optical sheet according to the present invention, the upper plate prism sheet and the lower plate prism sheet may be formed of a thermosetting resin or an ultraviolet ray curable resin. Examples of the transparent resin include unsaturated fatty acid esters, aromatic vinyl compounds, unsaturated fatty acids and derivatives thereof, Dibasic acids and derivatives thereof, vinylcyanide compounds such as methacrylonitrile, and the like.

Example

Hereinafter, the present invention will be described in more detail with reference to Examples. These examples are for the purpose of illustrating the present invention more specifically, and the present invention is not limited thereto.

Example 1. Manufacture of upper plate prism sheet

In the present embodiment, the surface roughness of the lower part of the upper plate prism was changed to observe a change in the adhesion force.

1.1

The top plate prism was made by filling the pattern prism mold with UV curable acrylic resin and covering the release film (17-100LIL3T, Yulchon Chemical) to increase the surface roughness under the top plate prism which is the top plate attachment surface. After adjusting the thickness using a laminator and releasing the release film, the resin is filled in the mold and cured. When the cured resin thus formed is cured by lamination on a lower prism formed by semi-curing, the upper plate prism and the lower plate prism adhere to each other and the mold can be pushed out of the upper portion. Thus, the upper plate prism is formed on the lower prism sheet.

The upper plate prism sheet is formed with a prism having a height of 25 mu m, a width of 50 mu m, an apex angle of 90 degrees, and a triangular cross section (Fig.

At this time, the surface roughness of the lower surface of the upper plate was measured using a Nanoview (surface roughness tester) manufactured by Nano Systems Co., and the results are shown in Table 1. It was confirmed that the surface of the lower part of the upper plate was transferred to the surface roughness similar to the surface roughness of the release film. It can be seen that the film with the fine pattern also transfers an equal level of roughness.

1.2 to 1.8

A top plate prism sheet was produced by changing the release film only in the same manner as in Example 1.1.

Example
1.1 Example
1.2 Example
1.3 Example
1.4 Example
1.5 Example
1.6 Example
1.7 Example
1.8 manufacturer Yulchon Chemical Yulchon Chemical Yulchon Chemical Yulchon Chemical LINTEK LINTEK COLUMN COLUMN product name 17-100 LIL3T 17-75 LIL3T 75-L3T (A) 75-L3T (C) PET 100T103-1 PLSS302160 MX-1
(Fine pattern) MX-2
(Fine pattern) Release film surface roughness
(nm) 47 36 28 27 26 38 100 200 prism
Bottom plate
Surface roughness
(nm) 50 40 30 30 30 40 100 200

Example 2. Bottom plate Manufacture of prism sheet

In this embodiment, the shape of the prism formed on the lower plate prism sheet was changed to observe a change in the adhesion force.

2.1.

In the production of the lower plate prism, a prism mold is filled with a UV curable acrylic resin, and then a urethane or acryl-primed PET film for preparing a prism sheet is placed thereon. Thereafter, the laminate is pressed to a desired thickness through the lamination process, and then the mold is peeled off by UV curing. Then, a prism shape is formed on the PET, and a semi-cured prism sheet is obtained by adjusting the exposure amount. In addition, prism sheets were manufactured by inserting pillars and protrusions on the prism pattern and microprojections on the PET film by inserting pillars and protrusions in the pattern roll process.

In the lower plate prism sheet, as shown in Fig. 2, a prism formed in such a shape that a column protrudes from a mountain portion of a triangle was formed.

The height h1 of the prism excluding the column was 25 占 퐉, the width w1 of the lower side was 50 占 퐉 and the two internal angles? Were 90 占 The height h2 of the column was 2 占 퐉 and the width w2 of the lower side was? A 4 mu m prism was formed.

2.2 to 2.5

The upper plate prism sheet was manufactured by changing the height and width of the rectangle of the prism section in the same manner as in Example 2.1.

Example 2.1 Example 2.2 Example 2.3 Example 2.4 Example 2.5 The isosceles trapezoid height (h1) 25 25 25 25 25 The width of the lower side of the isosceles trapezoid (w1) 50 50 50 50 50 cabinet 90 90 90 90 90 The rectangle height (h2) 2 μm 1.5 μm 1 μm 2um 2um Rectangular width (w2) 4um 4 μm 4μm 8um 12um

Example 3. Integrated type Optical sheet Produce

An integrated optical sheet was prepared using the upper plate prism sheet prepared in Example 1 and the lower plate prism sheet prepared in Example 2.

The lower plate prism sheet was semi-cured by UV exposure to such an extent that it could not be completely cured, and cured to maintain its shape, and the upper plate prism sheet was placed on the lower plate and exposed to light.

The composition of each optical sheet is shown in Table 3 below.

Experimental Example 1 Experimental Example 2 Experimental Example 3 Experimental Example 4 Experimental Example 5 Comparative Experimental Example 1 Comparative Experimental Example 2 Comparative Experimental Example 3 Comparative Experimental Example 4 Top plate Illumination 100um Illumination 100um Illumination 100um Illumination 100um Illumination 100um Lower plate illuminance 50um Lower plate illuminance 100um Lower plate illuminance 50um Lower plate roughness 200um Bottom plate H2 2um
W2 4um H2 1.5 um
W2 4um H2 1um
W2 4um H2 2um
W2 8um H2 2um
W2 12um No pillars No pillars With pole
H2 2um
W2 4um With pole
H2 2um
W2 4um

<Measurement method>

① Adhesion

The prepared sheet was subjected to 180 degree peel evaluation using a universal testing machine (UTM). At this time, the force required to separate the upper plate prism sheet and the lower plate prism sheet was measured.

② Brightness

Center brightness was measured using LG Electronics' 21.5 "LED BLU using TopCon's BM7-A. At this time, the structure of the sheet was measured by placing the comparative example and the example sample above the diffusion sheet (XC210, Kolon Industries).

&Lt; Measurement result >

The results of the measurement are shown in Table 4.

Experimental Example 1 Experimental Example 2 Experimental Example 3 Experimental Example 4 Experimental Example 5 Comparative Experimental Example 1 Comparative Experimental Example 2 Comparative Experimental Example 3 Comparative Experimental Example 4 Adhesion 70 g / inch ² 80g / inch ² 100 g / inch ² 130g / inch ² 200g / inch ² 70 g / inch ² 200g / inch ² 70 g / inch ² 150g / inch ² Luminance 93% 87% 83% 83% 75% 75% 75% 93% 93%

As can be seen from the results of Table 4 above, it was confirmed that the brightness is affected by the column height of the lower prism (when the column height is lower, the semi-prism is pressed by the column height or more, The brightness decreases because the area to be pressed is wider, so the adhesion can rise slightly. However, when there is no column in the lower prism, the lower prism is pressed directly on the upper prism, so that the adhesion is somewhat increased, but the brightness is significantly reduced. Therefore, it can be seen that the adhesion force varies greatly according to the lower surface roughness of the upper prism.

100: upper plate prism sheet
200: Lower plate prism sheet
300: integral optical sheet

Claims

A lower planar prism sheet including a base layer and a structure layer including a prism having a projected column formed in a mountain portion; And
And an upper plate prism sheet having a surface roughness of 50 nm to 200 nm under the sheet laminated on the upper surface of the lower plate prism sheet.

The method according to claim 1,
Wherein the upper plate prism sheet has a height of 10 to 30 占 퐉 in the cross section and 20 to 60 占 퐉 in the base.

The method according to claim 1,
Wherein a height h1 of the structural layer of the lower plate prism sheet excluding the column at its cross section is 10 to 30 占 퐉 and a base line w1 is 20 to 60 占 퐉.

The method according to claim 1,
Wherein a height (h2) of a columnar section of the structural layer of the lower plate prism sheet is 1 to 3 占 퐉 and a width (w2) is 2 to 4 占 퐉.

The method according to claim 1,
Wherein an upper portion of the column of the lower plate prism sheet is formed with fine irregularities and the upper surface roughness is 100 to 200 nm.

The method according to claim 1,
Wherein the adhesive force between the lower plate prism sheet and the upper plate prism sheet is 25 to 200 g / inch ² .

The method according to claim 1,
Wherein the integrated optical sheet has a luminance of 90% to 95%.

A backlight unit comprising the above-described opto-optical sheet according to any one of claims 1 to 7.