KR101090937B1 - Structured optical sheet package and a method of manufacturing the same - Google Patents

Abstract

PURPOSE: A structured optical sheet package and a manufacturing method thereof are provided to obtain a good light transmitting feature and prevent optical sheets from being peeled off each other in case of blanking. CONSTITUTION: A structured surface is formed on one side of a first optical sheet(230). A second optical sheet(235) is bonded with a side facing the structured side of the first optical sheet. The second optical sheet is bonded with the first optical sheet by partial bonding. A plurality of adhesive dots is formed on the flat side of the second optical sheet. The first optical sheet is a prism sheet. The second optical sheet is a prism sheet. The second optical sheet is a diffusion sheet.

Description

Structured Optical Sheet Package and a Method of Manufacturing the Same

The present invention relates to an optical sheet package in which an optical sheet for use in an optical display is laminated.

Optical displays such as liquid crystal displays (LCDs) are commonly used in mobile phones, personal digital assistants (PDAs), computer devices, and LCD monitors and televisions. Filmsheets of the type such as prismatic structured films, reflective polarizers and diffuser films have been used to improve display parameters such as output brightness, illumination uniformity, viewing angle and overall system efficiency.

1 schematically illustrates a conventional display system. A typical display system includes a backlight assembly 110 including a light source 115, a light diffusing plate 120, a first prism sheet 130, and a second prism sheet in which the extending directions of the first prism and the prism are vertically arranged. And a polarizing plate 140 and a liquid crystal display panel 150. Such optical films are laminated between the backlight assembly and the display panel, which film stack is optimized to achieve the desired special optical performance, and additional elements may be added or omitted as needed. Often, individual films or sheets, etc., have a protective liner attached to the surface at the time of manufacture to prevent damage such as surface scratches or foreign matter adhesion. However, problems have been pointed out such as excessive time taken to remove protective liners from individual optical films or inserting them into a frame during manufacture, individually handling and assembling, and increasing the likelihood of film damage.

The present invention is to improve the yield by minimizing damage to the optical sheet during handling, without lowering the optical properties of the optical sheet using an optical sheet package composed of the optical sheet is laminated.

An optical sheet package according to an embodiment of the present invention includes a first optical sheet having a structured surface on one side; And a second optical sheet bonded to the first optical sheet by partial adhesion by a plurality of adhesive dots dispersed and coated on a surface opposite the structured surface side of the first optical sheet.

The optical sheet package according to an embodiment of the present invention may be characterized in that the surface on which the adhesive dot of the second optical sheet is applied is a flat surface.

The optical sheet package according to an embodiment of the present invention may be characterized in that the total planar area of the adhesive dots has an area ratio of 5% or more and 60% or less with respect to the entire sheet area.

Optical sheet package according to an embodiment of the present invention may be characterized in that the thickness of the dot is 3μm or more and 15μm or less.

The optical sheet package according to an embodiment of the present invention may be characterized in that the first optical sheet is a prism sheet.

The optical sheet package according to the embodiment of the present invention may be characterized in that the second optical sheet is a prism sheet or a diffusion sheet.

Optical sheet package according to an embodiment of the present invention may be characterized in that the ratio of the equivalent diameter of the adhesive dot and the prism pitch is in the range of 1.5 to 8.0.

Optical sheet package according to an embodiment of the present invention may be characterized in that the equivalent diameter of the adhesive dot is in the range of 32 μm ~ 168 μm.

An optical sheet package manufacturing method according to an embodiment of the present invention comprises the steps of preparing a first optical sheet having a structured surface on one side; Preparing a second optical sheet having a flat surface on at least one surface; Preparing a stamp having a plurality of spot-shaped relief structures, and applying an adhesive to the relief structures; Stamping adhesive dots such that the adhesive applied to the stamp is transferred to the structured surface of the first optical sheet or the flat surface of the second optical sheet; And laminating the structured surface of the first optical sheet and the flat surface of the second optical sheet to face each other.

The optical sheet package manufacturing method according to an embodiment of the present invention may be characterized in that the area of the relief structure of the stamp has an area ratio of 5% or more and 60% or less with respect to the total area of the stamp.

Optical sheet package manufacturing method according to an embodiment of the present invention may be characterized in that the coating thickness of the adhesive applied to the stamp is 3μm or more and 15μm or less.

The optical sheet package manufacturing method according to an embodiment of the present invention may be characterized in that the first optical sheet is a prism sheet, and the ratio between the equivalent diameter of the spot and the prism pitch is in the range of 1.5 to 8.0.

The optical sheet package of the present invention is excellent in light transmission properties because the adhesion of the adhesive between the optical layer is made only a part of the total area, the peeling does not occur between the optical sheet layer at the time of punching, the shading spot pattern by the adhesive Provides an invisible effect. In addition, since a plurality of optical layers are bundled and packaged with an adhesive, problems such as warpage, deformation, and warpage that may occur in the case of an ultra-thin prism sheet are suppressed, and as a result, the use of a thinner ultra-thin prism sheet becomes possible. There is an advantage that can reduce the thickness of the backlight unit to which the optical sheet package is applied.

1 is a side schematic view of a conventional display system.
2 is a schematic cross-sectional view of an optical sheet package according to an embodiment of the present invention.
3 is a schematic cross-sectional view of an optical sheet package according to another embodiment of the present invention.
4 is a schematic plan view of an optical sheet package according to an embodiment of the present invention.
5 is a luminance graph according to the change in the area ratio between the adhesive coating thickness and the adhesive dot of the optical sheet package according to an embodiment of the present invention.

Hereinafter, specific embodiments according to the present invention will be described. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. The accompanying drawings of the present invention are for convenience of description and relative scales may be changed, and portions irrelevant to the description are omitted to clearly describe the present invention.

In the following, when a part is said to "include" a certain component, it means that it may further include a component in addition to the described component unless otherwise stated.

In order to slim down the display system shown in Fig. 1, the optical sheets of each layer are formed as thin as possible, and hence the rigidity is lowered, which makes handling more difficult. In addition, each optical sheet has a high probability of damage or defect occurrence during handling such as removal of the liner attached to the surface and assembly work after removing the liner.

The present invention relates to a laminate packaged by bundling two layers in FIG. 2 shows a structure of an optical sheet package according to the present invention. That is, the first optical sheet 230 and the second optical sheet 235 are partially bonded to each other by the adhesive dots 300. The first optical sheet 230 may have a structured surface on one side, and the second optical sheet 235 may have a flat surface on one side. In this case, the structured surface of the first optical sheet 230 and the flat surface of the second optical sheet 235 are oriented so as to face each other, and the adhesive dot 300 is dispersed and applied to the flat surface side. The surface on which the adhesive dot of the second optical sheet is dispersed and coated is not necessarily limited to the flat surface, and may have a wave shape or other lenient surfaces, beaded surfaces, scratch surfaces, or the like as shown in FIG. 3.

The structured surface may be, for example, a prism structure extending in one direction as shown in FIGS. 2 and 3, and as an example, the first prism sheet 130 and the second prism sheet 135 of FIG. 1 may be packaged. It can be mentioned. In another embodiment, the first optical sheet 230 may be a prism sheet, and the second optical sheet 235 may be a polarizing sheet or a diffusion sheet.

In the present invention, the partial adhesion means that the adhesive is not evenly applied over the entire surface, and as shown in FIG. 4, the adhesive dots are dispersed and coated so that only the corresponding area portion of the adhesive dots is bonded and laminated. Adhesive dots refer to individual adhesives that are isolated from one another as shown in FIGS. 2, 3 and 4.

As the adhesive of the present invention, ultraviolet or visible light curable acrylic adhesives or two-component curable adhesives and the like used for lamination of PVA resin films may be used, but are not particularly limited as long as they are lamination adhesives of optical sheets.

FIG. 5 shows the bonding of two prism sheets while measuring luminance while varying the ratio of the adhesive coating thickness and the area occupied by the adhesive dot. The reference luminance is the luminance transmitted through two prism sheets not bonded with an adhesive. As shown in FIG. 5, the brightness decreases as the thickness of the coating increases, and when the thickness ratio is 60% or less with respect to the total area of the flat surface to which the total surface area of the adhesive dots is bonded, the luminance decrease due to the increase in thickness. It can be seen that this is significantly slowed down.

The optical sheet package is supplied in a roll form, and is 'punched' to cut to a suitable size for use in a display device, wherein the optical sheet package is placed between the bottom plate of the cutting press and the upper plate having a predetermined cutting frame. Perform by positioning and pressurizing. At this time, a peeling phenomenon in which both optical sheets are separated at the outer edges may be observed, which depends on the thickness and area ratio of the adhesive. Table 1 below shows the results of the punching test while varying the thickness and area ratio of the adhesive dot, and the O table shows the case where peeling is observed, and the X table shows the case where peeling does not occur.

area
/thickness 2% 5% 8% 10% 15% 20% 30% 50% 60% 2㎛ O O O O O O O O X 5㎛ O X X X X X X X X 7㎛ O X X X X X X X X 9㎛ O X X X X X X X X 10 탆 O X X X X X X X X 12㎛ O X X X X X X X X 14 μm O X X X X X X X X 14 μm O X X X X X X X X 15 μm O X X X X X X X X

According to Table 1, it can be seen that the thicker the adhesive dot and the larger the area ratio, the more the peeling does not occur. In particular, when the thickness of the adhesive dot is 3 µm or more and the area ratio is 5% or more, the peeling is observed at the time of punching. Was not.

Therefore, considering the luminance characteristic and the peeling characteristic at the same time, the area ratio of the adhesive dot is preferably 5% or more and 60% or less. In order to prevent peeling, it is required that the thickness of the adhesive dot is at least 3 µm or more, and when the thickness of the adhesive exceeds 15 µm, there is a problem in that a shading pattern to be described later occurs. Therefore, the thickness of the adhesive is preferably in the range of 3 µm to 15 µm.

When the adhesive dots are deposited on the backlight and visually observed, shading spots in the form of gray spots may occur as shown in Figure 3, which is undesirable when applied to display systems. Shading spot generation depends mainly on the size of the adhesive dot and the prism pitch of the prism sheet. This is the result indicated by the X table when no O table or shading spots were observed.

Dot diameter
/pitch 20 탆 50 탆 100 μm 150 μm 200 μm 300㎛ 500 ㎛ 700 ㎛ 800㎛ 15 μm X X X O O O O O O 21 μm X X X X X O O O O 25 μm X X X X X O O O O 30 μm X X X X X O O O O 40 μm X X X X X X O O O 50 탆 X X X X X X O O O 80㎛ X X X X X X X X O

According to Table 2, the smaller the prism pitch, the smaller the dot size of the adhesive is formed, it can be seen that the shading spots are not observed. When converted into the ratio of the diameter of the adhesive dot and the prism pitch, the shading spot by the adhesive dot is observed when the ratio is 10 or more, and the shading spot is not observed when the ratio is 8 or less. Moreover, when the diameter of an adhesive dot is 1.5 times or less of a prism pitch, the phenomenon which adhesive strength falls remarkably arises. Therefore, in consideration of the occurrence of shading spots and the properties of the adhesive support, the ratio of the diameter of the adhesive dot and the prism pitch is preferably between 1.5 and 8.

Although the size of the adhesive dot is expressed above as a diameter, the dot may not necessarily have a circular shape, and in this case, the size may be represented as an equivalent diameter (D). The equivalent diameter (D) and the area of the dots, and satisfies the relationship of πD ^2/4 = (dot area), the diameter of the dots in the present invention means an equivalent diameter.

Even if the ratio of the diameter of the adhesive dot to the prism pitch is satisfied, shading spots are observed when the size of the adhesive dot increases and exceeds 168 µm. In addition, in consideration of the fact that the minimum pitch at which the flexural properties of the prism sheet are expressed is approximately 21 µm, the minimum diameter of the adhesive dot for securing the adhesive support force is 32 µm.

An optical sheet package manufacturing method according to the present invention comprises the steps of preparing a first optical sheet having a structured surface on one side; Preparing a second optical sheet having a flat surface on at least one surface; Preparing a stamp having a plurality of spot-shaped relief structures, and applying an adhesive to the relief structures; Stamping adhesive dots such that the adhesive applied to the stamp is transferred to the structured surface of the first optical sheet or the flat surface of the second optical sheet; And laminating the structured surface of the first optical sheet and the flat surface of the second optical sheet to face each other.

It is preferable that the area of the relief structure of the stamp has an area ratio of 5% or more and 60% or less with respect to the entire stamp area. Moreover, it is preferable that the application thickness of the adhesive agent apply | coated to a stamp is 3 micrometers or more and 15 micrometers or less. When the first optical sheet is a prism sheet, it is preferable that the ratio between the equivalent diameter of both spots and the prism pitch is in the range of 1.5 to 8.0.

The optical sheet package according to the present invention has a slim structure and structural rigidity is improved, luminance deterioration due to packaging is minimized, and shading by an adhesive is not generated. In addition, the optical sheet package according to the present invention has the advantage that peeling does not occur at the time of punching.

Various modifications are possible in the invention disclosed above without departing from the basic idea. Accordingly, the above embodiments should all be interpreted as illustrative and not restrictive. Therefore, the protection scope of the present invention should be defined according to the appended claims rather than the above-described embodiments. Substitution of equivalents of the appended claims is within the scope of the appended claims.

110: backlight assembly 115: light source
120: light diffusion plate 130: first prism sheet
135: second prism sheet 140: polarizing plate
150: liquid crystal display panel 230: first optical sheet
235: second optical sheet 300: adhesive dot

Claims (13)

A first optical sheet having a structured surface on one side; And
And a second optical sheet bonded to the first optical sheet by partial adhesion by a plurality of adhesive dots dispersed and coated on a surface opposite the structured surface side of the first optical sheet.
The method of claim 1,
The optical sheet package of which a 2nd optical sheet is a flat surface by which the adhesive dot is apply | coated.
The method of claim 1,
The total planar area of the adhesive dots has an area ratio of 5% or more and 60% or less with respect to the total sheet area.
The method of claim 1,
The thickness of the said adhesive dot is 3 micrometers or more and 15 micrometers or less.
The method of claim 1,
And the first optical sheet is a prism sheet.
The method of claim 5,
And the second optical sheet is a prism sheet.
The method of claim 5,
And the second optical sheet is a diffusion sheet.
The method of claim 5,
The equivalent diameter of the adhesive dot is 1.5 to 8.0 times the prism pitch formed on the prism sheet.
The method of claim 8,
Wherein the equivalent diameter of the adhesive dots is in the range of 32 μm to 168 μm.
Preparing a first optical sheet having a structured surface on one side;
Preparing a second optical sheet having a flat surface on at least one surface;
Preparing a stamp having a plurality of spot-shaped relief structures, and applying an adhesive to the relief structures;
Stamping adhesive dots such that the adhesive applied to the stamp is transferred to the structured surface of the first optical sheet or the flat surface of the second optical sheet; And
And laminating the structured surface of the first optical sheet and the flat surface of the second optical sheet so as to face each other.
The method of claim 10,
The area of the relief structure of the stamp is an optical sheet package manufacturing method having an area ratio of 5% or more and 60% or less with respect to the entire stamp area.
The method of claim 10,
The coating thickness of the adhesive agent apply | coated to a stamp is 3 micrometers or more and 15 micrometers or less.
The method of claim 10,
The first optical sheet is a prism sheet, the equivalent diameter of the embossed spot is 1.5 to 8.0 times the optical sheet package of the prism pitch formed on the prism sheet.

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