JP2002003838A - Phosphor and fluorescent lamp obtained by using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a rare earth aluminate phosphor improved in luminous intensity which is activated by bivalent manganese, and to provide a fluorescent lamp having good luminance maintaining ratio throughout the life obtained by using the same. SOLUTION: In a rare earth aluminate phosphor activated with bivalent manganese, a phosphor having a chemical composition represented by the general formula: (Ln, Ce)2O3.x(Mg1-a-bMaMnb)O.yAl2O3.zSiO2 is employed. In the formula, Ln is at least one element selected among Y, Gd and La; M is at least one element selected among Zn, Ba, Sr and Ca; 0.5<=x<=2.0; 4<=y<=7; 0<z<=1.0; 0<a<=0.6; and 0.05<=b<=0.4. As an example, 0.5(La0.2Ce0.8)2O3.(Mg0.75 Zn0.15Mn0.1)O.5.5Al2O3.0.1SiO2 can be cited.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a phosphor activated with divalent manganese and a fluorescent lamp using the same.

[0002]

2. Description of the Related Art In recent years, large-sized color image display devices that can be used outdoors have been developed and are being widely used. Japanese Patent Application Laid-Open No. 61-5585 discloses a flat emission type variable color fluorescent lamp used for pixels of such a large display.
No. 1 and JP-A-2-129847. These variable color fluorescent lamps have G (green), R (red), and B
It is composed of one or a plurality of sets of picture elements that emit monochromatic light from each of the phosphors that emit light in (blue). Among the phosphors used in such a flat display type fluorescent lamp for a large display, as a G component phosphor, for example, cerium magnesium aluminate activated with terbium (hereinafter, referred to as terbium)
CAT).

[0003]

As shown in FIG. 3, as a G component phosphor used in a conventional flat emission fluorescent lamp for a large display, trivalent terbium as represented by CAT is used. Since light emission is used, the color purity of green is not satisfactory, and there is a problem that the color reproduction range is narrower than that of a general color television, and improvement thereof has been desired. In FIG. 3, the R component phosphor is yttrium oxide (hereinafter abbreviated as YOX) activated with trivalent europium, and the B component phosphor is barium magnesium aluminate (hereinafter BAM) activated with divalent europium. Abbreviated).

As a phosphor having a good color purity of green light emission, light emission by divalent manganese is suitable, and zinc silicate activated by divalent manganese, divalent europium and divalent manganese are used. Co-activated barium magnesium aluminate and cerium magnesium aluminate activated with divalent manganese are known. But,
The fluorescent lamps for large displays described above are usually lighted under high load. In the case of zinc silicate activated with divalent manganese and barium magnesium aluminate coactivated with divalent europium and divalent manganese. Is inferior in the luminance maintenance rate during the lifetime, and in the case of cerium magnesium aluminate activated with divalent manganese, the luminance maintenance rate during the lifetime is good but the luminance itself is low. .

Regarding the improvement of the luminance of the cerium magnesium aluminate phosphor activated with divalent manganese, Japanese Patent No. 2663306 discloses a method in which part of magnesium is replaced with Ba, Sr, Ca, Zn, or the like. , Cerium is partially replaced by La, Gd, Y, In and the like. Patent No. 2753
No. 138 and Japanese Patent No. 2786329,
Cerium magnesium aluminate co-activated with divalent europium and divalent manganese is disclosed.

However, even in these improved phosphors, when activated alone with divalent manganese, the effect of improving the luminance retention rate by replacing part of cerium with La, Gd, Y, In or the like. However, it is difficult to stably form a solid solution of these divalent metal elements in the phosphor crystal by a method in which part of magnesium is replaced with Ba, Sr, Ca, Zn, or the like. In the case of (1), there is a disadvantage that the amount of the solid solution fluctuates greatly. Also,
The method disclosed in Japanese Patent No. 2,786,329, which enhances green light emission using sensitized light emission by divalent europium, has a disadvantage that the color purity of the light emission is slightly reduced.

The present invention relates to a phosphor for use in a fluorescent lamp which is operated under a high load condition such as for a large display. It is intended to provide a lamp.

[0008]

In order to solve this problem, the present inventor studied a conventional cerium magnesium aluminate phosphor activated with divalent manganese,
Part of cerium is replaced by at least one rare earth element selected from yttrium, gadolinium and lanthanum, and part of magnesium is replaced by at least one selected from zinc, barium, strontium and calcium However, they have found that a green phosphor having a high emission intensity can be synthesized by dissolving silicon oxide in a solid solution during the synthesis of the phosphor.

That is, the phosphor of the present invention is a rare earth aluminate phosphor activated with divalent manganese,
The chemical composition is represented by the following general formula.

[0010] _{(Ln m Ce n) 2 O} 3 · x (Mg 1-ab M a M
n _b ) O.yAl ₂ O ₃ .zSiO ₂ where Ln is at least one element selected from Y, Gd and La, and M is selected from Zn, Ba, Sr and Ca Represents at least one element,
x, y, z, a, b, m and n are 0.5 ≦ x ≦ 2.
0, 4 ≦ y ≦ 7, 0 <z ≦ 1.0, 0 <a ≦ 0.6,
0.05 ≦ b ≦ 0.4, represented by m + n = 1.

Further, a fluorescent lamp according to the present invention includes a fluorescent film formed of the above-mentioned phosphor.

As a result, the rare earth aluminate phosphor activated with divalent manganese of the present invention has at least one rare earth oxide selected from yttrium oxide, gadolinium oxide and lanthanum oxide during the synthesis of the phosphor. Product and silicon oxide as a solid solution, a higher emission intensity is obtained as compared to a conventional phosphor synthesized without using them, and the phosphor of the present invention was applied to a fluorescent lamp. Also in this case, since the divalent metal ion that substitutes for magnesium is stably dissolved in the crystal of the phosphor, characteristics that the luminance is hardly reduced throughout the life can be obtained.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of a rare earth aluminate phosphor activated with divalent manganese and a fluorescent lamp using the same according to the present invention will be described in detail.

(Embodiment 1) In the phosphor of the present invention,
Its phosphor having the chemical composition of the following general formula _{(Ln m Ce n) 2 O} 3 · x (Mg 1-ab M a Mn b) O · y
When represented by Al ₂ O ₃ .zSiO ₂ , Ln is at least one element selected from Y, Gd and La, and M is at least one element selected from Zn, Ba, Sr and Ca Wherein x, y, z, a and b are those whose amounts are limited as shown below. However, m + n = 1.

That is, a is a divalent metal element that partially substitutes for magnesium, b is the concentration of manganese as an activator, and 0 <a ≦ 0.6, 0.05 ≦ b ≦ 0 .4
Is limited in the range. When the substitution amount a of M exceeds 0.6, the regular generation of phosphor crystals is inhibited, and the emission intensity is reduced. On the other hand, if the manganese concentration b is 0.05 or less, sufficient light emission intensity cannot be obtained, and if it exceeds 0.4, the light emission intensity decreases due to concentration quenching.

On the other hand, x indicates the composition ratio of MgO partially substituted by another element, and 0.5 ≦ x ≦
Limited to 2.0. Further, y indicates the composition ratio of Al ₂ O ₃ , and in the range of 4 ≦ y ≦ 7, emission intensity equal to or higher than that of a conventional phosphor synthesized without adding silicon oxide can be obtained. Further, in the range of 4.5 ≦ y ≦ 6, the luminous intensity was clearly improved.

FIG. 1 shows a rare earth aluminate phosphor (La _0.2 Ce _0.8 ) ₂ O ₃ · 1.1 (Mg _0.7 Z) according to the present invention.
FIG. 4 is a diagram showing a change in green light emission intensity when the addition amount z of silicon oxide is changed in n _0.1 Mn _0.2 ) O.5.5Al ₂ O ₃ .zSiO ₂ . A clear increase in emission intensity was observed due to the solid solution of silicon oxide. As is clear from FIG. 1, the amount of silicon oxide added is 0 <z ≦ 1.
Limited by 0.

The rare earth aluminate phosphor according to the present invention can be obtained by the following production method.

As the phosphor material, at least one selected from the compounds of yttrium, gadolinium and lanthanum (L
n) at least one cerium source selected from cerium compounds such as cerium oxide and cerous nitrate;
Seeds, basic magnesium carbonate as a magnesium source,
At least one selected from magnesium compounds such as magnesium hydroxide and magnesium fluoride; at least one selected from manganese compounds such as manganese carbonate as a manganese source; aluminum oxide, aluminum hydroxide and the like as an aluminum source And at least one selected from silicon compounds such as silicon oxide as a silicon source.

A predetermined amount of these raw materials is weighed and mixed well. Put this mixture in a crucible and in the air,
Bake at 1600 ° C for 2-4 hours.

After the obtained fired product is pulverized, it is again put into a crucible, and is heated at 1400 to 1600 ° C. in a reducing atmosphere at 2 to 4 °
Bake for hours. The fired product was pulverized and washed with water to obtain a green light-emitting phosphor of the present invention.

In the above-described method for producing a phosphor according to the present invention, compounds such as aluminum fluoride, barium chloride, and magnesium fluoride, which are well known as flux materials used for rare earth aluminate phosphors,
Alternatively, addition of boric acid, boron oxide, or the like has a problem in adjusting the particle size distribution of the obtained phosphor, but it has been found that the addition of boric acid or boron oxide is effective in improving the luminance when the amount is appropriate.

Embodiment 2 In Embodiment 2, an example of a fluorescent lamp of the present invention will be described.

FIG. 4 shows a partially cutaway sectional view of the fluorescent lamp of the second embodiment. The fluorescent lamp according to the second embodiment includes a glass bulb 11, electrodes 12 formed at both ends of the glass bulb 11, and a fluorescent film 13 formed on the inner surface of the glass bulb.
And mercury and an inert gas (not shown) sealed in the glass bulb 11. Although FIG. 4 shows only one end of the fluorescent lamp, the other end is the same, so that the illustration is omitted. The fluorescent film 13 is provided in the first embodiment.
At least.

[0025]

Next, an embodiment of the present invention will be described.

Example 1 La ₂ O ₃ : 0.10 mol CeO ₂ : 0.80 mol Mg (OH) ₂ : 0.75 mol ZnO: 0.15 mol Al ₂ O ₃ : 5 50 mol SiO ₂ : 0.10 mol MnCO ₃ : 0.10 mol is weighed and mixed well. This raw material mixture was placed in an alumina crucible and calcined at 1400 ° C. for 3 hours in a reducing atmosphere using a mixed gas of 95% by volume of nitrogen and 5% by volume of hydrogen. The obtained fired product was pulverized, washed with pure water, filtered and dried to obtain a phosphor of the present invention. When this phosphor was analyzed, the composition formula was 0.5 (La _0.2 C
e _0.8 ) ₂ O _3. (Mg _0.75 Zn _0.15 Mn _0.1 ) O.5.5
Al ₂ O ₃ .0.1 SiO ₂ .

The emission intensity of this phosphor when excited by ultraviolet light of 254 nm was significantly improved to 110% as compared with a phosphor of the same composition fired without using silicon oxide.

FIG. 2 is a diagram showing an emission spectrum distribution of the phosphor of Example 1 in which the addition amount z of silicon oxide is 0.1 when excited by ultraviolet light of 254 nm.

FIG. 3 shows the chromaticity point of light emission of the phosphor of Example 1 when excited by ultraviolet light of 254 nm, using CAT and YO used in a conventional flat fluorescent lamp for a large display.
It is the figure shown on x, y coordinates with X, BAM. In FIG. 3, G, R, and B are chromaticity coordinates of the NTSC system used for a general color television. FIG. 3 shows that the color purity of the phosphor according to the present invention is good,
It can be seen that color reproduction equivalent to that of a general color television is realized by combining with OX and BAM.

This phosphor is applied to the inner surface of a glass bulb,
A 30 W, round fluorescent lamp was produced.

The luminance of this fluorescent lamp is 0.5 (La _0.2 C) which is a conventionally known phosphor fired for comparison.
e _0.8 ) ₂ O _3. (Mg _0.75 Zn _0.15 Mn _0.1 ) O.5.5
The luminance was 108% with respect to the luminance of the fluorescent lamp of the comparative example similarly manufactured using Al ₂ O ₃ .

The luminance maintenance ratio after lighting for 2000 hours at the rated voltage is 93.
5%, which is 87% in the fluorescent lamp manufactured as a comparative example.
%Met. That is, in the fluorescent lamp using the phosphor according to the present invention, characteristics that are clearly improved in both luminance and luminance maintenance ratio were obtained.

Example 2 La ₂ O ₃ : 0.20 mol Ce ₂ (NO ₃ ) ₃ .6H ₂ O: 0.30 mol Mg (OH) ₂ : 0.80 mol ZnO: 0 _{.02mol Al 2 O 3: 6.00mol SiO} 2: 0.50mol MnCO 3: weigh 0.18 mol, thoroughly mixed. This raw material mixture was placed in an alumina crucible and fired at 1450 ° C. for 3 hours in a reducing atmosphere using a mixed gas of 95% by volume of nitrogen and 5% by volume of hydrogen. The obtained fired product was pulverized, washed with pure water, filtered and dried to obtain a phosphor of the present invention. When this phosphor was analyzed, the composition formula was 0.5 (La _0.4 C
e _0.6 ) ₂ O _3. (Mg _0.8 Zn _0.02 Mn _0.18 ) O.6Al
₂ O ₃ · 0.5 SiO ₂ .

The emission intensity of this phosphor when excited by ultraviolet light at 254 nm was significantly improved to 105% as compared with a phosphor of the same composition fired without using silicon oxide.

This phosphor is applied to the inner surface of the glass bulb,
A 30 W, round fluorescent lamp was produced.

The luminance of this fluorescent lamp is 0.5 (La _0.4 C) which is a conventionally known phosphor fired for comparison.
e _0.6 ) ₂ O _3. (Mg _0.8 Zn _0.02 Mn _0.18 ) O.6Al
The luminance was 104% of the luminance of the fluorescent lamp of the comparative example similarly manufactured using ₂ O ₃ .

The luminance maintenance ratio after lighting for 2000 hours at the rated voltage is 92.0% for the fluorescent lamp of this embodiment.
5%, which is 88% for the fluorescent lamp manufactured as a comparative example.
%Met. That is, in the fluorescent lamp using the phosphor according to the present invention, characteristics that are clearly improved in both luminance and luminance maintenance ratio were obtained.

(Example 3) As raw materials of a phosphor,
Re Y_TwoO_Three : 0.10mol CeO_Two : 0.80 mol Mg (OH)_Two : 0.50 mol BaCO_Three : 0.20mol Al_TwoO_Three : 7.00 mol SiO_Two : 1.00mol MnCO_Three : Weigh 0.30 mol and mix well. This raw material mixture is converted to alumina
Put in a crucible a mixed gas of 95% by volume nitrogen-5% by volume hydrogen.
Baking at 1400 ° C for 3 hours in reducing atmosphere
did. The obtained fired product is pulverized, washed with pure water, and then filtered.
After drying, the phosphor of the present invention was obtained. This fluorescence
When the body was analyzed, the composition formula was 0.5 (Y _0.2Ce_0.8)
_TwoO_Three・ (Mg_0.5Ba_0.2Mn_0.3) O ・ 7Al_TwoO_Three・ S
iO_TwoMet.

The emission intensity of this phosphor when excited by ultraviolet light at 254 nm was significantly improved to 105% as compared with a phosphor of the same composition fired without using silicon oxide.

This phosphor is applied to the inner surface of a glass bulb,
A 30 W, round fluorescent lamp was produced.

As a comparison, the luminance of this fluorescent lamp was 0.5 (Y _0.2 Ce) which is a conventionally known phosphor fired.
_{0.8) 2 O 3 · (Mg} 0.5 Ba 0.2 Mn 0.3) O · 7Al 2 O 3
Was 103% of the luminance of the fluorescent lamp of the comparative example similarly manufactured using

The luminance maintenance ratio after lighting for 2000 hours at the rated voltage is 92.
0%, which is 89% for the fluorescent lamp manufactured as a comparative example.
%Met. That is, in the fluorescent lamp using the phosphor according to the present invention, characteristics that are clearly improved in both luminance and luminance maintenance ratio were obtained.

Example 4 Gd ₂ O ₃ : 0.10 mol CeO ₂ : 0.80 mol Mg (OH) ₂ : 0.75 mol SrCO ₃ : 0.20 mol Al ₂ O ₃ : 5 .50 mol SiO ₂ : 0.10 mol MnCO ₃ : 0.05 mol is weighed and mixed well. This raw material mixture was placed in an alumina crucible and calcined at 1400 ° C. for 3 hours in a reducing atmosphere using a mixed gas of 95% by volume of nitrogen and 5% by volume of hydrogen. The obtained fired product was pulverized, washed with pure water, filtered and dried to obtain a phosphor of the present invention. When this phosphor was analyzed, the composition formula was 0.5 (Gd _0.2 C
e _0.8 ) ₂ O _3. (Mg _0.75 Sr _0.2 Mn _0.05 ) O.5.5
Al ₂ O ₃ .0.1 SiO ₂ .

The emission intensity of this phosphor when excited by ultraviolet light at 254 nm was significantly improved to 108% as compared with a phosphor of the same composition fired without using silicon oxide.

This phosphor is applied to the inner surface of a glass bulb,
A 30 W, round fluorescent lamp was produced.

As a comparison, the luminance of this fluorescent lamp was 0.5 (Gd _0.2 C
e _0.8 ) ₂ O _3. (Mg _0.75 Sr _0.2 Mn _0.05 ) O.5.5
The luminance was 105% of the luminance of the fluorescent lamp of the comparative example similarly produced using Al ₂ O ₃ .

Further, regarding the luminance maintenance ratio after lighting for 2000 hours at the rated voltage, the fluorescent lamp of this embodiment has a luminance maintaining ratio of 91.
5%, and 86% in the fluorescent lamp manufactured as a comparative example.
%Met. That is, in the fluorescent lamp using the phosphor according to the present invention, characteristics that are clearly improved in both luminance and luminance maintenance ratio were obtained.

In this embodiment, a round tube fluorescent lamp is used. However, the present invention can achieve the effect even when applied directly to a straight tube fluorescent lamp or a compact fluorescent lamp or together with a protective film. is there.

[0049]

As described above, according to the present invention,
A green light-emitting phosphor made of divalent manganese, which has high luminance and has a good luminance maintenance rate throughout its life, can be obtained.

Further, when the phosphor according to the present invention is applied to a flat light emitting fluorescent lamp for a large display or a fluorescent lamp which is lit with a high load, green light with good color purity can be utilized. .

[Brief description of the drawings]

FIG. 1 is a view showing a relative peak height of green light emission intensity when a solid solution amount of SiO ₂ is changed in a phosphor of the present invention.

FIG. 2 is a diagram showing an emission spectrum distribution of a phosphor in Example 1.

FIG. 3 shows the chromaticity of the phosphor shown in Example 1 of the present invention together with the chromaticity of B, G, and R phosphors conventionally used;
It is the figure shown on the x, y chromaticity diagram.

FIG. 4 is a partially cutaway sectional view showing an example of the fluorescent lamp of the present invention.

[Explanation of symbols]

 11 glass bulb 12 electrode 13 fluorescent film

Claims (2)

[Claims] 1. A rare earth aluminate phosphor activated with divalent manganese, the chemical composition of which is represented by the following general formula. _{(Ln m Ce n) 2 O} 3 · x (Mg 1-ab M a Mn b) O · y
Al ₂ O ₃ .zSiO ₂ where Ln is at least one element selected from Y, Gd and La, and M is at least one element selected from Zn, Ba, Sr and Ca Represents an element,
x, y, z, a, b, m and n are 0.5 ≦ x ≦ 2.
0, 4 ≦ y ≦ 7, 0 <z ≦ 1.0, 0 <a ≦ 0.6,
0.05 ≦ b ≦ 0.4, represented by m + n = 1. 2. A fluorescent lamp comprising a phosphor film formed from the phosphor according to claim 1.