JPH04178491A - Aluminate fluorescent substance and fluorescent lamp using the same - Google Patents

Abstract

PURPOSE:To provide the subject fluorescent substance having good color purity, reduced in the lowering of brightness during the life thereof and suitable for fluorescent lamps used in large displays, etc., by employing co-activating agents comprising trivalent Ce, divalent Eu, etc. CONSTITUTION:The objective fluorescent substance represented by the formula (4.5<=Z<=15). The preparation of the fluorescent substance comprises e.g. sufficiently mixing raw materials comprising La2O3, CeO2, Mg(OH)2, Eu2O3, MnCO3, and Al2O3, baking the mixture at 1400 deg.C for 3hr in air, crushing and mixing the baked product, again baking the mixture at 1600 deg.C for 4hr in a reducing atmosphere, crushing, washing and mixing the products.

Description

DETAILED DESCRIPTION OF THE INVENTION 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.

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. A planar light-emitting type variable color fluorescent lamp used for pixels of such large displays is disclosed in Japanese Patent Application Laid-open No. 61-55851 and Japanese Patent Laid-Open No. 2003-11102.
It is shown in the publication No.-129847. These variable color fluorescent lamps are used as pixels in large displays.
It is composed of one or more sets of picture elements that each emit monochromatic phosphors that emit light in green, R (red), and B (blue). Among the phosphors used in such flat-emitting fluorescent lamps for large displays, for example, terbium-activated cerium magnesium aluminate (hereinafter abbreviated as CAT) is used as the G component phosphor.

Inventive power 1 Problem to be solved As shown in Figure 3, the G component phosphors used in conventional flat-emitting fluorescent lamps for large displays are:
Since it uses light emitted from trivalent terbium, as typified by CAT, the color purity of the green color is not satisfactory, and there is a problem that the color reproduction range as a display device is narrower than that of a general color TV. There was a desire for improvement. In the figure, the R component phosphor is yttrium oxide (hereinafter referred to as Y) activated with trivalent europium.
OX), and the B component phosphor is barium magnesium aluminate (hereinafter referred to as B) activated with divalent europium.
(abbreviated as AM).

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 divalent manganese, barium magnesium aluminate activated with divalent europium and manganese, and cerium magnesium aluminate activated with divalent manganese. 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 life is poor, and cerium activated with divalent manganese In the case of magnesium aluminate, the brightness maintenance rate during its life is good, but
The drawback was that the brightness itself was low.

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

Means to Solve the Problem In order to solve this problem, the aluminate phosphor of the present invention has the general formula: (Ln, Ce) (Mg, Eu, Mu) A I
2ZO2,5+32 (however, 4.5≦z≦15
).

Further, the fluorescent lamp of the present invention has the general formula: (Ln', Ce) (Mg, Eu, Mu) A
I 2z 02. s+:l□(However, 4.5≦z≦1
A fluorescent film made of an aluminate phosphor represented by 5) is provided on the inner surface of the glass tube.

Function: Since the aluminate phosphor of the present invention uses two types of coactivators, divalent europium and trivalent cerium, its sensitizing effect is noticeable, and the position of trivalent cerium is Since stabilization is achieved by replacing cerium with a rare earth element such as ytrium, gadolinium, or lanthanum, a clear improvement in brightness can be obtained compared to the conventional case of coactivation using only trivalent cerium. Furthermore, when applied to a fluorescent lamp, the above-mentioned sensitizing effect as well as the stabilizing effect due to rare earth element substitution work well, resulting in a property with little reduction in brightness throughout the life.

Examples of the present invention will be described below.

Example FIG. 1 shows an aluminate phosphor (Lao,
zCeo, s) (Mgo, 7sEuo, o+Mno,
2) The emission spectrum (curve 1) of AI++O+s by 254 nm ultraviolet excitation with conventional Eu-free CeM
It is shown in comparison with curve 2) of go, sM no, 2A 1 ++O+s. As is clear from FIG. 1, in the phosphor according to the present invention, the luminescence due to trivalent cerium present in the vicinity of 360 nm decreases, and at 450 nm.
It was discovered that light emission due to divalent europium was newly obtained near m. In other words, by adding divalent europium to the conventional trivalent cerium to create two types of co-activators, the luminescence of divalent manganese can be enhanced, and the luminescence of divalent europium can also be obtained. Therefore, the effects of the present invention are exhibited.

In addition, Figure 2 shows the general formula: (L ao, 4c eo, c
) (M go, 8-xE uxM no, 2) AI
The chromaticity point of the light emitted by a series of phosphors according to the present invention expressed by +5025 when excited by 254 nm ultraviolet rays is x, along with those of CAT, YOX, and BAM used in conventional flat-emitting fluorescent lamps for large displays. It is shown on the y coordinate. In FIG. 2, G.

R and B are NTSC, which is used in general color TVs.
These are the chromaticity coordinates of the method. From FIG. 2, it can be seen that the color purity of the phosphor according to the present invention is good, compared to conventional phosphors such as YOX and B.
It can be seen that by combining it with AM, it is possible to achieve color reproduction equivalent to that of a general color television.

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 yttrium, gadolinium, and lanthanum compounds as a cerium substitute, and at least one compound selected from cerium compounds such as cerium oxide and cerous nitrate as a cerium source. As a source of magnesium, at least one compound selected from magnesium compounds such as basic magnesium carbonate and magnesium fluoride; as a source of europium, at least one compound selected from europium compounds such as europium oxide and europium fluoride; Type 1, a manganese source with a small amount of compounds selected from manganese compounds such as manganese carbonate (both type 1,
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 is placed in a crucible and fired in air at 1200 to 1600°C for 2 to 4 hours.

After pulverizing the obtained fired product, it is put back into the crucible and fired at 1400 to 1600°C for 2 to 4 hours in a reducing atmosphere. The fired product was subjected to treatments such as pulverization and washing with water to obtain a green light-emitting aluminate phosphor of the present invention.

In the method for producing the phosphor according to the present invention described above, fluorides such as aluminum fluoride and magnesium fluoride, which are well known as flux materials used in aluminate phosphors, or poric acid and boron oxide are added. The results showed that if used in an appropriate amount, it is effective in improving brightness.

Next, examples of the present invention will be described.

Example 1 La2O30,10 moleCe02 0.80 moleMg (OH)20.79 moleEu2O30,005 moleMnCO30,20 moleAl2O35,50 mole The above raw materials were thoroughly mixed and heated in air at 1400°C for 3 hours. Fire. After pulverizing and mixing the obtained baked product, it was baked at 1600°C for 4 hours in a reducing atmosphere, pulverized, washed with water,
A phosphor was obtained by mixing.

The composition of the obtained phosphor is (L aa, 2c eo, e)
(M go, 7s E tJo, 01 M no, 2)
A I ++ O12 This phosphor was applied to the inner surface of a glass bulb to produce an FCL30/28 fluorescent lamp. The luminance of this fluorescent lamp was compared with C e (M ga, sM
no, 2) The brightness was 125% of that of a fluorescent lamp similarly produced using A I ++019. Furthermore, the lighting intensity maintenance rate after 2000 hours of lighting at the rated voltage was 92.5% for the fluorescent lamp of this example, and 87.0% for the fluorescent lamp produced in comparison. That is, the fluorescent lamp using the phosphor according to the present invention had clearly improved characteristics in both brightness and brightness maintenance rate.

Example 2 La203 0.20 mol Ce2(NO3
)3.6H200,30mol MgO0,88molEI4203 0.0025molMnC
A phosphor was obtained by the same treatment as in Example 1 using the above raw materials. The composition of the obtained phosphor was (Lao4Ceo6>(M gO,8
95Euo, oosM no, +o)A 115025
Met.

This phosphor is applied to the inner surface of the glass bulb, and FCL30/
28 fluorescent lamps were fabricated. The brightness of this fluorescent lamp is
For comparison, calcined Ce (Mgo, sM no, +>A
The brightness was 113% of that of a fluorescent lamp similarly prepared using I 1502F+. In addition, the lighting intensity maintenance rate after 2000 hours of lighting at the rated voltage was 94.0% for the fluorescent lamp of this example, and 89.0% for the lamp produced as a comparison. In the lamp using this method, clearly improved characteristics were obtained in both brightness and brightness maintenance rate, demonstrating the effectiveness of the present invention.

Example 3 Y2O20,10 mole Ce 02 0.80 mole Mg(OH)2 0.80 mole Eu2O30,025 mole MnCO30,15 mole Al2O36,00 mole 83 BO30,003 mole Using the above raw materials, the same treatment as in Example 1 was carried out. A phosphor was obtained. The composition of the obtained phosphor is (Yo, 2 Ceo, a)
(M go, aE uo, osM no, +s) A
It was 112020.5. This phosphor was applied to the inner surface of a glass bulb to produce an FCL30/28 fluorescent lamp. The brightness of this fluorescent lamp is compared to that of fired Ce.
(Mgo, ssMno, +s) A 112020.5
11 for the brightness of a fluorescent lamp made in the same way using
It was 0%. In addition, the lighting intensity maintenance rate after 2000 hours of lighting at the rated voltage was 92 for the fluorescent lamp of this example.
．． 5%, and 89% in the fluorescent lamp made as a comparison.
．． In other words, the lamp using the phosphor according to the present invention had clearly improved characteristics in both brightness and brightness maintenance rate, and the effects of the present invention were recognized.

Example 4 Gd203 0.20 mol Ce2(CO
3) 3.6820 0.30 mol Mg(OH)2
0.40 mol Eu2O30, 10 mol MnCO30, 40 mol Al(OH)3 20.00 mol Using the above raw materials, a phosphor was obtained by the same treatment as in Example 1.

The composition of the obtained phosphor is (Gda, 4Ceo, 6) (
M go, 4E LJo, 2M no, 4) A I 2
It was 0032.5. This phosphor was applied to the inner surface of a glass bulb to produce an F CL 30/28 fluorescent lamp. The brightness of this fluorescent lamp was determined by firing Ce (
The brightness was 106% of the brightness of a lamp similarly produced using Mgo, 4Mno, 4) A 120032.5. In addition, the lighting intensity maintenance rate after 2000 hours of lighting at the rated voltage was 91.0% for the fluorescent lamp of this example, and 85.0% for the fluorescent lamp prepared as a comparison. The fluorescent lamp using the fluorescent lamp has clearly improved characteristics in both brightness and brightness maintenance rate, and the effects of the present invention are recognized.

The aluminate phosphor according to the present invention is 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.

As described in detail, according to the present invention, two types of coactivators, divalent europium and trivalent cerium, are used simultaneously, and the position of trivalent cerium is replaced by a rare earth element. Because it is stabilized with cerium, it achieves high brightness that could not be obtained with conventional co-activation using only trivalent cerium.
Moreover, a green-emitting phosphor made of divalent manganese having a good luminance maintenance rate throughout its life can be obtained. Further, by applying the phosphor according to the present invention to a flat-emitting type fluorescent lamp for a large display or a fluorescent lamp that is lit under high load, the green light emission with good color purity can be utilized.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the emission spectrum of the aluminate phosphor according to the present invention in comparison with that of a conventional one, and FIG. 2 shows the chromaticity of the phosphor of Example 1 of the present invention. The diagram shown on the y-chromaticity diagram, Figure 3, shows B, G, and R of a flat-emitting fluorescent lamp used for conventional large displays.
It is a diagram showing the chromaticity of on an x,y chromaticity diagram. Agent's name: Patent attorney Haruaki Ogata, two idiots, Awa k (Oba, Kijochi)

Claims (2)

[Claims] (1) General formula: (Ln, Ce) (Mg, Eu, Mn) A
l_2_zO_2. ＿5＿＋＿3＿z (However, 4.5
≦z≦15). (2) General formula: (Ln, Ce) (Mg, Eu, Mn) A
l_2_zO_2. ＿5＿＋＿3＿z (However, 4.5
A fluorescent lamp characterized in that a fluorescent film made of an aluminate phosphor represented by z≦15) is provided on the inner surface of a glass tube.