KR101961029B1 - Bright enhancing film using phosphor - Google Patents

Abstract

The present invention relates to a brightness enhancement film to which a phosphor is applied, wherein a base film is coated with a coating layer comprising a YAG-base phosphor and a LuAG-base phosphor.

Description

[0001] The present invention relates to a brightness enhancing film using phosphor,

The present invention relates to a brightness enhancement film to which a phosphor is applied. More specifically, the present invention relates to a method for improving brightness of an LCD by coating a base film with a coating layer containing a YAG and a LuAG phosphor.

In the past, 40-inch TVs were the mainstream, but now more consumers are buying 50-inch TVs and even 60-inch TVs. Recently, competition for the manufacture of displays with excellent luminance and color has been emerging as the size competition ends.

OLED (Organic Light-Emitting Diode), which is the next generation display, is able to achieve 100% color reproduction rate (NTSC standard), but the existing LCD (Liquid Crystal Display) is 70% have.

Particularly, a liquid crystal display (LCD) displays images using the optical characteristics of liquid crystal. Since a liquid crystal panel for displaying an image is a non-light emitting type device that does not emit light by itself, And a backlight unit (BLU) for supplying light to the light source.

At this time, the BLU illuminates the backlight of the LCD which can not emit light evenly so that the display image can be seen. These BLUs use direct-lit BLUs, which are a method of evenly arranging LED BLUs behind the LCD panel, and LED BLUs at left and right corners, which are used to uniformly distribute the light generated from the LEDs (Edge-lit BLU), which is a method of reflecting light onto a substrate, and edge-type.

In the conventional liquid crystal display device, a brightness enhancement film is applied to increase the contrast, and the brightness enhancement film can be attached to the backlight unit by the light shielding tape. A reflection type polarizing film is used as a brightness enhancement film. The reflection type polarizing film is a film in which a high refractive index layer and a low refractive index layer are alternately repeatedly laminated. Commercially, DBEF (Dual Brightness Enhancement Film) of 3M Company is used.

Conventional LCD TVs using conventional brightness enhancement films are formed in a structure as shown in Fig. A white LED layer, a diffusion plate, a prism sheet, a DBEF film, and a panel are stacked in this order from the bottom. That is, the light from the white LED is condensed through the prism sheet and the brightness is improved by passing through the DBEF film.

However, there has been a need to develop a new substitute because no material has been developed to replace the conventional DBEF luminance enhancement film.

Recently, a method using a quantum dot (QD) has been applied to improve the color reproducibility in an LCD, but there is a disadvantage in that sealing through a barrier film is necessary because of inherent characteristics of a quantum dot weak in moisture and oxygen.

In order to solve the problems of the related art as described above, the present invention provides a luminance and color reproducibility improvement film employing a usable phosphor instead of a DBEF film.

The present invention also provides an improved brightness and color reproducibility of a brightness enhancement film using the phosphor as compared with conventional DBEF films.

The present invention provides a brightness enhancement film to which a phosphor is applied, characterized in that a base film is coated with a coating layer comprising a YAG-base phosphor and a LuAG-base phosphor.

The charging ratio of the YAG-base phosphor and the LuAG-base phosphor is 10 to 40 wt% with respect to the entire coating layer.

The coating thickness of the coating layer is 10 to 100 mu m.

In addition, YAG-base phosphor is _{Y 3 A1 5 0 12: Ce} 3 + (YAG: Ce), Tb 3 A1 5 0 12: Ce 3 + (TAG: Ce), Ca 3 (Sc, Mg) 2 Si 3 O 12 : and in that at least one of a Ce ^{3 +} a problem solution ^{_{means: Ce 3+, Y 3 Mg 2}} AlSi 2 O 12.

Also, LuAG base phosphor Lu ₃ Al ₅ O _12: a task that is at least one of a Ce ^{3 +} solution _{^{means: Ce 3 +, Tb 3 Al}} 5 O 12: Ce 3 +, Lu 2 CaMg 2 Si 3 O 12 do.

Further, the present invention further provides a back coating layer comprising PMMA particles or PMMA particles and an antistatic agent on one side of the brightness enhancement film.

In addition, the PMMA particles include 0.1 to 5 wt% of the back coat layer.

The antistatic agent is contained in an amount of 0.01 to 3 wt% relative to the back coat layer.

      The thickness of the back coating layer is 1 to 10 mu m.

When a brightness enhancement film to which the phosphor of the present invention is applied is applied, it is possible to realize excellent brightness compared to a conventional DBEF film.

In addition, when applied to LCD, it can achieve superior color quality compared to conventional LCD TV.

In addition, since it has excellent durability and high luminance compared to existing DBEF, it can achieve excellent contrast compared to conventional LCD TV when applied to LCD.

1 is a sectional view of a brightness enhancement film (HBF) of the present invention.
2 is a cross-sectional view of a backlight coating film formed on one side of the brightness enhancement film of the present invention.

The present invention will be described in detail below, and the following embodiments or examples are for illustrative purposes only and the present invention is not necessarily limited thereto.

According to the present invention, the brightness of the LCD can be improved by using a brightness enhancement film using a phosphor instead of the DBEF film, that is, a high brightness film (HBF) 100.

Specifically, according to a preferred embodiment of the present invention, a high-luminance film (not shown) coated with a coating layer including both a YAG (Yittrium aluminum garnet) -based phosphor 130 emitting yellow fluorescence and a LuAG (lutetium aluminum garnet) (100) is used to improve the brightness of the LCD.

Further, when the high brightness film 100 including the phosphor is used, the brightness can be improved as compared with the conventional DBEF film.

Examples of the base film used in the present invention include PET, TAC, PC, polyimide, and acryl film.

In the present invention, YAG (Yittrium aluminum garnet) -based phosphors and LuAG (Lutetium aluminum garnet) -based phosphors that emit yellow fluorescence may be used together to improve the luminance and color reproducibility.

The YAG-based fluorescent material 130 is _{Y 3 A1 5 0 12: Ce} 3 + (YAG: Ce), Tb 3 A1 5 0 12: Ce 3 + (TAG: Ce), Ca 3 (Sc, Mg) 2 Si 3 ^{_{O 12: Ce 3+, Y 3}} Mg 2 AlSi 2 O 12: it is preferable that at least one of a Ce ^{+ 3.}

The LuAG based fluorescent material 140 _{Lu 3 Al 5 O 12: Ce} 3 +, Tb 3 Al 5 O 12: Ce 3 +, Lu 2 CaMg 2 Si 3 O 12: it is preferable that at least one of a Ce ^{3 +} .

YAG-base phosphor and LuAG-base phosphor are mixed at a ratio of 10 wt%: 1 wt% to 40 wt%: 20 wt%.

That is, the amounts of the YAG-base phosphor and the LuAG-base phosphor are 10 wt% to 40 wt% for the YAG-based phosphor and 1 wt% to 20 wt% for the LuAG.

If the lower limit value of the YAG-base phosphor is less than 10 wt%, the luminance improvement effect is insignificant. If the upper limit value is more than 40 wt%, the color reproduction rate, which is important in LCD TV, is lowered. Therefore, the YAG content is preferably in the range of 10 wt% to 40 wt%.

When the lower limit value of the LuAG phosphor is less than 1 wt%, the luminance improvement effect is insignificant. When the upper limit value is more than 20 wt%, the important color reproduction rate is lowered in the LCD TV, and thus the LuAG content is preferably in the range of 1 wt% to 20 wt% .

Improvement of luminance and color recall ratio according to the content of YAG-base phosphor and LuAG-base phosphor division Ref. DBEF
(LED TV) Ref. DBEF
( QD  TV) YAG  : Luag
content wt% YAG  10 YAG  10
Luag  5 YAG  10
Luag  10 YAG  10
Luag  20 Luminance [nit] 430 450 Luminance [nit] 430 450 500 550 X 0.2730 0.2593 X 0.2350 0.2406 0.2531 0.2749 Y 0.2925 0.2911 Y 0.2577 0.2701 0.2860 0.2970 Color Reproducibility [ % ] 81.6 100 Color Reproducibility [ % ] 81.3 81.8 82.4 82.6 division Ref. DBEF
(LED TV) Ref. DBEF
( QD  TV) YAG  : Luag
content wt% YAG  20 YAG  20
Luag  5 YAG  20
Luag  10 YAG  20
Luag  20 Luminance [nit] 430 450 Luminance [nit] 480 520 560 600 X 0.2730 0.2593 X 0.2550 0.2606 0.2731 0.2801 Y 0.2925 0.2911 Y 0.2877 0.2801 0.2910 0.2970 Color Reproducibility [ % ] 81.6 100 Color Reproducibility [ % ] 82.6 82.3 82.4 82.6 division Ref. DBEF
(LED TV) Ref. DBEF
( QD  TV) YAG  : Luag
content wt% YAG  40 YAG  40
Luag  5 YAG  40
Luag  10 YAG  40
Luag  20 Luminance [nit] 430 450 Luminance [nit] 540 550 580 620 X 0.2730 0.2593 X 0.2750 0.2980 0.3031 0.3349 Y 0.2925 0.2911 Y 0.2935 0.2966 0.3140 0.3422 Color Reproducibility [ % ] 81.6 100 Color Reproducibility [ % ] 81.3 81.2 81.4 81.6

A coating solution containing the phosphor is prepared by combining the YAG-base phosphor and the LuAG-base phosphor with a polymer matrix for securing physical properties.

Specifically, the YAG-base phosphor and the LuAG-base phosphor are placed in the polymer matrix in an agitator and evenly dispersed to prepare a coating solution containing the phosphor.

The polymer matrix may be a monofunctional urethane acrylate oligomer, a monofunctional monomer or the like, and a photoinitiator, a leveling agent, a defoaming agent, and the like may be added.

Examples of the photoinitiator include IG184, IG907, TPO, CP4, and the like. Preferred photoinitiators are IG 184 and TPO.

Particularly, the physical properties refer to properties such as pencil hardness, adhesion, curl, flexural resistance and the like.

- Pencil Hardness: To measure the hardness of the surface of the coating layer, the pencil of various hardness was scratched with a constant load to evaluate the hardness (Specification: JIS K 5400-8.4)

- Adhesion force: In order to measure the adhesion between the base film and the coating layer, the coating layer was scratched at a predetermined interval of 10 * 10 (lattice spacing 1 mm), and a tape was attached and peeled off to evaluate the adhesion between the coating layer and the base layer (Specification: JIS K 5400- 8.5)

-Curl: Curl (curling) property evaluation of film by measuring the height of squares of coating film by cutting coating film to 100mm * 100mm

* When Curl is severe, the film is curled and workability is lowered.

- Flexibility: rounding the film on a round bar to evaluate the flexibility of the coating film and coating film

In the present invention, the coating solution is applied to one surface of a base film using a Mayer Bar, and then cured by irradiating UV rays using a non-electrode lamp to produce a high-brightness film containing the phosphor.

When the coating of the coating layer is performed, it may be coated on the cross section of the base film.

As the thickness of the coating layer becomes thicker, the curl characteristic deteriorates, and the resin applicable to the polymer matrix becomes limited. The thickness of the coating layer should not be too thick.

The luminance and color recall characteristics can be controlled by the thickness of the coating layer and the phosphor content.

Curl according to coating thickness Coating Thickness [탆] 5 10 30 50 70 100 120 150 Curl [mm] 0 3 4 7 10 18 22 25

When the coating layer is coated on the base film, the thickness of the coating layer is preferably 10 to 100 mu m

When the coating layer is less than 10 탆, the phosphor protrudes to cause appearance defects. When the coating layer is more than 100 탆, the curl becomes more than 20 mm to cause Curl failure.

The present invention may further include a back coating layer 150 on either side of the high luminance film.

The particles included in the back coating layer 150 prevent irregularities on the back surface of the optical film to prevent blocking with other optical sheets to improve workability and to prevent static electricity caused by friction in the process.

The coating solution used for the back coating layer is composed of a urethane acrylate oligomer, a monofunctional monomer, a photoinitiator, a leveling agent, a dispersant, and PMMA particles.

The PMMA particles are preferably contained in an amount of 0.1 to 5 wt% with respect to the entire back coating layer. When the amount is less than 0.1 wt%, sufficient irregularities can not be formed on the back surface of the optical film. When the amount exceeds 5 wt%, transmitted light loss due to a high haze occurs. Therefore, the haze of the back coating layer is adjusted to 1 to 20% .

An anti-static additive may be added to the back coat layer as needed. The surface resistance can be controlled by adding the antistatic agent. The antistatic agent is preferably contained in an amount of 0.01 to 3 wt% based on the whole amount of the back coat layer. When the content of the antistatic agent is less than 0.01 wt%, the surface resistance for preventing static electricity is insufficient. When the antistatic agent content is more than 3 wt%, an excessive amount of the antistatic agent is added excessively. As a result, an antistatic agent is added in an amount of 0.01 to 3 wt% 10 ¹⁰ to 10 ¹² Ohm / range. When the surface resistance is 10 ¹⁰ to 10 ¹² Ohm /, it is possible to prevent the film from being damaged in the dynamic state, and there is an effect that the charging phenomenon immediately after charging is immediately attenuated.

Back coating can be done by bar coating or slot-die coating.

The thickness of the back coating layer in the back coating is preferably 1 to 10 mu m. When the thickness is less than 1 占 퐉, sufficient irregularities are not formed on the back surface of the optical film, preventing blocking. On the other hand, when the thickness is more than 10 占 퐉, there is a problem of transmission light loss due to high haze.

Hereinafter, the present invention will be described in more detail with reference to production examples. It is to be understood that the following examples are for the purpose of illustration only and are not intended to limit the scope of the present invention.

[Manufacturing Example]

Manufacturing example

20 wt% of the YAG-based fluorescent material (Y3A15012: Ce3 +) and 2 wt% of LuAG-based fluorescent material (Lu3Al5O12: Ce3 +) are mixed and put into a polymer matrix and stirred for 60 minutes. As the polymer matrix, a monofunctional urethane acrylate oligomer and a monofunctional monomer were used. Two kinds of photoinitiators are added to the stirred mixture of the phosphor and the matrix. As the photoinitiator, 5 wt% of IG 184 and 2 kinds of TPO are mixed at a ratio of 5: 5, and a coating solution is prepared.

The coating solution thus prepared is coated on one side of the PET film to a predetermined thickness with a Mayer Bar and irradiated with a non-electrode lamp for about 5 seconds. The amount of light irradiated at this time is preferably 1000 mj or less.

How to measure luminance

The brightness and color reproducibility of the brightness enhancement film of the present invention were evaluated using a liquid crystal display and a BM-7FAST color luminance meter from Topcon. The liquid crystal display device actually used is UN55JS8500F (Samsung, 55-inch Blue-BLU), and its basic configuration is as follows. Edge blue LED light source, light guide plate, POP film (Prism on Prism), double brightness enhancement film (DBEF), and liquid crystal panel. In this apparatus, the high luminance film (HBF) of the present invention is placed between the light guide plate and the POP film to evaluate the luminance and color reproducibility. In the evaluation, the interval between the BM-7FAST apparatus and the liquid crystal display apparatus (UN55JS8500F) is kept constant at 50 cm.

100: HBF
120: substrate film
130: YAG-base phosphor
140: LuAG-based phosphor
150: back coating layer

Claims (9)

But the coating a coating layer containing the YAG-base phosphor and LuAG based fluorescent material in the base film, the YAG-base phosphor is _{Tb 3 A1 5 0 12: Ce} 3+ (TAG: Ce), Ca 3 (Sc, Mg) 2 Si 3 O ₁₂ : Ce ³⁺ , Y ₃ Mg ₂ AlSi ₂ O ₁₂ : Ce ³⁺ is contained in an amount of 10 to 40 wt% with respect to the entire coating layer, and the LuAG-based phosphor is at least one selected from Lu ₃ Al ₅ O ₁₂ : Ce ³⁺ , Tb ₃ Al ₅ O ₁₂ : Ce ³⁺ , and Lu ₂ CaMg ₂ Si ₃ O ₁₂ : Ce ³⁺ is contained in an amount of 1 to 20 wt% with respect to the entire coating layer.
delete The brightness enhancement film according to claim 1, wherein the thickness of the coating layer is 10 to 100 μm.
delete delete The brightness enhancement film according to any one of claims 1 to 3, further comprising a back coat layer comprising PMMA particles or PMMA particles and an antistatic agent on one side of the brightness enhancement film. The brightness enhancement film according to claim 6, wherein the PMMA particles comprise 0.1 to 5 wt% of the white coating layer. The brightness enhancement film according to claim 6, wherein the antistatic agent comprises 0.01 to 3 wt% of the white coating layer. The brightness enhancement film according to claim 6, wherein the thickness of the back coating layer is 1 to 10 μm.

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