KR20170006328A - WHITE LIGHT-EMITTING DEVICE FOR LCD Back-Light-Unit - Google Patents

Abstract

The present invention relates to a white light-emitting device which is excellent in luminance and color reproducibility, and thus can be used as an LCD backlight unit of a low cost and, more specifically, to a white light-emitting device, comprising: a green phosphor represented by chemical formula 1, (Lu_1-(x1+x2),R_x1,A_x2)_3(Al_(1-y),B_y)_5(O_(1-z),C_z)_12; M_2Si_5N_8:Eu^2+ (M is Ca, Sr, or Ba); and at least one red phosphor selected from (Ca,Sr)AlSiN_3:Eu^2+.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a white light emitting device for an LCD backlight unit,

The present invention relates to a white light emitting device which is excellent in luminance and color reproduction rate and can be used as a low cost LCD backlight unit.

As the information and communication industry has progressed, there has been a constant demand for high performance of portable information processing devices and mobile communication terminals, so that high performance and high quality of various components of the system are continuously required. LCDs, which are typically applied to monitors of medium and large terminals such as laptops, require a light source of white backlight on the back. Cold-cathode fluorescent lamps (CCFL) have been widely used as such backlight sources. Cold-cathode fluorescent lamps have advantages such as uniform white light with high luminance. However, Difficulty is expected. Therefore, a backlight source capable of replacing the CCFL has been actively studied. Among them, a backlight source using a white light emitting device including a light emitting diode has attracted attention as a light source replacing a conventional cold cathode fluorescent lamp.

As an example of a related art related to an LCD backlight source using a white light emitting element, the following Patent Document 1 can be exemplified.

Patent Document 1 discloses an LCD backlight light source module that converts blue light of a blue light emitting diode chip into white light by a phosphor, and then enters the light guide plate, thereby achieving uniform light distribution of the LCD, low power consumption and high durability.

The white light emitting device according to the related art can realize a uniform white light having a high luminance by using a blue light emitting diode chip and a fluorescent material. However, when the white light emitting device is used as a backlight white light source of an LCD, Since the color reproduction range that can be expressed is very narrow, it is greatly restricted in realizing an image closer to a natural color. In particular, it falls short of the color reproduction range defined by ADOBE RGB or the color reproduction range defined by NTSC, which makes it difficult to realize a more realistic color.

As an alternative prior art to this, the following Patent Document 2 can be exemplified.

Patent Document 2 discloses a white backlight light source using a white light emitting element or a three-color light emitting diode chip of red, blue, and green as an LCD backlight, and uses a microcomputer to calculate an input current of each light emitting diode chip, And finally controlling the current supplied to each LED chip.

The above-described conventional technique can achieve a significantly wider color reproduction range than the conventional CCFL by using the red, blue and green three-color LED chips, but since the thermal or temporal characteristics of the LED chips are different There is a disadvantage in that the color tone changes depending on the use environment, and in particular, uniform color mixture such as color unevenness occurs. Also, the output of each light emitting diode chip changes according to the ambient temperature, and the color coordinates are changed.

In other words, due to the decrease in the number of LED PKGs and the high driving current, the temperature of the LED chip itself rises in order to realize equivalent brightness of the conventional LCD BLU (Back-Light-Unit) A color coordinate change and a luminance lowering problem occur.

Although nitride-based phosphors are used to solve this problem, nitride-based phosphors are not suitable for low cost implementation of direct-type LCD BLU because of high cost.

Therefore, it is necessary to develop a low-cost phosphor for low-cost direct-current LCD BLU that can realize equal brightness and color reproduction of conventional LCD BLU.

KR publication 2002-0041480 A (2002.06.03.) KR 2004-0087974 A (2004.10.15.)

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and it is an object of the present invention to provide a low cost new green oxynitride containing a nitrogen atom and a conventional red nitride phosphor using an existing Garnet structure instead of expensive nitride- And a white light emitting device.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems of the conventional art,

To a green phosphor and a M ₂ Si ₅ N ₈ in the general formula 1: Eu ^{2 +} (M is, Ca, Sr, or Ba a), and (Ca, Sr) AlSiN _3: at least one type of compound selected from Eu ^{2 +} red phosphor Emitting device.

[Chemical Formula 1]

_{(Lu 1- (x1 + x2)} , R x1, A x2) 3 (Al (1-y), B y) 5 (O (1-z), C z) 12

A is at least one element selected from the group consisting of divalent or trivalent cation metal elements such as Y, Gd, Sm, Tb, La, Sr, Ba and Ca; B is at least one element selected from the group consisting of Group IV elements C, Si, Ge, Sn, Pb C is at least one element selected from the group consisting of F, Cl, Br, N and S, R is Ce and 0 <X1 + X2 <1, <Y <1, 0 <Z <1.

In the present invention, the use of the white light emitting device is for an LCD backlight unit.

The white light emitting device of the present invention has a higher color reproduction rate and an S-RGB value than the conventional LCD BLU.

Fig. 1 is a graph comparing LED emission spectra of Examples and Comparative Examples of the present invention.
2 is a graph comparing NTSC coordinates of the embodiment of the present invention and the comparative example.

Hereinafter, the present invention will be described in detail.

According to the present invention,

To a green phosphor and a M ₂ Si ₅ N ₈ in the general formula 1: Eu ^{2 +} (M is, Ca, Sr, or Ba a), and (Ca, Sr) AlSiN _3: at least one type of compound selected from Eu ^{2 +} red phosphor Emitting device.

[Chemical Formula 1]

_{(Lu 1- (x1 + x2)} , R x1, A x2) 3 (Al (1-y), B y) 5 (O (1-z), C z) 12

Here, A is at least one element selected from the group consisting of divalent or trivalent cation metal elements such as Y, Gd, Sm, Tb, La, Sr, Ba and Ca, B is at least one element selected from the group IV elements C, Si, Ge, Sn , Pb or an element selected from the group consisting of B and Ga, and C is an element selected from the group consisting of F, Cl, Br, N and S, R is Ce and 0 <X1 + X2 <1 0 < Y < 1, and 0 < Z <

The device of the present invention can be utilized for an LCD backlight unit.

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

Example

Preparation of green phosphors

1 parts by weight of Lu ₂ O ₃ powder, 0.046 parts by weight of CeO ₂ powder, 0.39 parts by weight of Al ₂ O ₃ powder and 0.05 part by weight of AlN powder were placed in an alumina crucible and heated at a temperature of 1400 to 1600 And nitrogen (N ₂ ) gas at a pressure of 1 bar for about 3 hours or more to finally produce a phosphor compound. The composition of the finally prepared phosphor compound was the same as [Lu _2.85 Ce _0.15 ] ₃ Al ₅ O _11.3 N _0.7 .

Green _{phosphor: (.. Lu 2 85 Ce} 0 15) 3 Al 5 O 11. ₃ N _{0 .7}

Preparation of Red Phosphor

BR-102C (TM) from Mitsubishi Chemical Company was used as a red phosphor. The composition of the phosphor was as follows.

Red _{phosphor: (... Sr 0 76} , Ca 0 2, Eu 0 04) AlSiN 3

The green phosphor and the red phosphor were mixed at a ratio of 70.1 wt% and 29.9 wt%, respectively, to prepare a white phosphor composition.

Comparative Example

Preparation of Yellow Phosphor

BY-201A (TM) from Mitsubishi Chemical Company was used as a red phosphor. The composition of the phosphor was as follows.

Yellow _{phosphor: (.. La 0 85,} Ce 0 15) 3 Si 6 N 11

Preparation of Red Phosphor

BR-102C (TM) from Mitsubishi Chemical Company was used as a red phosphor. The composition of the phosphor was as follows.

Red _{phosphor: (... Sr 0 76} , Ca 0 2, Eu 0 04) AlSiN 3

The yellow light body and the red phosphor were mixed at a ratio of 95 wt% and 5 wt%, respectively, to prepare a white phosphor composition.

Table 1 and Table 2 show the results of comparing the panel coordinates and NTSC / S-RGB of the above embodiments and comparative examples.

As shown in Tables 1 and 2, the present invention uses existing low-priced green green oxynitrides containing nitrogen atoms and existing red nitride phosphors in existing Garnet structures instead of expensive nitride-based yellow and green phosphors, (NTSC) of 68.7% and S-RGB of 97%, respectively, than the structure of the color reproduction ratio (66.8%, S-RGB: 94%

Claims (2)

To a green phosphor and a M ₂ Si ₅ N ₈ in the general formula 1: Eu ^{2 +} (M is, Ca, Sr, or Ba a), and (Ca, Sr) AlSiN _3: at least one type of compound selected from Eu ^{2 +} red phosphor Emitting device.
[Chemical Formula 1]
_{(Lu 1- (x1 + x2)} , R x1, A x2) 3 (Al (1-y), B y) 5 (O (1-z), C z) 12
A is at least one element selected from the group consisting of divalent or trivalent cation metal elements such as Y, Gd, Sm, Tb, La, Sr, Ba and Ca; B is at least one element selected from the group consisting of Group IV elements C, Si, Ge, Sn, Pb C is at least one element selected from the group consisting of F, Cl, Br, N and S, R is Ce and 0 <X1 + X2 <1, <Y <1, 0 <Z <1. The white light emitting device according to claim 1, wherein the use of the white light emitting device is for an LCD backlight unit.

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