KR20120090589A - Optical sheet, backlight assembly using the same and manufacturing method thereof - Google Patents

Abstract

PURPOSE: An optical sheet for a backlight assembly, a backlight assembly using the same, and a manufacturing method thereof are provided to form a micro pattern layer on a surface of an optical sheet with defects, thereby eliminating the defects. CONSTITUTION: A groove is formed on at least one side of an optical sheet(110). A micro pattern layer(120) is formed on a surface on which the groove is formed. The optical sheet is a brightness increasing film or a light guide plate. The micro pattern layer comprises a first pattern and a second pattern. The second pattern is formed in a second micro pattern area. The second micro pattern area corresponds to a second optical sheet area which is an area except for the first optical sheet area.

Description

Optical sheet, backlight assembly using the same and manufacturing method

The present invention relates to an optical sheet for a backlight assembly, a backlight assembly, and a method for manufacturing the same, and more particularly, to an optical sheet for a backlight assembly, a backlight assembly, and a method for manufacturing the same, which can be manufactured at low cost.

In the information display technology, the display device has occupied a position that CRT has been unique for more than half a century, but in the rapidly evolving information age, a larger and thinner display technology is required. As a result, flat panel display technology that can be enlarged and thinned has been developed. Liquid crystal display (LCD), projection display, and plasma display (PDP) have become mainstream, and field emission display (FED) and electroluminescent display ( ELD) has been developed along with the improvement of related technologies.

Compared with CRTs, LCDs are flat and large in size, and thus their use is expanding in display fields such as monitors and TVs, accounting for 80% of the flat panel market. The LCD includes a panel in which a liquid crystal and an electrode matrix are disposed between a pair of light absorbing optical films. In an LCD, the liquid crystal portion moves the liquid crystal portion by an electric field generated by applying a voltage to two electrodes, thereby having an optical state that is changed, and displaying an image using a polarized light in a specific direction. . Thus, the LCD includes a front optical film and a back optical film that induce polarization.

Since the LCD is not a self-luminous display, but a non-luminous display, it uses a light generated from the backlight including the backlight. Light emitted from the backlight passes through various kinds of optical sheets until it passes through the liquid crystal panel. The light guide plate or the optical sheet is made of a plastic resin-based material, and such plastic resins are highly likely to cause scratches or various defects on the surface during manufacturing or handling. These defects are affected by the hardness and surface roughness of the material.

Since the light guide plate or the optical sheet is located at the rear of the LCD, when the surface is defective, it can be detected by the human eye when viewed from the liquid crystal panel side. Therefore, even in the case of very fine defects are often treated as defective products, many problems occurred in the process or cost.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an optical sheet for backlight assembly, a backlight assembly and a method for manufacturing the same which can be manufactured at low cost.

Optical sheet for a backlight assembly according to an aspect of the present invention for achieving the above object is an optical sheet having a groove formed on at least one surface; And a micro pattern layer formed on the grooved surface. Here, the optical sheet may be a brightness enhancement film or a light guide plate.

The micro pattern layer may include a first pattern formed in the first micro pattern region corresponding to the first optical sheet region in which the grooves of the optical sheet are formed, and a second micro sheet corresponding to the second optical sheet region which is an area other than the first optical sheet region. It may include a second pattern formed in the pattern region. Here, the first pattern and the second pattern may be patterns having different shapes or patterns having different sizes. In particular, the size of the first pattern may be smaller than the size of the second pattern.

The micro pattern layer may be formed by repeating patterns having different shapes. In addition, the micro-pattern layer may include at least one of a lenticular pattern and a prismatic pattern.

The micro pattern layer may include a UV curable resin.

The thickness of the micro pattern layer may be 5 to 25㎛.

According to another aspect of the invention, the light source; A light guide plate for guiding the light from the light source to an emission surface, the light guide plate including a reflection plate reflecting light on an opposite surface of the emission surface; A diffusion plate formed on an upper surface of an emission surface of the light guide plate to diffuse light; A prism sheet for condensing light from the diffusion plate to the emission surface; And a brightness enhancement film formed on an upper surface of the prism sheet, having a groove formed on at least one surface thereof, and including a micro pattern layer formed on the surface on which the groove is formed.

According to another aspect of the invention, the step of preparing an optical sheet having a groove formed on at least one surface; And forming a micro-pattern layer on the groove-formed surface.

Forming the micro pattern layer, the step of applying a UV curable resin on the surface of the grooved optical sheet; Contacting the micro pattern mold corresponding to the pattern shape of the micro pattern layer with the UV curable resin; Irradiating UV; And separating the micro pattern mold from the optical sheet.

In the optical sheet for backlight assembly according to the present invention, in the case of the optical sheet having a surface defect, a micro pattern layer may be formed on the surface to solve the surface defect problem, thereby manufacturing the optical sheet for the backlight assembly at a low cost with a more efficient process. It has an effect.

1 is a cross-sectional view of an optical sheet for a backlight assembly according to an embodiment of the present invention.
2 is a cross-sectional view of an optical sheet for a backlight assembly according to another embodiment of the present invention.
3A to 3C illustrate different patterns or patterns having different sizes in regions where grooves are formed and regions other than the grooves formed in the optical sheet for backlight assembly according to another embodiment of the present invention.
4A to 4C are views provided to explain a method of manufacturing an optical sheet for a backlight assembly according to an embodiment of the present invention.
5 is a cross-sectional view of the backlight assembly according to an embodiment of the present invention.
6A and 6B illustrate forming shallow grooves and deep grooves on the optical sheet, respectively.
FIG. 7A illustrates a light guide plate on which a micro pattern layer is not formed, and FIG. 7B illustrates a light guide plate on which a lenticular pattern is formed in Example 1. FIG.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, embodiments of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below. Embodiments of the present invention are provided to more fully describe the present invention to those skilled in the art. In the accompanying drawings, there may be a component having a specific pattern or having a predetermined thickness, but this is for convenience of description or distinction. It is not limited only.

1 is a cross-sectional view of an optical sheet for a backlight assembly according to an embodiment of the present invention. The optical sheet for backlight assembly 100 according to the present embodiment includes an optical sheet 110 having a groove 111 formed on at least one surface thereof; And a micro pattern layer 120 formed on a surface on which the groove 111 is formed.

The optical sheet 110 is an optical sheet used in the backlight assembly, and may be used as long as defects may occur on the surface. The optical sheet 110 may be, for example, a light guide plate or a brightness enhancing film. The optical sheet 110 has grooves 111 formed on one or both surfaces thereof. The groove 111 is an example of surface defects, and refers to a shape in which the groove 111 is inserted into the surface from the surface of the optical sheet 110 at a predetermined depth by long grooves or pressed marks formed by scratches or the like. In FIG. 1, the groove 111 is illustrated as a dent in a V-shape at the center of the optical sheet 110, but is not necessarily limited to this shape.

In the case of an optical sheet or a light guide plate used for a backlight assembly of a non-light emitting display, it is formed of a plastic resin-based material. Therefore, in the case of the plastic resin, grooves long formed by rollers or the like may be formed in the manufacturing process, and may be pressed by other devices during the transportation or processing process to generate marks. Due to the characteristics of the final product display, surface defects are generally recognized when inspected by the human eye, and thus the tolerance is very low. Therefore, the probability that an optical sheet is recognized as a defective article and discarded is very high.

In this case, when the micro pattern layer 120 is formed on the optical sheet 110, the groove 111 is not recognized by the micro pattern, and thus the optical sheet may be used without discarding the optical sheet. In order to screen the groove 111, the micro pattern layer 120 may include various patterns having a micro size. For example, the micro pattern layer 120 may include a lenticular pattern or a prismatic pattern. In FIG. 1, the micro pattern layer 120 has a lenticular pattern formed on an upper surface thereof.

The light path that travels in the optical sheet 110 in a predetermined light path is changed by the groove 111. Therefore, the light is focused and scattered while passing through the groove 111 so that the groove 111 is perceived from the outside. However, when the micro-pattern layer 120 is formed on the optical sheet 110, the path of the light that is collected and scattered while the light passes through the grooves 111 is formed on the refractive index of the micro-pattern layer 120 and the micro size formed on the surface. You can change it in the pattern. Therefore, the groove 111 is screened because the light that has been scattered and diffracted is re-condensed in the micro-pattern layer 120, and the optical path is adjusted while the image focus of the groove 111 is changed.

The micro pattern layer 120 may have a thickness of 5 to 25㎛. If the thickness of the micro pattern layer 120 is smaller than 5 μm, the groove 111 is too small to be screened, and if the thickness of the micro pattern layer 120 is larger than 25 μm, the thickness of the micro pattern layer 431 is too thick, so that the top focus of the groove 111 is increased. There is a possibility of being too long than the distance and at the same time there is a problem that the thickness of the entire backlight assembly is thickened. This will be described later through the following examples.

2 is a cross-sectional view of an optical sheet for a backlight assembly according to another embodiment of the present invention. The groove 211 is formed on the optical sheet 210, and the micro pattern layer 220 is formed thereon. The micro pattern layer 220 may be formed by repeating patterns having different shapes. As illustrated in FIG. 2, the micro pattern layer 220 may be formed by alternating a lenticular pattern and a prism pattern. By mixing the micro patterns, the grooves 211 on the optical sheet 210 can be screened more effectively.

3A to 3C illustrate different patterns or patterns having different sizes in regions where grooves are formed and regions other than the grooves formed in the optical sheet for backlight assembly according to another embodiment of the present invention. In FIG. 3A, a groove 311 is formed on the optical sheet 310. Here, if the region in which the groove 311 is formed is called the first optical sheet region A ₁ , and the regions other than the first optical sheet region A ₁ are called the second optical sheet region A ₂ , the micro pattern layer In FIG. 320, regions corresponding to the first optical sheet region A ₁ and the second optical sheet region A ₂ may be referred to as a first micro pattern region B ₁ and a second micro pattern region B _2, respectively. Can be. The micro pattern formed in the first micro pattern region B ₁ will be referred to as a first pattern, and the micro pattern formed in the second micro pattern region B ₂ will be referred to as a second pattern.

The micro pattern layer 320 may include different micro patterns in the first micro pattern region B ₁ and the second micro pattern region B ₂ . In FIG. 3B, the micro pattern layer 320 includes a prism pattern as the first pattern P ₁ in the first micro pattern region B ₁ , and a second pattern in the second micro pattern region B ₂ . P ₂ ) as the lenticular pattern. The groove 311 may be screened more effectively by forming a micro pattern having a good function of screening the groove 311 in the region where the groove 311 is formed in the micro pattern layer 320.

In FIG. 3C, the micro pattern of the micro pattern layer 320 is a lenticular pattern in both the first pattern P ₃ and the second pattern P ₄ . However, the diameter of the first pattern P ₃ is D _1, and the diameter of the second pattern P ₂ is D _2, but D ₁ is smaller than D ₂ . Accordingly, the micro pattern layer 320 has a small lenticular pattern formed in the region where the groove 311 is formed, and a larger lenticular pattern is formed in the region where the groove 311 is not formed. Therefore, a small lenticular pattern is formed on the upper portion of the groove 311, so that the groove 311 can be screened more effectively.

4A to 4C are views provided to explain a method of manufacturing an optical sheet for a backlight assembly according to an embodiment of the present invention. In this embodiment, a micropattern layer is formed on the surface of the optical sheet having grooves formed on at least one surface thereof. The micropattern layer may include a UV curable resin, and the micropattern may be formed by curing the UV curable resin.

The micro pattern layer 431 may be formed by directly transferring the optical sheet 410 or by attaching a micro pattern sheet having a micro pattern on the substrate layer to the optical sheet 410. When the micro-pattern layer 431 is directly formed on the optical sheet 410, the thickness of the substrate layer may not be reflected, so that the overall thickness of the backlight assembly is reduced.

4A to 4C, a method of forming the micro pattern layer 431 on the optical sheet 410 is used. The method of UV imprinting, which is relatively simple and at low cost, enables accurate pattern formation. In the UV imprinting method, a pattern is formed using a UV curable material, and UV is cured by irradiating UV to form a micro pattern.

In FIG. 4A, the UV curable resin is coated on the optical sheet 410 on which the groove 411 is formed to form the UV curable resin layer 430. UV curable resin is resin which hardens when irradiated with UV. In this case, the refractive index of the UV curable resin may be determined in consideration of the shape of the micro pattern to be formed later, or additionally, the light concentration function or the light diffusion function, preferably 1.46 to 1.48, or 1.55 to 1.57.

The micro pattern mold 440 corresponding to the shape of the micro pattern is positioned on the UV curable resin layer 430. The shape of the micro pattern mold 440 'corresponds to the shape of the micro pattern. The term 'corresponding' to the shape of the micropattern means that the shape is not the same as the shape of the micropattern, but the shape for forming the micropattern. That is, when the micro pattern mold 440 is in close contact with the UV curable resin layer 430 to form a micro pattern, the micro pattern mold 440 may have a shape that may leave a micro pattern shape on the UV curable resin layer 430.

The micro pattern mold 440 first forms a micro pattern master (not shown) having the same shape as the micro pattern to be formed on the optical sheet 410, and then performs electroplating method or soft molding from the micro pattern master (not shown). It can be obtained by forming a replica of the reverse phase through the same replication process as the method. The micro pattern master (not shown) may be referred to as a type of mold having a micro pattern using a process capable of realizing a pattern shape such as machining and photolithography.

When the micro pattern mold 440 is mounted on the UV imprinting apparatus and the micro pattern mold 440 is closely attached to the UV curable resin layer 430 to irradiate UV (FIG. 4B), the micro pattern mold 440 may be UV curable resin is cured. When the micro pattern mold 440 is separated from the UV curable resin layer 430, the micro pattern 431 is transferred onto the optical sheet 410 as shown in FIG. 4C. Through this process, it is possible to directly transfer the micro pattern on one side or both sides of the optical sheet.

Alternatively, the micropattern layer can be formed without using a separate resin layer. When the micro pattern mold is directly placed on the surface of the optical sheet, pressurized and heated, a micro pattern layer may be formed on the surface of the optical sheet.

5 is a cross-sectional view of the backlight assembly according to an embodiment of the present invention. The backlight assembly of the present embodiment includes a light source 510; A light guide plate 530 which guides the light from the light source 510 to an emission surface to emit light, and includes a reflecting plate 520 reflecting light on an opposite surface of the emission surface; A diffuser plate 540 formed on an exit surface side of the light guide plate 530 to diffuse light; A prism sheet 550 for condensing light from the diffusion plate 540 to the emission surface; And a luminance enhancement film 560 formed on the prism sheet 550 and including a micro pattern layer 570 formed on a surface on which at least one groove 561 is formed and on which the groove 561 is formed. Include.

The light source 510 is for supplying light from the back of the display device. For example, a light source such as a cold cathode fluorescent lamp (CCFL) or a light emitting diode (LED) may be used. . The light source 510 may be located on one surface of the light guide plate 530 as shown in FIG. 5, and may be located on various surfaces of the light guide plate 530. In FIG. 5, the light source 510 is illustrated in the form of an edge type backlight positioned on one side of the light guide plate 530. However, the light source 510 is located directly on the opposite side of the emission surface, that is, the bottom surface of the light guide plate. It may also be implemented in the form of a backlight.

The light guide plate 530 is made of a transparent resin and guides light from the light source 510 to the emission surface to uniformly transmit light to the entire display device. On the opposite side of the emitting surface of the light guide plate 530 is provided with a reflecting plate 520 for reflecting light traveling toward the opposite surface side of the emitting surface back to the emitting surface side. A diffusion plate 540 is disposed on the emission surface side of the light guide plate 530 to uniformly diffuse the light traveling from the light guide plate 530.

Above the diffusion plate 540 is a prism sheet 550 in which an optical element such as a prism is formed. The prism sheet 550 focuses light to the front of the panel.

The luminance enhancing film 560 is positioned on the prism sheet 550. As the light is absorbed while passing through various components from the light source to the display panel, light utilization efficiency is lowered. Therefore, the brightness enhancing film 560 for improving the brightness may be disposed on the prism sheet 550 to increase the light efficiency. The luminance enhancing film 560 may be a retroreflective optical sheet.

When the luminance enhancement film 560 is a retroreflective optical sheet, the light incident on the luminance enhancement film 560 is returned back to the light guide plate 530, and the light propagated to the light guide plate 530 is reflected on the rear reflection plate 520. Is reflected by the light and is reincident to the luminance enhancing film 560 again. The re-incident light may be converted into optical characteristics by the light guide plate 530 and the reflective plate 520, and may pass through the brightness enhancement film 560 to proceed to the display panel.

Grooves 561 are formed on the top surface of the brightness enhancement film 560. The micro pattern layer 570 is formed on the surface on which the groove 561 is formed. The groove 561 is formed in the luminance enhancement film 560, but the micro pattern layer 570 is formed thereon to screen the groove 561 so that it cannot be recognized from the outside. The pattern of the micro-pattern layer 570 may be a lenticular pattern as shown in FIG. 5, or may be a different pattern.

In FIG. 5, although the groove 561 is formed on the brightness enhancement film 560, and the groove 561 is screened by the micro pattern layer 570, the groove is formed on the light guide plate 530. The grooves may be screened by forming a micro pattern layer on the light guide plate 530.

The present invention will be described in more detail with reference to the following.

[Example]

In order to manufacture the optical sheet for backlight assembly according to the present invention, grooves were formed by various scratches on the surface of the light guide plate made of PMMA. 6A and 6B illustrate forming shallow grooves and deep grooves on the light guide plate, respectively. In the case of Figure 6a, the blade was raised to form a deep groove, in the case of Figure 6b by laying the blade to form a shallow groove of a large area. Each UV curable resin was coated on the light guide plate having the grooves formed thereon, and a micro pattern was formed using a UV imprinting process.

Example 1

A lenticular pattern was formed on the light guide plate having a deep groove.

[Example 2]

Prismatic patterns were formed in the light guide plate having the deep grooves.

[Example 3]

A lenticular pattern was formed on the light guide plate having shallow grooves.

Example 4

Prismatic patterns were formed on the light guide plates having shallow grooves.

Comparative Example 1

No pattern was formed in the light guide plate having the deep grooves.

Comparative Example 2

No pattern was formed on the light guide plate having the shallow grooves.

Whether surface defects of the optical sheets for backlight assemblies of Examples 1 to 4 and Comparative Examples 1 to 2 were screened was visually evaluated as follows.

* Excellent: The groove of the light guide plate is not recognized at all.

* Good: The groove of the light guide plate is minutely recognized.

* Defect: groove of the light guide plate is recognized

Type of home pattern Screening effect Example 1 quirk Lenticular Pattern Great Example 2 quirk Prismatic Pattern Good Example 3 Paddling home Lenticular Pattern Great Example 4 Paddling home Prismatic Pattern Great Comparative Example 1 quirk No pattern Bad Comparative Example 2 Paddling home No pattern Bad

As can be seen from Table 1, Comparative Example 1 and Comparative Example 2, which did not form a pattern, were recognized as both shallow grooves and deep grooves, but in Examples 1 to 4 where patterns were formed, they were evaluated as excellent or good. FIG. 7A illustrates a light guide plate having deep grooves, and in FIG. 7B, a lenticular pattern is formed on the light guide plate of FIG. 7A as in Embodiment 1, so that the grooves are not visible. In FIG. 7B, the area where the groove is located is indicated by a black line.

In addition, in the case of Example 1 and Example 3 in which the lenticular pattern was formed, the evaluation results were excellent in the shallow grooves and also in the deep grooves. The grooves showed good results. Therefore, it can be seen that the screening effect of the lenticular pattern is greater than that of the prismatic pattern in the deep grooves.

The invention is not to be limited by the foregoing embodiments and the accompanying drawings, but should be construed by the appended claims. In addition, it will be apparent to those skilled in the art that various forms of substitution, modification, and alteration are possible within the scope of the present invention without departing from the technical spirit of the present invention.

Optical sheet for 100 backlight assembly
110, 210, 310, 410, 560 Optical Sheet
111, 211, 311, 411, 561 home
120, 220, 320, 431, 570 Micro Pattern Layer
A ₁ , A ₂ Optical Sheet Area
B ₁ , B ₂ Micro Pattern Area
Diameter of D ₁ , D ₂ micropattern
P ₁ , P ₂ , P ₃ , P ₄ Micro Pattern
430 UV Curable Resin Layer
440 micro pattern mold
510 light source
520 reflector
530 light guide plate
540 diffuser plate
550 Prism Sheet

Claims (13)

An optical sheet having a groove formed on at least one surface thereof; And
And a micro-pattern layer formed on the surface on which the groove is formed.
The method of claim 1,
The optical sheet is an optical sheet for a backlight assembly, characterized in that the brightness enhancement film or light guide plate.
The method according to claim 1,
The micro pattern layer corresponds to a first pattern formed in a first micro pattern region corresponding to the first optical sheet region in which the groove of the optical sheet is formed and a second optical sheet region which is an area other than the first optical sheet region. An optical sheet for a backlight assembly comprising a second pattern formed in the second micro pattern region.
The method according to claim 3,
And the first pattern and the second pattern are patterns having different shapes.
The method according to claim 3,
And the first pattern and the second pattern are patterns having different sizes having the same shape.
The method according to claim 5,
The size of the first pattern is smaller than the size of the second pattern optical sheet for a backlight assembly.
The method according to claim 1,
The micro pattern layer is an optical sheet for a backlight assembly, characterized in that the patterns having a different shape are formed repeatedly.
The method according to claim 1,
The micro-pattern layer includes at least one of a lenticular pattern and a prismatic pattern.
The method according to claim 1,
The micro pattern layer is an optical sheet for a backlight assembly, characterized in that it comprises a UV curable resin.
The method according to claim 1,
The thickness of the micro pattern layer is an optical sheet for a backlight assembly, characterized in that 5 to 25㎛.
Light source;
A light guide plate guiding the light from the light source to an emission surface to reflect light to an opposite surface of the emission surface;
A diffusion plate formed on an upper surface of an emission surface of the light guide plate to diffuse light;
A prism sheet for condensing light from the diffusion plate onto an exit surface; And
And a luminance enhancement film formed on the prism sheet and having a groove formed on at least one surface thereof and including a micro pattern layer formed on a surface on which the groove is formed.
Preparing an optical sheet having a groove formed on at least one surface thereof; And
Forming a micro-pattern layer on a surface on which the groove is formed.
The method of claim 12,
Forming the micro pattern layer,
Coating a UV curable resin on a surface of the optical sheet on which the groove is formed;
Contacting the micro pattern mold corresponding to the pattern shape of the micro pattern layer with the UV curable resin;
Irradiating UV; And
Separating the micro pattern mold from the optical sheet; Method for manufacturing an optical sheet for a backlight assembly comprising a.

Images