KR20090030909A - Phosphor powder, preparation thereof, and surface light source having the same - Google Patents

Abstract

Phosphor powder is provided to suppress the reactivity with discharge gas in a discharge lamp and to prevent the deterioration by heat by reinforcing the protection function of fluorescent particles comprising a fluorescent layer. Phosphor powder has a non-particle amorphous inorganic coating layer(300) encapsulated on the surface of the fluorescent particles(210) with the thickness of nano-scale. The thickness of the coating layer is formed with less than 50 nm. A method for manufacturing the phosphor powder comprises a step of preparing the mixed solution containing heat-decomposable visible rays-permeable inorganic compound and solvent; a step of agitating the mixture; a step of dispersing the fluorescent particles in the mixed solution; a step of separating the fluorescent particles from the mixed solution; and a step of drying and heat-treating the separated fluorescent particles.

Description

Phosphor powder, preparation method thereof, and surface light source device having the same {PHOSPHOR POWDER, PREPARATION THEREOF, AND SURFACE LIGHT SOURCE HAVING THE SAME}

The present invention relates to a fluorescent layer of a fluorescent lamp, a manufacturing method thereof and a surface light source device having the same.

With the introduction of information technology, the display field that processes and displays a large amount of information has been rapidly developed. In recent years, as a thin film transistor liquid crystal display device with excellent performance of thinning, light weight, and low power consumption has been developed, the existing cathode ray tube Is replacing.

The liquid crystal display is a light-receiving element that does not have a light emitting element, and thus requires a backlight as a separate light source. Recently, liquid crystal displays have become slim and large in area, and large area liquid crystal displays generally include a high brightness direct type backlight assembly.

1 and 2, a typical cold cathode backlight 10 for a large area liquid crystal display includes a box-shaped lower plate 20 having an open front surface, a reflective plate 30 disposed on an inner surface of the lower plate, And a plurality of cold cathode fluorescent lamps 40 and a diffusion plate 50 arranged side by side in front of the reflecting plate. The plurality of cold cathode fluorescent lamps 40 are fixed by a pair of side supporters 45 fixed to the lower plate across both ends thereof, and the diffusion plate 50 borders the edges to the lower plate 20. It is fixed by the side panel 55 to be coupled.

Since the cold cathode fluorescent lamp 40 emits light through ion emission due to electron collision, it has a long life and high quality light while having low power consumption and heat generation. However, an inverter is required for each lamp individually, and in order to improve the size of the backlight, it is necessary to extend the length of each lamp and increase the number of lamps. In addition, a direct type backlight including a plurality of lamps tends to generate a temperature gradient depending on a position, and thus has a problem of lowering luminance uniformity.

On the other hand, recently, flat fluorescent lamps or surface light source devices have been proposed to form a plurality of discharge channels in one light source body and discharge light by discharging the gas enclosed in the discharge channel by external electrodes. 3 and 4, the light source body 110 may be formed by, for example, the upper substrate 110a and the lower substrate 110b, and the plurality of discharge channels 120 and the partition wall 130 partitioning the plurality of discharge channels 120 may be formed. ). The electrode unit 140 formed on the surface of the light source body at both ends of the discharge channel applies a voltage to the discharge channel to discharge the gas inside the channel.

The surface light source device is advantageous in that a plurality of light emitting portions (ie, discharge channels) are formed in one body rather than an individual tubular lamp, and a single inverter can be used, and mass production is easy and luminance and luminance uniformity are excellent.

The inner surface of the cold cathode fluorescent lamp or the surface light source device is coated with a fluorescent layer using a liquid slurry or paste containing phosphor particles. The fluorescent layer formed by the coating affects the light efficiency and luminance uniformity of the lamp since the thickness distribution may vary depending on the coating efficiency. In addition, the fluorescent layer tends to be degraded by heat or ultraviolet rays during use of the lamp, shortening the life of the lamp, and reducing the fluorescent layer used for emitting light by reacting with the discharge gas.

In order to increase the size and mass production of the backlight, a large-area light source having a uniform luminance is indispensable. In particular, improvement of fluorescent layer characteristics is required for durability and long life of a lamp.

The object of the present invention proposed under this background is to improve the fluorescent layer properties of fluorescent lamps.

It is also an object of the present invention to produce phosphor powders having improved properties against thermal degradation in a simple and inexpensive manner.

Another object of the present invention is to provide a new oxide (or oxide-fluoride) nano coating layer for phosphor particle protection.

Still another object of the present invention is to provide a light source for a backlight which has excellent light emission characteristics and improved lifespan by improving the quality of the fluorescent layer and preventing deterioration during use.

The present invention provides a phosphor powder, characterized in that the non-particle amorphous inorganic coating layer is encapsulated in a nanometer thickness on the surface of the phosphor particles.

Preferably, the coating layer is formed to a thickness of 50 nm or less, and the coating layer composition may include one or more xoxides and optionally further include fluorine.

In addition, the present invention is to prepare a mixed solution containing a pyrolysable visible light-transmitting inorganic compound and a solvent, agitate the mixed solution, disperse the phosphor particles in the mixed solution, and separate the phosphor particles from the mixed solution, separation It provides a method for producing a phosphor powder comprising the step of drying and heat-treated phosphor particles.

The heat treatment of the phosphor particles may be performed during the fluorescent lamp manufacturing process.

In addition, the present invention is a light source body including a discharge channel therein, and a fluorescent layer formed on the inner surface of the light source body, the phosphor particles constituting the fluorescent layer is a non-particle amorphous inorganic coating layer of a nanometer thickness Provided is a surface light source device which is encapsulated.

According to the present invention, the protective function of the phosphor particles constituting the phosphor layer is further enhanced, so that reactivity with the discharge gas is suppressed and deterioration due to heat is prevented. Therefore, the lifetime of the fluorescent lamp can be increased and the light emitting characteristics can be improved. In addition, a protective layer additionally formed to protect the fluorescent layer of the fluorescent lamp may be omitted.

In addition, phosphor nano-encapsulation is possible in connection with a large-area fluorescent lamp manufacturing process such as a surface light source device has the advantage that the process can be unified. Therefore, the present invention may be utilized as a core technology of large area backlight manufacturing.

1 is a perspective view of a cold cathode backlight;

FIG. 2 is a cross-sectional view taken along line II of FIG. 1. FIG.

3 is a plan view showing a flat fluorescent lamp including a plurality of discharge channels.

4 is a cross-sectional view taken along the line II-II of FIG.

5 is a schematic diagram of phosphor particles according to the present invention;

6 is a schematic diagram of phosphor particles coated by adsorption.

7 is a schematic view of a coating layer formed on the surface of BAM phosphor particles.

8 and 9 are graphs showing emission spectra of BAM phosphor particles.

10 is an emission spectrum showing the effect of the heat treatment temperature on the protective properties of the coating layer on the BAM phosphor.

11 is an SEM photograph of an uncoated phosphor and a coated phosphor.

12 is a graph showing an XPS spectrum of phosphor particles.

13 is a graph showing the results of DTA analysis of phosphor particles.

14 is a SEM photograph of the phosphor particles initially formed with a coating layer and the phosphor particles after heat treatment.

15 is a graph showing emission spectra of phosphor particles.

16 is a perspective view showing an example of a flat surface light source device.

17 is a cross-sectional view showing a fluorescent layer formed on a substrate of the surface light source device taken along the line Y-Y 'of FIG.

18 is a schematic view showing the microstructure of the fluorescent layer according to the present invention.

*** Explanation of symbols for the main parts of the drawing ***

215, 225: fluorescent layer 310: phosphor particles

400: nano coating layer

The phosphor may be degraded by heat, and the degradation of the phosphor directly affects the luminescence properties and luminance of the fluorescent lamp. In particular, when mercury is used as the discharge gas, mercury and the phosphor may react to reduce mercury or the phosphor, thereby reducing the lifetime of the fluorescent lamp. For example, BaMgAl ₁₀ O ₁₇ : Eu (BAM) is used as a blue phosphor of a fluorescent lamp or a plasma display panel. However, since the phosphor is exposed to a high temperature of about 500 to 600 ° C. during the lamp or PDP manufacturing process, the luminescence property is significantly reduced. Examination of the fluorescence (PL) emission spectrum shows that the blue emission characteristic of the 450 nm peak decreases with increasing slow cooling temperature.

In the present invention, the phosphor surface is coated with an amorphous protective material that is less reactive with mercury and prevents deterioration by heat, thereby preventing deterioration of the phosphor. In particular, in the present invention, the protective material made of nanoparticles is coated on the phosphor to completely cover the surface, thereby improving durability of the internal fluorescent layer of the fluorescent lamp and improving luminescence properties and lamp life. FIG. 5 schematically shows phosphors 210 particles in which the nanocoating layer 300 is encapsulated. The particles are uniformly dispersed in a liquid precursor solution and rapidly heat treated, so that the thickness (t) of the surface of the phosphors is very minute at a nanometer level. A surface treatment layer is formed. FIG. 6 schematically illustrates a case in which the nanoparticles 300 ′ are adsorbed on the surface of the phosphor 210 by, for example, physical adsorption or the like. If the nanoparticle protective material is simply coated by adsorption, the surface of the phosphor may not be completely coated, and the blocking effect of the phosphor surface may be halved. In addition, binding the protective material to the surface of the phosphor by adsorption may weaken the phosphor protective coating during prolonged use of the fluorescent lamp, thereby losing the phosphor protective function.

The present invention proposes a phosphor powder having improved performance against thermal deterioration and a method for producing the same. Specifically, the phosphor powder is coated using an alcohol-containing liquid solution of an inorganic compound. In the phosphor nanocomposite in which the amorphous nanocoating layer according to the present invention is formed on the surface of phosphor particles, the coating layer has a continuous and non-particle nature.

In the present invention, a coating layer is formed using a low-cost precursor that can be easily purchased, and the coating layer improves durability against thermal degradation of the phosphor.

The coating layer may be formed on the surface of the phosphor layer to reduce deterioration of the phosphor by physical contact between the discharge gas and the phosphor particles. The purpose or effect of the coating layer formed on the surface of the material is i) optical properties of the coating material, and ii) It is determined in terms of the thickness and morphology of the coating layer and the material to be coated.

Forming the coating layer wet on the surface of the particulate layer can change the morphology of the particulate layer. If the coating liquid penetrates into the porous layer and the coating component causes non-uniform precipitation within the particulate layer, the optical properties of the particulate layer may change significantly. In addition, the particulate layer composed of small particles has a very large surface area, and the precipitation mechanism of the coating liquid can be changed because the particles can act as crystallization nuclei.

The thickness and morphology of the coating layer is particularly important when forming a protective layer on the surface of the phosphor particles. In this case, the thickness of the coating layer determines the protective properties of the coating layer and greatly affects the deterioration of the luminescence properties of the phosphor particles. The thickness of the protective coating layer of phosphor particles depends on the characteristics of the coating material and the characteristics of the discharge device that determine the excitation irradiation parameters.

According to the experiments of the present inventors, the optimum thickness of the B ₂ O ₃ (B ₂ O _{3- x} F _2x ; B ₂ O ₃ -Al ₂ O ₃ ) -based coating layer was about 5 to 20 nm. The coating layer of this ultrathin film did not change the morphology of the phosphor particles and greatly reduced the thermal degradation of the phosphor particles.

On the other hand, for example, it is well known that the degradation of the phosphor is more severe due to the mutual reaction in the gas discharge region in the lamp manufacturing process. The protective layer formed on the surface of the phosphor particles improves the luminescence property stability of the phosphor in the lamp manufacturing process. Therefore, in order to obtain the positive effect of the protective layer, it is necessary to select an appropriate chemical composition and to select the optimum thickness.

According to the experiments of the present inventors, when the coating material is amorphous and the coating layer is a non-particulate continuous thin film structure, it is possible to achieve full coverage of the phosphor particles and obtain high protection characteristics. It was confirmed.

Phosphor particles coated with a continuous amorphous protective layer are schematically illustrated in FIG. 7A. 7B illustrates a particulate coating layer, which shows a discontinuous structure due to the presence of pores and may not exhibit sufficient protective properties. In addition, the phosphor particles on which the particulate coating layer is formed are severely deteriorated due to external influences due to the high specific surface area.

The present inventors confirmed that the light emitting property of the phosphor was increased by coating only the inorganic nano thin film on the phosphor particles through experiments.

In the present invention, an oxide, a fluorine-substituted oxide, an oxide-fluoride, or the like may be selected as the ultra-thin coating layer material. Specifically, one or two or more oxides of Al ₂ O ₃ , Y ₂ O ₃ , SiO ₂ , B ₂ O ₃ , and the like may be selected, and a material in which fluorine is substituted in the selected oxide may be included. For example, for B ₂ O ₃ , B ₂ O _{3 -x} F _2x or B ₂ O ₃ -Al ₂ O ₃ may be selected as the coating layer material. These materials have high ultraviolet transmission and low reflectivity in the bulk state. However, the present inventors have confirmed through the experiment that the thickness and the microstructure of the coating layer is a very important factor for the emission characteristics of the phosphor particles. The coating layer should be thin in thickness so that the phosphor particles can be sufficiently excited by ultraviolet irradiation.

The coating layer according to the present invention also improves the adsorption of the phosphor particles on the glass surface of the lamp. The inclusion of fluorine in the coating layer composition has the advantage of lowering the sensitivity to moisture in the external atmosphere. The concentration of fluorine is very important for the optimization of the protective properties of the oxide containing coating layer. The concentration of fluorine is preferably 3wt% or less in the coating layer composition. Containing 3 wt% or more of fluorine may lower the protective properties of the coating layer.

During the heat treatment of the coated phosphor or during the manufacture of the discharge device (PDP, fluorescent lamp, etc.), the ultrathin coating layer may come into contact with another material (another phosphor, glass, or another coating layer), which reacts with the coating layer. The composition of the coating layer may be changed slightly.

The present inventors experimented with 10 wt% of a material selected from Y, Si, La, Mg, Ba, Eu, Sr, Cs, P, Zn, Ca, Na, K, Sc, Zr or oxides thereof in addition to the coating layer composition. It can be added up to this case, even in this case it was confirmed that the protective properties of the nano-coating layer does not significantly change.

The manufacturing method of the coating layer is very important from an industrial point of view. Coating layer production based on gas phase synthesis is expensive and requires special manufacturing equipment. In the present invention, the inorganic coating layer of the thin film is coated on the surface of the phosphor particle by a simple wet method.

The process according to the invention comprises a) preparing a homogeneous and transparent mixed solution of pyrolysable inorganic compounds, b) adding ammonium fluoride and / or basic materials to the solution, if necessary, c) stirring the mixed solution, d) dispersing the phosphor particles in a transparent mixed solution, e) stirring the mixed solution for about 0.2 to 12 hours, f) separating the phosphor particles from the mixed solution, g) drying the phosphor particles and heat-treating in the range of 400 to 700 ℃ It may include the step.

After the phosphor particles are wet treated with pure solvent (alcohol, alcohol / water mixture) and filtered, the luminescence properties of the phosphor particles may be reduced during the drying and heat treatment processes. However, the inventors of the present invention confirmed that the light emission characteristics of the phosphor particles were greatly improved by using a dilute solution of the inorganic compound.

In addition, the present inventors have experimentally confirmed that the nano-coating layer proposed in the present invention can be applied to the protective coating on the surface of various phosphor particles, and the applicable phosphors include red phosphor (Y, Gd) BO ₃ : Eu, Y ₂ O ₃ : Eu, Y (P, V) O ₄ : Eu, green phosphor LaPO ₄ : (Ce, Tb), Zn ₂ SiO ₄ : Mn, GdMgB ₅ O ₁₀ : (Ce, Tb), CeMgAl ₁₁ O ₁₉ : Tb, blue phosphor CaMgSi ₂ O ₆ : Eu, BaMgAl ₁₀ O ₁₇ : Eu may be included.

Example 1

Solution B1 was prepared by dissolving 3.6 g of boric acid in 100 ml of ethanol. A solution A14 was prepared by dissolving 0.5 g of Al (NO ₃ ) ₃ 9H ₂ O in a mixture of 5 ml of water and 500 ml of ethanol. A BA1-2 solution was prepared by mixing 2 ml of A14 solution with 20 ml of B1 solution and 20 ml of ethanol. 4 ml of A14 solution was mixed with 20 ml of B1 solution and 20 ml of ethanol to prepare a BA1-2-1 solution. 20 ml of B1 solution was mixed with 20 ml of ethanol to prepare a B1-2 solution. 15 ml of B1 solution was mixed with 25 ml of ethanol to prepare a B1-4 solution. 20 ml of B1 solution was mixed with 10 ml of ethanol to prepare a B1-5 solution.

N1 ammonium fluoride solution was prepared by dissolving 0.122 g of NH ₄ F in a mixture of 1.2 ml of water and 48.8 ml of ethanol. A BF1 solution was prepared by mixing 20 ml of B1 solution with 5 ml of N1 solution and 20 ml of ethanol. BF2 solution was prepared by mixing 20 ml of B1 solution with 5 ml of N1 solution.

40 ml of B1-4 solution (B1-4 specimen), 40 ml of B1-2 solution (B1-2 specimen), 44 ml of BA1-2-1 solution (BA1-2-1 specimen), 42 ml of BA1-2 solution ( BA1-2 specimens) were respectively mixed with 2.0 g of blue phosphor (BAM) particles to form a surface coating layer.

The process of forming the coating layer from the liquid solution includes first dispersing the phosphor particles in the liquid solution and then separating the phosphor particles from the liquid solution.

The present inventors conducted a separate experiment to investigate the effect that the coating layer formation process may affect the luminescence properties of the coated phosphor. First, 2.0 g of BAM particles were mixed with 20 ml of ethanol (BAM-ethanol specimen). After 1 hour, the phosphor particles were separated from the solution by filtration. After drying, the phosphor particles were heat treated at 500 or 560 ° C. for 45 minutes or 90 minutes.

The compositions of the coating solution and the coating layer are shown in Table 1 and Table 2.

TABLE 1

Psalter Coating solution composition H ₃ BO ₃ , g Water, ml Ethanol, ml Al (NO ₃ ) ₃ , g PVP, g NH ₄ F, g B ₂ O ₃ B1 0.720 20.00 B1-2 0.720 40.00 B1-3 0.360 10.00 B1-4 0.540 40.00 B1-5 0.720 30.00 BA1-2 0.720 0.02 41.98 0.002 BA1-2-1 0.720 0.04 43.96 0.004 BF1 0.720 0.12 44.88 0.012 BF2 1.440 0.01 40.39 0.001 BF3 0.720 0.02 20.48 0.001 BF3-1 0.720 0.03 20.97 0.003 BF3-2 0.720 0.05 21.95 0.006 BF3-3 0.720 0.08 22.92 0.008 AlF ₃ AF2 1.28 18.72 0.014 0.030 0.029 AF2-1 0.96 19.04 0.011 0.023 0.022 AF2-2 0.64 19.36 0.007 0.015 0.015 AF2-3 0.32 19.68 0.004 0.008 0.007 AF2-4 0.13 19.87 0.001 0.003 0.003

TABLE 2

Psalter Coating Layer Composition Coating Layer Inorganic / Phosphor Weight Ratio Phosphor weight ratio to coating solution volume B ₂ O ₃ B1 B ₂ O ₃ 0.200 10.0ml / 1g B1-2 B ₂ O ₃ 0.200 20.0ml / 1g B1-3 B ₂ O ₃ 0.100 5.0ml / 1g B1-4 B ₂ O ₃ 0.150 20.0ml / 1g B1-5 B ₂ O ₃ 0.200 15.0ml / 1g BA1-2 B ₂ O ₃ 99.93%, Al ₂ O ₃ 0.07% 0.200 21.0ml / 1g BA1-2-1 B ₂ O ₃ 99.86%, Al ₂ O ₃ 0.14% 0.200 22.0ml / 1g BF1 B ₂ O _{3- x} F _{2 x} 0.211 22.5ml / 1g BF2 B ₂ O _{3- x} F _{2 x} 0.411 10.1ml / 1g BF3 B ₂ O _{3- x} F _{2 x} 0.206 10.3ml / 1g BF3-1 B ₂ O _{3- x} F _{2 x} 0.207 10.5ml / 1g BF3-2 B ₂ O _{3- x} F _{2 x} 0.208 11.0ml / 1g BF3-3 B ₂ O _{3- x} F _{2 x} 0.209 11.5ml / 1g AlF ₃ AF2 Al ₂ O ₃ -AlF ₃ 0.0017 10.0ml / 1g AF2-1 Al ₂ O ₃ -AlF ₃ 0.0013 10.0ml / 1g AF2-2 Al ₂ O ₃ -AlF ₃ 0.0009 10.0ml / 1g AF2-3 Al ₂ O ₃ -AlF ₃ 0.0004 10.0ml / 1g AF2-4 Al ₂ O ₃ -AlF ₃ 0.0002 10.0ml / 1g

8 and 9 show excitation irradiation emission spectra of 254 nm (1, 3) wavelength and 174 nm wavelength (2, 4) for uncoated and coated specimens. In FIG. 8, graph 1 is an uncoated BAM phosphor, graph 2 is a BAM phosphor heat-treated at 560 ° C. for 45 minutes, and graph 3 is a BAM phosphor heat-treated at 560 ° C. for 45 minutes, and graph 4 is B _2. BAM phosphor coated with O ₃ (Sample B1-4 in Table 1) and heat-treated at 560 ° C. for 45 minutes, Graph 5 coated B ₂ O ₃ -Al ₂ O ₃ (Sample BA1-2-1 in Table 1) The light emission characteristics of the BAM phosphor heat-treated at 560 ° C. for 45 minutes are shown. In Figure 9 Graph 1 shows an uncoated BAM phosphor, graph 2 shows a BAM phosphor heat-treated at 560 ° C. for 45 minutes, graph 3 shows a BAM phosphor heat-treated at 560 ° C. for 45 minutes, and graph 4 shows B ₂ O ₃ . BAM phosphor coated and (annealed B1-4 in Table 1) for 45 minutes at 560 ℃, Graph 5 coated B ₂ O ₃ -Al ₂ O ₃ (Sample BA1-2-1 in Table 1) at 560 ℃ BAM phosphor heat-treated for 45 minutes, Graph 6 shows the light emission characteristics of the BAM phosphor, coated with B ₂ O ₃ (Sample B1 in Table 1) and heat-treated for 45 minutes at 560 ℃.

In all graphs a broad band was observed near the maximum of 450 nm. These results due to 5d-4f transition of Eu ^{2 +.} Comparing graphs 1 and 2 in Figs. 8 and 9, the effect of heat treatment on the luminescence properties of the phosphor particles can be seen. In addition, when comparing graphs 1 and 2 in FIGS. 8 and 9, it can be seen that the degree of deterioration of the emission characteristics under VUV (174 nm) is higher than that of UV (254 nm). This fact can be explained by the strong deterioration of the surface layer of phosphor particles during the heat treatment process.

8 and 9 show the emission spectra of BAM phosphors dispersed in ethanol without a coating layer formed in the VUV (FIG. 3) and UV (FIG. 2) excitation situations. Comparing this graph 3 with the graph 2, it can be seen that the treatment of the wet method (filtering after contact with the liquid solution) without forming a coating layer significantly reduces the luminescence properties of the BAM phosphor.

It can be seen from the results of FIGS. 8 and 9 that the thermal degradation of the BAM phosphor can be greatly reduced by forming the B ₂ O ₃ and B ₂ O ₃ -Al ₂ O ₃ coating layers. The coated BAM phosphor showed higher luminescence properties than the uncoated phosphor under the same conditions. The improvement of the luminescence properties of the phosphor particles is a B ₂ O _3-containing layer may be described with respect to preventing the oxidation of Eu _{2 +.}

Figure 10 shows the effect of the heat treatment temperature on the protective properties of the B ₂ O ₃ coating layer on the BAM phosphor (Sample B1-5 in Table 1). Graphs 1 and 2 are for the emission emission spectra (254 nm) of the uncoated phosphors, graphs 3 and 4, and graphs 2 and 4 were heat treated for 45 minutes at 500 ° C. and graphs 1 and 3 at 560 ° C., respectively. It shows the light emission characteristics of the phosphor. It can be seen from this spectrum that the protective effect of the coating layer is improved with increasing the heat treatment temperature. By increasing the heat treatment temperature from 500 ° C. to 560 ° C., the peak intensity of the uncoated BAM phosphor particles was reduced from 7334 (arb. Units) to 7080. With the same temperature change, the brightness of the B ₂ O ₃ coated BAM phosphor (Sample B1-5 in Table 1) was reduced from 7330 (arb. Units) to 7240. It can be seen that the protective effect of the coating layer depends on the phosphor heat treatment temperature. Increasing the heat treatment temperature drastically increased the deterioration of the uncoated BaMgAl ₁₀ O ₁₇ : Eu ²⁺ phosphor, but the degradation was relatively weak in the coated phosphor.

Table 3 below shows luminance data of the coated BAM phosphor.

TABLE 3

Psalter Peak intensity (450 nm) during UV (254 nm) excitation Peak Intensity at VUV (174 nm) Excitation (450 nm) Arb. units % Arb. units % Uncoated BAM Phosphor 7780 100 4019 100 Uncoated BAM Phosphor Heated at 500 ° C for 45 Minutes 7334 94.3 Uncoated BAM Phosphor Heated at 560 ℃ for 45 Minutes 7080 91.0 2823 70.2 Uncoated BAM phosphor heat-treated for 45 minutes at 560 ℃ after 1 hour dispersion in ethanol 6760 86.9 2244 55.8 AF2 (560 ℃, 45 minutes) 6611 85.0 2510 62.5 AF2-1 (560 ℃, 45 minutes) 6844 88.0 AF2-3 (560 ℃, 45 minutes) 7142 91.8 2501 62.2 AF2-4 (560 ℃, 45 minutes) 7142 91.8 2756 68.6 B1 (560 ° C., 45 minutes) 7639 98.2 3725 92.7 B1-2 (560 ° C., 45 minutes) 8050 103.5 3672 91.4 B1-3 (560 ℃, 45 minutes) 7830 100.6 3604 89.7 B1-4 (560 ° C, 45 minutes) 7100 91.3 2787 69.3 B1-5 (500 ℃, 45 minutes) 7330 94.2 B1-5 (560 ℃, 45 minutes) 7240 93.1 BF1 (560 ℃, 45 minutes) 6940 89.2 BF2 (560 ℃, 45 minutes) 7673 98.6 BF2 (560 ℃, 90 minutes) 7465 96.0 BA1-2 (560 ° C., 45 minutes) 7130 91.6 3103 77.2 BA2-1-1 (560 ° C., 45 minutes) 7200 92.5 3148 78.3

FIG. 11 is a SEM photograph showing BAM phosphors (c and d) and uncoated phosphors (a and b) in which a B ₂ O ₃ coating layer is present. It can be seen from this photograph that the morphology of the phosphor particles did not change even after the coating layer was formed in a wet manner. It can be seen from the coated BAM phosphor photograph that the thickness of the B ₂ O ₃ coating layer is very thin (15-20 nm).

For various BAM phosphor in Eu 3 d _5/2 Figure 12 a XPS spectrum of the core region Shown. In this XPS spectrum Eu 3 d _5/2 form the core region and the energy position of the Eu ^{2 +} and Eu ^{3 +} state of the Eu compound, are distinguished from each other. E _b is a relatively weak peak of a change in a strong peak in the near place 1134eV and is due to Eu ^{3 +} ion, E _b near 1124eV may be associated with Eu ^{2 +} ions. Form is similar to the XPS spectrum of each sample, and Eu ^{2 +} Eu ³⁺ and the peak area to estimate the relative amount of Eu ^{2 +} phosphor and Eu ^{3 +} ions in the specimen from the ratio between the two peaks to some extent proportional to the concentration of Eu Can be. Table 4 shows the ratio of I _{Eu3 +} / I _{Eu2 +} in the XPS spectrum for the different phosphor particles.

TABLE 4

Psalter I _{Eu3 +} / I _{Eu2 +} Uncoated BAM Phosphor 0.47 Uncoated BAM Phosphor Heated at 560 ℃ for 45 Minutes 0.30 B ₂ O ₃ coated BAM phosphor heat-treated at 560 ℃ for 45 minutes 0.34

10 and from the data in Table 4, the heat treatment of the BAM phosphor can be seen Sikkim relatively reduce the Eu ^{2 +} concentration.

The heat treatment of the BAM phosphor changes chromaticity coordinates so that the chromaticity changes from blue to green as the fluorescence efficiency deteriorates. Table 5 shows the effect of heat treatment on the color coordinates (x; y) of the CIE color points in the emission spectra of the different BAM phosphors.

TABLE 5

Psalter UV (254 nm) excitation VUV (174 nm) excitation x y x y Uncoated BAM Phosphor 0.145 0.065 0.145 0.054 Uncoated BAM Phosphor Heated at 560 ℃ for 45 Minutes 0.144 0.071 0.142 0.066 Uncoated BAM phosphor heat-treated for 45 minutes at 560 ℃ after 1 hour dispersion in ethanol 0.145 0.067 0.142 0.064 B1-4 (560 ° C, 45 minutes) 0.144 0.070 0.142 0.063 BA1-2 (560 ° C., 45 minutes) 0.145 0.069 0.144 0.058 BF1 (560 ℃, 45 minutes) 0.145 0.069 BA1-2-1 (560 ° C., 45 minutes) 0.144 0.070 0.143 0.060 B1 (560 ° C., 45 minutes) 0.145 0.064 B1-2 (560 ° C, 90 minutes) 0.146 0.062 B1-3 (560 ℃, 45 minutes) 0.146 0.060

According to the experimental results, the heat treatment did not affect the x coordinate, but had a significant change in the y coordinate. From the results in Table 5, the B ₂ O ₃ -Al ₂ O ₃ coating layer (Sample BA1-2), B ₂ O _3-x F _2x coating layer (Sample BF1), B ₂ O ₃ coating layer (Samples B1, B1-2) were obtained. When formed, it can be seen that color transition can be prevented in the emission spectrum of the heat-treated BAM phosphor.

Example 2

Solution B1 was prepared by dissolving 3.6 g of boric acid in 100 ml of ethanol. Ammonium fluoride solution N2 was prepared by dissolving 0.1 g of NH ₄ F in a mixture of 1 ml of water and 37 ml of ethanol. BF3 solution was prepared by mixing 20 ml of B1 solution with 0.5 ml of N2 solution. 20 ml of B1 solution was mixed with 1 ml of N2 solution to prepare a BF3-1 solution. 20 ml of B1 solution was mixed with 2.0 ml of N2 solution to prepare a BF3-2 solution. 20 ml of B1 solution was mixed with 3.0 ml of N2 solution to prepare a BF3-3 solution. The prepared solution was clear and uniform.

20.5 ml of BF3 solution (BF3 specimen), 21 ml of BF3-1 solution (BF3-1 specimen), 22 ml of BF3-2 solution (BF3-2 specimen) and 23 ml of BF3-3 solution (BF3-3 specimen) A surface coating layer was formed by mixing with 2.0 g of phosphor (BAM) particles.

The change in heat of the B ₂ O _{3 ×} F _2x coated BAM phosphor was investigated via differential thermal analysys (DTA). In this study, the temperature was elevated at 10 ° C / min in air and the specimens were heated in the range of 50-230 ° C.

FIG. 13 is a graph showing DTA results of B ₂ O _{3 ×} F _2x coated BAM phosphors using the BF3-2 solution of Table 6. FIG. Three endothermic peaks were observed at 90 ° C., 140 ° C. and 170 ° C., respectively. These three peaks are due to three stages of H ₃ BO ₃ degradation into HBO ₂ , H ₂ B ₄ O ₇ and B ₂ O ₃ . Complete decomposition of the original coating layer, which consists primarily of boric acid, terminates near 200 ° C. This temperature is considerably lower than, for example, the manufacturing process temperature (500-600 ° C.) of the fluorescent lamp. Therefore, the coating layer formation may be included in the lamp manufacturing process without a separate heat treatment.

The chemical composition of the heat treated coating layer and the luminescence properties (peak intensity 450 nm) upon UV (254 nm) excitation of the coated BAM phosphor specimens are shown in Table 6.

TABLE 6

Psalter Heat treatment temperature, ℃ Fluorine (F) content, mol% Luminance, arb. units Uncoated BAM Phosphor 480 - 6829 BF3 480 0.6 6717 BF3-1 480 1.2 6792 BF3-2 480 2.5 6736 BF3-3 480 3.7 6706 BF3 500 0.6 6960 BF3-1 500 1.2 7083 BF3-2 500 2.5 6894 BF3-3 500 3.7 6821

FIG. 14 is a SEM photograph (a) of BAM phosphor particles having an initial coating layer (using coating solution BF3-3) of H ₃ BO ₃ + NH ₄ F and a B ₂ O _{3- x} F _2x coating layer heat-treated at 500 ° C. for 45 minutes. SEM photograph (b). This photograph shows that the B ₂ O _{3 -x} F _2x coating layer was formed from the first H ₃ BO ₃ + NH ₄ F nano coating layer. In addition, the phosphor morphology was not changed during the heat treatment of the coated BAM phosphor.

15 shows emission spectra of uncoated BAM phosphors and coated phosphors. In Figure 15 Graph 1 is an uncoated BAM phosphor, Graph 2 is a BAM phosphor heat-treated at 500 ° C. for 45 minutes, Graph 3 is a BAM phosphor (Sample BF 3) heat-treated at 500 ° C. for 45 minutes after B ₂ O _{3- x} F _2x coating, and graph 4 is a BAM phosphor (Sample BF3-1) heated at 500 ° C. for 45 minutes after B ₂ O _{3- x} F _2x coating, and FIG. 5 is a BAM phosphor heat treated at 500 ° C. for 45 minutes after B ₂ O _{3- x} F _2x coating. (Sample BF3-2), Graph 6 shows the light emission characteristics of the BAM phosphor (Sample BF3-3) heat-treated for 45 minutes at 500 ℃ after B ₂ O _{3- x} F _2x coating. From these graphs, it can be seen that the composition of the B ₂ O _{3 -x} F _2x coating layer with increased fluorine content greatly changes the emission intensity of the BAM phosphor. In addition, an appropriate concentration range of the coating solution can be seen. The fluorine content is preferably 3 mol% or less. The data in Table 6 shows that when the fluorine content exceeds 3 mol%, the protective properties of the coating layer are lowered.

Phosphor encapsulated nano coating layer according to the present invention can be used as the internal fluorescent layer of a flat fluorescent lamp or a tubular fluorescent lamp. In particular, the fluorescent layer according to the present invention is suitable for a surface light source device including a discharge space therein.

Referring to FIG. 16, a surface light source device 200 according to an embodiment of the present invention is shown. The surface light source device 200 includes a planar first substrate 210 and a planar second substrate 220 having the same shape as the light source body. The surface light source device has a discharge space enclosed therein, and it is preferable to form a surface electrode at least partially covering the surface on one surface 210 '. Fluorescent layers 215 and 225 are applied to the inner surfaces of the first substrate 210 and the second substrate 220 as shown in FIG. 17, and a reflective film (not shown) is further applied to any one of the first substrate and the second substrate 220. Can be formed. The first substrate 210 and the second substrate 220 face each other at predetermined intervals, and side spacers 230 are inserted at edges to form a sealed internal discharge space 240.

FIG. 18 schematically illustrates a phosphor layer formed on a substrate, in which a nano-coating layer 400 encapsulated in individual phosphor particles 310 may be formed, and adjacent phosphor particles 320 may include one nano-coating layer 410. May be encapsulated by

Such a fluorescent layer may be applied to a fluorescent lamp, in particular, a flat substrate or a molded substrate of a large area surface light source device, thereby improving durability and lifespan of the surface light source device.

When the light source body of the surface light source device includes the first substrate and the second substrate, heat treatment of the phosphor may be performed in parallel during the process for bonding the two substrates. Thus, the overall process can be shortened and manufacturing equipment can be reduced. In order to simultaneously proceed the bonding process of the substrate and the phosphor heat treatment process, the phosphor particles dispersed in the liquid precursor may be applied to the surface of the visible light transmitting substrate to form a phosphor layer, and the substrate and the phosphor layer may be simultaneously heat treated.

Although described above with reference to preferred embodiments of the present invention, those skilled in the art or those skilled in the art without departing from the spirit and scope of the invention described in the claims to be described later Various modifications and variations can be made in the present invention without departing from the scope thereof.

Claims (19)

Non-particulate amorphous inorganic coating layer is encapsulated in the nanometer thickness on the surface of the phosphor particles Phosphor powder. The phosphor powder of claim 1, wherein the coating layer is formed to a thickness of 50 nm or less. The phosphor powder of claim 1, wherein the coating layer comprises an oxide. The phosphor powder of claim 3, wherein the oxide comprises B 2 O 3. The phosphor powder of claim 3, wherein the coating layer comprises two or more kinds of oxides. The phosphor powder of claim 3, wherein the coating layer comprises an oxide containing fluorine. The phosphor powder of claim 6, wherein the fluorine content of the coating layer is 3 wt% or less. The phosphor powder according to claim 1, wherein the phosphor particles are blue phosphors. Preparing a mixed solution containing a pyrolysable visible light transmitting inorganic compound and a solvent, Stirring the mixed solution, Dispersing the phosphor particles in the mixed solution, Phosphor particles are separated from the mixed solution, Drying and heat treating the separated phosphor particles. Phosphor powder production method. The method of claim 9, wherein the mixed solution further comprises ammonium fluoride. The method of claim 9, wherein the inorganic compound comprises B ₂ O ₃ . The method of claim 9, wherein the heat treatment of the phosphor particles is performed during the fluorescent lamp manufacturing process. The method of claim 9, wherein the inorganic compound includes two or more kinds of oxides. The method for producing a phosphor powder according to claim 9, wherein the inorganic compound is an oxide containing fluorine. 15. The method of claim 14, wherein the fluorine content of the oxide is 3 mol% or less. 10. The method of claim 9, wherein the inorganic compound additionally comprises a phosphor powder further comprising a material selected from Y, Si, La, Mg, Ba, Eu, Sr, Cs, P, Zn, Ca, Na, K, Sc, Zr. Way. The method of claim 9, wherein the heat treatment temperature is a phosphor powder manufacturing method, characterized in that in the range of 400 ~ 700 ℃. A light source body including a discharge space therein, A fluorescent layer formed on the inner surface of the light source body, the phosphor particles constituting the fluorescent layer is characterized in that the non-particle amorphous inorganic coating layer is encapsulated to a thickness of nanometer level Surface light source device. 19. The surface light source device of claim 18, wherein the light source body includes a first substrate and a second substrate, and the fluorescent layer is formed on inner surfaces of the first substrate and the second substrate, respectively.