JP2001240858A - Fluorescent substance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a color liquid crystal display apparatus provided with a light emitting diode having a fluorescent substance radiating in a good red color region at high brightness. SOLUTION: The light emitting diode 6, which is prepared by covering a gallium nitride semiconductor tip 13 placed in a case 11 with a luminous layer 14 containing the fluorescent substance, is placed on the circumference of an emission board 5. A diffuser is placed on the front surface where the color liquid crystal panel 3 is laminated, and a reflection sheet is placed on the back surface of the emission board 5. The light emitting diode 6 is a semiconductor tip 13 having the peak wave length of >=310 nm and <=530 nm. The fluorescent substance is expressed by the general formula: (Y1-x, Gdx)3(Al1-y, Gay)5O12: Cez, Prw (wherein, 0<=x<=0.5, 0<=y<=0.5, 0.001<=z<=0.5 and 0.001<=w<=0.5). By composing the substrate of YAG having a garnet structure, and containing Ce as an activator and Pr as a co-activator, the fluorescent substance generates a luminescence peak in red color region at a sufficient brightness and radiates excellently in red color region. Liquid crystal display having an improved red brightness is realized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a compound of the present invention wherein R is Y and Gd.
M is Al and at least one of the elements
And at least one element of Ga and Ga
General formula is R₃M₅O ₁₂: For phosphors represented by Ce and Pr
Related.

[0002]

2. Description of the Related Art Conventionally, as a light emitting diode used for a light emitting diode display, a backlight light source, a traffic light, various indicators, and the like, a light emitting diode having a gallium nitride compound semiconductor chip has been known. When this light-emitting diode is used as a white light source, a light-emitting diode having a gallium nitride-based compound semiconductor chip emits blue light, for example, as described in Japanese Patent No. 2927279, Yttrium (Y), aluminum (Al), and garnet (YA) that emit red light that becomes white when mixed
A configuration using a G) -based phosphor is known.

The light emitting diode described in Japanese Patent No. 2927279 has a gallium nitride-based compound semiconductor chip in a cup, and yttrium (Y) aluminum (A) which emits light when excited by the light emission of the semiconductor chip.
l) is a garnet (YAG) phosphor _{(R 1-x, Sm x} ) 3 (Al y Ga 1-y) 5 O: C
e, a transparent resin containing a phosphor (R is at least one element of Y and Gd and 0 ≦ x <1, 0 ≦ y ≦ 1) and filled in a cup or provided in a layer form. ing.

In order to improve the color rendering of a high-pressure mercury lamp as a light source, for example, Japanese Patent Publication No. 7-979
As described in Japanese Patent Publication No. 3 (1999), Y activated with trivalent cerium
A configuration in which an AG-based phosphor is formed on the inner surface of the outer tube is also known.

[0005]

By the way, with the recent spread of color liquid crystal display devices, a color liquid crystal display device capable of obtaining a brighter and clearer display is desired. Also,
In a high-pressure mercury lamp as well, since the mercury emission line output of the high-pressure mercury lamp itself is too strong, further improvement in color rendering is desired.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a phosphor capable of obtaining a bright and clear red light emission.

[0007]

According to a first aspect of the present invention, R is yttrium (Y) and gadolinium (G).
d) at least one of the elements, M is at least one of aluminum (Al) and gallium (Ga), and the general formula is R ₃ M ₅ O.
₁₂ : represented by Ce, Pr.

The general formula is R ₃ M ₅ O ₁₂ : Ce,
R is at least one of yttrium (Y) and gadolinium (Gd), and M is aluminum (Al) and gallium (Ga).
By using at least one of the elements, sufficient luminance can be obtained, and a new emission peak of a wavelength component that emits red light can be obtained. For example, a light source such as a blue light emitting diode or a high-pressure mercury lamp When the color liquid crystal device is used as a backlight source for a color liquid crystal device, a clear red display can be obtained.

A phosphor according to a second aspect is the phosphor according to the first aspect, wherein M is Al.

When M is Al, the luminance increases and the intensity of the new emission peak of the wavelength component of the red emission increases.

The phosphor according to claim 3 has the general formula (Y
_{1-x, Gd x) 3} (Al 1-y, Ga y) 5 O 12:
Represented by Ce _z , Pr _w , 0 ≦ x ≦ 0.5, 0 ≦ y ≦
0.5, 0.001 ≦ z ≦ 0.5, and 0.001
≦ w ≦ 0.5.

The general formula is (Y _1-x , Gd _x ) _{3
(Al 1-y, Ga y} ) 5 O 12: Ce z, is represented by _{Pr w, 0 ≦ x ≦ 0.5,0} ≦ y ≦ 0.5,0.001 ≦
By satisfying z ≦ 0.5 and 0.001 ≦ w ≦ 0.5, sufficient luminance can be obtained, and a new emission peak of a wavelength component that becomes reddish emission can be obtained. When installed in a light source such as a light-emitting diode or high-pressure mercury lamp, white light with sufficient luminance is obtained by color mixing, and color rendering is also improved.When used as a backlight source for color liquid crystal devices, a clear red display is obtained. Can be

Here, when the value of x is larger than 0.5, the ratio of Gd increases, and there is a possibility that the luminance may be reduced. Therefore, 0 ≦ x ≦ 0.5. On the other hand, if the value of y is larger than 0.5, the proportion of Ga increases, and the luminance may decrease, so that 0 ≦ y ≦ 0.
5 is assumed. Further, when the value of z is larger than 0.001, the ratio of Ce as an activator decreases, and the luminance decreases.
Is greater than 0.5, the emission intensity may decrease due to an increase in the concentration of the activator, and concentration quenching may occur, resulting in a decrease in luminance. Further, when the value of w is less than 0.001, the ratio of Pr decreases, and the peak intensity of the wavelength component of red light emission decreases,
If the value of w is larger than 0.5, the luminance may be reduced, so that 0.001 ≦ w ≦ 0.5.

A phosphor according to a fourth aspect is the phosphor according to the third aspect, wherein y = 0.

By setting Y = 0, Ga disappears, the luminance increases, and the intensity of the new emission peak of the wavelength component of red emission increases.

A phosphor according to a fifth aspect is the phosphor according to any one of the first to fourth aspects, wherein the wavelength is 250 nm.
Excitation light having an emission peak at 530 nm or less increases the special color rendering index of red.

The wavelength is 250 nm or more and 530 nm.
By setting the composition ratio such that the special color rendering index of red is increased by the excitation light having the emission peak below, it is sufficiently excited to obtain high luminance, and the intensity of the new emission peak of the wavelength component of red emission is obtained. Increases, for example, when the wavelength is 2
By providing the light source having an emission peak at 50 nm or more and 530 nm or less, good white light and good color rendering can be obtained by mixing with the light source.

Here, if the peak wavelength is shorter than 250 nm or longer than 530 nm, the phosphor is not sufficiently excited, and it is not possible to improve the luminance and increase the special color rendering index of red. 250nm
It is used for a light source of not less than 530 nm.

According to a sixth aspect of the present invention, in the phosphor according to any one of the first to fifth aspects, the phosphor is provided in a light source including a semiconductor chip containing a gallium nitride-based compound as a main component.

By providing the light source provided with a semiconductor chip containing a gallium nitride-based compound as a main component, the emission spectrum from the light source forming a part of the excitation spectrum increases the luminance and reduces the wavelength component of the red emission. A new increase in emission peak intensity can be easily obtained, and good white light and good color rendering can be easily obtained by mixing with a light source.

According to a seventh aspect of the present invention, there is provided the phosphor according to any one of the first to fifth aspects, wherein the light source irradiates light to a liquid crystal panel for displaying image data in color.

By providing a light source for irradiating light to a liquid crystal panel for displaying image data in color, a new light emission peak of a wavelength component of red light emission substantially matching the transmittance of a filter of a red component of the liquid crystal panel is obtained. The display property of the red component is improved by the light from the increased light source, and a good display is obtained.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of a color liquid crystal display according to an embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a color liquid crystal display device. The color liquid crystal display device 1 includes a backlight unit 2 and a liquid crystal panel 3 for displaying image data in color by light from the backlight unit 2. I have.

The liquid crystal panel 3 is, for example, a TFT
A counter substrate having a glass substrate on which a color filter, a common electrode, and an alignment film (not shown) are stacked by a (Thin Film Transistor) method is provided. The liquid crystal panel 3
Is provided with an array substrate including a glass substrate having a TFT element as a switching element for each pixel and having an alignment film laminated on the surface. The liquid crystal panel 3 is configured such that liquid crystal is sealed between the opposing substrate and the array substrate. Furthermore, on both surfaces of the liquid crystal panel 3, polarizing plates (not shown) are arranged in a laminated manner.

The backlight unit 2 includes a light guide plate 5 and a light emitting diode 6 as a light source disposed on the periphery of the light guide plate 5. On the surface of the light guide plate 5 where the liquid crystal panel 3 is located, a diffusion plate 7 for uniformly diffusing light from the light guide plate 5 is formed. Further, on the back surface of the light guide plate 5, a reflection sheet 8 is formed by lamination.

The light emitting diode 6 has a case body 11 having a pair of electrodes (not shown), and a peak wavelength of 250 nm, which is disposed in the case body 11 and connected to the electrodes by conductive wires 12 and 12, respectively. A semiconductor chip 13 serving as a light source that emits light at 530 nm or less, for example, a blue light mainly containing a gallium nitride-based compound, and a light emitting layer that covers the semiconductor chip 13 and contains a phosphor that emits red light. It has 14 and.

Here, the peak wavelength of the light source is 250.
nm or more and 530 nm or less, and as the light emitting diode 6,
The peak wavelength is preferably 310 nm or more and 530 nm or less. That is, when the peak wavelength of the light source is shorter than 250 nm or longer than 530 nm, the phosphor is not sufficiently excited, and the phosphor cannot emit light with high luminance. If the peak wavelength of the light emitting diode 6 is shorter than 310 nm, the emission of the semiconductor chip 13 as a light source is in an ultraviolet region, and good blue light emission cannot be obtained. On the other hand, if the peak wavelength is longer than 530 nm, the emission of the semiconductor chip 13 changes from green to red, and good blue emission cannot be obtained. And, because good blue light emission cannot be obtained,
Light obtained by mixing color with red light emission by the phosphor mixed into the light emitting layer 14 does not become visually good white light. Further, when the peak wavelength is shorter than 310 nm or longer than 530 nm, the excitation of the phosphor becomes insufficient and the luminance decreases, and the red luminance decreases.
Visually good white light due to color mixing cannot be obtained. For this reason, when the light emitting diode 6 is used as a light source, a light source that emits light with a peak wavelength of 310 nm or more and 530 nm or less, for example, a light emitting diode 6 including a semiconductor chip 13 serving as a light source mainly containing a gallium nitride-based compound is used. .

In the light emitting layer 14, a phosphor is uniformly dispersed in a heat-resistant transparent resin such as an epoxy resin, a silicon resin, and a urea resin.

The phosphor is an yttrium (Y) -aluminum (Al) -garnet (YAG) system having a garnet structure, wherein R is at least one of yttrium (Y) and gadolinium (Gd). And M is aluminum (Al) and gallium (G
a) cerium (Ce) as an activator and praseodymium (P) as a co-activator
The general formula doped with r) is R ₃ M ₅ O ₁₂ : Ce, Pr
In particular, 0 ≦ x ≦ 0.5, 0 ≦ y ≦ 0.5, 0.
001 ≦ z ≦ 0.5 and 0.001 ≦ w ≦ 0.5
And the general formula is (Y _1-x , Gd _x ) ₃ (A
_{l 1-y, Ga y)} 5 O 12: in which Ce z, represented by Pr _w.

Here, when the value of x is larger than 0.5, the ratio of Gd increases, and the luminance of the phosphor may be reduced. Therefore, 0 ≦ x ≦ 0.5. Also,
When the value of y is larger than 0.5, the proportion of Ga increases, and the luminance may decrease.
Let y ≦ 0.5. Further, when the value of z is larger than 0.001, the proportion of Ce as an activator decreases, and the luminance decreases. When the value of z is larger than 0.5, the emission intensity decreases due to an increase in the concentration of the activator. Concentration quenching may occur and the luminance may decrease, so that 0.001 ≦ z ≦
0.5. When the value of w is less than 0.001, the ratio of Pr decreases, and the peak intensity of a wavelength component that emits red light in the emission spectrum of the phosphor decreases, and w
Is larger than 0.5, the luminance may be reduced. Therefore, it is set to 0.001 ≦ w ≦ 0.5.

The color liquid crystal display device 1 is configured such that the liquid crystal panels 3 are integrally disposed on the light guide plate 5 of the backlight unit 2 on the side where the diffusion plate 7 is provided. The backlight unit 2 and the liquid crystal panel 3
A lens film or the like for condensing light may be interposed between the lens and the lens.

Further, the light emitting diode 6 is not limited to the above-mentioned structure, but can be of any structure.
In addition to covering the semiconductor chip 13, any structure that can mix colors, such as forming a thin film on the inner surface or outer surface of the case body, can be used as the device 14.

Next, the operation of the color liquid crystal display of the above embodiment will be described.

By applying a predetermined voltage between a pair of electrodes of the light emitting diode 6, the semiconductor chip 13
Light is emitted in a blue color having an emission spectrum having a peak wavelength of not less than m and not more than 460 nm. By this light emission, the light emitting layer
The 14 phosphors are excited to emit red light, which changes from yellow to orange. The light guide plate 5 is illuminated with light that becomes visually white by mixing colors due to the light emission of the semiconductor chip 13 and the phosphor. Then, the light from the light guide plate 5 is uniformly illuminated via the diffusion plate 7 to the liquid crystal panel 3 to which a voltage is appropriately applied in accordance with the image data separately, and the light is transmitted through the liquid crystal panel 3 so that a predetermined amount of light is transmitted. Is displayed in color.

Next, the function of the phosphor in the above embodiment will be described.

(Experimental Example 1) First, an experiment was conducted to examine the effect of praseodymium (Pr) as a co-activator.

As a raw material, yttrium oxide (Y
₂ O ₃₎ powder 335.31g (1.485mol), aluminum oxide _(Al 2 _{O 3)} powder 255 g (1.00
mol), 5.16 g of cerium oxide (CeO ₂ ) powder
(0.03 mol), and 17.86 g of barium fluoride (BaF ₂ ) powder as a flux (3% by mass in external formulation) are mixed by a ball mill. This mixed powder is fired at 1450 ° C. for 4 hours in a reducing atmosphere (nitrogen (N ₂ ) 95% + hydrogen (H ₂ ) 5%). Then, after cooling, the mixture is pulverized with a bead mill, washed with distilled water to separate and remove impurities, dried, and passed through a predetermined mesh sieve to obtain a general formula having a particle size distribution of about 6 μm at D-50. Y ₃ Al ₅
A phosphor powder (sample 1-1) represented by O ₁₂ : Ce is obtained. Here, the value of D-50 is the particle size at which the total volume integrated value from the fine side reaches 50% of the total volume integrated value by measuring the particle size distribution by the laser diffraction scattering method, that is, the particle size from the fine side. Means that the particle size becomes about 6 μm at the position where the total volume integrated value becomes 50%.

Similarly, Y ₃ Al ₅ O ₁₂ : C is obtained by mixing yttrium oxide, aluminum oxide and cerium oxide at the compounding ratios shown in Table 1 as appropriate and having different composition ratios.
phosphor powder represented by e (Sample 1-2 to Sample 1-5)
Get. FIG. 3 shows a graph of the particle size distribution of Sample 1-2.

[0040]

[Table 1]The general formula of each obtained composition ratio is Y₃Al
₅O₁₂: Relative luminance, grain of phosphor powder represented by Ce
The power distribution and chromaticity were measured. Table 2 shows the results.
Here, the luminance and chromaticity are half that of the gallium nitride-based compound.
It is equipped with a conductive chip 13 and emits light at about 460 nm as shown in FIG.
Blue visible light using the light emitting diode 6 having
And a wavelength of 500 nm or less by a Y-50 filter.
Cut to color chromaticity meter (Minolta Camera Co., Ltd.
(Product name: CS-100). And relative
The brightness is the brightness of the phosphor powder with the highest brightness (sample 1-2).
The degree was calculated as 100%. The particle size distribution is
Distribution measuring device (product name: SK L, manufactured by Seishin Enterprise Co., Ltd.)
Laser diffraction scatter using ASER MICRON SIZER PRO 7000S)
Measured by the random method. Here, the value of D-50 is the particle size
By measuring the cloth, the total volume integrated value from the fine side
Particle size reaching 50% of product integrated value, that is, fine particle size
Particle size at the position where the total volume integrated value from the side is 50%
Means The composition ratio shown in Table 2 is (Y
_{1-z / 3-W / 3}Ce_{z / 3}Pr_{w / 3})₃Al₅O
₁₂Describe based on.

[0041]

[Table 2] From the results shown in Table 2, the luminance was highest in Sample 1-2 in which the composition ratio of cerium (Ce) was 0.02. Also,
It was found that as the amount of Ce increased, the value of chromaticity X increased and the value of Y decreased, resulting in a reddish emission color.

Next, the above general formula is represented by Y ₃ Al ₅ O ₁₂ : C
As with the preparation of the powder of the phosphor represented by e, Y ₂
Along with O ₃ powder, Al ₂ O ₃ powder and CeO ₂ powder, praseodymium oxide (Pr ₆ O ₁₁ ), terbium oxide (Tb ₄ O ₇ ), europium oxide (Eu)
₂ O ₃ ) or neodymium oxide (Nd ₂ O ₃ )
r, Tb, Eu, and Nd are blended so as to be 0.003 mol, and in the same manner as in the case of preparing the phosphor powder of Y ₃ Al ₅ O ₁₂ : Ce, by a ball mill together with BaF ₂ powder as a flux. After mixing and firing in a reducing atmosphere, the general formula having a different composition ratio is represented by Y ₃ Al ₅ O ₁₂ :
Ce _0.06 , Pr _0.03 , Y ₃ Al ₅ O ₁₂ : Ce
_{0.06, Tb 0.03, Y 3 Al} 5 O 12: Ce
_0.06 , Eu _0.03 , Y ₃ Al ₅ O ₁₂ : Ce
A phosphor powder represented by _0.06 and Nd _0.03 is obtained.

Then, as a result of measuring the luminance of each phosphor powder of different co-activator, Pr was added to the co-activator.
Are the highest in brightness, and Tb, Eu and Nd
Is used as a co-activator, Y ₃ A having no co-activator
l ₅ O ₁₂ : Same or lower luminance than Ce.

For this reason, based on the compounding ratio shown in Table 3,
As above, Y₂O₃Powder, Al ₂O₃Powder and C
eO₂Along with the powder, praseodymium oxide (Pr₆O
₁₁) Mix powder and use BaF as flux₂With powder
Mix by a ball mill, fire similarly in a reducing atmosphere,
A general formula having a different composition ratio is Y₃Al₅O₁₂: Ce, Pr
_0.003Phosphor powder (samples 1-6 to sample
1-10) is obtained.

The general formula of each of the obtained composition ratios is Y ₃
Al ₅ O _{12: Ce,} the relative brightness of the phosphor powder is represented by _{Pr 0.00 3,} was similarly measured particle size distribution and the chromaticity. Here, the relative luminance is the highest in Sample 1-.
The luminance of the phosphor powder of No. 2 was calculated as 100%. Table 4 shows the results. The composition ratio shown in Table 4 is (Y
_{1-z / 3-W / 3} Cez _{/ 3} Pr _{w / 3} ) ₃ Al ₅ O
₁₂ will be described. FIG. 4 shows the particle size distribution of Sample 1-7.

[0046]

[Table 3]

[Table 4] From the results shown in Table 4, Table 2 shows that Pr was not used as a co-activator.
Similarly to the experimental results shown in FIG.
Sample 1-7 of 02 mol had the highest luminance. Further, it was found that as the amount of Ce increased, the value of chromaticity X increased and the value of Y decreased, indicating a tendency to emit reddish light.

From the results shown in Tables 2 and 4,
Table 5 shows a comparison of the luminance and chromaticity of each sample corresponding to the composition ratio.

[0048]

[Table 5] From the results shown in Table 5, by using praseodymium as a co-activator as a cerium activator, Sample 1-1
The general formula using cerium as an activator is Y ₃ A
l ₅ O _12: in comparison with the phosphor powder represented by Ce, the general formula for Pr is a sample 1-6～1-10 was co-activator is _{Y 3 Al 5 O 12: Ce} , Pr 0 although _{.0 03} luminance of phosphor powder represented drops 8.6% from 5.8%, the general formula _Y 3 _Al 5 _O 12: in comparison with the phosphor powder is represented by Ce The general formula is Y ₃ Al ₅ O ₁₂ : Ce,
The value of X of the chromaticity of the phosphor powder represented by Pr _0.003 is +0.001 to +0.004, and the value of Y is -0.002.
−−0.004 shift. From this, the general formula is Y
₃ Al ₅ O _12: Formula than phosphor powder represented by Ce is _{Y 3 Al 5 O 12: Ce} , towards the phosphor powder represented by _{Pr 0.003} is emission color reddish I understand.

Also, Samples 1-2 and 1 having high brightness
FIGS. 5 and 7 show the excitation spectrum of -7, and FIGS. 6 and 8 show the emission spectrum thereof. From the excitation spectrum, although not shown in the sample 1-2 shown in FIG. 5, FIG.
In sample 1-7, a large peak was observed at about 290 nm. From the emission spectrum, the sample 1-2 shown in FIG. 6 has a single waveform having one peak at about 560 nm, whereas the sample 1-7 shown in FIG.
In addition to the peak of, a large peak was observed at about 610 nm, which was reddish, and a peak was observed at about 640 nm, which was reddish. From this emission spectrum, it is considered that the chromaticity shift as shown in Table 5 occurred due to the newly generated reddish peak.

(Experimental Example 2) Next, praseodymium (P
An experiment was conducted to study the composition ratio of r).

As raw materials, as in Experimental Example 1, Table 6
Y at the compounding ratio shown in₂O₃Powder, Al ₂O₃Powder and C
eO₂Pr along with the powder₆O₁₁1.53g
(0.0015 mol), and BaF is used as a flux.₂
Mix the powder with a ball mill, and mix in a reducing atmosphere.
And the general formula having a different composition ratio is Y₃Al
₅O₁₂: Ce and Y₃Al₅O₁₂: Ce, Pr
_0.009Phosphor powder (sample 2-1 to sample
2-6) is obtained.

[0052]

[Table 6]The general formula of each obtained composition ratio is Y₃Al
_FiveO₁₂: Ce and Y₃Al ₅O₁₂: Ce, Pr
_0.009Phosphor powder (sample 2-1 to sample
The relative luminance, particle size distribution and chromaticity of 2-6) were measured in the same manner.
did. The relative luminance is the highest luminance of the phosphor powder.
The brightness of (Sample 2-2) was calculated as 100%. That
Table 7 shows the results. The composition ratio shown in Table 7 is
(Y_{1-z / 3-W / 3}Ce_{z / 3}Pr_{w / 3})₃Al
₅O₁₂Describe based on. In addition, Gane of Table 7
Compare the brightness and chromaticity of each sample corresponding to the composition of the dot structure.
Table 8 shows the results of the comparison.

[0053]

[Table 7]

[Table 8]From the results shown in Tables 7 and 8, the same as in Experimental Example 1 was obtained.
The composition ratio of Ce is 0.017 without using Pr as a co-activator.
Sample 2-2 had the highest luminance. Sample 2-
The general formula using Ce as an activator is 1-2 which is Y₃Al
₅O₁₂: Sample compared to phosphor powder represented by Ce
General formula using Pr which is 2-4 to 2-6 as a co-activator is represented by Y
₃Al₅O₁₂: Ce, Pr_0.009Fluorescence represented by
The brightness of the body powder decreases from 9.3% to 23.0%
Of the general formula Y₃Al₅O₁₂: Phosphor represented by Ce
Of the general formula Y₃Al₅O₁₂: Ce, P
r_{0 . 009}The value of X of the chromaticity of the phosphor powder represented by
+0.003 to +0.004, Y value is -0.001 to
-0.004 shift. From this, the general formula is Y ₃
Al₅O₁₂: The general formula is higher than that of the phosphor powder represented by Ce
Y₃Al₅O₁₂: Ce, Pr_0.009Fireflies represented by
It turns out that the light body powder has a reddish emission color
Was.

The excitation spectra of Samples 2-3 and 2-6 are shown in FIGS. 9 and 11, and the emission spectra are shown in FIGS. 10 and 12. From the excitation spectrum, although not appearing in the sample 2-3 shown in FIG. 9, FIG.
In sample 2-6, a large peak was observed at about 290 nm. Further, from the emission spectrum, the sample 2-3 shown in FIG. 10 has a single waveform having one peak at about 550 nm, whereas the sample 2-6 shown in FIG.
In addition to the peak of nm, a large peak is observed at about 610 nm, which is a red color, and at about 640 nm of the red color.
A peak was observed. From this emission spectrum, it is considered that the chromaticity shift as shown in Table 8 occurred due to the newly generated reddish peak.

(Experimental Example 3) Next, an experiment for examining the replacement of yttrium (Y) with gadolinium (Gd) was conducted.

As raw materials, as in Experimental Example 2,
In addition, gadolinium oxide (Gd _{2) is} used together with Y ₂ O ₃ powder, Al ₂ O ₃ powder and CeO ₂ powder at a ratio of replacing Gd with Y by about 50% in a molar ratio so that the composition ratio shown in FIG.
O ₃ ), and appropriately 1.53 g of Pr ₆ O ₁₁ (0.
0015 mol), mixed with a BaF ₂ powder as a flux by a ball mill, fired similarly in a reducing atmosphere, and represented by a general formula (Y, Gd) ₃ Al ₅ O having a different composition ratio.
₁₂ : A phosphor powder represented by Ce, Pr _0.009 is obtained. The composition ratio shown in Table 9 is (Y
_{1-xz / 3-W / 3} Gd _x Cez _{/ 3} Pr _{w / 3} )
Described on the basis of ₃ Al ₅ O _12.

The relative luminance, particle size distribution and chromaticity of the phosphor powder represented by the general formula of each obtained composition ratio are represented by (Y, Gd) ₃ Al ₅ O ₁₂ : Ce, Pr _0.009. Measured similarly. The relative luminance was calculated with the luminance of the phosphor powder having the highest luminance (sample 3-1) as 100%. The results are shown in Table 9. And Table 9
Table 10 shows the results of comparison of the brightness and chromaticity of each sample corresponding to the composition ratio.

[0058]

[Table 9]

[Table 10] From the results shown in Tables 9 and 10, it can be seen that Sample 3-1 of 0.003 having a lower Ce composition ratio than Experimental Examples 1 and 2 has the highest luminance, and the luminance decreases as the amount of Ce increases. I tended to. Further, similarly to Experimental Example 2, as the amount of Ce increased, the value of chromaticity X decreased and the value of Y increased.

The general formula using (Y, Gd) ₃ Al ₅ O ₁₂ : Ce using Ce as an activator, which is Samples 3-1 to 3-3, is as follows.
Samples 3-4 to 3-6 compared to the phosphor powder represented by
The general formula using Pr as a co-activator is (Y, Gd) ₃ A
l ₅ O ₁₂ : Ce, Pr _{0. Although} the luminance of the phosphor powder represented by ₀₀₉ decreases from 7.0% to 21.0%,
Compared with the phosphor powder represented by the general formula (Y, Gd) ₃ Al ₅ O ₁₂ : Ce, the general formula is (Y, Gd) ₃ Al ₅
The X value of the chromaticity of the phosphor powder represented by O ₁₂ : Ce, Pr _0.009 shifted by +0.003 to +0.004, and the Y value shifted by −0.002 to −0.004. Therefore, the general formula _{(Y, Gd) 3 Al 5} O 1 2: Formula than phosphor powder represented by Ce is _{(Y, Gd) 3 Al 5} O
₁₂ : It was found that the phosphor powder represented by Ce, Pr _0.009 had a reddish emission color.

FIGS. 13 and 15 show the waveforms of the excitation spectra of Samples 3-2 and 3-5, and FIGS. 14 and 16 show the waveforms of the emission spectra. Then, from the waveform diagram of the excitation spectrum, the sample 3 shown in FIG.
-2, a small peak is observed at about 270 nm,
In sample 3-5 shown in FIG. 15, a large peak was observed at about 290 nm. Further, from the waveform of the emission spectrum, the sample 3-2 shown in FIG. 14 has a single waveform having one peak at about 580 nm, but the sample 3-5 shown in FIG. About 61 to be red
A large peak was observed at 0 nm, and a peak was observed at about 640 nm for the red system. From the waveform diagram of this emission spectrum, by the newly generated reddish peak,
It is considered that the chromaticity shift as shown in Table 10 occurred.

From FIG. 7, FIG. 11 and FIG. 15, it can be seen that the light source having a peak wavelength at about 250 nm or more and 530 nm can sufficiently excite the phosphor using Pr as a co-activator. When a light emitting diode is used as an excitation light source, the peak wavelength for blue light emission is 310 nm.
It is preferable to provide a semiconductor chip 13 having a thickness of not less than 530 nm. That is, if the peak wavelength is shorter than 310 nm, good blue light is not emitted, and white light may not be obtained due to mixing with light emitted from the phosphor.

(Experimental Example 4) Next, an experiment for examining the color rendering properties was performed.

A light-emitting diode 6 was provided, comprising a semiconductor chip 13 formed of a gallium nitride compound emitting blue light having a light emission peak of 470 nm and provided with a light-emitting layer 14 containing phosphor powders of various compositions. The light-emitting diodes 6 were allowed to emit light, and the color rendering properties were evaluated.

Here, the phosphor powder has a general formula of Y
₃ Al ₅ O _12: Samples 2-3 are represented by Ce, the general formula _Y 3 _Al 5 _{O 12:} using _Ce, sample 2-6 represented by _{Pr 0.009.} The evaluation of the color rendering properties is based on the method for evaluating the color rendering properties of the light source according to JIS-Z-8726, and the distance from the light emitting diode 6 to the light receiving surface is set to 10 cm.
Electric current was applied at 0 mA and 40 mA to emit light, the spectral reflectance was measured, and the color rendering properties were evaluated. The results are shown in Tables 11 and 12. 18 to 21 show emission spectra of the obtained light emitting diode 6. Here, FIG.
8 is a light-emitting diode using the phosphor of Sample 2-3, which is energized at 20 mA, FIG. 19 is a light-emitting diode using the phosphor of Sample 2-6, which is energized at 20 mA, and FIG. FIG. 21 shows a light-emitting diode using the phosphor of Sample 2-6.
It is the one that was energized.

[0065]

[Table 11]

[Table 12] From these results, the illuminance of the sample 2-3 represented by Y ₃ Al ₅ O ₁₂ : Ce in which the general formula not using Pr as a co-activator was larger, but the average color rendering index (Ra) was higher than that of the general formula. Is represented by Y ₃ Al ₅ O ₁₂ : Ce, Pr _{0.009. The} sample 2-6 has a current of 20 mA and is 72.0 to 72.7.
It can be seen that the current is improved from 73.7 to 74.3 at a current of 40 mA. In particular, the red special color rendering index (R9) changes from 2 to 13 at a current of 20 mA,
It can be seen that the current is significantly improved from 5 to 15 at a current of 40 mA. That is, P
From the result that a new red-based peak is generated by using r as a co-activator, the red special color rendering index (R9)
Is considered to have been greatly improved.

The transmittance of the red component in the color filter of the liquid crystal panel 3 of the color liquid crystal display device 1 which is generally widely used, and the special color rendering index of red (R9)
Color chart No. as an index of The spectral reflectance of No. 9 is shown in FIG.

As shown in FIG. 17, the color chart No. serving as an index of the red special color rendering index (R9). Since the spectral reflectance of No. 9 substantially matches the transmittance of the red component in the color filter of the liquid crystal panel, the special color rendering index (R9) of red becomes large by co-activating Pr. It is considered that the color liquid crystal display device 1 using a light emitting diode provided with a phosphor using Pr as a co-activator as a backlight light source significantly improves red luminance.

As described above, the phosphor YAG: Ce, Pr using cerium as an activator and praseodymium as a co-activator with the base being YAG having a garnet structure, that is, R is one of yttrium (Y) and gadolinium (Gd) Wherein M is at least one of aluminum (Al) and gallium (Ga), and the general formula is R ₃ M ₅ O ₁₂ : C
e, Pr, especially 0 ≦ x ≦ 0.5, 0 ≦ y ≦ 0.5, 0.
001 ≦ z ≦ 0.5 and 0.001 ≦ w ≦ 0.5
Is a general formula (Y _1-x , Gd _x ) ₃ (Al _1-y ,
_{Ga y) 5 O 12: Ce} z, Pr by a phosphor represented by _w, and sufficient peak intensity of the wavelength component as a red light-emitting with luminance can be obtained increases, red special color rendering index The value of (R9) is greatly increased, and a reddish luminescent color is obtained.

For this reason, for example, when provided in a blue light emitting diode, a high-pressure mercury lamp, or the like, white light with sufficient luminance can be obtained visually by color mixing, and good color rendering properties can be obtained. Further, when this light-emitting diode is used as a backlight light source of a color liquid crystal display device, the luminance of red is improved and a clear red display is obtained.

Then, the general formula is (Y _1-x , Gd _x ) _{3
(Al 1-y, Ga y} ) 5 O 12: Ce z, is represented by _{Pr w 0 ≦ x ≦ 0.5,0 ≦} y ≦ 0.5,0.001 ≦ z
By satisfying ≦ 0.5 and 0.001 ≦ w ≦ 0.5, sufficient luminance can be obtained, a good red component peak can be obtained, and good reddish luminescence can be obtained. .

Further, since a light source having a peak wavelength of 250 nm or more and 530 nm or less is used as a light source for exciting the phosphor, the phosphor is sufficiently excited to obtain high luminance. In particular, when a phosphor is provided on the light emitting diode 6, a semiconductor chip having a peak wavelength of 310 nm or more and 530 nm or less is used.
By using the light-emitting device provided with 13, excellent white light with high luminance can be obtained visually by mixing colors.

Further, when the peak wavelength is 250 nm or more and 53
0 nm or less light source, especially 310 nm or more peak wavelength 5
When the light emitting diode 6 having the semiconductor chip 13 of 30 nm or less is used as a backlight light source of the color liquid crystal display device 1, a good white display is obtained and
The red luminance can be greatly improved, and a clear red display can be obtained.

The peak wavelength is at least 310 nm and 53
A semiconductor chip 13 made of a gallium nitride compound widely used as a light emitting diode of 0 nm or less.
, A visually good white light can be easily obtained by color mixing.

In the above embodiment, the phosphor is not limited to the color liquid crystal display device, but may be used for any light source, display, toy, or the like.

Further, the light source is not limited to the light emitting diode 6, and the light source can excite the fluorescent substance at 250 nm to 530 nm.
Any light source having the following emission spectrum may be used.

When preparing a phosphor, any flux may be used. By using barium fluoride, the phosphor had a large crystal grain size and high luminance was obtained.

[0077]

According to the first aspect of the present invention, the general formula is represented by R ₃ M ₅ O ₁₂ : Ce, Pr, and R is at least one of yttrium (Y) and gadolinium (Gd). One element, M is aluminum (Al)
And at least one of gallium (Ga)
As a single element, sufficient brightness can be obtained,
A new emission peak of a wavelength component that becomes red light emission is obtained, and reddish red light emission can be obtained.For example, when provided in a light source such as a blue light emitting diode or a high pressure mercury lamp, color mixing may occur. White light and color rendering with sufficient luminance can be obtained, and a clear red display can be obtained when used as a backlight source of a color liquid crystal device.

According to the second aspect of the present invention, there is provided the phosphor of the first aspect.
In addition to the effect of the phosphor described, by setting M to Al, the luminance can be increased, the intensity of a new peak of the wavelength component of red light emission can be increased, and good red light emission can be obtained. .

[0079] According to the phosphor of claim 3 wherein the general formula _{(Y 1-x, Gd x} ) 3 (Al 1- y, Ga y) 5 O
₁₂ : represented by Ce _z , Pr _w , 0 ≦ x ≦ 0.5, 0 ≦
y ≦ 0.5, 0.001 ≦ z ≦ 0.5, and 0.0
For satisfying 01 ≦ w ≦ 0.5, sufficient luminance can be obtained, and a reddish reddish emission can be obtained by increasing a new emission peak of a wavelength component to be reddish emission, For example, when provided in a light source such as a blue light emitting diode or a high-pressure mercury lamp, white light and color rendering properties of sufficient luminance can be obtained by mixing colors, and when used as a backlight light source for a color liquid crystal device, a clear red light is used. Can be obtained.

According to the fourth aspect of the present invention, there is provided the phosphor of the third aspect.
In addition to the effect of the phosphor described, by setting Y = 0,
Ga disappears, the luminance increases, and the intensity of the new emission peak of the wavelength component of red light emission increases, so that good red light emission can be obtained.

According to the fifth aspect of the present invention, there is provided the phosphor of the first aspect.
In addition to the effects of the phosphor described in any one of (4) to (4), the composition ratio is such that the special color rendering index of red is increased by excitation light having an emission peak at a wavelength of 250 nm or more and 530 nm or less. And the intensity of the new emission peak of the wavelength component of red emission increases, and for example, by providing a light source having an emission peak at a wavelength of 250 nm or more and 530 nm or less, a good white color is obtained by mixing with the light source. Light and color rendering can be obtained.

According to the phosphor described in claim 6, claim 1 is provided.
In addition to the effect of the phosphor according to any one of (5) to (5), in order to provide the light source provided with a semiconductor chip containing a gallium nitride-based compound as a main component, the emission spectrum from the light source having a peak value substantially the same as the excitation spectrum In addition, it is possible to easily increase the luminance and the new emission peak intensity of the wavelength component of red emission, and easily obtain good white light and color rendering properties by mixing with the light source.

According to the phosphor described in claim 7, claim 1 is provided.
In addition to the effects of the phosphor described in any one of the above items 5, the light source for irradiating the liquid crystal panel with a color display of image data with light is provided. The light from the light source having the new emission peak of the wavelength component increased can improve the display property of the red component and obtain good display.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a color liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is a graph showing an emission spectrum of the light emitting diode.

FIG. 3 is a graph showing a particle size distribution of Y ₃ Al ₅ O ₁₂ : Ce (sample 1-2).

FIG. 4 is a graph showing a particle size distribution of Y ₃ Al ₅ O ₁₂ : Ce (sample 1-7).

FIG. 5 is a graph showing an excitation spectrum of Y ₃ Al ₅ O ₁₂ : Ce (Sample 1-2).

FIG. 6 is a graph showing an emission spectrum of Y ₃ Al ₅ O ₁₂ : Ce (sample 1-2).

FIG. 7: Y ₃ Al ₅ O ₁₂ : Ce, Pr (sample 1-
It is a graph which shows the excitation spectrum of 7).

FIG. 8: Y ₃ Al ₅ O ₁₂ : Ce, Pr (sample 1-
It is a graph which shows the emission spectrum of 7).

FIG. 9 is a graph showing an excitation spectrum of Y ₃ Al ₅ O ₁₂ : Ce (sample 2-3).

FIG. 10: Y ₃ Al ₅ O ₁₂ : Ce as above (sample 2-3)
3 is a graph showing an emission spectrum of the present invention.

FIG. 11: Y ₃ Al ₅ O ₁₂ : Ce, Pr (sample 2)
It is a graph which shows the excitation spectrum of -6).

FIG. 12: Y ₃ Al ₅ O ₁₂ : Ce, Pr (sample 2)
It is a graph which shows the emission spectrum of -6).

FIG. 13 is a graph showing an excitation spectrum of (Y, Gd) ₃ Al ₅ O ₁₂ : Ce (sample 3-2).

FIG. 14 is a graph showing an emission spectrum of (Y, Gd) ₃ Al ₅ O ₁₂ : Ce (Sample 3-2).

FIG. 15 Same as above (Y, Gd) ₃ Al ₅ O ₁₂ : Ce, P
It is a graph which shows the excitation spectrum of r (sample 3-5).

FIG. 16 Same as above (Y, Gd) ₃ Al ₅ O ₁₂ : Ce, P
It is a graph which shows the emission spectrum of r (sample 3-5).

FIG. 17 is a graph showing a relationship between the transmittance of a red component in a color filter of the color liquid crystal panel and the spectral reflectance of a color chart of a special color rendering index of red.

FIG. 18: Y ₃ Al ₅ O ₁₂ : Ce (sample 2-3)
5 is a graph showing an emission spectrum when a current is applied to a light-emitting diode using 20 mA at 20 mA.

FIG. 19: Y ₃ Al ₅ O ₁₂ : Ce, Pr (sample 2)
It is a graph which shows the light emission spectrum at the time of energizing with 20 mA to the light emitting diode using -6).

FIG. 20: Y ₃ Al ₅ O ₁₂ : Ce (sample 2-3)
5 is a graph showing an emission spectrum when a light emitting diode using is supplied with electric current at 40 mA.

FIG. 21 shows a sample of Y ₃ Al ₅ O ₁₂ : Ce, Pr (sample 2)
6 is a graph showing an emission spectrum when a current of 40 mA is applied to a light emitting diode using -6).

[Explanation of symbols]

 3 Liquid crystal panel 6 Light emitting diode as light source 13 Semiconductor chip as light source

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Tomokazu Sagara 15-1 Kamiogi, Suginami-ku, Tokyo Marusan Building Nemoto Special Chemical Co., Ltd. F-term (reference) 2H091 FA43Z LA15 LA16 4G076 AA02 AA18 AB02 DA11 4H001 CA02 XA08 XA13 XA31 XA39 XA64 YA58 YA59 5F041 AA12 CA34 CB31 DA81 EE23 EE25 FF01

Claims (7)

[Claims] 1. R is at least one element of yttrium (Y) and gadolinium (Gd), and M is aluminum (Al) and gallium (Ga)
And at least one of the elements represented by the general formula R
₃ M ₅ O ₁₂ : a phosphor represented by Ce, Pr. 2. The phosphor according to claim 1, wherein M is Al. 3. The general formula is represented by (Y _1-x , Gd _x ) ₃ (Al
_{1-y, Ga y) 5} O 12: Ce z, is represented by _{Pr w, 0 ≦ x ≦ 0.5,0} ≦ y ≦ 0.5,0.001 ≦ z ≦
0.5 and 0.001 ≦ w ≦ 0.5. 4. The method according to claim 3, wherein y = 0.
The phosphor according to claim 1. 5. The phosphor according to claim 1, wherein the excitation light having an emission peak at a wavelength of 250 nm or more and 530 nm or less increases the special color rendering index of red. 6. The phosphor according to claim 1, which is provided in a light source provided with a semiconductor chip containing a gallium nitride-based compound as a main component. 7. The phosphor according to claim 1, wherein said phosphor is provided in a light source for irradiating light to a liquid crystal panel for displaying image data in color.