JP4702565B2 - Manganese-activated rare earth aluminate phosphor and fluorescent lamp using the same - Google Patents

Description

  The present invention relates to a manganese-activated rare earth aluminate phosphor and a fluorescent lamp using the same, and more particularly to a cold cathode fluorescent lamp used for a backlight of a liquid crystal display device.

  The liquid crystal display device is a non-light-emitting display device that displays an image on a panel by a combination of a liquid crystal shutter and a backlight, and a cold cathode fluorescent lamp that is easily thinned is mainly used for the backlight. A cold cathode fluorescent lamp used for such a backlight is required to have a high luminous flux and a wide color reproduction range. Further, a three-wavelength phosphor has been conventionally used as a phosphor for a cold cathode fluorescent lamp, and a manganese-activated zinc silicate phosphor, europium, and manganese-activated alkaline earth metal alumina as a green light-emitting phosphor having good color purity. Acid phosphate phosphors, manganese-activated rare earth aluminate phosphors, and the like are used. However, manganese-activated zinc silicate phosphors and europium and manganese-activated alkaline earth metal aluminate phosphors have poor lifetime characteristics, and fluorescent lamps using these phosphors have a problem that the lamp luminous flux decreases with time. was there. Manganese-activated rare earth aluminate phosphors have good lifetime characteristics but poor light emission characteristics, and fluorescent lamps using these phosphors have a problem of low lamp luminous flux.

For such problems, for example, regarding the improvement of the light emission characteristics of the manganese-activated cerium magnesium aluminate phosphor, Japanese Patent Laid-Open No. 5-230454 may replace part of magnesium with zinc to improve the luminance. Although disclosed in Japanese Patent Application Laid-Open No. 2002-3838, it is disclosed that a phosphor having high emission intensity can be synthesized by dissolving silicon oxide in a solid solution, none of which is sufficient and improvement has been demanded.
Japanese Patent Laid-Open No. 5-230454 JP 2002-3838 A

  The present invention has been made to solve such problems. An object of the present invention is to provide a manganese-activated rare earth aluminate phosphor with high emission intensity and good color purity, and further to provide a fluorescent lamp with a high lamp luminous flux and a wide color reproduction range. .

  In order to achieve the above object, the present inventors have conducted intensive studies. As a result, the manganese-activated rare earth aluminate phosphor having a specific composition has high emission intensity and good color purity, and The fluorescent lamp used has newly found that the lamp luminous flux is high and the color reproduction range is wide, and the present invention has been completed.

(1) The manganese-activated rare earth aluminate phosphor of the present invention is characterized in that the general formula is represented by the following formula.
_{Ce (Mg a, Zn b,} Mn c) z Al 11 O 19
(However, 0.10 ≦ z ≦ 0.90, 0 <a × z ≦ 0.45, 0 <b × z ≦ 0.45, 0.05 ≦ c × z ≦ 0.50, a + b + c = 1)

(2) The manganese-activated rare earth aluminate phosphor of the present invention is the manganese-activated rare earth aluminate phosphor according to (1), wherein x and y of the chromaticity coordinate values of the phosphor are: They are respectively in the ranges of 0.150 ≦ x ≦ 0.190 and 0.520 ≦ y ≦ 0.750.

(3) A fluorescent lamp of the present invention includes a light-transmitting airtight container, a phosphor layer formed in the light-transmitting airtight container, a discharge medium sealed in the light-transmitting airtight container, and an electrode. In the fluorescent lamp, the phosphor layer includes the manganese-activated rare earth aluminate phosphor described in (1) or (2).

(4) The fluorescent lamp of the present invention is the fluorescent lamp described in (3), wherein the fluorescent lamp is a cold cathode fluorescent lamp.

  The phosphor of the present invention is a manganese-activated rare earth aluminate phosphor with high emission intensity by ultraviolet excitation and good color purity. By using the phosphor of the present invention, the fluorescent light has a high lamp luminous flux and a wide color reproduction range. A lamp can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the embodiment shown below exemplifies a manganese-activated rare earth aluminate phosphor for embodying the technical idea of the present invention and a fluorescent lamp using the same. The active rare earth aluminate phosphor and the fluorescent lamp using the same are not specified as follows.

Here, the manufacturing method of the manganese activation rare earth aluminate phosphor which concerns on one embodiment of this invention is demonstrated in detail. As phosphor materials, and a cerium compound, a magnesium compound, a zinc compound, using an aluminum compound, a manganese compound, for each compound, the general formula _{Ce (Mg a, Zn b,} Mn c) z Al 11 O 19 ( where 0.10 ≦ z ≦ 0.90, 0 <a × z ≦ 0.45, 0 <b × z ≦ 0.45, 0.05 ≦ c × z ≦ 0.50, a + b + c = 1) The materials are weighed and mixed, or fluxes are added to these phosphor materials and mixed to obtain a material mixture. After filling this raw material mixture into a crucible, it is placed in a furnace and fired at 1200 to 1600 ° C. in a reducing atmosphere. After cooling, the fired product is wet-dispersed and then separated and dried to obtain the manganese-activated rare earth aluminate phosphor of the present invention.

  About a cerium compound, a magnesium compound, a zinc compound, an aluminum compound, and a manganese compound, the compound which becomes an oxide by an oxide or thermal decomposition is used preferably. For example, a compound which decomposes at a high temperature and becomes an oxide such as carbonate, hydroxide, nitrate, oxalate is preferable. Further, a coprecipitate containing all or part of the elements constituting the phosphor or an oxide obtained by calcining these can be used. Moreover, as a flux, boric acid, a fluoride, etc. are preferable, and it adds in 0.1-1.0 weight part with respect to 100 weight part of fluorescent substance raw materials. These are mixed with a ball mill, a V-type mixer, etc., and then filled in a crucible such as alumina, quartz, silicon carbide, etc., and reduced in a reducing atmosphere with hydrogen / nitrogen, carbon, carbon monoxide, etc. at 1200-1600 ° C. It is preferable to bake for 20 hours. If the firing temperature is lower than 1200 ° C., the reaction does not proceed. If the firing temperature is higher than 1600 ° C., the sintering proceeds excessively and the dispersion treatment becomes difficult. When firing, the temperature is increased from room temperature to the maximum temperature at a temperature increase rate of 100 to 300 ° C./hour, maintained at the maximum temperature for a certain time, and then the temperature is decreased from the maximum temperature to the room temperature at a temperature decrease rate of 100 to 300 ° C./hour. preferable. The firing atmosphere is preferably a hydrogen / nitrogen atmosphere, and more preferably a hydrogen / nitrogen atmosphere having a hydrogen concentration of 1 to 4%. By firing in this manner, the manganese-activated rare earth aluminate phosphor of the present invention having excellent light emission characteristics can be obtained.

  Next, a cold cathode fluorescent lamp is produced using the manganese-activated rare earth aluminate phosphor of the present invention. First, a phosphor and a binder such as calcium pyrophosphate and calcium barium borate are added to a nitrocellulose / butyl acetate solution, and these are mixed and suspended to prepare a phosphor-coated suspension. The obtained phosphor-coated suspension is poured into the inner surface of the glass tube, and then dried by passing warm air through the glass tube, followed by baking, exhausting, attaching a filament, and attaching a base to obtain a cold cathode fluorescent lamp.

  FIG. 1 shows an example of the cold cathode fluorescent lamp of the present invention. A phosphor layer 12 made of one or more phosphors and a binder is formed on the inner wall of the light-transmitting hermetic container 11 made of glass or the like. Inside the translucent airtight container 11, a discharge medium 13 made of a rare gas such as neon and mercury vapor is sealed, and both ends of the translucent airtight container 11 are sealed by a pair of electrodes 14a and 14b. A voltage is applied between both electrodes to cause discharge in the discharge medium 13, and ultraviolet rays are emitted from the excited mercury, and the phosphors in the phosphor layer 12 are excited by the ultraviolet rays to emit light.

Next, the characteristics of the manganese-activated rare earth aluminate phosphor of the present invention will be described with reference to the drawings. FIG. 2 shows _a Ce (Mg _a , Zn _b , Mn _c ) _z Al ₁₁ O ₁₉ phosphor obtained by changing the amount of MgCO ₃ added in Example 3 (where b × z = 0.2, c × For z = 0.3, a + b + c = 1), the relationship between relative luminance and a × z when excited with 254 nm ultraviolet light is shown. Here, the relative luminance is measured using a Hitachi spectrophotometer by irradiating the phosphor with 254 nm ultraviolet rays using a low-pressure mercury lamp manufactured by Hamamatsu Photonics Co., Ltd. The relative value when it is set to 100% is shown. From this figure, the relative luminance is high when a × z is in the range of 0 <a × z ≦ 0.45, higher in the range of 0 <a × z ≦ 0.35, and 0.001 ≦ a × z ≦ 0. It can be seen that it is even higher in the range of 25.

Figure 3, _Ce obtained by changing the amount of ZnO in Example _{3 (Mg a, Zn b,} Mn c) z Al 11 O 19 phosphor (where, a × z = 0.03, c × z = 0.3, a + b + c = 1), the relationship between the relative luminance when excited with 254 nm ultraviolet light and b × z was shown. From this figure, the relative luminance is high in the range 0 <b × z ≦ 0.45, higher in the range 0 <b × z ≦ 0.40, and in the range 0.001 ≦ b × z ≦ 0.35. It can be seen that it is even higher.

FIG. 4 shows Ce (Mg _a , Zn _b , Mn _c ) _z Al ₁₁ O ₁₉ phosphor obtained by changing the amount of MnCO ₃ added in Example 3 (provided that a × z = 0.03, b × For z = 0.2, a + b + c = 1), the relationship between relative luminance and c × z when excited with 254 nm ultraviolet light was shown. From this figure, the relative luminance is higher in the range of 0.05 ≦ c × z ≦ 0.50, higher in the range of 0.1 ≦ c × z ≦ 0.45, and 0.15 ≦ b × z ≦ 0. It can be seen that it is even higher in the range of 40.

Figure 5, _Ce obtained by changing the amount of ZnO in Example _{3 (Mg a, Zn b,} Mn c) z Al 11 O 19 phosphor (where, a × z = 0.03, c × z = 0.3, a + b + c = 1), the relationship between the relative luminance and the z value when excited with 254 nm ultraviolet light is shown. From this figure, the relative luminance is higher in the range of z value 0.10 ≦ z ≦ 0.90, higher in the range of 0.20 ≦ z ≦ 0.85, and in the range of 0.30 ≦ z ≦ 0.75. It turns out that it is still higher.

FIG. 6 shows Ce (Mg _0.048 , Zn _0.476 , Mn _0.476 ) _0.63 Al ₁₁ O ₁₉ phosphor of Example 1 and Ce (Mg _0.350 , Zn _{0. 500} , Mn _0.150 ) _1.00 Al ₁₁ O ₁₉ phosphor and the Ce (Mg _0.900 , Mn _0.100 ) _1.00 Al ₁₁ O ₁₉ phosphor of Comparative Example 3 were excited by 254 nm ultraviolet light. The CIE chromaticity diagram is shown. In the figure, the chromaticity coordinate values of BaMgAl ₁₀ O ₁₇ : Eu blue phosphor and Y ₂ O ₃ : Eu red phosphor used in the cold cathode fluorescent lamp are also plotted. From this figure, the phosphor of Example 1 of the present invention has good color purity, and by combining with the conventional blue and red phosphors, color reproduction is achieved compared to the case of using the phosphors of Comparative Examples 1 and 3. It can be seen that a cold cathode fluorescent lamp with a wide range can be obtained.

The average particle size of the phosphor used in the present invention is preferably in the range of 3 to 6 μm. If the average particle size is smaller than 3 μm, the light emission efficiency is lowered. Conversely, if the average particle size is larger than 6 μm, the coating amount of the fluorescent lamp is increased.

The cold cathode fluorescent lamp is used as a backlight of a color liquid crystal display, and the tube diameter is as thin as 1 to 4 mm, and it is necessary to select a particle size suitable for the process. The phosphor used in the present invention has a preferred particle size as a green phosphor for a cold cathode lamp.

  Examples of the present invention will be described below, but it goes without saying that the present invention is not limited to specific examples.

[Example 1]
<Phosphor>
CeO ₂ 1.00 mol, MgF ₂ 0.03 mol, ZnO 0.10 mol, MnCO ₃ 0.30 mol, and Al ₂ O ₃ 5.50 mol were mixed by a ball mill as raw materials, and this raw material mixture was filled in an alumina crucible and reduced atmosphere. Bake at 1400 ° C. for 5 hours in medium (3% H ₂ / N ₂ ). In this case, the temperature is increased from room temperature to 1400 ° C. at a temperature increase rate of 150 to 200 ° C./hour, maintained at 1400 ° C. for 5 hours, and then the temperature is decreased from 1400 ° C. to room temperature at a temperature decrease rate of 150 to 200 ° C./hour. After cooling, it is wet-dispersed, passed through a sieve, dehydrated and dried. The general formula is Ce (Mg _0.048 , Zn _0.476 , Mn _0.476 ) _0.63 Al ₁₁ O ₁₉ A manganese activated rare earth aluminate phosphor is obtained. This phosphor emits green light with 254 nm ultraviolet excitation, and the chromaticity coordinate value is (x, y) = (0.167, 0.721).

<Single color fluorescent lamp>
The phosphor thus obtained and the binder are added to a nitrocellulose / butyl acetate solution and mixed to prepare a phosphor coating slurry. This is poured into a glass tube having a tube diameter of 3 mm and a length of 400 mm, applied to the inner surface, dried through warm air, and baked at 580 ° C. for 15 minutes to form a fluorescent film. Then, according to a normal method, exhaust, electrode mounting, and attachment of a base are performed to obtain a monochrome cold cathode fluorescent lamp that emits green light. The lamp luminous flux of this monochromatic fluorescent lamp is 157% when the luminous flux of the monochromatic fluorescent lamp of Comparative Example 1 is 100%.

<White fluorescent lamp>
Next, the above-described manganese-activated rare earth aluminate phosphor emitting green light, BaMgAl ₁₀ O ₁₇ : Eu blue phosphor, and Y ₂ O ₃ : Eu red light-emitting phosphor in a weight ratio of blue: green: red = 50. : Mix in a ratio of 20:30. This mixed phosphor and binder are added to a nitrocellulose / butyl acetate solution and mixed to prepare a phosphor-coated slurry. This is poured into a glass tube having a tube diameter of 3 mm and a length of 400 mm, applied to the inner surface, dried through warm air, and baked at 580 ° C. for 15 minutes to form a fluorescent film. Then, according to a normal method, exhaust, electrode mounting, and attachment of a base are performed to obtain a white cold cathode fluorescent lamp. The lamp luminous flux of this white fluorescent lamp is 131% when the lamp luminous flux of the white fluorescent lamp of Comparative Example 1 is 100%.

[Examples 2 to 10]
A manganese-activated rare earth aluminate phosphor is produced in the same manner as in Example 1 except that the raw materials are mixed in the amounts shown in Table 1.

[Comparative Example 1]
CeO ₂ 1.00 mol, MgF ₂ 0.03 mol, MgCO ₃ 0.32 mol, ZnO 0.50 mol, MnCO ₃ 0.15 mol, and Al ₂ O ₃ 5.50 mol were used as raw materials, and the others were the same as in Example 1. Thus, a manganese-activated rare earth aluminate phosphor represented by the general formula Ce (Mg _0.350 , Zn _0.500 , Mn _0.150 ) _1.00 Al ₁₁ O ₁₉ is obtained. The chromaticity coordinate value when this phosphor is excited by 254 nm ultraviolet rays is (x, y) = (0.155, 0.685). Next, using this phosphor, a monochromatic cold cathode fluorescent lamp and a white cold cathode fluorescent lamp are produced in the same manner as in Example 1.

[Comparative Examples 2 to 4]
A manganese-activated rare earth aluminate phosphor is produced in the same manner as in Example 1 except that the raw materials are mixed in the amounts shown in Table 1.

  For the manganese-activated rare earth aluminate phosphors obtained in Examples 1 to 10 and Comparative Examples 1 to 4, the values of a, b, c, and z in the general formula are excited in Table 2, and Table 3 is excited with 254 nm ultraviolet light. The relative luminance and chromaticity coordinate values are shown. Here, the relative luminance is measured using a Hitachi spectrophotometer by irradiating the phosphor with 254 nm ultraviolet rays using a low-pressure mercury lamp manufactured by Hamamatsu Photonics Co., Ltd. The relative value when it is set to 100% is shown. Table 3 also shows the average particle diameter of the phosphor. From this table, it can be seen that the chromaticity coordinate values x and y of the phosphor of the present invention are in the ranges of 0.150 ≦ x ≦ 0.190 and 0.520 ≦ y ≦ 0.750, respectively. Moreover, it turns out that the average particle diameter of the fluorescent substance of this invention exists in the range of 3-6 micrometers.

  As described above, according to the present invention, it is possible to provide a manganese-activated rare earth aluminate phosphor having high emission intensity by ultraviolet excitation and good color purity, and further having a high lamp luminous flux and a wide color reproduction range. A lamp can be provided.

It is a figure which shows an example of the cold cathode fluorescent lamp of this invention. It is a figure which shows the relationship between the relative luminance of the fluorescent substance of this invention, and axz. It is a figure which shows the relationship between the relative luminance of the fluorescent substance of this invention, and bxz. It is a figure which shows the relationship between the relative luminance of the fluorescent substance of this invention, and cxz. It is a figure which shows the relationship between the relative luminance and z value of the fluorescent substance of this invention. 4 is a CIE chromaticity diagram of phosphors of Example 1, Comparative Example 1, and Comparative Example 3. FIG.

Explanation of symbols

11 Translucent airtight container
12 Phosphor layer
13 Discharge medium
14a, 14b electrode

Claims (4)

A manganese-activated rare earth aluminate phosphor characterized by the following general formula:
_{Ce (Mg a, Zn b,} Mn c) z Al 11 O 19
(However, 0. 2 0 ≦ z ≦ 0. 85, 0 <a × z ≦ 0.45,0 <b × z ≦ 0.45,0.05 ≦ c × z ≦ 0.50, a + b + c = 1) 2. The manganese according to claim 1, wherein x and y of chromaticity coordinate values of the phosphor are in a range of 0.150 ≦ x ≦ 0.190 and 0.520 ≦ y ≦ 0.750, respectively. Activated rare earth aluminate phosphor. In a fluorescent lamp comprising a translucent airtight container, a phosphor layer formed in the translucent airtight container, a discharge medium enclosed in the translucent airtight container, and an electrode, the phosphor layer is A fluorescent lamp comprising the manganese-activated rare earth aluminate phosphor according to claim 1. The fluorescent lamp according to claim 3, wherein the fluorescent lamp is a cold cathode fluorescent lamp.

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