JPH04239590A - Aluminate fluophor and fluorescent lamp using the same - Google Patents

Abstract

PURPOSE:To provide the title fluophor and fluorescent lamp of good color purity with suppressed luminance decline throughout its working life. CONSTITUTION:The objective aluminate fluophor of the general formula Ce(Mg, M, Eu, Mn)Al2zO2.5+3z (M is at least one element selected from Ba, Sr and Ca; 4.5<=z<=15) and the other objective fluorescent lamp provided with a fluorescent film consisting of this fluophor on the inner surface of a glass tube.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminate phosphor that emits green light when exposed to ultraviolet rays from a low-pressure mercury discharge, and a fluorescent lamp using the same.

0002

2. Description of the Related Art In recent years, large color image display devices that can be used outdoors have been developed and are becoming more popular. Plane-emitting type variable color fluorescent lamps used in pixels of such large-sized displays are disclosed in Japanese Patent Laid-Open Nos. 55851-1985 and 129847-1999. These variable color fluorescent lamps are made up of one or more sets of picture elements that emit monochromatic phosphors each of which emits G (green), R (red), and B (blue) to form pixels in large displays. has been done. Among these phosphors, for example, terbium-activated cerium magnesium aluminate (hereinafter abbreviated as CAT) is used as the G component phosphor.

0003

[Problems to be Solved by the Invention] As shown in FIG. 3, the G component phosphor used in conventional flat-emitting fluorescent lamps for large displays uses trivalent terbium as represented by CAT. Because it uses light emission, the color purity of green color is not satisfactory, and the color reproduction range as a display device is narrower than that of general color televisions.Therefore, there has been a desire to improve this problem. In FIG. 3, the R component phosphor is yttrium oxide activated with trivalent europium, and the B component phosphor is barium magnesium aluminate activated with divalent europium. Divalent manganese is suitable as a phosphor that emits green light with good color purity, and divalent manganese is suitable for use in fluorescent lamps.
Known examples include zinc silicate activated with valent manganese, barium magnesium aluminate activated with divalent europium and manganese, and cerium magnesium aluminate activated with divalent manganese. The fluorescent lamps for large displays mentioned above are usually lit under high load, so
In the case of divalent manganese-activated zinc silicate, divalent europium, and manganese-activated barium magnesium aluminate, the brightness maintenance rate during the life is inferior, while cerium magnesium activated with divalent manganese In the case of aluminate, the brightness maintenance rate during the life is good, but the brightness itself is low.

The present invention is directed to an aluminate phosphor that has good color purity and low brightness reduction throughout its life, and a phosphor using the same, which is used in fluorescent lamps that are operated under high load conditions such as those for large displays. It provides a lamp.

[0005]

[Means for Solving the Problems] In order to solve these problems, the aluminate phosphor of the present invention has the general formula: C
e(Mg,M,Eu,Mn)Al2zO2.5+3z(
However, M is at least one element selected from Ba, Sr, and Ca, and z is a number satisfying the condition of 4.5≦z≦15.

Further, the fluorescent lamp of the present invention has the general formula: C
e(Mg,M,Eu,Mn)Al2zO2.5+3z(
However, M is at least one element selected from Ba, Sr, and Ca, and z is a number satisfying the condition of 4.5≦z≦15). It has a body membrane on the inner surface of the tube.

[0007]

[Function] As shown in the above general formula, the aluminate phosphor of the present invention replaces a portion of divalent magnesium with barium,
Since the element is replaced with at least one element selected from strontium and calcium and divalent europium, the luminescence due to divalent manganese is enhanced, and luminescence due to divalent europium is also obtained. Further, when such a phosphor is applied to a fluorescent lamp, the effect of the above-mentioned replacement works well, and a property with little reduction in brightness throughout the life of the lamp can be obtained.

Examples of the present invention will be described below.

[0009]

[Example] Figure 1 shows the aluminate phosphor C according to the present invention.
eMg0.59Ba0.2Eu0.01Mn0.2Al
The emission spectrum of 11O19 by 254 nm ultraviolet excitation was compared to the conventional Ba and Eu-free CeMg0.8M.
It is shown in comparison with that of n0.2Al11O19. As is clear from FIG. 1, it was found that in the phosphor according to the present invention, the luminescence due to divalent manganese near 517 nm was enhanced, and the luminescence due to divalent europium at 450 nm was also obtained. In addition, Fig. 2 shows CeMg0.59Ba0.2Eu0.01Mn0.2A
2 of the phosphor according to the present invention represented by l15O25
The chromaticity point P of light emitted by 54 nm ultraviolet excitation is x, y
This is shown on the coordinates. In FIG. 2, G, R, and B are chromaticity coordinates of the NTSC system used in general color televisions. Furthermore, it was confirmed that the chromaticity point of the light emission of the phosphor according to the present invention shows almost the same color purity regardless of the type of element M that replaces a part of the divalent magnesium. That is, from FIG. 2, the color purity of the phosphor according to the present invention is good, and compared to the conventional ones such as YOX and BAM.
It can be seen that in combination with this, it is possible to achieve color reproduction equivalent to that of a regular color TV.

The aluminate phosphor according to the present invention can be obtained by the following manufacturing method.

The phosphor raw material contains at least one compound selected from cerium compounds such as cerium oxide and cerous nitrate as a cerium source, and at least one compound selected from among cerium compounds such as basic magnesium carbonate and magnesium fluoride as a magnesium source. For example, in the case of barium, at least one compound selected from barium carbonate as the barium source,
At least one compound selected from barium compounds such as barium oxide and barium fluoride; at least one compound selected from europium compounds such as europium oxide and europium fluoride as a europium source; and a manganese compound such as manganese carbonate as a manganese source. At least one compound selected from the following is used, and at least one compound selected from aluminum compounds such as aluminum oxide and aluminum hydroxide is used as the aluminum source. A predetermined amount of these raw materials is weighed and thoroughly mixed. This mixture was put into a crucible and heated to 1200 to 16
Bake at 00°C for 2-4 hours. After pulverizing the obtained fired product, it was put back into the crucible and heated to 1400 to 1
Bake at 600°C for 2 to 4 hours. The fired product was subjected to treatments such as pulverization and washing with water to obtain a green-emitting aluminate phosphor of the present invention.

In the method for producing a phosphor according to the present invention, fluorides such as aluminum fluoride and magnesium fluoride, which are well known as flux materials used in aluminate phosphors, or fluorides such as boric acid and boron oxide are used. It has been found that addition in an appropriate amount is effective in improving brightness. On the other hand, since it is not common to evaluate prototypes using fluorescent lamps using flat-emitting fluorescent lamps for large displays, F
A CL30/28 lamp was used.

Examples 1, 2, 3 and 4 will be described below. Example 1 CeO2
1.00 mol Mg(OH)2
0.40 mol B
aCO3
0.39 mol Eu2O3
0.005 mol MnCO3
0.20
Mol Al2O3
5.50 mol of the above raw materials are thoroughly mixed and calcined in air at 1300° C. for 3 hours. The obtained fired product was pulverized and mixed, then fired at 1500° C. for 4 hours in a reducing atmosphere, pulverized, washed with water, and mixed to obtain a phosphor. The composition of the obtained phosphor was Ce(Mg0.4
Ba0.39Eu0.01Mn0.2)Al11O19
Met. This phosphor is applied to the inner surface of the glass tube, and FCL
A 30/28 lamp was made. For comparison, the luminance of this lamp was determined by firing a conventionally known phosphor, Ce(
The brightness was 135% of the brightness of a lamp similarly produced using Mg0.8Mn0.2)Al11O19. Furthermore, the luminance maintenance rate after 2000 hours of lighting at the rated voltage was 92% for the fluorescent lamp of the example of the present invention, and 87.0% for the fluorescent lamp prepared as a comparison. That is, the fluorescent lamp using the phosphor according to the present invention had clearly improved characteristics in terms of both brightness and brightness maintenance rate.

Example 2 Ce2(NO3)3.6H2O 0.50
Mol MgO
0.65 mol BaCO3
0.05 mol E
u2O3
0.10 mol MnCO3
0.10 mol Al2O3
7.5
0 mol MgF2
A phosphor was obtained by the same treatment as in Example 1 using 0.015 mol of the above raw material. The composition of the obtained phosphor was Ce(Mg0.65Ba0.05Eu0
．． 2Mn0.1)Al15O25. This phosphor was applied to the inner surface of a glass tube to produce an FCL30/28 fluorescent lamp. The brightness of this lamp was 125% of the brightness of a fluorescent lamp similarly produced using fired Ce(Mg0.9Mn0.1)Al15O25 as a comparison. Furthermore, the luminance maintenance rate after 2000 hours of lighting at the rated voltage was 93% for the fluorescent lamp of the example of the present invention, and 89.0% for the fluorescent lamp prepared as a comparison. That is, the fluorescent lamp using the phosphor according to the present invention had clearly improved characteristics in terms of both brightness and brightness maintenance rate, and the effects of the present invention were recognized.

Example 3 CeO2
1.00 mol Mg(OH)2
0.65 mol BaCO
3 0.1
0 mol Eu2O3
0.05 mol MnCO
3 0.1
5 moles Al2O3
6.00 mol H3BO
3 0.
003 mol A phosphor was obtained by the same treatment as in Example 1 using the above raw materials. The composition of the obtained phosphor was Ce(
Mg0.65Ba0.1Eu0.1Mn0.15)Al
It was 12O20.5. This phosphor was applied to the inner surface of a glass tube to produce an FCL30/28 fluorescent lamp. The brightness of this lamp was determined by firing Ce (Mg0.8
The brightness was 130% of that of a fluorescent lamp similarly produced using 5Mn0.15)Al12O20.5. Furthermore, the luminance maintenance rate after 2000 hours of lighting at the rated voltage was 91.5% for the fluorescent lamp of the example of the present invention, and 89.0% for the fluorescent lamp prepared as a comparison.

That is, in the fluorescent lamp using the phosphor according to the present invention, clearly improved characteristics in both brightness and brightness maintenance rate were obtained, and the effects of the present invention were recognized.

Example 4 Ce2(CO3)3.6H2O 0.50
Mol Mg(OH)2
0.40 mol SrCO3
0.195 mol Eu
F3
0.005 mol MnCO3
0.40 mol Al(OH)3
A phosphor was obtained by the same treatment as in Example 1 using 20.00 mol of the above raw materials. The composition of the obtained phosphor was Ce(Mg0.4Sr0
．． 19Eu0.01Mn0.4)Al20O32.5. This phosphor is applied to the inner surface of the glass tube, and FCL3
A 0/28 fluorescent lamp was manufactured. The brightness of this lamp is
For comparison, fired Ce(Mg0.4Mn0.4)Al
The brightness was 110% of that of a fluorescent lamp similarly produced using 20O32.5. Also, 20 at the rated voltage
The luminance maintenance rate after 00 hours of lighting was also 91% for the fluorescent lamp of the example of the present invention, and 85.0% for the fluorescent lamp prepared as a comparison.

That is, even in a fluorescent lamp using the phosphor according to the present invention in which a part of magnesium is replaced with strontium, the effect is somewhat low, but the characteristics are clearly improved in terms of both brightness and brightness maintenance rate. was obtained, and the effect of the present invention was recognized.

Although not shown in the examples, similar effects were also observed when some of the magnesium was replaced with calcium.

The phosphor according to the present invention can be used not only in flat-emitting fluorescent lamps for large displays and fluorescent lamps for general lighting that are lit under high loads, but also in fluorescent lamps that utilize excitation in the vacuum ultraviolet region. Its effects are recognized in the field as well.

[0021]

[Effects of the Invention] As explained above, according to the present invention,
Since a part of divalent magnesium is replaced with at least one element selected from barium, strontium, and calcium and divalent europium,
In addition to enhancing the luminescence of valent manganese, luminescence due to divalent europium is also obtained, and a clear improvement in brightness can be obtained compared to conventional phosphors. Further, when the phosphor according to the present invention is applied to a fluorescent lamp, the effect of the above-mentioned substitution works well, and a property with little reduction in brightness throughout the life can be obtained. Further, by applying the phosphor according to the present invention to a flat-emitting fluorescent lamp for large displays or a fluorescent lamp that is lit under high load, the green light emission with good color purity can be utilized.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the emission spectrum of an aluminate phosphor according to the present invention in comparison with a conventional one.

[Fig. 2] A diagram showing the chromaticity of the fluorescent lamp shown in Example 1 of the present invention on an x,y chromaticity diagram.

[Figure 3] A diagram showing the B, G, and R chromaticities of a conventional flat-emitting fluorescent lamp used for large displays on an x,y chromaticity diagram.

Claims (2)

[Claims] [Claim 1] General formula: Ce(Mg, M, Eu, Mn)A
l2zO2.5+3z (However, M is at least one element selected from Ba, Sr and Ca, and z
is a number that satisfies the condition of 4.5≦z≦15). [Claim 2] General formula: Ce(Mg, M, Eu, Mn)A
l2zO2.5+3z (However, M is at least one element selected from Ba, Sr and Ca, and z
z is a number satisfying the condition 4.5≦z≦15).