JP2008050390A - Vacuum ultraviolet excited aluminate phosphor and vacuum ultraviolet excited light emitting device using the same - Google Patents

Abstract

An object of the present invention is to provide a vacuum ultraviolet ray excited aluminate phosphor having a good dispersibility and a good luminance maintenance rate by gas discharge, and a vacuum ultraviolet ray excited light emitting device using the same.
By covering 0.1 to 4.0 wt% of zinc oxide on the surface of particles of aluminate phosphor activated by at least one activator of Eu and Mn. Thus, it is possible to obtain a vacuum ultraviolet ray excited aluminate phosphor having good dispersibility and good luminance maintenance rate by gas discharge. Further, by using this vacuum ultraviolet ray excited aluminate phosphor in a light emitting device such as a PDP or a rare gas discharge lamp, it is possible to provide a vacuum ultraviolet ray excited light emitting device having excellent coating characteristics and life characteristics.
[Selection] Figure 1

Description

  The present invention relates to a vacuum ultraviolet ray excited aluminate phosphor and a vacuum ultraviolet ray excited light emitting device using the same, and more particularly, a vacuum ultraviolet ray excited aluminate phosphor having a good luminance maintenance rate by gas discharge and a vacuum using the same. The present invention relates to an ultraviolet-excited light emitting device.

  Vacuum ultraviolet-excited phosphors are used in light-emitting devices (vacuum ultraviolet-excited light-emitting devices) such as plasma displays (hereinafter referred to as PDP) and rare gas discharge lamps. A PDP is a structure in which a sealed gas space sandwiched between two glass plates is divided by partition walls and minute discharge spaces called display cells (discharge cells) are arranged in a matrix, and each display cell has red, blue, A phosphor that emits green light is applied, and emits light when excited by vacuum ultraviolet rays generated by discharge. The rare gas discharge lamp is coated with a three-color phosphor mixed with phosphors emitting red, blue and green on the inner wall of a glass tube, and emits light when excited by vacuum ultraviolet rays generated by the rare gas discharge.

Compared to various flat displays, PDPs are widely developed as the most promising candidates for high-definition wall-mounted TVs because of their features such as the largest size, high-speed response, wide viewing angle, and color reproducibility. . The phosphor used in this PDP has high efficiency and short afterglow with respect to excitation of vacuum ultraviolet rays (VUV) having a wavelength of 200 nm or less obtained by discharge of a rare gas, and sufficient color as three primary colors. In addition to having a degree and a hue, characteristics such as life characteristics and temperature characteristics are required. In particular, the aluminate phosphor activated with divalent europium such as BaMgAl ₁₀ O ₁₇ : Eu has a large deterioration with respect to vacuum ultraviolet rays and ion bombardment, and has a problem in life characteristics.

  When such an aluminate phosphor is used as a blue light-emitting phosphor in a PDP or a rare gas discharge lamp, luminance deterioration with time is larger than that of other light-emitting phosphors. It was. That is, when used in a PDP, there are problems such as a decrease in color temperature due to a change in chromaticity and burn-in due to a fixed display. was there.

  In addition, in PDPs and rare gas discharge lamps using aluminate phosphors, improvement in practical characteristics such as suitability for manufacturing processes is required, and improvement in coating characteristics is required. In particular, in the PDP, there is a problem of improving coating characteristics that can form a thin and dense phosphor screen corresponding to a fine discharge cell structure.

Regarding vacuum ultraviolet-excited aluminate phosphors, Japanese Patent Laid-Open No. 7-320645 discloses 3 (Ba, Mg) O.8Al ₂ O ₃ : Eu as a translucent material having a lower refractive index than silicon dioxide, fluorine. Although it is disclosed to coat with a thin film of magnesium fluoride, alumina or the like, the luminance maintenance rate and dispersibility by gas discharge are not sufficient, and improvement is necessary.
JP 7-320645 A

  The present invention has been made to solve such problems. An object of the present invention is to provide a vacuum ultraviolet ray excited aluminate phosphor having a good dispersibility and a good luminance maintenance rate by gas discharge, and a vacuum ultraviolet ray excited light emitting device using the same.

  As a result of intensive studies to solve the above-mentioned problems, the present inventor has found that the above problems can be solved by a vacuum ultraviolet ray excited aluminate phosphor coated with a specific amount of zinc oxide, and the present invention has been completed. I came to let you.

(1) The vacuum ultraviolet-excited aluminate phosphor of the present invention has zinc oxide on the surface of particles of aluminate phosphor activated by at least one activator of Eu and Mn. It is characterized by being coated with 0.1 to 4.0 wt%. When the amount of zinc oxide is less than 0.1 wt%, the luminance maintenance rate due to gas discharge is lowered, and when it is more than 4.0 wt%, the emission luminance due to vacuum ultraviolet excitation is lowered. A more preferable range is 0.1 to 3.0 wt%, and a further preferable range is 0.3 to 3.0 wt%.

(2) The vacuum ultraviolet ray excited aluminate phosphor of the present invention is the vacuum ultraviolet ray excited aluminate phosphor according to (1), wherein the zinc oxide has an average particle diameter of 0.01 to 1.0 μm. It is a range. When the average particle diameter of zinc oxide is smaller than 0.01 μm, the dispersibility of the phosphor is deteriorated and the coating properties are deteriorated. On the contrary, when the average particle size is larger than 1.0 μm, the reflectance is deteriorated, and the light emission luminance due to vacuum ultraviolet excitation is lowered. A more preferable range is 0.05 to 0.5 μm.

(3) The vacuum ultraviolet ray excited aluminate phosphor of the present invention is the vacuum ultraviolet ray excited aluminate phosphor according to (1) or (2), wherein the phosphor is a BaMgAl ₁₀ O ₁₇ : Eu phosphor. Or, it is a BaMgAl ₁₀ O ₁₇ : Eu, Mn phosphor. The present invention is effective in alkaline earth metal aluminate phosphors, but is particularly effective in BaMgAl ₁₀ O ₁₇ : Eu phosphors or BaMgAl ₁₀ O ₁₇ : Eu, Mn phosphors. The maintenance factor is improved and the deterioration against vacuum ultraviolet rays and ion bombardment is improved.

(4) The vacuum ultraviolet ray excited aluminate phosphor of the present invention is the vacuum ultraviolet ray excited aluminate phosphor according to any one of (1) to (3), wherein the phosphor has an average particle size of 1.0 to The range is 4.0 μm, the median particle size is in the range of 1.5 to 6.0 μm, and the dispersity is in the range of 0.55 to 0.85. Here, the average particle diameter is a value measured using a Fischer sub-sieve sizer (FSSS) by the air permeation method, and indicates the size of primary particles. The median particle diameter is measured by using an electric resistance method Coulter Multisizer II (manufactured by Coulter), and indicates a 50% particle diameter (volume basis). In this case, if the particles are strongly aggregated, it is difficult to disperse them to the primary particles, and the aggregated secondary particles are taken for measurement. The dispersity is a value obtained by dividing the average particle diameter by the median particle diameter, and this is defined as the dispersity. It can be evaluated that the larger the value, the better the dispersibility of the phosphor.

  The average particle diameter of the phosphor is preferably in the range of 1.0 to 4.0 μm, more preferably in the range of 1.0 to 3.5 μm. Even if the average particle size is smaller than 1.0 μm, or conversely, larger than 4.0 μm, the emission characteristics are deteriorated when used in a vacuum ultraviolet ray excited light emitting device. When the average particle size is smaller than 1.0 μm, the luminous efficiency of the phosphor is low, and when it is larger than 4.0 μm, the surface area of the phosphor particles becomes small and the luminance of light emitted by vacuum ultraviolet excitation is lowered. The vacuum ultraviolet rays reach from the particle surface shallowly, and are excited at the particle surface to emit light. Therefore, when the average particle size is larger than 4.0 μm and the surface area of the phosphor particles is reduced, the emission luminance is lowered. On the other hand, when the average particle size is larger than 4.0 μm, the coating properties are also deteriorated. The median particle size is preferably in the range of 1.5 to 6.0 μm, and more preferably in the range of 1.5 to 4.0 μm. When the median particle size is larger than 6.0 μm, the coating properties are deteriorated. The dispersity is preferably in the range of 0.55 to 0.85, and more preferably in the range of 0.65 to 0.85. If the degree of dispersion is less than 0.55, there are many agglomerated particles, so that the coating properties are degraded. The median particle size may be less than 1.5 μm and the degree of dispersion may be greater than 0.85, but is limited by the average particle size range.

(5) A vacuum ultraviolet ray excited light emitting device of the present invention comprises the vacuum ultraviolet ray excited aluminate phosphor described in (1) to (4). As the vacuum ultraviolet light-excited light emitting device, a light emitting device such as a plasma display display device or a rare gas discharge lamp is preferable.

(6) A plasma display device of the present invention comprises the vacuum ultraviolet ray excited aluminate phosphor described in (1) to (4). As the plasma display device, a DC type or AC type color display PDP is preferable. As the AC type, a counter type, a surface discharge type, or the like is preferable.

(7) The plasma display device of the present invention includes a front substrate and a rear substrate that are spaced apart from each other by a predetermined distance, a plurality of barrier ribs that form a discharge space by the front substrate and the rear substrate, and a space between the barrier ribs. And a plurality of display electrodes facing and intersecting with the address electrodes, a plurality of discharge cells formed at intersections of the address electrodes and the display electrodes, and at least a part of the inner surface of the discharge cell A plasma display panel comprising: a phosphor layer formed on the substrate; a plasma display panel including a discharge gas sealed in a discharge space between the front substrate and the rear substrate; and a drive circuit for driving the plasma display panel. In the apparatus, the phosphor layer is a phosphor layer having the vacuum ultraviolet ray excited aluminate phosphor described in (1) to (4). To. The thickness of the phosphor layer is preferably in the range of 10 to 25 μm. If the thickness of the phosphor layer is less than 10 μm, the brightness of the PDP display device is low. Conversely, if the thickness is greater than 25 μm, the discharge space is narrowed and the light emission efficiency is lowered. Further, if the average particle diameter of zinc oxide contained in the vacuum ultraviolet-excited aluminate phosphor is smaller than 0.1 μm, the dispersibility of the phosphor is deteriorated, the coating characteristics are deteriorated, and the phosphor layer is thick. As a result, the luminous efficiency decreases.

  Vacuum ultraviolet-excited aluminate phosphor in a vacuum ultraviolet-excited aluminate phosphor, containing 0.1 to 4.0 wt% of zinc oxide with respect to the phosphor, providing good dispersibility and good luminance maintenance rate by gas discharge You can get a body. Further, when this vacuum ultraviolet ray excited aluminate phosphor is used in a light emitting device such as a PDP or a rare gas discharge lamp, a vacuum ultraviolet ray excited light emitting device having excellent life characteristics can be obtained.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the embodiment described below exemplifies a vacuum ultraviolet ray excited aluminate phosphor for embodying the technical idea of the present invention and a vacuum ultraviolet ray excited light emitting device using the phosphor, and the present invention is The vacuum ultraviolet-excited aluminate phosphor and the vacuum ultraviolet-excited light emitting device using the same are not specified as follows.

  Here, the manufacturing method of the vacuum ultraviolet ray excitation aluminate phosphor which concerns on one embodiment of this invention is demonstrated in detail. First, a barium compound, a europium compound, a magnesium compound, an aluminum compound, and, if necessary, a manganese compound and a flux are weighed and mixed. After this raw material mixture is filled in a crucible, it is put 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 an aluminate phosphor.

  As the phosphor material, an oxide or a compound that becomes an oxide by thermal decomposition is preferably used. For example, the barium compound, europium compound, and magnesium compound are preferably oxides, carbonates, hydroxides, and the like. In addition, a coprecipitate containing all or part of each element of Ba, Eu, Mg, and Mn as required, or an oxide obtained by calcining these may be used. As the aluminum compound, aluminum oxide is preferable.

  As the flux, fluoride is preferable, and magnesium fluoride, aluminum fluoride, and the like are preferable. The amount of flux added is preferably in the range of 0.0001 to 0.05 mole per mole of phosphor. The range of 0.001 to 0.04 mol is more preferable, and the range of 0.005 to 0.03 mol is more preferable. For the reducing atmosphere, a general method such as a nitrogen-hydrogen mixed atmosphere is used.

  The aluminate phosphor thus obtained is mixed with an appropriate amount of zinc oxide fine particles in a dry process to obtain the vacuum ultraviolet ray excited aluminate phosphor of the present invention in which the surface of the phosphor particles is coated with zinc oxide. be able to. In order to obtain a uniform coating, the phosphor and zinc oxide are suspended in a solvent such as water, mixed thoroughly by a ball mill or the like, and then the suspension is separated and dried to make the zinc oxide more uniform. Can be coated on the surface of the phosphor particles. In these methods, zinc oxide is directly mixed with the phosphor.

  In order to obtain a more uniform coating of zinc oxide, it is preferable to apply a method using the following chemical reaction. For example, a phosphor is suspended in water, a water-soluble zinc compound is added to the suspension, an aqueous alkaline solution is added to the suspension, and the pH is adjusted to 6 to 10 to adjust the zinc hydroxide to phosphor particles. By depositing it on the surface, separating it into solid and liquid, and drying it at a temperature of 125 ° C. or higher, the vacuum ultraviolet ray excited aluminate phosphor of the present invention whose particle surface is coated with zinc oxide can be obtained. Here, zinc chloride, zinc nitrate, or the like can be used as the water-soluble zinc compound. An aqueous ammonia solution can be used as the aqueous alkaline solution for adjusting the pH of the suspension.

  Next, a surface discharge type PDP is fabricated as a vacuum ultraviolet light excitation light emitting device using the vacuum ultraviolet light excitation aluminate phosphor of the present invention. First, a striped electrode is formed on the back substrate, a striped electrode is formed in a direction orthogonal to the electrode group, and an insulating film and MgO are formed thereon. Further, the aluminate phosphor of the present invention is formed on the counter substrate. The two substrates are combined with a gap of about 100 μm. In this gap, about 670 hPa of a mixed gas of He and Xe, a mixed gas of Ne and Xe, or the like that radiates vacuum ultraviolet rays by discharge is sealed to obtain a surface discharge type PDP.

<Relationship between luminance maintenance ratio and zinc oxide coating amount>
FIG. 1 is a plot of the relationship between the luminance maintenance ratio (%) and the coating amount (wt%) of zinc oxide for a BaMgAl ₁₀ O ₁₇ : Eu phosphor coated with zinc oxide. The measurement is as follows: 1) Measure the relative emission luminance when the phosphor measurement sample is excited with vacuum ultraviolet light having a wavelength of 147 nm using a vacuum ultraviolet spectrophotometer, and then 2) mix the sample with a mixed gas of Ne-Xe. It is set in a glass tube sealed at a pressure of 100 Pa, and arc discharge is performed with an irradiation power of 350 W and an irradiation time of 1 hour to forcibly degrade the phosphor particle surface. 3) Measure the relative light emission luminance at the time of excitation of the forcibly deteriorated sample with vacuum ultraviolet light having a wavelength of 147 nm, and obtain the percentage of the value obtained by dividing the measured value obtained in 3) by the measured value obtained in 1). This is the luminance maintenance rate. All measurement samples were mixed with a vehicle to form a paste, dried at 170 ° C. for 1 hour, and then baked at 500 ° C. for 1 hour. This is because baking is performed for the purpose of removing the binder used when forming the phosphor layer as described above in the application of light emitting devices such as plasma displays, and the measurement sample baked under this condition is actually This is because it approximates the case of mounting on a light emitting device.

As shown in FIG. 1, the luminance maintenance factor of the phosphor not coated with zinc oxide is 84.0%, but as the zinc oxide coating amount increases, the luminance maintenance factor increases, and the coating amount is 4. The luminance maintenance rate is saturated around 0 wt%. On the other hand, when the zinc oxide coating amount is increased, the light emission luminance due to excitation by vacuum ultraviolet rays is lowered. Therefore, in order to satisfy both the light emission luminance and the luminance maintenance rate, the zinc oxide coating amount is 0.1% with respect to the phosphor. A range of ˜4.0 wt% is preferred. A more preferable range is 0.1 to 3.0 wt%, and a further preferable range is 0.3 to 3.0 wt%. Here, _BaMgAl 10 _O 17: showed the relationship between the luminance sustain ratio for Eu phosphor (%) and the coating amount of zinc oxide, BaMgAl ₁₀ O _17: Eu, is similar result for Mn phosphor obtained It is done.

  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>
A BaMgAl ₁₀ O ₁₇ : Eu phosphor or a phosphor is produced as follows.
BaCO ₃ ··············· 0.90 mol Mg ₄ (CO ₃ ) ₃ (OH) ₂ .3H ₂ O... 0.245 mol Eu ₂ O ₃・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 0.10 mol α-Al ₂ O ₃・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 5.00 mol All of these 100 0.02 mol of MgF ₂ is added as a flux with respect to parts by weight, and ball mill mixing is performed in a magnetic pot.

The raw material mixture is filled in an alumina crucible, covered, and fired at 1400 ° C. for 8 hours in a reducing atmosphere (3% H ₂ / N ₂ ). After cooling, dispersion treatment is performed, and after passing through a 300-mesh sieve, dehydration and drying are performed, and a phosphor whose general formula is represented by (Ba _0.9 Eu _0.1 ) MgAl ₁₀ O ₁₇ (hereinafter referred to as BAM phosphor) Obtain). This phosphor emits blue light with 147 nm ultraviolet excitation.

<Coating of zinc oxide by chemical reaction>
100 g of the obtained BAM phosphor is suspended in 500 g of pure water, and a solution obtained by dissolving 0.37 g of Zn (NO ₃ ) ₂ .6H ₂ O in 100 g of pure water is added and mixed. Next, while stirring the obtained suspension, aqueous ammonia is added dropwise to adjust the pH of the suspension to 8.0. Next, when the stirring is stopped and the mixture is allowed to stand, the phosphor settles and the particle surface is coated with zinc hydroxide. The precipitate is separated, washed with water, dried at 130 ° C., and then passed through a sieve to obtain the vacuum ultraviolet ray excited aluminate phosphor of the present invention in which zinc oxide is coated at 0.1 wt% on the phosphor.

[Example 2]
A phosphor in which 0.3 wt% of zinc oxide is coated on the phosphor is obtained in the same manner as in Example 1 except that the charged amount of Zn (NO ₃ ) ₂ .6H ₂ O is 1.10 g.

[Example 3]
A phosphor in which 1.0 wt% of zinc oxide is coated on the phosphor is obtained in the same manner as in Example 1 except that the charged amount of Zn (NO ₃ ) ₂ .6H ₂ O is 3.66 g.

[Example 4]
A phosphor in which 3.0 wt% of zinc oxide is coated on the phosphor is obtained in the same manner as in Example 1 except that the charged amount of Zn (NO ₃ ) ₂ .6H ₂ O is 11.0 g.

<Coating of zinc oxide by wet mixing>
[Example 5]
To 100 g of the BAM phosphor, 1000 g of water and 0.1 g of ZnO having an average particle size of 0.05 μm were added and wet-mixed with a ball mill, followed by drying at 120 ° C. for 12 hours. A phosphor coated with 1 wt% is obtained.

[Example 6]
A phosphor in which zinc oxide is coated at 0.3 wt% is obtained in the same manner as in Example 5 except that 0.3 g of ZnO having an average particle diameter of 0.05 μm is added.

[Example 7]
A phosphor in which 1.0 wt% of zinc oxide is coated on the phosphor is obtained in the same manner as in Example 5 except that 1.0 g of ZnO having an average particle diameter of 0.05 μm is added.

[Example 8]
In the same manner as in Example 5 except that 3.0 g of ZnO having an average particle diameter of 0.05 μm is added, a phosphor in which 3.0 wt% of zinc oxide is coated on the phosphor is obtained.

[Example 9]
In the same manner as in Example 5 except that 0.1 g of ZnO having an average particle diameter of 0.5 μm is added, a phosphor in which 0.1 wt% of zinc oxide is coated on the phosphor is obtained.

[Example 10]
In the same manner as in Example 5 except that 0.3 g of ZnO having an average particle size of 0.5 μm is added, a phosphor in which 0.3 wt% of zinc oxide is coated on the phosphor is obtained.

[Example 11]
A phosphor in which 1.0 wt% of zinc oxide is coated on the phosphor is obtained in the same manner as in Example 5 except that 1.0 g of ZnO having an average particle size of 0.5 μm is added.

[Example 12]
A phosphor in which 3.0 wt% of zinc oxide is coated on the phosphor is obtained in the same manner as in Example 5 except that 3.0 g of ZnO having an average particle size of 0.5 μm is added.

[Comparative Example 1]
The BAM phosphor before coating with zinc oxide in Examples 1 to 12 is the phosphor of Comparative Example 1.

  For the europium activated aluminate phosphors obtained in Examples 1 to 12 and Comparative Example 1, the results of measuring the luminance maintenance rate by gas discharge by the method described above are shown in Table 1. Table 1 shows the average particle size, median particle size, and degree of dispersion of these phosphors. From this table, it can be seen that the phosphors of Examples 1 to 12 of the present invention have a higher luminance maintenance rate due to gas discharge than the phosphor of Comparative Example 1 before coating with zinc oxide. As described above, in the present invention, it is possible to obtain a vacuum ultraviolet ray-excited aluminate phosphor having good emission luminance and good luminance maintenance rate by gas discharge. Moreover, since the fluorescent substance of Examples 1-12 of this invention has a large dispersion degree compared with the fluorescent substance of the comparative example 1, it turns out that a dispersibility is good and an application | coating characteristic is excellent.

  As described above, the vacuum ultraviolet ray excited aluminate phosphor of the present invention has a high luminance maintenance rate by gas discharge, and this vacuum ultraviolet ray excited aluminate phosphor is used for light emitting devices such as PDPs and rare gas discharge lamps. Thus, it is possible to provide a vacuum ultraviolet light-excited light emitting device having excellent life characteristics. Further, since the vacuum ultraviolet ray excited aluminate phosphor of the present invention has good dispersibility, when used in a light emitting device such as a PDP or a rare gas discharge lamp, the coating characteristics are improved.

It is a graph which shows the relationship between a luminance maintenance factor and the coating amount of zinc oxide.

Claims (7)

  The particle surface of the aluminate phosphor activated by at least one activator of Eu and Mn is coated with 0.1 to 4.0 wt% of zinc oxide with respect to the phosphor. Vacuum ultraviolet excited aluminate phosphor.   2. The vacuum ultraviolet ray excited aluminate phosphor according to claim 1, wherein an average particle diameter of the zinc oxide is in a range of 0.01 to 1.0 μm. 3. The vacuum ultraviolet ray excited aluminate phosphor according to claim 1, wherein the phosphor is a BaMgAl ₁₀ O ₁₇ : Eu phosphor or a BaMgAl ₁₀ O ₁₇ : Eu, Mn phosphor.   The average particle size of the phosphor is in the range of 1.0 to 4.0 μm, the median particle size is in the range of 1.5 to 6.0 μm, and the dispersity is in the range of 0.55 to 0.85. The vacuum ultraviolet-excited aluminate phosphor according to any one of claims 1 to 3, wherein   A vacuum ultraviolet ray excitation light-emitting device comprising the vacuum ultraviolet ray excitation aluminate phosphor according to claim 1.   A plasma display device comprising the vacuum ultraviolet ray excited aluminate phosphor according to claim 1. A front substrate and a rear substrate that are spaced apart from each other by a predetermined distance, a plurality of barrier ribs that form a discharge space by the front substrate and the rear substrate, an address electrode formed between the barrier ribs, and the address electrode; A plurality of display electrodes that cross each other, a plurality of discharge cells formed at intersections of the address electrodes and the display electrodes, a phosphor layer formed on at least a part of the inner surface of the discharge cells, and the front substrate And a plasma display panel including a discharge gas sealed in a discharge space between the rear substrate and a driving circuit for driving the plasma display panel, wherein the phosphor layer is claimed in claim 5. A plasma display device comprising a phosphor layer having the vacuum ultraviolet ray excited aluminate phosphor according to 1 to 4.

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