KR20150004473A - Diffusion reflective sheet for LED light - Google Patents

Abstract

To improve lens mura generated by brightness difference due to the reduction of light distance according to the slimming of BLU (back light unit) for display, the present invention relates to a diffusion reflective sheet. Diffusion is increased by uniformly spraying spherical particles on a side of a reflective sheet which is arranged on the same line as an LED light source, thereby reducing the amount of light reflected from a slope. The diffusion reflective sheet for an LED light source has spherical particles of a size of 0.1 to 500μm which are coated on a side of a refractive sheet. Because the diffusion reflective sheet for an LED light source has a side which is coated with spherical organic particles by a specific resin binder, a diffusion sheet provides superior diffusion to a side of a reflective plate in an LED direct type backlight unit structure and prevents the lens mura of an LED point light source, and solves an existing problem.

Description

[0001] Diffusion reflective sheet for LED light [0002]

The present invention relates to a diffuse reflection sheet for an LED light source, and more particularly, to a diffuse reflection sheet for an LED light source, and more particularly, to a diffuse reflection sheet for an LED light source, The present invention relates to a reflective sheet for enhancing the diffusibility by reducing the amount of specularly reflected light by uniformly applying specific spherical particles to one side of a reflective sheet arranged on the same line as the LED light source to improve the Lenz mura .

LCDs (liquid crystal display devices) are mainly used as displays, and unlike the AMOLED method, which is self-emitting, LCDs can not self-emit light, so a backlight unit, which is a surface light source device for supplying a light source, is being used. The backlight unit uses the CCFL, LED, and point light source as the surface light source, and the light emitted from the light source must be transmitted to the panel. Therefore, the light guide plate and the light guide plate are required to be suitable for the edge-lit and direct- Diffusion plates are applied and various kinds of optical sheets (diffusion film, prism, DEBEF) are constituted to diffuse and concentrate the light source to convert to the surface light source.

The edge type backlight unit is configured to emit light from a light source from one end face of the light guide plate and emit light from the light exit face of the light guide plate to the liquid crystal cell and is generally used for a small size liquid crystal display device such as a mobile phone, It is mainly used. On the other hand, the direct-type backlight unit has a configuration in which a direct-type CCFL light source is disposed at the lower part of the liquid crystal cell to emit light to the front surface of the diffuser plate, and is mainly used for TV. However, And the LED light source is also applied to direct type models that do not use LGP for cost reduction.

However, the direct-type backlight to which the LED light source of the conventional type is applied does not have a problem in use even though the surface of the reflective sheet is not treated separately. However, due to the reduction of the LED light source and the reduction of the light distance due to the continuous reduction of the cost, A lens type (Lenz type) having a diffusing property and a reflective sheet have been required to prevent this. That is, in the backlight unit structure using the environmentally friendly LED light source, the number of LED light sources is reduced and the BLU is slimmer, so that the light distance reaching from the LED to the diffusion plate is shortened. Due to the nature of the point light source, the light source is bright, As the lens becomes darker, a lens shift due to a brightness difference is generated, and an improvement measure is required. Accordingly, various studies have been conducted to solve such a problem. As one of the objects having a similar purpose to solving such a problem, Korean Patent Laid-Open Publication No. 2010-0088423 discloses a direct-type backlight unit, Discloses a direct-type backlight unit including a plurality of linear light sources arranged at regular intervals in parallel, a light-transmitting structure surrounding the linear light sources, and a lower case accommodating the linear light sources and the light-transmitting structure .

However, the invention disclosed in the above document has been proposed for improving the lamp unevenness because the structure of the backlight unit is specified, and the intention of the inventors of the present invention to fundamentally solve the problem of the lens mismatch of the backlight unit can not be satisfied, Therefore, the inventors of the present invention have continued to improve the above-mentioned lens moulin, and as a result, they have found that the above problem can be fundamentally solved by specifically treating the surface of the reflective sheet.

Patent Document 1: Korean Patent Publication No. 2010-0088423

SUMMARY OF THE INVENTION Accordingly, the present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a backlight unit for a direct-type backlight unit in which the light emitted from an LED light source is mirror- The light distance is shortened due to the characteristic of the point light source due to the slimness, so that the light source is bright and the light source is away from the light source, so that the luminance difference is caused by the difference in brightness. Therefore, the main object of the present invention is to suppress the occurrence of the above- A diffuse reflection sheet for an LED light source.

Another object of the present invention is to provide a method for improving the lens shift by providing a diffuse reflection sheet for an LED light source having the above characteristics by uniformly coating spherical particles on one surface of a reflective sheet to reduce the specular reflection of light to impart diffusibility .

The present invention may also be directed to accomplish these and other objects, which can be easily derived by those skilled in the art from the overall description of the present specification, in addition to the above-mentioned and obvious objects.

It is an object of the present invention to recognize that it is also a major factor to develop such a surface treatment method by recognizing that the inventors of the present invention can improve the lens mura by performing a surface treatment having diffusibility on one side of a reflection sheet, In order to improve the lens unevenness, specific spherical particles are uniformly applied to one side of a reflective sheet arranged on the same line as the LED light source, thereby imparting diffusibility to reduce the amount of light reflected at the mirror surface.

According to an aspect of the present invention, there is provided a diffuse reflection sheet for an LED light source,

And one surface of the reflective sheet base is coated with spherical particles of 0.1 to 500 탆 in size.

According to another aspect of the present invention, the spherical particles are selected from urethane-based materials, nylon-based materials, acrylics, and copolymers thereof.

According to still another aspect of the present invention, the coating density of the spherical particles is in a range effective for canceling out the lens mura.

According to another aspect of the present invention, the coating of the spherical particles is formed by using a thermosetting and ultraviolet (UV) curable resin as a binder.

The diffuse reflection sheet for an LED light source of the present invention having the above structure is formed by coating a spherical organic particle on a surface thereof with a specific resin binder so that the diffuse reflection sheet has excellent diffusibility on one side of the reflector in a structure directly under the LED backlight unit Which is an industrially advantageous invention to solve the above-described conventional problem by suppressing the occurrence of lens blur of the LED point light source.

1 is a schematic cross-sectional view of a reflective sheet to which only a spherical particle coating method of a diffuse reflection sheet for a backlight unit according to a preferred embodiment of the present invention is applied,
Figs. 2 to 4 are graphs showing the results of the light output distribution of the 30 째, 45 째 and 60 째 outgoing angles of a predetermined reflective sheet, respectively.

Hereinafter, the present invention will be described in more detail with reference to the preferred embodiments. However, it is to be understood that the present invention is not limited by these embodiments, It will be obvious to those of ordinary skill in the art.

1 is a schematic cross-sectional view of a reflective sheet to which only a spherical particle coating method of a diffuse reflection sheet for a backlight unit according to a preferred embodiment of the present invention is applied.

1, a diffuse reflection sheet for an LED light source according to a preferred embodiment of the present invention includes spherical particles 3 (0.1 to 500 m in size) on one surface of a reflective film 1 having pores formed therein, Are dispersed in the resin layer 2 so as to be dispersed, thereby reducing the amount of specular reflection of light emitted from the LED light source to impart diffusibility. It is a key point of the present invention to find the proper diffusibility by controlling the density of the particles in accordance with the light distance characteristics of the backlight unit when such diffusion property is given.

As described above, in the present invention, the spherical particles 3 are uniformly coated on one surface of the reflective film 1 in which voids are formed inside the base material, and organic particles are used as the spherical particles . Generally, inorganic particles are not preferable because of the problem of light absorption. Most preferably, spherical organic particles having a size of 0.1 to 500 μm are applied to a thermosetting and UV-curable resin binder, and the material thereof is one of acrylate, epoxy, melamine, polyurethane and urethane acrylate resins Or two or more of them may be mixed and used.

According to another preferred embodiment of the present invention, the organic particles may be, but are not limited to, spherical organic particles, and may be made of a urethane-based material, nylon, acrylic, or a copolymer thereof. As the solvent, MEK, TOL, EA, MeOH, Annon, MFG, and the like can be generally used. For the composition of the coating liquid for coating these spherical organic particles, It is generally used. The coating liquid may contain an antifoaming agent, a wetting and dispersing agent, a slipping agent, an antistatic agent, a leveling agent and the like as additives, if necessary.

Hereinafter, the present invention will be described in detail with reference to examples. It is needless to say that the following practical examples are merely illustrative of the present invention and the scope of the present invention is not limited to the following examples.

Example 1

Using a TAK XJSV-225 占 퐉 as a reflective film, a coating liquid having the following composition was applied on one surface of the reflective film to prepare a diffuse reflection sheet.

Composition of coating liquid

- Binder resin (Senso 3A): 25 wt%

- Curing agent (Aekyung DN980S): 5 wt%

- average diameter 50 占 퐉 PMMA (poly methyl methacrylate) particles (Advanced Hisoft-X500): 15%

- methyl ethyl ketone: 27 wt%

- Toluene: 27 wt%

- Slip agent: 1 wt%

Example 2

Using a TAK XJSV-225 占 퐉 as a reflective film, a coating liquid having the following composition was applied on one surface of the reflective film to prepare a diffuse reflection sheet.

Composition of coating liquid

- Binder resin (Aekyung A811): 20 wt%

- Curing agent (Aekyung DN980S): 2 wt%

- Nylon particles having an average diameter of 10 mu m (Toray SP-10): 25 wt%

- EA: 26 wt%

- Toluene: 26 wt%

- Slip agent: 1 wt%

- Antistatic agent: 1 wt%

Example 3

Using a TAK XJSV-225 占 퐉 as a reflective film, a coating liquid having the following composition was applied on one surface of the reflective film to prepare a diffuse reflection sheet.

Composition of coating liquid

- UV binder resin (ADAM Cam AD-1): 20 wt%

- Curing agent (Shiba IRGACURE 184): 1 wt%

- average diameter 5 占 퐉 PMMA particles (Kolon MH5FD): 25%

- average diameter 10 mu m PMMA particles (Soken MX-1000): 5 wt%

Methyl ethyl ketone: 24 wt%

- toluene: 24 wt%

- Antistatic agent: 1% by weight < tb >

Experimental Example

The reflective films used in the examples and the diffuse reflective sheets prepared according to the examples were measured for physical properties as described below and shown in Tables 1 and 2 to 4.

1. Reflectance

The reflectance of the reflective film XJSV-225 占 퐉 and the reflectance of 550 nm wavelength ranges of Example 1, Example 2, and Example 3 were measured using a UV3600 instrument manufactured by Shimadzu Corporation.

2. Glossiness

Using a BYK Gardner instrument, the gloss was measured at 60 ° specular reflection.

3. Light emission  Distribution

Using a gonie meter, the light output distribution was measured at -85 ° to + 85 ° for each emission angle (30 °, 45 °, 60 °).

4. Diffusibility  Evaluation results

The reflective film of the reflective film XJSV-225 mu m and the diffuse reflection sheet of Example 1, Example 2, and Example 3 were fastened to the LED direct-type backlight unit, and the state of the lens unevenness was confirmed in the state of being lit.

division XJSV-225 탆
(Reflective film) Example 1 Example 2 Example 3 reflectivity(%) 98 98 98 98 Glossiness (%) 60 20 10 5 Diffusibility
Evaluation results x ○ ○ ◎

(Lens Novel Level: x = High Level, △ = Heavy Level, ∘ = Approximate Level, ◎ = Not Occurred)

As can be seen from the above Table 1, when confirming the light output distribution of the reflective sheet of the embodiments in which spherical organic particles were coated on one side of the XJSV-225 mu m fabric without any treatment on one side according to the present invention, It can be confirmed that the diffusive property is increased by reducing the amount of light reflected at the mirror surface. When the lens mura is compared, it is also confirmed that the better the diffusivity of the light output distribution is, the more the lens mura is improved.

As described above, in the present invention, spherical particles are uniformly coated on one surface of a reflective film to impart diffusibility to improve the lens unevenness of the point light source. Price competitiveness and technology improvement. In accordance with this tendency, the backlight unit also deviates from the conventional edge type, and it is getting price competitiveness by going down to direct type, reducing the number of LEDs by reducing the cost continuously, In view of such changes in the LCD display industry, the diffuse reflection sheet of the present invention, which has improved the lens mura of the present invention, is expected to be applied to an LED direct-type backlight unit do.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

1 --- Reflective film
2 --- resin layer
3 --- spherical particles

Claims (4)

Wherein one side of the reflective sheet base is coated with spherical particles having a size of 0.1 to 500 탆.
The diffuse reflection sheet for an LED light source according to claim 1, wherein the spherical particles are selected from urethane-based materials, nylon-based materials, acrylics, and copolymers thereof.
The diffuse reflection sheet for an LED light source according to claim 1, wherein the coating density of the spherical particles is in a range effective for canceling the lens mura.
The diffuse reflection sheet for an LED light source according to claim 1, wherein the coating of the spherical particles is formed using a thermosetting and UV curable resin as a binder.

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