JP2018026550A - Light emitting device, lighting device, image display device, and vehicle indicator lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an excellent light emitting device and a lighting device having high conversion efficiency, high brightness, and less change in brightness and color shift due to a change in excitation light intensity and temperature. SOLUTION: The sintered phosphor 3 containing a nitride phosphor and a fluoride inorganic binder is provided with a gallium nitride LED or a laser as a light source, and the sintered phosphor absorbs at least a part of the light of the light source. A light emitting device that emits light having a wavelength different from that of the light source. [Selection diagram] FIG. 10

Description

  The present invention relates to a light emitting device including a sintered phosphor containing a nitride phosphor and a fluoride inorganic binder and a gallium nitride LED or laser.

  A light emitting diode (LED) is widely known as a semiconductor light emitting device or a semiconductor light source capable of generating light having a peak wavelength in a specific region of an optical spectrum. LEDs are usually used as light sources for lighting fixtures, signs, vehicle headlamps and displays. As a light-emitting device using LEDs and phosphors, a light-emitting device that emits white light in combination with an LED chip that emits blue light and a YAG (yttrium, aluminum, garnet) phosphor that converts blue light into yellow is known. It has been. The YAG phosphor is disposed around the LED chip as a wavelength conversion light emitting layer dispersed in an epoxy resin or a silicone resin. In addition to the wavelength-converted light-emitting layer dispersed in the resin, a ceramic layer made of a phosphor or a wavelength-converted light-emitting layer (light-emitting ceramic layer) made only of an inorganic material in which the phosphor is dispersed in ceramic is exemplified. (Patent Document 1).

  On the other hand, in recent years, many new materials have been manufactured for nitrides composed of elements of ternary or higher elements, and in recent years, excellent in multi-system nitrides and oxynitrides based on silicon nitride. A phosphor material having characteristics has been developed and used for a wavelength-converting light emitting layer. These phosphor materials are known to exhibit yellow or red light emission when excited by a blue LED or near-ultraviolet LED, and have higher luminance and higher conversion efficiency than oxide-based phosphors. Furthermore, the temperature dependency of luminous efficiency is excellent (Patent Document 2).

  Conventionally, a wavelength conversion light emitting layer dispersed in an organic binder such as an epoxy resin or a silicone resin has insufficient durability, heat resistance, and light emission intensity. Therefore, in order to obtain a wavelength-converting light-emitting layer with better durability and heat resistance, a method for producing a wavelength-converted light-emitting layer (light-emitting ceramic layer) made only of an inorganic material as exemplified in Patent Document 1 is studied. Has been.

  In Patent Document 3, YAG: Ce phosphor particles are contained in an inorganic binder made of any one of calcium fluoride, strontium fluoride, and lanthanum fluoride, or made of calcium fluoride and strontium fluoride. Dispersed phosphor ceramics are illustrated.

In Patent Document 4, a combination of Y ₃ (Al, Ga) ₅ O ₁₂ : Ce oxide phosphor, Lu ₃ Al ₅ O ₁₂ : Ce oxide phosphor and CaSiAlN ₃ : Eu nitride phosphor is subjected to discharge plasma sintering. The wavelength conversion light emitting layer which consists only of inorganic materials is produced by melting the glass powder which has a glass transition point of 200 degreeC or more using a sintering method.

Special table 2008-502131 International Publication No. 2008/132951 International Publication No. 2009/154193 JP 2009-91546 A

However, in Patent Document 1, an aluminum garnet phosphor is used as the luminescent ceramic layer. This was obtained by producing a YAG powder from Y ₂ O ₃ , Al ₂ O ₃ (99.999%) and CeO ₂ , obtaining a molded body consisting only of YAG powder, and firing at 1300 ° C. YAG sintered phosphor is used as the luminescent ceramic layer. The luminescent ceramic layer does not use an inorganic binder and forms a sintered body only with a YAG oxide phosphor. Therefore, there has been a demand for sintered phosphors of nitride phosphors that have high luminance, high conversion efficiency, and excellent temperature dependence of luminous efficiency.

Moreover, as exemplified in Patent Document 3, the ceramic composite of the YAG oxide phosphor phase and the fluoride matrix phase has a problem that the internal quantum efficiency is a low value of 55% or less.
In Patent Document 4, although a YAG oxide phosphor or a combination of a LuAG oxide phosphor and a CASN nitride phosphor is dispersed in glass by melting glass powder, a wavelength conversion light emitting layer is produced. Since the inorganic binder is glass, it has heat resistance, but its thermal conductivity is as low as 2 to 3 W / mK, and its heat dissipation is low, so that the temperature of the phosphor rises and the brightness decreases (deterioration of the phosphor). ).

  Under such circumstances, when the intensity of the excitation light changes or when used under a high temperature for a long time, the phosphor does not decrease in brightness and the color deviation is small, and the light emitting device using the same Was demanded.

  Conventionally, when an oxide phosphor and a fluoride inorganic binder are sintered, in general, since the ionic radii of the oxygen of the phosphor and the fluorine of the inorganic binder are close, solid solution substitution occurs, and an oxyfluoride is formed. It was thought to cause a decrease in internal quantum efficiency. Accordingly, the inventors have found that when the nitride phosphor and the fluoride inorganic binder are mixed and sintered, the internal quantum efficiency of the original nitride phosphor can be maintained. . This is thought to be because solid solution substitution does not easily occur with nitrogen and fluorine having different ionic radii.

In addition, by using a fluoride inorganic binder, the sintering temperature can be lowered compared to, for example, when Al ₂ O ₃ is used as an inorganic binder, thereby suppressing the reaction between the nitride phosphor and the inorganic binder. Can be made. Thus, the present inventors have conceived that a sintered phosphor of a nitride phosphor having a high internal quantum efficiency can be obtained.
Further, for example, trigonal Al ₂ O ₃ has birefringence, so that when sintered, Al ₂ O ₃ becomes a polycrystal and has insufficient translucency, whereas CaF ₂ , BaF _2. If a cubic inorganic fluoride binder such as SrF ₂ is used, it is possible to produce a sintered phosphor having no birefringence and high transparency.

Accordingly, the present inventors invented a sintered phosphor for LED having high internal quantum efficiency, high heat resistance, high transmittance, low absorption rate, and high thermal conductivity using a nitride phosphor. It came to. Furthermore, the sintered phosphor is used in combination with a high-power gallium nitride light source, and has an excellent light-emitting device that has high conversion efficiency, high brightness, and little brightness change and color shift due to changes in excitation light intensity and temperature. Invented the lighting device.
The present invention is as follows.
(1) A sintered phosphor containing a nitride phosphor and a fluoride inorganic binder, and a gallium nitride LED or laser as a light source,
The light-emitting device, wherein the sintered phosphor absorbs at least a part of light from the light source and emits light having a wavelength different from that of the light source.
(2) The nitride phosphor contained in the sintered phosphor is LSN represented by the following general formula; Ln _x Si _y N _n : Z (wherein Ln is a rare earth element excluding an element used as an activator) Z is an activator.2.7 ≦ x ≦ 3.3, 5.4 ≦ y ≦ 6.6, 10 ≦ n ≦ 12)), β sialon represented by the following general formula Si _6-z Al _z O _z N _8-z : Eu, where 0 <z <4.2), CaAlSiN ₃ , SCASN represented by the following general formula; (Ca, Sr, Ba, Mg) AlSiN ₃ : Eu and / or (Ca, Sr, Ba) AlSi (N, O) ₃ : Eu and Sr ₂ Si ₅ N ₈ represented by the following general formula; (Sr, Ca, Ba) ₂ Al _x Si _{5-x O x N 8-} x: Eu containing at least one of nitride phosphor selected from the group consisting of (0 ≦ x ≦ 2 wherein), according to (1) Light-emitting device.
(3) The light emitting device according to (1) or (2), wherein the sintered phosphor is rectangular.
(4) The sintered phosphor has a chromaticity point Cy of light emitted from the sintered phosphor when excited with blue light having a wavelength of 450 nm, and a conversion efficiency CE (Lm / W) of the sintered phosphor. The light-emitting device according to any one of (1) to (3), wherein when C is plotted in a Cy-CE diagram, Cy ≧ 100 × Cy + 120 is satisfied when Cy is in a range of 0.25 to 0.45.
(5) In the above-mentioned sintered phosphor, in the region vertically above the light emitting surface of the light source, the reduction in conversion efficiency when driven at a region temperature of 200 ° C. or more for 1000 hours is less than 10%. The light-emitting device according to any one of (1) to (4).
(6) In the sintered phosphor, in the region vertically above the light emitting surface of the light source, the change in chromaticity point when driven at a region temperature of 200 ° C. or more for 1000 hours is 5/1000 or less. The light-emitting device according to any one of (1) to (5), wherein
(7) An illumination device comprising the light-emitting device according to any one of (1) to (6).
(8) An image display device comprising the light-emitting device according to any one of (1) to (6).
(9) A vehicle indicator lamp comprising the light emitting device according to any one of (1) to (6).

  According to the present invention, a light-emitting device using a sintered phosphor for LED having high heat resistance, high thermal conductivity, high brightness, and high conversion efficiency, and having less brightness change and color shift due to changes in excitation light intensity and temperature, and An illumination device and a vehicle indicator lamp using the light-emitting device can be provided. In particular, there are provided a highly reliable light-emitting device that does not decrease in luminance even when used under a high temperature for a long time and has a small color shift, and a lighting device and a vehicle indicator lamp using the light-emitting device. be able to.

It is a schematic diagram which shows the structural example of the light-emitting device which concerns on the embodiment of this invention. It is a schematic diagram which shows the structural example of the light-emitting device which concerns on the embodiment of this invention. It is a graph which shows the optical characteristic with respect to LED light quantity of the sintered fluorescent substance used in Example 1 of this invention. (A) shows current and conversion efficiency, (b) shows current, conversion efficiency and chromaticity point, and (c) shows the relationship between current and relative luminous flux. It is a graph which shows the relationship between a chromaticity point and conversion efficiency of the sintering fluorescent substance used in Example 2 of this invention. It is a graph which shows the reliability test result of the sintered fluorescent substance used in Example 3 of this invention. (A) and (b) show time and chromaticity points, and (c) shows the relationship between time and light quantity. It is a schematic diagram of the light-emitting device for evaluation used in the Example of this invention. It is a schematic diagram of the light-emitting device for evaluation used in the Example of this invention. It is a schematic diagram of the light-emitting device for evaluation used in the Example of this invention. It is a schematic diagram of the light-emitting device for evaluation used in the Example of this invention. It is a schematic diagram which shows the positional relationship of LED used by the Example of this invention, sintered fluorescent substance, a sample holder, and a package. It is a schematic diagram of the measuring apparatus used in Example 4 of the present invention. (A) is a schematic diagram of a reflected light spectrum measuring device, (b) is a schematic diagram of a transmitted light spectrum measuring device. It is a graph which shows the luminous flux maintenance factor after temperature rising when the luminous efficiency before temperature rising start of the sintered phosphor used in Example 4 of the present invention is 1. R is based on reflection measurement, and T is based on transmission measurement. LSN phosphor sintered phosphor, raw LSN phosphor (powder), resin-sealed LSN phosphor sintered phosphor (fired in a high heat resistant resin) used in Example 4 of the present invention (A) a graph showing the luminous flux maintenance factor after the temperature rise when the luminous efficiency before the temperature rise is 1 and (b) the ambient temperature and the chromaticity coordinates Cx (C) is a graph showing the relationship between the ambient temperature and the chromaticity coordinates Cy. R is based on reflection measurement, and T is based on transmission measurement. It is a schematic diagram of the light-emitting device for evaluation used in Example 5 of the present invention. (A) It is a graph which shows the relationship between the electric current IF of the light-emitting device using sintered fluorescent substance or resin sealing, and relative light flux based on Example 5 of this invention. (B) It is a graph which shows the relationship between current IF and temperature of the light-emitting device which uses only sintered fluorescent substance, resin sealing, or LED based on Example 5 of this invention.

In the composition formulas of the phosphors in this specification, each composition formula is delimited by a punctuation mark (,). In addition, when a plurality of elements are listed by separating them with commas (,), one or two or more of the listed elements may be contained in any combination and composition. For example, the composition formula “(Ca, Sr, Ba) Al ₂ O ₄ : Eu” has “CaAl ₂ O ₄ : Eu”, “SrAl ₂ O ₄ : Eu”, and “BaAl ₂ O ₄ : Eu”. “Ca _1−x Sr _x Al ₂ O ₄ : Eu”, “Sr _1−x Ba _x Al ₂ O ₄ : Eu”, “Ca _1−x Ba _x Al ₂ O ₄ : Eu”, _{"Ca 1-x-y Sr x} Ba y Al 2 O 4: Eu " (. in the formula, 0 <x <1,0 <y <1,0 < a x + y <1) all the comprehensive It shall be shown in

<Sintered phosphor>
The sintered phosphor according to the embodiment of the present invention is a sintered phosphor containing a nitride phosphor and a fluoride inorganic binder. Preferably, the nitride phosphor is dispersed in a fluoride inorganic binder, and is a composite that holds the phosphor mainly by sintering the crystalline inorganic binder, and the nitride phosphor and the fluoride. A compound inorganic binder is an integrated composite by physical and / or chemical bonding. The fluoride inorganic binder used is preferably at least heat resistant and has high thermal conductivity.

Examples of the method for confirming the thermal conductivity of the sintered phosphor according to this embodiment include a method of measuring by a steady heating method, a laser flash method, and a periodic heating method.
The thermal conductivity of the sintered phosphor is usually 3.0 W / (m · K) or more, preferably 5.0 W / (m · K) or more, more preferably 10.0 W / (m · K) or more. . If the thermal conductivity is less than 3.0 W / (m · K), the temperature of the sintered body due to irradiation with strong excitation light increases, and the phosphor and peripheral members tend to deteriorate. For this reason, the said range is preferable.

The method for producing the sintered phosphor is not particularly limited. For example, a nitride phosphor and fluoride inorganic binder particles are used as main raw materials, and a mixture of these is compacted and sintered, whereby a sintered phosphor that is a composite is obtained. Can be manufactured. More specifically, it is preferable to include any of the following steps.
(Step 1) Step of stirring and mixing nitride phosphor (or garnet-based phosphor and nitride phosphor) and inorganic binder particles, press-pressing, and sintering the molded body (Step 2) nitride fluorescence The body (or garnet phosphor and nitride phosphor) and inorganic binder particles are agitated and mixed and sintered simultaneously with the pressure press

The sintered phosphor may be used as manufactured, but it is usually sliced at a predetermined thickness, and further processed to a predetermined thickness plate by grinding and polishing, so that a plate-like sintered phosphor is obtained. can get. Grinding / polishing conditions are not particularly limited. For example, a # 800 diamond grindstone is polished at a grindstone rotation speed of 80 rpm, a workpiece rotation speed of 80 rpm, and 50 g / cm ² , and processed into a plate shape. The lower limit of the final thickness of the sintered phosphor is usually 30 μm or more, preferably 50 μm or more, more preferably 100 μm or more, and the upper limit is usually 2000 μm or less, preferably 1000 μm or less, more preferably 800 μm or less, more Preferably it is 500 micrometers or less. If the thickness of the sintered phosphor plate is less than this range, the sintered phosphor plate is easily damaged.
Further, after the surface is appropriately polished, the unevenness may be appropriately formed by wet etching treatment, dry wet etching treatment or the like.

  The sintered phosphor plate can be used after being processed into an arbitrary shape suitable for combination with a light source by dicing or the like. For example, a disk shape may be sufficient and a rectangular plate shape may be sufficient. In the case of a rectangular shape, the size is not particularly limited and can be appropriately set according to the light source. However, one side is usually 1 mm, preferably 5 mm or more, and usually 10 cm or less, preferably Is 5 cm or less.

  The sintered phosphor is preferably fixed so that the contact area with the internal member of the device having higher thermal conductivity is increased from the viewpoint of heat dissipation, but the sintered phosphor is used for stress relaxation due to the difference in thermal expansion coefficient. Only a part of the body may be adhered, or a method in which the body is not adhered and fixed by being dropped into the counterbore part may be mentioned. Further, a heat radiating member for releasing the heat of the sintered phosphor can be installed.

The sintered phosphor according to this embodiment can maintain high conversion efficiency even when the chromaticity changes. That is, the chromaticity point Cy (CIE-y) of light emitted from the sintered phosphor when excited by blue light having a wavelength of 450 nm and the conversion efficiency CE (Lm / W) of the sintered phosphor are expressed as Cy−. When plotted in a CE diagram, it is preferable that CE ≧ 100 × Cy + 120 is satisfied when Cy is in the range of 0.25 to 0.45.
Cy is a y-axis in the CIE color system, and this is the x-axis, and the Cy-CE diagram with the conversion efficiency CE as the y-axis shows the transition of conversion efficiency when the chromaticity of the emitted light changes. Therefore, by satisfying the above range, it can be said that it is a sintered phosphor capable of maintaining high conversion efficiency with respect to a change in chromaticity of light emitted from the sintered phosphor. More preferably, CE ≧ 100 × Cy + 125 is satisfied.
In order to satisfy the above range, it is possible to reduce voids in the sintered phosphor, reduce the grain size in the sintered phosphor, etc., and further increase the temperature rise and sintering time during sintering. Adjustments such as are effective.

<Nitride phosphor>
The nitride phosphor is characterized in that it absorbs at least the excitation light emitted from the light emitting element, performs wavelength conversion, and emits light having a wavelength different from that of the light emitting element. The type of the phosphor is not particularly limited as long as the phosphor contains nitrogen in the phosphor composition. For example, a nitride phosphor containing strontium and silicon in the crystal phase (specifically, SCASN, Sr ₂ Si ₅ N ₈ ), nitride phosphor containing calcium and silicon in the crystal phase (specifically, SCASN, CASN, CASON), nitride phosphor containing strontium, silicon, and aluminum in the crystal phase (specifically, , SCASN), nitride phosphor containing calcium, silicon, and aluminum in crystal phase (specifically, SCASN, CASN, CASON), nitride phosphor containing barium, silicon in crystal phase (specifically, BSON) ).
The classification from another aspect of the nitride phosphor includes lanthanum nitridosilicate (specifically, LSN), alkaline earth metal nitridosilicate (specifically, Sr ₂ Si ₅ N ₈ ), alkaline earth. Metal nitridosilicates (CASN, SCASN, α sialon, (Ca, Sr) AlSi ₄ N ₇ ) and the like.
More specifically, for example,
Β sialon that can be represented by the following general formula: Si _6-z Al _z O _z N _8-z : Eu (where 0 <z <4.2), α sialon,
LSN represented by the following general formula: Ln _x Si _y N _n : Z (wherein Ln is a rare earth element excluding an element used as an activator. Z is an activator. 2.7 ≦ x ≦ 3 .3, 5.4 ≦ y ≦ 6.6, 10 ≦ n ≦ 12)
CASN represented by the following general formula; CaAlSiN ₃ : Eu,
SCASN that can be represented by the following general formula: (Ca, Sr, Ba, Mg) AlSiN ₃ : Eu and / or (Ca, Sr, Ba) AlSi (N, O) ₃ : Eu,
CASON that can be represented by the following general formula: (CaAlSiN ₃ ) _1-x (Si ₂ N ₂ O) _x : Eu (where 0 <x <0.5),
CaAlSi ₄ N ₇ which can be expressed by the following general formula; Eu _y (Sr, Ca, Ba) _1-y : Al _{1 + x} Si _4−x O _x N _7−x (where 0 ≦ x <4 , 0 ≦ y <0.2),
Sr ₂ Si ₅ N ₈ can be represented by the following general formula; (Sr, Ca, Ba) 2 Al x Si 5-x O x N 8-x: Eu ( wherein 0 ≦ x ≦ 2)
BSON can be represented by the following general _{formula; M x Ba y (Sr,} Ca, Mg, Zn) z L 6 O 12 N 2 ( where, M is Cr, Mn, Fe, lanthanide (La, Pm, Gd , Lu is excluded), L represents a metal element belonging to Group 4 or Group 14 of the periodic table containing Si, and x, y, and z each independently represents the following formula: Examples of the phosphor include 0.03 ≦ x ≦ 0.9, 0.9 ≦ y ≦ 2.95, and x + y + z = 3).
Among these phosphors, nitride phosphors that do not contain oxygen as a constituent element (including oxygen that is inevitably mixed), that is, LSN, from the viewpoint that luminance when sintered phosphors are not reduced. It is preferable to use a nitride phosphor such as CaAlSiN ₃ , SCASN, Sr ₂ Si ₅ N ₈ , β sialon, or BSON.

  The volume fraction of the nitride phosphor with respect to the total volume of the sintered phosphor is usually 1% or more and 50% or less. If the volume fraction of the nitride phosphor is too low, the phosphor layer needs to be thickened to control it to an arbitrary chromaticity, resulting in a decrease in translucency, and if the volume fraction is too high, the degree of sintering This is because the light transmission and the translucency are also reduced.

<Fluoride inorganic binder>
The fluoride inorganic binder is used as a matrix for dispersing the nitride phosphor, and is preferably a crystalline matrix. The matrix may contain other than the fluoride inorganic binder, but is preferably a crystalline compound. The fluoride inorganic binder is preferably one that transmits a part of the excitation light emitted from the light emitting element or at least a part of the light emitted from the nitride phosphor. In order to efficiently extract light emitted from the nitride phosphor, it is preferable that the refractive index of the fluoride inorganic binder is close to the refractive index of the phosphor. Furthermore, it is preferable to withstand heat generation caused by irradiation with strong excitation light and to have a heat dissipation property. Moreover, the moldability of a sintered fluorescent substance becomes favorable by using a fluoride inorganic binder.
Specific examples of the fluoride inorganic binder include CaF ₂ (calcium fluoride), MgF ₂ (magnesium fluoride), BaF ₂ (barium fluoride), SrF ₂ (strontium fluoride), LaF ₃ (lanthanum fluoride). ), Alkaline earth metals such as YF ₃ (yttrium fluoride), AlF ₃ (aluminum fluoride), fluorides of rare earth metals and fluorides of typical metals, and any of these composites One or more types are listed. Particularly preferably CaF _2.
The fluoride inorganic binder is configured by physically and / or chemically combining particles having the same composition as the fluoride inorganic binder.

The total volume fraction of the nitride phosphor and the fluoride inorganic binder with respect to the total volume of the sintered phosphor is preferably 80% or more, more preferably 90% or more, and particularly preferably 95% or more. This is because if the total volume fraction is low, the effects of the present invention cannot be exhibited.
The volume fraction of the fluoride inorganic binder with respect to the total volume of the nitride phosphor and the fluoride inorganic binder is usually 50% or more, preferably 60% or more, more preferably 70% or more, and usually 99% or less, preferably Is 98% or less, more preferably 97% or less.

  Fluoride binder particles as a raw material for the fluoride inorganic binder have a volume median diameter of usually 0.01 μm or more, preferably 0.02 μm or more, more preferably 0.03 μm or more, and particularly preferably 0.05 μm or more. Moreover, it is 15 micrometers or less normally, Preferably it is 10 micrometers or less, More preferably, it is 5 micrometers or less. When the fluoride inorganic binder particles are in the above range, the sintering temperature can be reduced, and the deactivation of the nitride phosphor due to the reaction between the nitride phosphor and the inorganic binder can be suppressed, A decrease in internal quantum efficiency of the sintered phosphor can be suppressed. The volume median diameter can be measured by, for example, the above-mentioned Coulter counter method, and other representative apparatuses include laser diffraction particle size distribution measurement, scanning electron microscope (SEM), transmission electron microscope (TEM), precision particle size. Measurement is performed using a distribution measuring device Multisizer (manufactured by Beckman Coulter).

  The refractive index nb of the fluoride inorganic binder particles is such that the ratio nb / np to the refractive index np of the nitride phosphor is 1 or less, preferably 0.8 or less, more preferably 0.6 or less. Moreover, it is a value larger than 0 normally. If the refractive index ratio is greater than 1, the light extraction efficiency after sintering tends to be reduced. For this reason, the said range is preferable.

  The fluoride inorganic binder particles preferably have a low melting point. By using fluoride inorganic binder particles having a low melting point, it becomes possible to reduce the sintering temperature, and can suppress the deactivation of the nitride phosphor due to the reaction between the nitride phosphor and the inorganic binder, A decrease in internal quantum efficiency of the sintered phosphor can be suppressed. Specifically, the melting point is preferably 1500 ° C. or lower. The lower limit temperature is not particularly limited and is usually 500 ° C. or higher.

<Light emitting device>
An embodiment of the present invention is a light emitting device including a sintered phosphor and a gallium nitride light emitting element.
The light-emitting device according to this embodiment includes at least a blue semiconductor light-emitting element (blue light-emitting diode or blue semiconductor laser) and a wavelength conversion member that converts the wavelength of blue light. It contains. The blue semiconductor light emitting element and the sintered phosphor may be in close contact with each other or may be separated from each other, and a transparent resin may be provided therebetween, or a space may be provided. As shown schematically in FIG. 1, a structure having a space between the semiconductor light emitting element 1 and the sintered phosphor 3 is preferable.

<Light emitting element>
Gallium nitride-based materials are currently widely used for fabricating light-emitting elements such as semiconductor light-emitting elements (LEDs) and semiconductor lasers (LDs). An n-type layer and a p-type layer are formed mainly in the c (+) direction ([0001] axis direction) using a sapphire substrate, and an InGaN-based quantum well light-emitting layer is formed between the n-type layer and the p-type layer. . In order to increase the light extraction efficiency, vertical structure type LEDs with a sapphire substrate peeled off and flip chip type LEDs that do not use wires are also manufactured.

A light-emitting element using a sapphire substrate has a problem that threading dislocations cannot be avoided due to a mismatch in lattice constant between the sapphire substrate and a gallium nitride-based material. Therefore, in the case where light having a high light density and a large luminous flux is required, a light-emitting element manufactured using a self-supporting gallium nitride substrate can be used in order to ensure characteristics and reliability.

Hereinafter, the configuration will be described with reference to FIGS.
FIG. 2 is a schematic view of a light emitting device according to a specific embodiment of the present invention.
The light emitting device 10 includes at least the blue semiconductor light emitting element 1 and the sintered phosphor 3 as its constituent members. The blue semiconductor light emitting element 1 emits excitation light for exciting the phosphor contained in the sintered phosphor 3.

The blue semiconductor light emitting element 1 usually emits excitation light having a peak wavelength of 425 nm to 475 nm, and preferably emits excitation light having a peak wavelength of 430 nm to 470 nm. The number of blue semiconductor light emitting elements 1 can be appropriately set depending on the intensity of excitation light required by the apparatus.
On the other hand, a purple semiconductor light emitting element can be used instead of the blue semiconductor light emitting element 1. The violet semiconductor light emitting device usually emits excitation light having a peak wavelength of 390 nm to 425 nm, and preferably emits excitation light having a peak wavelength of 395 to 415 nm.

  The blue semiconductor light emitting element 1 is mounted on the chip mounting surface 2 a of the wiring board 2. A wiring pattern (not shown) for supplying electrodes to these blue semiconductor light emitting elements 1 is formed on the wiring substrate 2 to constitute an electric circuit. In FIG. 2, it is displayed that the sintered phosphor 3 is placed on the wiring substrate 2, but this is not a limitation, and the wiring substrate 2 and the sintered phosphor 3 may be arranged via other members. Good.

For example, in FIG. 1, the wiring board 2 and the sintered phosphor 3 are arranged via the frame body 4. The frame body 4 may have a tapered shape in order to give light directivity. The frame 4 may be a reflective material.
From the viewpoint of improving the light emission efficiency of the light emitting device 10, the wiring board 2 is preferably excellent in electrical insulation, has good heat dissipation, and preferably has a high reflectance, but on the chip mounting surface of the wiring board 2. Thus, a reflective plate having a high reflectance can be provided on the surface where the blue semiconductor light emitting element 1 does not exist, or on at least a part of the inner surface of another member connecting the wiring substrate 2 and the sintered phosphor 3.

  The sintered phosphor 3 converts the wavelength of a part of incident light emitted from the blue semiconductor light emitting element 1 and emits outgoing light having a wavelength different from that of the incident light. The sintered phosphor 3 contains an inorganic binder and a nitride phosphor. The types of nitride phosphors (not shown), garnet phosphors emitting yellow or green, and nitride phosphors emitting red are not particularly limited. If the light emitting device is a white light emitting device, a semiconductor According to the type of excitation light of the light emitting element, the type of phosphor may be adjusted as appropriate so as to emit white light.

  When the semiconductor light emitting element is a blue semiconductor light emitting element, a light emitting device that emits white light can be obtained by using a yellow phosphor as the nitride phosphor and a red phosphor as the nitride phosphor. A garnet phosphor may be used as the phosphor. The sintered phosphor 3 preferably has a distance from the blue semiconductor light emitting element 1. A space may be provided between the sintered phosphor 3 and the blue semiconductor light emitting element 1, and a transparent resin may be provided. Thus, by the aspect which has distance between the sintered fluorescent substance 3 and the blue semiconductor light-emitting device 1, the fluorescent substance contained in the sintered fluorescent substance 3 and the sintered fluorescent substance by the heat which the blue semiconductor light-emitting device 1 emits Deterioration can be suppressed. The distance between the blue semiconductor light-emitting element 1 and the sintered phosphor 3 is preferably 10 μm or more, more preferably 100 μm or more, particularly preferably 1.0 mm or more, while 1.0 m or less is preferable, and 500 mm or less is more preferable. 100 mm or less is particularly preferable.

The light emitting device according to this embodiment is preferably a light emitting device that emits white light. In the light emitting device that emits white light, the light emitted from the light emitting device preferably has a deviation duv from the light-colored black body radiation locus of −0.0200 to 0.0200.
Thus, the light-emitting device which radiate | emits white light is suitably provided in an illuminating device. The light emitting device according to the present embodiment desirably has a small temperature change such as light flux and chromaticity during light emission. By using a sintered phosphor using LSN and LYSN as the phosphor, it is possible to provide a light emitting device that suppresses a decrease in conversion efficiency to about 10% even in a 200 ° C. environment.

In the light emitting device according to the present embodiment, in the region vertically above the light emitting direction of the light source of the light source of the sintered phosphor, the conversion efficiency decreases when driven at a region temperature of 200 ° C. or more for 1000 hours. It is preferable that it is less than%. Further, in the sintered phosphor, in the region vertically above the light emitting surface of the light source, the change in chromaticity point when driven at a region temperature of 200 ° C. or more for 1000 hours is 5/1000 or less. Is preferred. A light-emitting device in such a range is preferable because it is a highly reliable light-emitting device in which luminance does not decrease even after long-time use at high temperatures and color misregistration is small.
In the sintered phosphor 3 shown in FIG. 10, a region vertically above the light emitting direction with respect to the light emitting surface of the blue semiconductor light emitting element 1 as a light source is indicated by a broken line 6. This region is a region where the intensity of light emitted from a light source such as a semiconductor light emitting element or a laser is high, and the region where the sintered phosphor is most likely to deteriorate. In the present embodiment, even in a region where the deterioration of the sintered phosphor is most likely to occur, the reduction in conversion efficiency when driven at a region temperature of 200 ° C. or more for 1000 hours is less than 10%, or chromaticity A high-performance light-emitting device having a point change of 5/1000 or less can be provided.

<Lighting device>
Another embodiment of the present invention is a lighting device including the light emitting device.
As described above, since a high total luminous flux is emitted from the light emitting device, a lighting fixture having a high total luminous flux can be obtained. The luminaire is preferably provided with a diffusing member that covers the sintered phosphor in the light emitting device so that the color of the sintered phosphor is not noticeable when the light is extinguished.

<Image display device>
Another embodiment of the present invention is an image display device including the light emitting device.
When the light emitting device is used as a light source of an image display device, the specific configuration of the image display device is not limited, but is preferably used with a color filter. For example, when the image display device is a color image display device using a color liquid crystal display element, the light emitting device is a backlight, a light shutter using liquid crystal and a color filter having red, green, and blue pixels; By combining these, an image display device can be formed.

<Vehicle indicator light>
Another embodiment of the present invention is a vehicle indicator lamp including the light emitting device.
The light emitting device used for the vehicle indicator lamp is preferably a light emitting device that emits white light. In the light emitting device that emits white light, the light emitted from the light emitting device has a deviation duv from the light-colored black body radiation locus of −0.0200 to 0.0200, and the color temperature is 5000 K or more and 30000 K or less. It is preferable that
The vehicle indicator lamp includes illumination provided in the vehicle for the purpose of displaying something to other vehicles or people, such as a vehicle headlamp, side lamp, back lamp, turn signal, brake lamp, and fog lamp.

EXAMPLES Next, specific embodiments of the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.
{Measuring method}
(optical properties)
A light-emitting device capable of obtaining light emission of the sintered phosphor was produced by irradiating blue light emitted from an LED chip (peak wavelength: 450 nm) that can be irradiated with light having a light-emitting surface intensity of 2 W / mm ² . The emission spectrum was observed from the apparatus using a 1-m integrating sphere (manufactured by Labspher) and a spectroscope MC-9800 (manufactured by Otsuka Electronics Co., Ltd.), and the color temperature and color when excited with light having an emission surface intensity of 2 W / mm ² were obtained. Degree coordinates and luminous flux were measured. Furthermore, the conversion efficiency (lm / W) was calculated for each intensity from the luminous flux (lumen) and the irradiation energy (W) of the LED chip.

In addition, a light-emitting device capable of obtaining light emission by arranging four LED chips (peak wavelength 450 nm) that can emit light having a light emitting surface intensity of 1 W / mm ² and combining sintered phosphors with a minimum size of 2 mm. did. The emission spectrum was observed from the apparatus using a 1 m integrating sphere (manufactured by Labspher) and a spectroscope MC-9800 (manufactured by Otsuka Electronics Co., Ltd.), and the color temperature and chromaticity coordinates when excited while changing the light emitting surface intensity, The luminous flux was measured. Furthermore, the conversion efficiency (lm / W) was calculated for each intensity from the luminous flux (lumen) and the irradiation energy (W) of the LED chip.

(reliability)
Four LED chips (peak wavelength 450 nm) capable of irradiating light with a light emitting surface intensity of 1 W / mm ² were arranged, and a light emitting device capable of obtaining light emission was produced by combining a 3 mm size sintered phosphor. The apparatus was driven up to 1,000 hours to measure changes in luminous flux and chromaticity coordinates. In order to investigate the characteristics of the sintered phosphor, only the sintered phosphor was taken out from the apparatus and incorporated in another apparatus, and the emission spectrum was observed using a 1 m integrating sphere manufactured by Labsphere and a spectrometer MC-9800 manufactured by Otsuka Electronics.

[Method for producing sintered phosphor]
(Production Example 1)
10.0 g of CaF ₂ powder (High Purity Chemical Laboratory) is used as the fluoride inorganic binder material of the sintered phosphor, and the LSN phosphor (La ₃ Si ₆ N ₁₁ : Ce) is used as the phosphor in the sintered body. Were weighed and mixed so that the phosphor concentration was 5% by volume. After adding 50 g of 3 mmφ alumina beads to these powders and dry-mixing them for 6 hours with a ball mill, they were sieved (a sieve having an opening of 90 μm) and used as a phosphor material for sintering.

After setting 2.0 g of this raw material on a uniaxial pressing die (stainless steel, Φ20 mm) consisting of an upper punch, lower punch and cylindrical die, pressurize 30 MPa, hold for 5 min, and then pellets Φ20 mm, thickness 3 mm Got.
The obtained pellets were vacuum laminated packed, introduced into a cold isostatic pressing (CIP) apparatus (Nikkiso Rubber Press), and pressurized at 300 MPa for 1 min. Then, it introduce | transduces into a baking furnace (tubular furnace) (Irie Seisakusho tubular furnace IRH), heats up to 1200 degreeC at 10 degreeC / min, hold | maintains for 60 minutes, cools in a furnace, Φ20mm, thickness 3mm sintered compact Obtained.

  The obtained sintered phosphor having a diameter of 20 mm and a thickness of 5 mm was cut to a thickness of about 0.5 mm with a diamond cutter, and further, a plate-like sintered phosphor having a diameter of 20 mm and a thickness of 0.2 mm was prepared by using grinder grinding. . Further, a sintered phosphor obtained by cutting the plate-like sintered phosphor into a 3 mm size was produced.

(Production Example 2)
Except that the LYSN phosphor ((La, Y) ₃ Si ₆ N ₁₁ : Ce) was used as the phosphor and the phosphor concentration in the sintered body was weighed and mixed to be 6% by volume. A sintered phosphor was produced in the same manner as in Production Example 1.

(Production Example 3)
A sintered phosphor was produced in the same manner as in Production Example 1 except that a YAG phosphor (Y ₃ Al ₅ O ₁₂ : Ce) was used as the phosphor.

{Manufacture and evaluation of light emitting devices}
<Example 1>
(Conversion efficiency of sintered phosphor part)
As shown in FIG. 6, a vertically structured LED (□ 1 mm) is mounted on a package via AuSn eutectic solder and manufactured at the same position as the height of the reflector of the package (position about 0.35 mm away from the LED chip surface). The sintered phosphor of Example 1 was installed and the optical characteristics were evaluated.

  Further, as shown in FIG. 7, vertical structure type LEDs (□ 1 mm) are mounted on a package in two series and two parallel via AuSn eutectic solder, and are made of 1 mm aluminum at a position of about 2.5 mm on the surface of the LED chip. A sample holder is installed (see FIG. 9), and the sintered phosphor of Production Example 1 is installed on a φ2 mm aperture formed at a position where the LED emission density of the sample holder is highest, and the LED light quantity is sintered. The characteristics of the phosphor were confirmed.

  As shown in Table 1 and FIG. 3, the sintered phosphor in the present invention can maintain high conversion efficiency even at an optical density at which problems such as deformation and cracking are likely to occur in an organic binder. Therefore, the light emitting device of the present invention is excellent in durability and heat resistance.

<Example 2>
(Optical characteristics of sintered phosphor)
As shown in FIG. 6, a vertically structured LED (□ 1 mm) is mounted on a package via AuSn eutectic solder, and aluminum having a thickness of 2 mm is mounted on the reflector of the package (position about 0.35 mm from the LED chip surface). A sample holder was installed (see FIG. 9), and the sintered phosphor of Production Example 1 was placed on the φ2 mm aperture formed at the position where the LED light emission density of the sample holder was highest, and optical characteristics were evaluated. did.
The results are shown in FIG. When the chromaticity point Cy when excited by blue light having a wavelength of 450 nm and the conversion efficiency CE (Lm / W) of the sintered phosphor are plotted in a Cy-CE diagram, the correlation is obtained between CE and Cy in the vicinity of Cy = 0.35. Is seen. The sintered phosphor used in this embodiment exhibits a conversion efficiency higher than the value represented by y = 100 × Cy + 120 when Cy is in the range of 0.25 to 0.45.

<Example 3>
(Method for manufacturing light emitting device)
For continuous lighting, as shown in FIG. 7, vertically structured LEDs (□ 1 mm) are mounted on a package in two series and two parallel via AuSn eutectic solder, and the thickness is about 2.5 mm on the surface of the LED chip. A 2 mm alumina sample holder was installed (see FIG. 9), and the sintered phosphor of Production Example 1 was installed on a φ2.8 mm aperture formed at a position where the LED emission density of the sample holder was highest. The LED package was placed on a heat sink (100 × 100 × 40 mm) made of aluminum via heat conductive grease.

(Reliability test of sintered phosphor)
As shown in FIG. 6, a vertically structured LED (□ 1 mm) is mounted on a package via AuSn eutectic solder, and aluminum having a thickness of 2 mm is mounted on the reflector of the package (position about 0.35 mm from the LED chip surface). A sample holder is installed (see Fig. 9), and the sintered phosphor taken out from the light-emitting device is placed on the φ2mm aperture formed at the position where the LED light emission density of the sample holder is highest, and optical evaluation is performed. did.
In the light emitting device for continuous lighting, the temperature of each part when the current per LED is 1,000 mA and 10 minutes elapse is as shown in Table 2 below. Under these conditions, a lighting test was conducted for up to 1,000 hours. PKG is a package.

  As shown in Table 2 and FIG. 5, when the energization was performed for up to 1,000 hours in an environment where the temperature of the sintered phosphor portion reached a temperature range where a problem in use occurred in an organic binder, the chromaticity point Since Cx: less than −1/1000, Cy: about −3/1000, and luminous flux maintenance factor: about 93%, the light emitting device of the present invention can exhibit stable characteristics even after long-term use.

<Example 4>
(Temperature characteristics of sintered phosphor)
As shown in FIG. 11, the light source is installed outside the oven and guided to the sintered phosphor manufactured in Production Example 1, Production Example 2 or Production Example 3 installed inside the oven using an optical fiber. Evaluation of optical characteristics of only the sintered phosphor portion when the temperature was changed was performed. Using the apparatus of FIG. 11A, the reflected light spectrum of the sintered phosphor was measured (reflection measurement). The transmitted light spectrum of the sintered phosphor was measured using the apparatus of FIG. 11B (transmission measurement).
Next, when the temperature inside the oven is raised from room temperature to 250 ° C., the excitation light density at the optical fiber output end is 0.16 mW / mm ² , the pulse width is 1 msec, and the distance from the optical fiber output end to the sintered phosphor is The change of the emission spectrum when it was about 1.1 mm was measured. FIG. 12 shows the result of the luminous flux maintenance factor after the temperature rise, assuming that the luminous efficiency before the temperature rise is 1. In addition, the sintered phosphor used in the present embodiment indicated as LSN and LYSN had a luminous flux maintenance factor of about 95% at room temperature at 150 ° C. and 80% or more at room temperature at 250 ° C.
In addition, the same LSN phosphor as used in Production Example 1 is sintered phosphor, unprocessed (powder), or resin-encapsulated sintered phosphor (phosphor in high heat resistant resin). As the embedding), the luminous flux maintenance factor when the temperature changed under the same conditions was evaluated. The result is shown in FIG. Furthermore, the change in chromaticity coordinates when the temperature changed was evaluated. The results are shown in FIGS. 13 (b) and (c).
As shown in FIG. 13, even if the same phosphor is used, an improvement tendency of the luminous flux maintenance factor and the chromaticity point change can be seen by processing the sintered phosphor used in this embodiment.

<Example 5>
(Thermal conduction of sintered phosphor)
As shown in FIG. 14, the phosphor sheet produced by embedding the sintered phosphor produced in Production Example 1 or the same LSN phosphor used in Production Example 1 in a silicone resin (resin sealing) The evaluation of the optical characteristics and temperature measurement were carried out on the thin GaN type- □ 1 mm size LED. Optical characteristics were measured and evaluated 10 seconds after lighting using an integrating sphere total luminous flux measurement system. Moreover, the temperature measurement read the value of the light emission part about 30 seconds after it lighted using thermography.
The results are shown in FIGS. 15 (a) and (b). FIG. 15A shows that the relative luminous flux of the sintered phosphor does not decrease even when the current IF increases as compared with the resin sealing (phosphor sheet). Further, FIG. 15B shows that the temperature rise of the sintered phosphor is suppressed as compared with the resin sealing (phosphor sheet).

DESCRIPTION OF SYMBOLS 10 Light-emitting device 1 Blue semiconductor light-emitting element 2 Wiring board 2a Chip mounting surface 3 Plate-shaped sintered fluorescent substance 4 Frame body 5 Sample holder 6 Area | region LED light emission direction perpendicular | vertical direction LED Semiconductor light-emitting element PKG Package

Claims (9)

A sintered phosphor containing a nitride phosphor and a fluoride inorganic binder, and a gallium nitride LED or laser as a light source,
The light-emitting device, wherein the sintered phosphor absorbs at least a part of light from the light source and emits light having a wavelength different from that of the light source. The nitride phosphor contained in the sintered phosphor is LSN represented by the following general formula; Ln _x Si _y N _n : Z (wherein Ln is a rare earth element excluding an element used as an activator. Z is an activator: 2.7 ≦ x ≦ 3.3, 5.4 ≦ y ≦ 6.6, 10 ≦ n ≦ 12), β sialon represented by the following general formula: Si _{6 -z Al z O z N 8-} z: Eu, wherein 0 <z <4.2), CaAlSiN 3, SCASN represented by the following general formula; (Ca, Sr, Ba, Mg) AlSiN 3: Eu And / or (Ca, Sr, Ba) AlSi (N, O) ₃ : Eu and Sr ₂ Si ₅ N ₈ represented by the following general formula; (Sr, Ca, Ba) ₂ Al _x Si _5-x The light emitting device according to claim 1, comprising at least one nitride phosphor selected from the group consisting of O _x N _8-x : Eu (where 0 ≦ x ≦ 2). Optical device.   The light emitting device according to claim 1, wherein the sintered phosphor is rectangular.   The sintered phosphor has a chromaticity point Cy of light emitted from the sintered phosphor when excited by blue light having a wavelength of 450 nm and a conversion efficiency CE (Lm / W) of the sintered phosphor. The light-emitting device according to any one of claims 1 to 3, which satisfies CE ≧ 100 × Cy + 120 when Cy is plotted in a CE diagram in a range of Cy from 0.25 to 0.45.   A reduction in conversion efficiency when driven for 1000 hours at a region temperature of 200 ° C. or higher in a region vertically above the light emitting direction of the light source of the light source of the sintered phosphor is less than 10%. The light-emitting device according to claim 1.   In the sintered phosphor, in the region vertically above the light emitting surface of the light source, the change in chromaticity point when driven at a region temperature of 200 ° C. or more for 1000 hours is 5/1000 or less. The light emitting device according to claim 1, wherein the light emitting device is characterized.   An illumination device comprising the light emitting device according to any one of claims 1 to 6.   An image display device comprising the light emitting device according to claim 1.   A vehicle indicator lamp comprising the light emitting device according to claim 1.