TW201414016A - Light-emitting device - Google Patents

Abstract

To provide a light-emitting device in which it is possible to suppress a drop in reflectance resulting from a silver reflector reacting with sulfur components and thus becoming silver sulfide and blackening. The light-emitting device is provided with a light-emitting element (22), a reflector (26) which is made from silver and which reflects the light from the light-emitting element (22), and a fluorescent material (10). A coating (26a), containing zinc oxide (ZnO), is formed on at least one part of the surface of the reflector (26). Thus, the zinc oxide reacts with the sulfur components, thereby inhibiting the generation of silver sulfide.

Description

Illuminating device

The present invention relates to a light-emitting device having a reflector made of silver.

At present, LED backlights are attracting attention in terms of backlighting or next-generation lighting of LCD TVs. In order to cause the LED lamp to emit white light, it is necessary to superimpose the light emitted from the LED element itself through a lens coated or blended with a phosphor such as red, blue or green to superimpose the light emitted from the phosphor, thereby obtaining white color. In recent years, in order to improve color rendering properties, sulfur-containing sulfide-based phosphors have attracted attention. However, the fluorescent system has a weak point in which the luminescent properties are lowered when exposed to moisture, heat, or ultraviolet rays. In particular, the sulfide-based fluorescent system is chemically unstable, and has a problem that hydrogen sulfide is generated by the reaction of the surface of the phosphor with water, which causes a significant adverse effect on surrounding members. Therefore, there are very few cases in which practical use has been achieved. Therefore, in order to protect from such external influences, it is proposed to form a coating layer on the surface of the phosphor particles (see, for example, Patent Document 1).

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Application No. 2010-248411

However, the formation of the coating layer can suppress the deterioration of the phosphor particles themselves to a minimum, but it is not sufficient to suppress the influence by hydrogen sulfide, and there may be hydrogen sulfide and surrounding components. For example, the problem that the reflector, the wiring, or the sealing resin is deteriorated. In particular, when silver is used for the reflector, silver easily reacts with hydrogen sulfide to form silver sulfide, which is blackened, and the reflectance is remarkably lowered.

Further, even in the atmosphere or a member constituting the LED, particularly a trace amount of the sulfur component contained in the resin member, the decrease in the reflectance due to the blackening of the reflector is negligible from the viewpoint of long-term device life. problem.

The present invention has been made in view of the above-mentioned problems, and it is an object of the invention to provide a light-emitting device capable of suppressing the formation of silver sulfide by a reaction between a reflector made of silver and a sulfur component, thereby reducing the reflectance. .

The light-emitting device of the present invention includes a light-emitting element, a reflector made of silver that reflects light from the light-emitting element, and a phosphor material, and the reflection system has a film containing zinc oxide on at least a part of the surface. .

According to the light-emitting device of the present invention, at least a part of the surface of the reflector made of silver is provided with a film containing zinc oxide. Therefore, by reacting with the sulfur component, generation of silver sulfide can be suppressed, and the reflectance can be suppressed from being lowered. .

In particular, when the thickness of the film is 20 nm or more and 1 μm or less, a higher effect can be obtained.

Further, when the phosphor material contains the phosphor particles formed of the sulfide-based phosphor, the hydrogen sulfide generated by the phosphor particles is decomposed by reacting with the zinc oxide on the surface of the reflector, thereby being harmless. Chemical. Therefore, the influence on the reflector or the surrounding member due to the occurrence of hydrogen sulfide can be reduced, and deterioration in characteristics can be suppressed.

Further, when a coating layer containing zinc oxide is provided on the surface of the phosphor particles, hydrogen sulfide generated by the phosphor particles is decomposed by reacting with zinc oxide on the surface of the phosphor particles, thereby being harmless. Therefore, the influence on the reflector or the surrounding member due to the occurrence of hydrogen sulfide can be reduced, and deterioration in characteristics can be suppressed.

In addition, the amount of the zinc oxide layer in the coating layer is 0.75 wt% or more and 30 wt% or less by weight of the weight of the zinc oxide to the weight of the phosphor particles, and a zinc oxide layer is provided on the coating layer, and When the thickness of the zinc oxide layer is 30 nm or more and 1 μm or less, the brightness maintenance rate can be improved.

Further, if the coating layer has a zinc oxide layer and a ceria layer, the brightness maintenance rate can be further improved, and the influence on the surrounding members due to the occurrence of hydrogen sulfide can be further reduced.

10‧‧‧Fluorescent materials

11‧‧‧Silver particles

12‧‧‧ Cover

20‧‧‧Lighting device

21‧‧‧Substrate

22‧‧‧Lighting elements

23‧‧‧ wiring

24‧‧‧Wire

25‧‧‧ reflector frame

26‧‧‧ reflector

26a‧‧‧film

27‧‧‧ Sealing layer

31‧‧‧ Silver board

32‧‧‧Contained containers

33‧‧‧ water

Fig. 1 is a view showing the configuration of a light-emitting device according to an embodiment of the present invention.

Figure 2 is a view showing the phosphor material used in the light-emitting device of Figure 1. A schematic diagram of an example of the configuration.

Fig. 3 is a view showing the experimental apparatus used in the examples.

Fig. 4 is a characteristic diagram showing changes with time in the light-emitting luminances of Reference Examples 1-1 to 1-3 and 1-7.

Fig. 5 is a characteristic diagram showing changes with time in the light-emitting luminance of Reference Examples 1-1, 1-7, and 2-1.

[Formation of the Invention]

Embodiments of the present invention will be described in detail below with reference to the drawings.

Fig. 1 is a view showing an example of a configuration of a light-emitting device 20 according to an embodiment of the present invention. In the light-emitting device 20, a light-emitting element 22 is mounted on a substrate 21, and the light-emitting element 22 is electrically connected by a wiring 23 and a wire 24 formed on the substrate 21. The wiring 23 and the wire 24 are made of, for example, copper or the like. Further, for example, a reflector frame 25 is formed around the light-emitting element 22. On the inner side surface of the reflector frame 25, that is, the surface on the side of the light-emitting element 22, for example, a reflector 26 made of silver that reflects light from the light-emitting element 22 is formed. A sealing layer 27 is formed on the light-emitting element 22 so as to cover the light-emitting element 22. The sealing layer 27 is made of, for example, a resin that disperses the phosphor material 10.

A film 26a containing zinc oxide (ZnO) is formed on at least a part of the surface of the reflector 26. Thereby, zinc oxide reacts with the sulfur component to suppress the occurrence of silver sulfide, and the decrease in reflectance due to blackening can be suppressed. The film 26a is preferably a white turbid film which does not significantly impair the reflectance of the reflector 26, and is preferably a dense and uniform film. The thickness of the film 26a is For example, it is preferably 20 nm or more and 1 μm or less, and more preferably 40 nm or more and 600 nm or less. When the thickness is thin, the effect of suppressing the decrease in reflectance by the film 26a is small, and if the thickness is thick, the initial reflectance of the reflector 26 is lowered.

The film 26a is formed by silver, for example, by various methods.

The surface of the resulting reflector 26. Specifically, for example, a sol-gel method, a method of adhering fine particles of zinc oxide to the surface of the reflector 26 by various methods such as wet or dry, a CVD method, a PVD method, or a sputtering method can be mentioned. Further, the film formation may be carried out once, or may be divided into a plurality of times to form a film. Further, after the film formation, in order to fix the film 26a, heat treatment may be performed as needed.

In the light-emitting element 22, for example, ultraviolet light, blue light is emitted. Light, or green light, acts as an excitation light.

In the case of the phosphor material 10, one type or as needed For example, a person who emits red light by excitation light emitted from the light-emitting element 22, a person who emits blue light, a person who emits green light, a person who emits yellow light, or the like.

Fig. 2 is a diagram showing an example of a phosphor material 10. The The phosphor material 10 preferably has phosphor particles 11 and a coating layer 12 provided on the surface of the phosphor particles 11. Further, the coating layer 12 may not be formed.

Examples of the phosphor particles 11 include blue phosphors such as BaMgAl ₁₀ O ₁₇ :Eu, ZnS:Ag, Cl, BaAl ₂ S ₄ :Eu or CaMgSi ₂ O ₆ :Eu, and Zn ₂ SiO. ₄ : Mn, (Y, Gd) BO ₃ : Tb, ZnS: Cu, Al, SrGa ₂ S ₄ : Eu, or (Ba, Sr, Mg) O. a green phosphor such as aAl ₂ O ₃ : Mn, a yellow phosphor such as CaGa ₂ S ₄ :Eu, (Y,Gd)BO ₃ :Eu, Y ₂ O ₂ S:Eu, YPVO ₄ :Eu, La ₂ O ₂ S: Eu, CaS:Eu, SrS:Eu, or a red-based phosphor such as (Ca, Sr)S:Eu. The particle diameter of the phosphor particles 11 is substantially constant, but the average particle diameter is about 5 μm to 20 μm, and it is preferable that the particle diameters are as uniform as possible. The characteristics can be stabilized.

Sulfur is also used in the phosphor particles 11 as shown above.

a compound-based phosphor such as a blue-based phosphor such as ZnS:Ag, Cl or BaAl ₂ S ₄ :Eu, a green-based phosphor such as ZnS:Cu, Al or SrGa ₂ S ₄ :Eu, or CaGa ₂ S ₄ : When a yellow phosphor such as Eu or a red phosphor such as Y ₂ O ₂ S:Eu, La ₂ O ₂ S:Eu, CaS:Eu, SrS:Eu, or (Ca,Sr)S:Eu The phosphor particles 11 react with water or the like to generate hydrogen sulfide (H ₂ S), and the blackening of the reflector 26 is likely to occur. However, according to the present embodiment, blackening due to the occurrence of silver sulfide can be effectively suppressed.

The zinc oxide contained in the coating film 26a is easily reacted with hydrogen sulfide at normal temperature and pressure, and is converted into zinc sulfide (ZnS) and water (H ₂ O) which have little influence on optical characteristics. The reason.

ZnO+H ₂ S → ZnS+H ₂ O. . . (1)

The coating layer 12 of the phosphor material 10 preferably contains zinc oxide, and particularly preferably, the phosphor particles 11 are formed of a sulfide-based phosphor. As described above, by the zinc oxide, hydrogen sulfide can be converted into zinc sulfide and water which have less influence on optical characteristics. The coating layer 12 is preferably composed of a single layer of a zinc oxide layer made of zinc oxide, but is preferably formed of a plurality of layers in which a zinc oxide layer and another one or more layers are laminated. By laminating with other layers, deterioration of the phosphor particles 11 can be suppressed, and hydrogen sulfide can be suppressed by this.

Other layers include, for example, magnesium oxide (MgO), aluminum oxide (Al ₂ O ₃ ), cerium oxide (SiO ₂ ), titanium oxide (TiO ₂ ), and cerium oxide (Y ₂ O ₃ ). A layer of at least one selected from the group consisting of lanthanum oxide (La ₂ O ₃ ), cerium oxide (CeO ₂ ), cerium oxide (Gd ₂ O ₃ ), and zirconia (ZrO ₂ ). When the other layer contains two or more kinds of compounds, they may be mixed or compositely contained in one layer, or may be contained in a layered manner in a plurality of layers. Further, in other layers, it is preferable to contain cerium oxide, and it is more preferable if it is formed to have a cerium oxide layer formed of cerium oxide. Can get higher results.

The thickness of the zinc oxide layer is preferably, for example, 30 nm or more and 1 μm. Next, it is more preferably 100 nm or more and 500 nm or less. Further, the amount of zinc oxide in the coating layer 12 is preferably from 0.75% by weight to 30% by weight, based on the weight ratio of the zinc oxide to the weight of the phosphor particles 11, and is from 2.5% by weight to 15% by weight. Better. If the thickness of the zinc oxide layer is thin or the amount of zinc oxide is small, the effect of reducing the influence of hydrogen sulfide on the surrounding members is small, if the thickness of the zinc oxide layer is thicker or the amount of zinc oxide is smaller. For a long time, the decrease in the initial luminance and the deterioration of the luminance over time become large. The thickness of the other layer is preferably, for example, 30 nm or more and 1 μm or less, and more preferably 100 nm or more and 500 nm or less. Within this range, higher effects can be obtained.

The order of lamination of the zinc oxide layer and other layers is not particularly limited. . For example, the zinc oxide layer may be on the side of the phosphor particles 11, and the other layers may be on the side of the phosphor particles 11. Further, another layer may be interposed between the zinc oxide layers, and a zinc oxide layer may be interposed between the other layers.

In addition, the coating layer 12 may also be configured to have zinc oxide. And a mixed layer or composite layer of other substances. The other substance may, for example, be at least one selected from the group consisting of magnesium oxide, aluminum oxide, cerium oxide, titanium oxide, cerium oxide, cerium oxide, cerium oxide, cerium oxide, or zirconium oxide. Further, a structure in which a mixed layer or a composite layer containing zinc oxide and another substance and the other layer are laminated may be formed. In this case, the amount of zinc oxide in the coating layer 12 is preferably 0.75% by weight or more and 30% by weight or less based on the weight ratio of the zinc oxide to the weight of the phosphor particles 11, and is 3% by weight or more and 15% by weight or less. The following is better.

The phosphor material 10 is made, for example, by using various methods. The coating layer 12 is formed on the surface of the phosphor particles 11. Specifically, for example, a sol-gel method or a method of adhering fine particles constituting the coating layer 12 to the surface of the phosphor particles 11 by various methods such as wet or dry can be mentioned.

In the light-emitting device 20 as shown above, due to sulfur in the air The yellow component or the hydrogen sulfide generated by the phosphor particles 11 of the phosphor material 10, the reflector 26, the wiring 23, the wires 24, the sealing layer 27, and the like are deteriorated. In particular, since the reflector 26 is made of silver, the reactivity of silver with a sulfur component, particularly hydrogen sulfide, is high, and silver sulfide is formed, and deterioration such as a decrease in reflectance due to blackening is remarkable. However, according to the present embodiment, the coating film 26a containing zinc oxide is formed on at least a part of the surface of the reflector 26, whereby zinc oxide reacts with the sulfur component, thereby suppressing the occurrence of silver sulfide and suppressing the occurrence of silver sulfide. The decrease in reflectance due to blackening, and the like. In addition, when the coating layer 12 containing zinc oxide is formed on the surface of the phosphor particles 11, the occurrence of hydrogen sulfide can be suppressed, and deterioration of the reflector 26, the wiring 23, the wires 24, and the sealing layer 27 can be suppressed.

As shown above, in the present embodiment, the opposite is made by silver. At least a part of the surface of the projectile 26 is provided with the film 26a containing zinc oxide. Therefore, by reacting with the sulfur component, the occurrence of silver sulfide can be suppressed, and the decrease in reflectance can be suppressed.

In particular, when the thickness of the film 26a is 20 nm or more Below 1μm, higher results can be obtained.

In addition, if the phosphor material 10 contains sulfuric acid When the phosphor particles 11 are formed by the light body, the hydrogen sulfide generated by the phosphor particles 11 is decomposed by reacting with zinc oxide, and is harmless. Therefore, the influence on the reflector 26 or the surrounding members due to the occurrence of hydrogen sulfide can be reduced, and deterioration in characteristics can be suppressed.

Further, if oxygen is contained on the surface of the phosphor particles 11, The coating layer 12 of zinc is decomposed by reacting hydrogen sulfide generated by the phosphor particles 11 with zinc oxide of the coating layer 12, thereby being harmless. Therefore, it is possible to reduce the influence on the surrounding members such as the reflector 26, the wiring 23, the wiring 24, and the sealing layer 27 due to the occurrence of hydrogen sulfide, and it is possible to suppress deterioration in characteristics.

In addition, if the amount of the zinc oxide layer in the coating layer 12 is to be The weight ratio of the weight of the zinc oxide to the weight of the phosphor particles 11 is 0.75 wt% or more and 30 wt% or less, and the zinc oxide layer is provided on the coating layer 12, and the thickness of the zinc oxide layer 12 is 30 nm or more and 1 μm or less. , the brightness maintenance rate can be improved.

Furthermore, if the coating layer 12 has a zinc oxide layer and two The ruthenium oxide layer can further improve the brightness maintenance rate and can further reduce the influence on the surrounding members due to the occurrence of hydrogen sulfide.

[Examples]

(Example 1-1)

As shown in Fig. 3, a silver plate 31 having a film of zinc oxide formed on the surface thereof and a phosphor particle 11 made of a sulfide-based phosphor (Ca, Sr) S: Eu are formed without being coated. The phosphor material 10 of the layer 12 was housed in the sealed container 32, and subjected to a high-temperature wet environment exposure test at 85 °C. Water 33 is placed in the sealed container 32, and the silver plate 31 and the phosphor material 10 are disposed above the water 33 so as not to be immersed in the water 33. The film on the surface of the silver plate 31 is formed by dispersing zinc oxide fine particles having an average particle diameter of 20 nm in an alcohol solvent, and applying them to the surface of the silver plate 31 so as to have a thickness of about 100 nm, and drying them.

The change in the reflectance of the silver plate 31 against the exposure time was measured by a spectrophotometer every 30 minutes. In the judgment criterion, if the measured reflectance of the silver plate is 80% or more, it is regarded as pass, and when it is less than 80%, the reflectance of silver is considered to be remarkably lowered, and the test is terminated. Table 1 shows the initial reflectance and the reflectance of the silver plate 31 of less than 80% and the reflectance at that time. The reflectance of Table 1 is prepared by separately preparing a silver plate as a reference (when no film is formed), and expressing the relative value when the reflectance of the silver plate as a reference is 100. Further, the initial reflectance of Example 1-1 is the reflectance after the silver plate 31 is formed into a film.

In Comparative Example 1-1, a silver plate 31 having no film formed thereon was prepared, and in Comparative Example 1-2, a silver plate 31 having a film of yttrium oxide (Y ₂ O ₃ ) formed on the surface was prepared. In Comparative Example 1-3, a silver plate 31 on which a film of zirconium oxide (ZrO ₂ ) was formed was prepared, and in Comparative Example 1-4, a film in which ceria (SiO ₂ ) was formed on the surface was prepared. Silver plate 31. In Comparative Examples 1-2, 1-3, and 1-4, except for using cerium oxide fine particles, zirconia fine particles, or cerium oxide fine particles in place of zinc oxide fine particles, the other silver was used in the same manner as in Example 1-1. The surface of the plate 31 forms a film. In the same manner as in Example 1-1, Comparative Example 1-1 to Comparative Example 1-4 were combined with the phosphor particles of the sulfide-based phosphor (Ca, Sr) S: Eu. The body material 10 was placed in the sealed container 32 together with the silver plate 31, and subjected to a high temperature wet environment exposure test at 85 °C. The results obtained are shown together in Table 1. Further, the initial reflectances of Comparative Examples 1-2, 1-3, and 1-4 are reflectances after the silver plate 31 was formed into a film.

As shown in Table 1, in Example 1-1, the reflectance of the silver plate 31 was less than 80% after 16 hours passed, whereas in Comparative Example 1-1, Comparative Example 1-2, and Comparative Example. In 1-3, the reflectance of the silver plate 31 was less than 80% in 30 minutes, and also in the comparative example 1-4 for 3 hours, and the reflectance of the silver plate 31 was less than 80%. Further, in Example 1-1, a film of zinc oxide was formed on the surface of the silver plate 31, but the initial reflectance was the same as that of the silver plate on which the film was not formed, and the reflectance was not found to be lowered.

In other words, when the film 26a containing zinc oxide is provided on the surface of the reflector 26, it is possible to suppress blackening of the reflector 26 due to hydrogen sulfide and to suppress a decrease in reflectance.

(Example 2-1)

In the same manner as in Example 1-1, a silver plate 31 in which a film of zinc oxide is formed, and a phosphor material made of phosphor particles 11 of a sulfide-based phosphor (Ca, Sr) S: Eu are formed. 10 is stored in the sealed container 32, and water 33 is not placed in the sealed container 32, and a high-temperature environmental exposure test is performed at 85 ° C to investigate the change in the reflectance of the silver plate 31. Example 2-1 was a test which was not actively humidified and kept at 85 °C. Further, in Comparative Example 2-1, the silver plate 31 in which the film was not formed was subjected to a high-temperature environmental exposure test at 85 ° C in the same manner as in Example 2-1, and the change in the reflectance of the silver plate 31 was examined. At this time, the inside of the sealed container 32 and the entire contents of the phosphor material 10 and the silver plate 31 provided inside the sealed container 32 are not particularly dried beforehand, and the adsorbed water is heated in a closed container. The inside of the 32 is evaporatively diffused, whereby an environment in which a certain amount of moisture exists in the inside of the hermetic container 32 is formed.

The results obtained are shown in Table 2. In addition, the reflectance of Table 2 is prepared separately as a reference silver plate (when no film is formed), and the relative value when the reflectance of the silver plate as a reference is 100 is shown. Further, the initial reflectance of Example 2-1 is the reflectance after the silver plate 31 forms a film.

As shown in Table 2, in Comparative Example 2-1, it was 9 hours, silver The reflectance of the plate 31 was less than 80%. On the other hand, in Example 2-1, the reflectance was about 100% even after 1000 hours passed. In Comparative Example 2-1, it is considered that the reason why the reflectance is not lowered in the case where the water 33 is not placed inside the sealed container 32 is considered to be due to evaporation and diffusion of a certain amount of adsorbed water existing inside the sealed container 32. When the moisture is adsorbed, the phosphor material 10 reacts to generate hydrogen sulfide, so that the silver plate 31 is discolored. In other words, when the film 26a containing zinc oxide is provided on the surface of the reflector 26, it is possible to effectively suppress the blackening of the reflector 26 due to hydrogen sulfide and to suppress a decrease in reflectance.

(Examples 3-1 to 3-5)

The high-temperature wet environment exposure test at 85 ° C was carried out in the same manner as in Example 1-1, except that the thickness of the film of zinc oxide formed on the surface of the silver plate 31 was changed. The thickness of the film of zinc oxide formed on the surface of the silver plate 31 is 20 nm in Example 3-1, 40 nm in Example 3-2, 400 nm in Example 3-3, and 600 nm in Example 3-4. -5 is 1000 nm. In either case, the coating layer 12 is not formed in the phosphor particles 11 .

The results obtained were combined with those of Example 1-1 and Comparative Example 1-1. The results are shown together in Table 3. In addition, the reflectance of Table 3 was prepared separately as a reference silver plate (when no film was formed), and the relative value when the reflectance of the silver plate as a reference was 100 was shown. Further, the initial reflectances of Examples 1-1 and 3-1 to 3-5 are reflectances after the silver plate 31 forms a film.

As shown in Table 3, the reflectance of the silver plate 31 is less than 80%, In Example 3-1, after 1 hour, in Example 3-2, after 2 hours, in Example 3-3, after 30 hours, and in Example 3-4, after 40 hours. In Example 3-5, after 75 hours, in either of them, the decrease in reflectance was slower than in Comparative Example 1-1. It is understood that this effect is such that the thicker the film of the silver plate 31 is, the higher the thickness is. Further, the initial reflectance becomes lower as the thickness of the film becomes thicker. In other words, it is preferable that the thickness of the zinc oxide-containing coating 26a provided on the surface of the reflector 26 is 20 nm or more and 1 μm or less.

(Example 4-1)

On the surface of the phosphor particles 11 made of a sulfide-based phosphor (Ca, Sr) S: Eu, a cerium oxide layer made of cerium oxide and a zinc oxide layer made of zinc oxide are formed. As the coating layer 12, a phosphor material 10 is produced. A zinc oxide layer is formed on the ceria layer, the ceria layer has a thickness of about 300 nm, and the zinc oxide layer has a thickness of about 200 nm. The cerium oxide layer is dried and heat-treated by mixing the phosphor particles 11 with a cerium-containing precursor solution in which perhydropolyazane and a solvent are mixed. form. The zinc oxide layer is formed by applying a slurry in which fine particles of zinc oxide are dispersed in a solvent to the phosphor particles 11 and heat-treating.

The produced phosphor material 10 is formed on the surface The silver plate 31 of the film of zinc oxide was housed in the sealed container 32 as shown in Fig. 3, and a high-temperature wet environment exposure test at 85 ° C was carried out in the same manner as in Example 1-1. Example 3-1 is the same as Example 1 except that the coating layer 12 having a two-layer structure having a cerium oxide layer and a zinc oxide layer formed on the surface of the phosphor particles 11 is used as the phosphor material 10. -1 is the same. The results obtained are shown in Table 4 together with the results of Example 1-1 and Comparative Example 1-1. In addition, the reflectance of Table 4 is prepared separately as a reference silver plate (when no film is formed), and the relative value when the reflectance of the silver plate as a reference is 100 is shown. Further, the initial reflectances of Examples 1-1 and 3-1 are reflectances after the silver plate 31 was formed into a film.

As shown in Table 4, in Example 1-1, the reflection of the silver plate 31 The time when the rate is less than 80% is after 16 hours, whereas the time when the reflectance of the silver plate 31 is less than 80% is after 20 hours by the embodiment 3-1. In other words, it is understood that when the coating film 26a containing zinc oxide is provided on the surface of the reflector 26, and the coating layer 12 is provided on the surface of the phosphor particles 11, a higher effect can be obtained.

(Reference Example 1-1~1-7)

In Reference Examples 1-1 to 1-6, a zinc oxide layer made of zinc oxide is formed on the surface of the phosphor particles 11 made of a sulfide-based phosphor (Ca, Sr) S: Eu. The phosphor layer material 10 is formed by coating the layer 12. The coating layer 12 is formed by applying a slurry in which fine particles of zinc oxide are dispersed in a solvent to the phosphor particles 11 and heat-treating. At this time, in Reference Examples 1-1 to 1-6, the amount of the fine particles of zinc oxide dispersed in the solvent was changed, whereby the thickness of the coating layer 12 (that is, the zinc oxide layer) was changed. The thickness of the coating layer 12 is about 200 nm in Reference Example 1-1, about 500 nm in Reference Example 1-2, about 1 μm in Reference Example 1-3, about 100 nm in Reference Example 1-4, and about 40 nm in Reference Example 1-5. Reference Examples 1-6 were about 20 nm. Further, when the amount of the coating layer 12 (i.e., the zinc oxide layer) is converted into the weight ratio of the zinc oxide to the weight of the phosphor particles 11, the reference example 1-1 is about 5% by weight, and the reference example 1-2 is about 15% by weight, Reference Examples 1-3 are about 30% by weight, Reference Examples 1-4 are about 2.5% by weight, Reference Examples 1-5 are about 1.0% by weight, and Reference Examples 1-6 are about 0.5% by weight.

The produced phosphor material 10 and the silver plate 31 are as in the third As shown in the figure, in a sealed container 32, a high-temperature wet environment exposure test at 85 ° C was carried out in the same manner as in Example 1-1. In the reference examples 1-1 to 1-6, the coating material 12 made of zinc oxide is formed on the surface of the phosphor particles 11 as the phosphor material 10, and the film is not formed on the surface of the silver plate 31. In the judgment criterion, if the measured reflectance of the silver plate 31 is 80% or more, it is considered to be acceptable, and when it is less than 80%, the reflectance of the silver plate 31 is considered to be remarkably lowered, and the test is terminated. The results obtained are shown in Table 5. Further, the reflectance is additionally prepared as a reference silver plate, and is expressed as a relative value when the reflectance of the silver plate as a reference is 100.

Further, in the case of Reference Examples 1-7, preparation was not formed with a coating The phosphor material 10 of the layer, that is, the phosphor particles 11, was subjected to a high-temperature wet environment exposure test at 85 ° C in the same manner as in Reference Examples 1-1 to 1-6, and the change in reflectance of the silver plate 31 was examined. The phosphor particles 11 were used in the same manner as in Reference Examples 1-1 to 1-6. The results of Reference Example 1-1 are also shown in Table 5.

As shown in Table 5, in Reference Examples 1 to 1 to 1-6 in which the coating layer 12 of zinc oxide was formed, reflection was performed as compared with Reference Example 1-7 in which the coating layer 12 was not formed on the phosphor particles 11. The rate of decrease is slower. In other words, it is understood that when the coating layer 12 containing zinc oxide is provided, the influence of the occurrence of hydrogen sulfide on the surrounding members such as the reflector 26 can be reduced, and deterioration in characteristics can be suppressed. It can be seen that this effect is that the thicker the thickness of the zinc oxide layer, the higher the thickness.

Further, the phosphor materials 10 of Reference Examples 1-1 to 1-3 and 1-7 were subjected to a high-temperature and high-humidity environment exposure test at 85 ° C and 85% RH, and the temporal change in luminance was examined. The results obtained are shown in Fig. 4. In Fig. 4, the vertical axis indicates the relative luminance value when the initial luminance of Reference Example 1-7 is 100.

As shown in Fig. 4, in Reference Examples 1-1 to 1-3, and reference In the case of Example 1-7, the initial luminance was lowered, but by referring to Examples 1-1 and 1-2, the luminance maintenance ratio was improved as compared with Reference Example 1-7. In other words, when the thickness of the zinc oxide layer is 500 nm or less, the brightness maintenance rate can be improved, and the decrease in the initial brightness can be suppressed.

(Reference example 2-1)

A phosphor material was produced in the same manner as in Reference Example 1-1, except that the coating layer 12 was formed into a two-layer structure of a cerium oxide layer made of cerium oxide and a zinc oxide layer made of zinc oxide. 10. A zinc oxide layer is formed on the ceria layer, the ceria layer has a thickness of about 300 nm, and the zinc oxide layer has a thickness of about 200 nm. In the cerium oxide layer, the phosphor particles 11 are mixed in a cerium-containing precursor solution in which perhydropolyazane and a solvent are mixed, dried, and formed by heat treatment.

The phosphor material 10 of Reference Example 2-1 is also referred to the reference example. In the same manner, a high-temperature wet environment exposure test at 85 ° C in which the sealed container 32 was housed together with the silver plate 31 and a high-temperature and high-humidity environment exposure test at 85 ° C and 85% RH were carried out. The results obtained are shown in Tables 6 and 5 together with the results of Reference Examples 1-1 and 1-7. The reflectance of Table 6 is separately prepared as a reference silver plate, and is expressed as a relative value when the reflectance of the silver plate as a reference is 100. In Fig. 5, the vertical axis is the relative luminance value when the initial luminance of Reference Example 1-7 is set to 100.

As shown in Table 6, with reference to Example 2-1, the characteristics were greatly improved as compared with Reference Example 1-1. Further, as shown in FIG. 5, with reference to Example 2-1, the brightness maintenance rate can be greatly improved as compared with Reference Example 1-1. In other words, it is understood that when the coating layer 12 including the cerium oxide layer and the zinc oxide is provided, the influence of the occurrence of hydrogen sulfide on the surrounding members such as the reflector 26 can be further reduced, and the brightness maintenance rate can be further improved.

The present invention has been described with reference to the embodiments and examples, but the present invention may be variously modified and not limited to the above-described embodiments and examples. For example, in the above embodiment, the configuration of the light-emitting device 20 will be specifically described, but other configurations may be employed. Further, in the above embodiment, the influence on silver was specifically investigated, but the same effect can be obtained with respect to the influence of hydrogen sulfide on other members.

[Industrial availability]

A light-emitting device such as an LED can be used.

10‧‧‧Fluorescent materials

20‧‧‧Lighting device

21‧‧‧Substrate

22‧‧‧Lighting elements

23‧‧‧ wiring

24‧‧‧Wire

25‧‧‧ reflector frame

26‧‧‧ reflector

26a‧‧‧film

27‧‧‧ Sealing layer

Claims (8)

A light-emitting device comprising: a light-emitting element; a reflector made of silver that reflects light from the light-emitting element; and a phosphor material, wherein the reflection system has at least a part of a surface containing zinc oxide. Membrane. The light-emitting device according to claim 1, wherein the film has a thickness of 20 nm or more and 1 μm or less. The light-emitting device according to claim 1, wherein the phosphor material contains phosphor particles made of a sulfide-based phosphor. The light-emitting device according to the first aspect of the invention, wherein the phosphor material comprises: a phosphor particle; and a coating layer provided on the surface of the phosphor particle and containing zinc oxide. The light-emitting device according to claim 4, wherein the amount of the zinc oxide layer in the coating layer is 0.75% by weight or more and 30% by weight or less based on the weight ratio of the zinc oxide to the weight of the phosphor particles. The light-emitting device of claim 4, wherein the coating layer has a zinc oxide layer formed of zinc oxide. The light-emitting device of claim 6, wherein the zinc oxide layer has a thickness of 30 nm or more and 1 μm or less. The illuminating device of claim 6, wherein the coating layer further has a cerium oxide layer formed of cerium oxide.