JP6802983B2 - Wavelength conversion member and wavelength conversion element, and light emitting device using them - Google Patents

Description

The present invention provides a wavelength conversion member and a wavelength conversion element that convert the wavelength of light emitted by a light emitting diode (LED: Light Emitting Diode), a laser diode (LD: Laser Diode), or the like into another wavelength, and a light emitting device using them. Regarding.

In recent years, as a next-generation light emitting device that replaces fluorescent lamps and incandescent lamps, attention has been increasing to light emitting devices using LEDs and LDs from the viewpoints of low power consumption, small size and light weight, and easy light intensity adjustment. As an example of such a next-generation light emitting device, for example, in Patent Document 1, a wavelength conversion member that absorbs a part of the light from the LED and converts it into yellow light is arranged on the LED that emits blue light. The light emitting device is disclosed. This light emitting device emits white light, which is a composite light of blue light emitted from an LED and yellow light emitted from a wavelength conversion member.

Conventionally, as the wavelength conversion member, a member in which inorganic phosphor particles are dispersed in a resin matrix has been used. However, when the wavelength conversion member is used, there is a problem that the resin matrix is discolored or deformed by the light from the LED. Therefore, a wavelength conversion member made of a completely inorganic solid in which a phosphor is dispersed and fixed in a glass matrix instead of a resin has been proposed (see, for example, Patent Documents 2 and 3). The wavelength conversion member has a feature that the glass matrix as a base material is less likely to be deteriorated by heat from an LED or irradiation light, and problems such as discoloration and deformation are less likely to occur.

Japanese Unexamined Patent Publication No. 2000-208815 Japanese Unexamined Patent Publication No. 2003-258308 Japanese Patent No. 4895541

In recent years, the output of LEDs and LDs used as light sources has been increasing for the purpose of increasing the power of light emitting devices. Along with this, there is a problem that the temperature of the wavelength conversion member rises due to the heat of the light source and the heat generated from the phosphor irradiated with the excitation light, and as a result, the emission intensity decreases with time (temperature quenching). Further, in some cases, the temperature of the wavelength conversion member rises remarkably, and the constituent material (glass matrix or the like) may be melted.

In view of the above, the present invention comprises a wavelength conversion member and a wavelength conversion element capable of suppressing a decrease in emission intensity and dissolution of constituent materials over time when irradiated with high-power LED or LD light. It is an object of the present invention to provide a light emitting device using them.

The wavelength conversion member of the present invention is a wavelength conversion member containing inorganic phosphor particles and magnesium oxide particles, in which magnesium oxide particles are interposed between the inorganic phosphor particles, and the inorganic phosphor particles are present. It is characterized in that it is bound by magnesium oxide particles.

In the wavelength conversion member of the present invention, magnesium oxide particles are interposed between the inorganic phosphor particles. Here, since the magnesium oxide particles are superior in thermal conductivity as compared with glass or the like, the heat generated by the inorganic phosphor particles can be efficiently released to the outside. As a result, the temperature rise of the wavelength conversion member is suppressed, and temperature quenching is less likely to occur. In addition, since magnesium oxide particles have excellent heat resistance, they are difficult to dissolve even when irradiated with high-power LED or LD light, or they suppress the occurrence of problems such as thermal cracks due to a sudden temperature rise. There is also an advantage that it can be done. Further, the magnesium oxide particles have an advantage that they can be sintered at a lower temperature than ceramic particles such as aluminum oxide and zirconium oxide. Therefore, the firing temperature at the time of manufacturing the wavelength conversion member can be lowered, and the deterioration of the inorganic phosphor powder at the time of firing can be suppressed.

The wavelength conversion member of the present invention preferably contains 3 to 80% of inorganic phosphor particles and 20 to 97% of magnesium oxide particles in mass%.

In the wavelength conversion member of the present invention, the average particle size of the magnesium oxide particles is preferably 0.01 to 10 μm. By doing so, the denseness of the wavelength conversion member is improved and the heat conduction path is easily formed, so that the heat generated by the inorganic phosphor particles can be released to the outside more efficiently.

In the wavelength conversion member of the present invention, the purity of the magnesium oxide particles is preferably 99% or more. In this way, the magnesium oxide particles can be sintered at a relatively low temperature.

In the wavelength conversion member of the present invention, the average particle size of the inorganic phosphor particles is preferably 1 to 50 μm.

In the wavelength conversion member of the present invention, it is preferable that the inorganic phosphor particles are made of an oxide phosphor having a garnet structure. Since the oxide phosphor having a garnet structure has excellent heat resistance, deterioration of the inorganic phosphor particles themselves can be suppressed when irradiated with high-power LED or LD light.

In the wavelength conversion member of the present invention, (average particle size of magnesium oxide particles) / (average particle size of inorganic phosphor particles) is preferably 0.5 or less. By doing so, the denseness of the wavelength conversion member is improved and the heat conduction path is easily formed, so that the heat generated by the inorganic phosphor particles can be released to the outside more efficiently.

The wavelength conversion element of the present invention is characterized by being composed of a laminated body in which the above-mentioned wavelength conversion member and a heat radiating layer having a higher thermal conductivity than the wavelength conversion member are laminated. By doing so, the heat generated by the wavelength conversion member can be transferred to the heat radiating layer, so that it becomes easy to suppress the temperature rise of the wavelength conversion member.

In the wavelength conversion element of the present invention, a heat-dissipating layer made of translucent ceramics can be used.

In the wavelength conversion element of the present invention, as translucent ceramics, aluminum oxide-based ceramics, aluminum nitride-based ceramics, silicon carbide-based ceramics, boron nitride-based ceramics, magnesium oxide-based ceramics, titanium oxide-based ceramics, niobium oxide-based ceramics, and oxidation At least one selected from zinc-based ceramics and yttrium oxide-based ceramics can be used.

The light emitting device of the present invention is characterized by comprising the above-mentioned wavelength conversion member and a light source for irradiating the wavelength conversion member with excitation light.

The light emitting device of the present invention is characterized by comprising the above-mentioned wavelength conversion element and a light source for irradiating the wavelength conversion element with excitation light.

In the light emitting device of the present invention, it is preferable that the light source is a laser diode. Since the wavelength conversion member and the wavelength conversion element of the present invention are excellent in heat resistance and heat dissipation, it is easy to enjoy the effects of the invention when a laser diode having a relatively high power is used as a light source.

According to the present invention, a wavelength conversion member and a wavelength conversion element capable of suppressing a decrease in emission intensity and dissolution of constituent materials over time when irradiated with high-power LED or LD light, and a wavelength conversion element thereof. The light emitting device used can be provided.

It is a schematic cross-sectional view which shows one Embodiment of the wavelength conversion member of this invention. It is a schematic cross-sectional view which shows one Embodiment of the wavelength conversion element of this invention. It is a schematic side view which shows one Embodiment of the light emitting device of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the following embodiments are merely examples, and the present invention is not limited to the following embodiments.

(Wavelength conversion member)
FIG. 1 is a schematic cross-sectional view showing an embodiment of the wavelength conversion member of the present invention. The wavelength conversion member 10 contains inorganic phosphor particles 1 and magnesium oxide particles 2. Here, the magnesium oxide particles 2 are interposed between the inorganic phosphor particles 1, and the inorganic phosphor particles 1 are bound by the magnesium oxide particles 2.

The inorganic phosphor particles 1 are not particularly limited as long as they emit fluorescence when the excitation light is incident. Specific examples of the inorganic phosphor particles 1 include oxide phosphors, nitride phosphors, oxynitride phosphors, chloride phosphors, acidified phosphors, sulfide phosphors, and acid sulfide phosphors. , Halogenated fluorescent material, chalcogenized fluorescent material, aluminate fluorescent material, halophosphated fluorescent material and the like. These can be used alone or in admixture of two or more. As will be described later, since the wavelength conversion member 10 is produced by sintering mixed particles of the inorganic phosphor particles 1 and magnesium oxide particles 2, the inorganic phosphor particles 1 are prevented from being thermally deteriorated during sintering. Those having excellent heat resistance are preferable. From such a viewpoint, the inorganic phosphor particles 1 are oxide phosphors, particularly oxide phosphors having a garnet structure (Y ₃ Al ₅ O ₁₂ : Ce ³⁺ , Lu ₃ Al ₅ O ₁₂ : Ce ^3+, etc.). It is preferable to have.

The average particle size (D ₅₀ ) of the inorganic phosphor particles 1 is preferably 1 to ₅₀ μm, particularly preferably 5 to 25 μm. If the average particle size of the inorganic phosphor particles 1 is too small, the emission intensity tends to decrease. On the other hand, if the average particle size of the inorganic phosphor particles 1 is too large, the emission color tends to be non-uniform.

The average particle size (D ₅₀ ) of the magnesium oxide particles 2 is preferably 0.01 to 10 μm, particularly 0.05 to 5 μm, and particularly preferably 0.08 to 1 μm. By setting the average particle size in the above range, the magnesium oxide particles 2 can be sintered at a relatively low temperature.

The purity of the magnesium oxide particles 2 is preferably 99% or more, 99.9% or more, and particularly preferably 99.98% or more. By setting the purity of the magnesium oxide particles 2 in the above range, the magnesium oxide particles 2 can be sintered at a relatively low temperature.

As described above, the sintering temperature can be lowered by appropriately adjusting the average particle size and purity of the magnesium oxide particles 2. Specifically, it can be densely sintered even if it is fired at a relatively low temperature of 1000 to 1400 ° C., 1020 to 1250 ° C., and further less than 1050 to 1100 ° C.

Examples of the method for producing the magnesium oxide particles 2 include a synthesis method by a vapor phase oxidation reaction, an underwater spark discharge method, and the like. Of these, the synthetic method based on the vapor phase oxidation reaction is preferable because high-purity magnesium oxide particles can be easily obtained. As a commercially available product of magnesium oxide particles, 50A, 2000A, etc. manufactured by Ube Material Industries Ltd. can be used.

The (average particle size of the magnesium oxide particles 2) / (average particle size of the inorganic phosphor particles 1) is preferably 0.5 or less, 0.2 or less, 0.1 or less, and particularly preferably 0.05 or less. .. By doing so, the denseness of the wavelength conversion member 10 is improved and the heat conduction path is easily formed, so that the heat generated by the inorganic phosphor particles 1 can be released to the outside more efficiently.

The ratio of the inorganic phosphor particles 1 and the magnesium oxide particles 2 in the wavelength conversion member 10 is preferably 3 to 80% of the inorganic phosphor particles and 20 to 97% of the magnesium oxide particles, and is preferably an inorganic phosphor. The particles 1 are 15 to 75%, the magnesium oxide particles are 25 to 95%, and the inorganic phosphor particles are 18 to 70%, and the magnesium oxide particles are 2 30 to 92%. If the content of the inorganic phosphor particles 1 is too small (the content of the magnesium oxide particles 2 is too large), the emission intensity of the wavelength conversion member 10 tends to decrease. On the other hand, if the content of the inorganic phosphor particles 1 is too large (the content of the magnesium oxide particles 2 is too small), it becomes difficult for the wavelength conversion member 10 to form a heat conduction path composed of the magnesium oxide particles 2, so that the inorganic fluorescence The heat generated by the body particles 1 is less likely to be released to the outside. In addition, the binding property of the inorganic phosphor particles 1 is lowered, and the mechanical strength of the wavelength conversion member 10 is likely to be lowered.

The shape of the wavelength conversion member 10 is not particularly limited, but is usually plate-shaped (rectangular plate-shaped, disk-shaped, etc.). It is preferable that the thickness of the wavelength conversion member 10 is appropriately selected so as to obtain light having a desired hue. Specifically, the thickness of the wavelength conversion member 10 is preferably 2 mm or less, 1 mm or less, and particularly preferably 0.8 mm or less. However, if the thickness of the wavelength conversion member 10 is too small, the mechanical strength tends to decrease, so the thickness is preferably 0.03 mm or more.

The wavelength conversion member 10 can be manufactured by premolding a raw material powder obtained by mixing inorganic phosphor particles 1 and magnesium oxide particles 2 in a predetermined ratio, and then firing the raw material powder. Here, an organic component such as a binder or a solvent may be added to the raw material powder to form a paste, which may be then fired. By doing so, it becomes easy to form a preformed body having a desired shape by using a method such as green sheet molding. At this time, by first removing the organic component in the degreasing step (about 600 ° C.) and then firing at the sintering temperature of the magnesium oxide particles 2, a dense sintered body can be easily obtained. Further, after the primary firing, HIP (hot hydrostatic pressure press) treatment may be performed at a firing temperature of ± 150 ° C. By doing so, the pores in the wavelength conversion member 10 can be contracted and extinguished, and excessive light scattering can be suppressed.

As the binder, polypropylene carbonate, polybutyl methacrylate, polyvinyl butyral, polymethyl methacrylate, polyethyl methacrylate, ethyl cellulose, nitrocellulose, polyester carbonate and the like can be used, and these can be used alone or in combination.

As the solvent, terpineol, isoamyl acetate, toluene, methyl ethyl ketone, diethylene glycol monobutyl ether acetate, 2,2,4-trimethyl-1,3-pentadiol monoisobutyrate and the like can be used alone or in combination.

A sintering aid may be contained in the paste. Examples of the sintering aid include crystalline powders such as magnesium phosphate, zirconium phosphate, manganese oxide, barium oxide, yttrium oxide and silicon oxide, and amorphous oxide powders such as silicic acid and phosphoric acid. Can be used.

(Wavelength conversion element)
FIG. 2 is a schematic cross-sectional view showing an embodiment of the wavelength conversion element of the present invention. The wavelength conversion element 20 is composed of a laminate in which a wavelength conversion member 10 and a heat radiating layer 3 having a higher thermal conductivity than the wavelength conversion member 10 are laminated. In the present embodiment, the heat generated by irradiating the wavelength conversion member 10 with the excitation light is efficiently released to the outside through the heat radiating layer 3. Therefore, it is possible to prevent the temperature of the wavelength conversion member 10 from rising excessively.

The heat radiating layer 3 has a higher thermal conductivity than the wavelength conversion member 10. Specifically, the thermal conductivity of the heat radiating layer 3 is preferably 5 W / m · K or more, 10 W / m · K or more, and particularly preferably 20 W / m · K or more.

The thickness of the heat radiating layer 3 is preferably 0.05 to 1 mm, 0.07 to 0.8 mm, and particularly preferably 0.1 to 0.5 mm. If the thickness of the heat radiating layer 3 is too small, the mechanical strength tends to decrease. On the other hand, if the heat dissipation layer 3 is too thick, the wavelength conversion element tends to be large.

As the heat radiating layer 3, one made of translucent ceramics can be used. In this way, excitation light or fluorescence can be transmitted, so that it can be used as a transmission type wavelength conversion element. The total light transmittance of the heat radiating layer made of translucent ceramics at a wavelength of 400 to 800 nm is preferably 10% or more, 20% or more, 30% or more, 40%, particularly 50% or more.

Translucent ceramics include aluminum oxide-based ceramics, aluminum nitride-based ceramics, silicon carbide-based ceramics, boron nitride-based ceramics, magnesium oxide-based ceramics, titanium oxide-based ceramics, niobium oxide-based ceramics, zinc oxide-based ceramics, and yttrium oxide-based ceramics. At least one selected from ceramics can be used.

In the wavelength conversion element 20 of the present embodiment, the heat dissipation layer 3 is formed only on one main surface of the wavelength conversion member 10, but the heat dissipation layer 3 may be formed on both main surfaces of the wavelength conversion member 10. In this way, the heat generated by the wavelength conversion member 10 can be released to the outside more efficiently. Further, it may be a laminated body having four or more layers in which the wavelength conversion member 10 and the heat radiating layer 3 are alternately laminated.

The heat radiating layer 3 may be a layer made of a metal such as Cu, Al, or Ag, in addition to the one made of translucent ceramics. In this way, it can be used as a reflection type wavelength conversion element.

(Light emitting device)
FIG. 3 is a schematic side view showing an embodiment of the light emitting device of the present invention. The light emitting device according to the present embodiment is a light emitting device using a transmission type wavelength conversion member. As shown in FIG. 3, the light emitting device 30 includes a wavelength conversion member 10 and a light source 4. The excitation light L0 emitted from the light source 4 is wavelength-converted by the wavelength conversion member 10 into fluorescence L1 having a wavelength longer than that of the excitation light L0. Further, a part of the excitation light L0 passes through the wavelength conversion member 10. Therefore, the combined light L2 of the excitation light L0 and the fluorescence L1 is emitted from the wavelength conversion member 10. For example, when the excitation light L0 is blue light and the fluorescence L1 is yellow light, white synthetic light L2 can be obtained. In addition, instead of the wavelength conversion member 10, the wavelength conversion element 20 described above may be used.

Examples of the light source 4 include LEDs and LDs. From the viewpoint of increasing the light emission intensity of the light emitting device 30, it is preferable to use an LD capable of emitting high intensity light as the light source 4.

1 Inorganic phosphor particles 2 Magnesium oxide particles 3 Heat dissipation layer 4 Light source 10 Wavelength conversion member 20 Wavelength conversion element 30 Light emitting device

Claims (12)

A wavelength conversion member containing inorganic phosphor particles having an average particle diameter of 1 to 50 μm and magnesium oxide particles having a purity of 99% or more .
A wavelength conversion member characterized in that magnesium oxide particles are interposed between the inorganic phosphor particles, and the inorganic phosphor particles are a sintered body bound by magnesium oxide particles. The wavelength conversion member according to claim 1, wherein the wavelength conversion member contains 3 to 80% of inorganic phosphor particles and 20 to 97% of magnesium oxide particles in mass%. The wavelength conversion member according to claim 1 or 2, wherein the average particle size of the magnesium oxide particles is 0.01 to 10 μm. The ceramic wavelength conversion member according to any one of claims 1 to 3 , wherein the inorganic phosphor particles are made of an oxide phosphor having a garnet structure. The wavelength conversion member according to any one of claims 1 to 4 , wherein (average particle size of magnesium oxide particles) / (average particle size of inorganic phosphor particles) is 0.5 or less. A wavelength conversion element comprising a laminate in which the wavelength conversion member according to any one of claims 1 to 5 and a heat radiating layer having a higher thermal conductivity than the wavelength conversion member are laminated. The wavelength conversion element according to claim 6 , wherein the heat radiating layer is made of translucent ceramics. Translucent ceramics include aluminum oxide ceramics, aluminum nitride ceramics, silicon carbide ceramics, boron nitride ceramics, magnesium oxide ceramics, titanium oxide ceramics, niobium oxide ceramics, zinc oxide ceramics and yttrium oxide ceramics. The wavelength conversion element according to claim 7 , wherein the wavelength conversion element is at least one selected from the above. A light emitting device comprising the wavelength conversion member according to any one of claims 1 to 5 and a light source for irradiating the wavelength conversion member with excitation light. A light emitting device comprising the wavelength conversion element according to any one of claims 6 to 8 and a light source for irradiating the wavelength conversion element with excitation light. The light emitting device according to claim 9 or 10 , wherein the light source is a laser diode. A method for producing a wavelength conversion member containing inorganic phosphor particles having an average particle diameter of 1 to 50 μm and magnesium oxide particles having a purity of 99% or more.
By firing the raw material powder obtained by mixing the inorganic phosphor particles and the magnesium oxide particles at 1400 ° C. or lower, the magnesium oxide particles are interposed between the inorganic phosphor particles, and the inorganic phosphor particles are the magnesium oxide particles. A method for manufacturing a wavelength conversion member, which comprises manufacturing a wavelength conversion member which is a sintered body bonded to the particles.