JP7147138B2 - Light-emitting device, lighting device, image display device, and vehicle indicator light - Google Patents

Description

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

Light emitting diodes (LEDs) are widely known as semiconductor light emitting devices, or semiconductor light sources, capable of producing light having a peak wavelength in a specific region of the light spectrum. LEDs are commonly used as light sources in luminaires, signs, automotive headlamps and displays. As a light-emitting device using an LED and a phosphor, a light-emitting device that emits white light by combining an LED chip that emits blue light and a YAG (yttrium-aluminum-garnet) phosphor that converts blue light into yellow is known. It is The YAG phosphor is placed around the LED chip as a wavelength-converting light-emitting layer dispersed in an epoxy resin or silicone resin. In addition to the wavelength-converting light-emitting layer dispersed in the resin, a ceramic layer made of a phosphor, or a wavelength-converting light-emitting layer (a light-emitting ceramic layer) made of only an inorganic material, in which a phosphor is dispersed in a ceramic, is exemplified. (Patent Document 1).

On the other hand, in recent years, many new materials have been produced for nitrides composed of ternary or higher elements, and recently, in particular, multi-component nitrides and oxynitrides based on silicon nitride have been excellent. Phosphor materials with specific properties have been developed and used in wavelength-converting light-emitting layers. These phosphor materials are known to emit yellow to red light 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 dependence of the luminous efficiency is excellent (Patent Document 2).

Conventionally, wavelength-converting light-emitting layers dispersed in organic binders such as epoxy resins and silicone resins have been insufficient in durability, heat resistance, and light emission intensity. Therefore, in order to obtain a wavelength-converting light-emitting layer with superior durability and heat resistance, research has been conducted on a method of producing a wavelength-converting light-emitting layer (light-emitting ceramic layer) made only of inorganic materials, as exemplified in Patent Document 1. It is

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 exemplified.

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 firing. By melting glass powder having a glass transition point of 200.degree.

Japanese Patent Publication No. 2008-502131 WO2008/132954 WO2009/154193 JP 2009-91546 A

However, in Patent Document 1, an aluminum garnet phosphor is used as the light-emitting ceramic layer. This was obtained by preparing 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 then firing it at 1300 ° C. A 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-based phosphor. Therefore, there has been a demand for a sintered nitride phosphor that has high luminance, high conversion efficiency, and excellent temperature dependence of luminous efficiency.

Further, as exemplified in Patent Document 3, a ceramic composite of a YAG oxide phosphor phase and a fluoride matrix phase has a problem that both internal quantum efficiencies are as low as 55% or less.
In Patent Document 4, a combination of a YAG oxide phosphor or a LuAG oxide phosphor and a CASN nitride phosphor is dispersed in glass by melting glass powder to produce a wavelength conversion light-emitting layer. , Since the inorganic binder is glass, although it has heat resistance, the thermal conductivity is as low as 2 to 3 W/mK, and the heat dissipation is low. ).

Under these circumstances, a sintered phosphor that does not decrease in brightness even when the intensity of excitation light changes or is used at high temperatures for a long time and has a small color shift, and a light emitting device using the same was sought.

Conventionally, when an oxide phosphor and a fluoride inorganic binder are sintered, since the ionic radii of oxygen in the phosphor and fluorine in the inorganic binder are close, solid-solution substitution generally occurs to form an acid fluoride. It was thought that this would lead to a decrease in internal quantum efficiency. Therefore, the present inventors found that by mixing and sintering a nitride phosphor and a fluoride inorganic binder, it is possible to maintain the original internal quantum efficiency of the nitride phosphor. . This is probably because solid solution substitution does not occur easily between nitrogen and fluorine, which have different ionic radii.

In addition, by using a fluoride inorganic binder, the sintering temperature can be lowered compared to, for example, the case of using Al ₂ O ₃ as an inorganic binder, so the reaction between the nitride phosphor and the inorganic binder is suppressed. can be made The present inventors conceived that a sintered nitride phosphor having a high internal quantum efficiency can be obtained in this way.
Furthermore, for example, Al ₂ O ₃ , which is a trigonal system, has birefringence, so when it is made into a sintered body, Al ₂ O ₃ becomes a polycrystalline body and has insufficient translucency, whereas CaF ₂ and BaF ₂ , SrF ₂ , etc., it is possible to produce a sintered phosphor having no birefringence and high transparency.

Accordingly, the present inventors use a nitride phosphor to invent a sintered phosphor for LED that has high internal quantum efficiency, high heat resistance, high transmittance, low absorptance, and high thermal conductivity. reached. Furthermore, by using the sintered phosphor in combination with a high-output gallium nitride light source, an excellent light-emitting device with high conversion efficiency, high luminance, and little change in brightness and color shift due to changes in excitation light intensity and temperature. and invented a 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,
A light-emitting device, wherein the sintered phosphor absorbs at least part of the 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; Z is an activator satisfying 2.7 ≤ x ≤ 3.3, 5.4 ≤ y ≤ 6.6, 10 ≤ n ≤ 12), β-sialon represented by the following general formula Si6- _{zAlzOzN8-z : Eu} , where 0< _z <4.2), _CaAlSiN3 , 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 _Sr2Si5N8 represented by the following general formula: ₍ Sr,Ca,Ba _{) 2AlxSi} The light-emitting device according to (1), comprising at least one nitride phosphor selected from the group consisting of _5- xOxN8 _{-x :} Eu (where 0≤x≤2).
(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), which satisfies CE≧100×Cy+120 when Cy is in the range of 0.25 to 0.45 when plotted on a Cy-CE diagram.
(5) A reduction in conversion efficiency of less than 10% when driven for 1000 hours at a region temperature of 200° C. or higher in a region of the sintered phosphor that is perpendicular to the light emitting surface of the light source in the direction of light emission. The light-emitting device according to any one of (1) to (4), characterized by:
(6) The sintered phosphor has a change in chromaticity point of 5/1000 or less when driven for 1000 hours at a region temperature of 200° C. or higher in a region perpendicular to the light emitting surface of the light source in the light emitting direction. The light-emitting device according to any one of (1) to (5), characterized in that
(7) A lighting 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 light comprising the light emitting device according to any one of (1) to (6).

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

1 is a schematic diagram showing a configuration example of a light emitting device according to an embodiment of the present invention; FIG. 1 is a schematic diagram showing a configuration example of a light emitting device according to an embodiment of the present invention; FIG. 4 is a graph showing the optical characteristics of the sintered phosphor used in Example 1 of the present invention with respect to the amount of LED light. (a) shows the relationship between current and conversion efficiency, (b) shows the relationship between current and conversion efficiency and chromaticity point, and (c) shows the relationship between current and relative luminous flux. 4 is a graph showing the relationship between the chromaticity point and the conversion efficiency of the sintered phosphor used in Example 2 of the present invention. 4 is a graph showing reliability test results of a sintered phosphor used in Example 3 of the present invention. (a) and (b) show the relationship between time and chromaticity point, and (c) shows the relationship between time and light intensity. 1 is a schematic diagram of a light-emitting device for evaluation used in Examples of the present invention. FIG. 1 is a schematic diagram of a light-emitting device for evaluation used in Examples of the present invention. FIG. 1 is a schematic diagram of a light-emitting device for evaluation used in Examples of the present invention. FIG. 1 is a schematic diagram of a light-emitting device for evaluation used in Examples of the present invention. FIG. FIG. 2 is a schematic diagram showing the positional relationship among LEDs, sintered phosphors, sample holders, and packages used in Examples of the present invention. 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, and (b) is a schematic diagram of a transmitted light spectrum measuring device. FIG. 10 is a graph showing the luminous flux maintenance factor after temperature rise when the luminous efficiency before the start of temperature rise is set to 1 for the sintered phosphor used in Example 4 of the present invention. R is from reflection measurements and T is from transmission measurements. The sintered phosphor of the LSN phosphor, the unprocessed LSN phosphor (powder), and the sintered phosphor of the resin-encapsulated LSN phosphor (fired in a high heat-resistant resin) used in Example 4 of the present invention (a) Graph showing the luminous flux maintenance factor after temperature rise when the luminous efficiency before the start of temperature rise is set to 1, (b) atmosphere temperature and chromaticity coordinate Cx and (c) a graph showing the relationship between the ambient temperature and the chromaticity coordinate Cy. R is from reflection measurements and T is from transmission measurements. It is a schematic diagram of the light-emitting device for evaluation used in Example 5 of the present invention. (a) is a graph showing the relationship between the current IF and the relative luminous flux of a light-emitting device using a sintered phosphor or resin sealing according to Example 5 of the present invention; (b) is a graph showing the relationship between current IF and temperature of a light-emitting device using only a sintered phosphor, resin-sealed, or LED, according to Example 5 of the present invention.

In the compositional formulas of the phosphors in this specification, each compositional formula is delimited by a comma (,). In addition, when a plurality of elements are listed separated by commas (,), it indicates that one 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” is composed of “CaAl ₂ O ₄ :Eu”, “SrAl ₂ O ₄ :Eu” and “BaAl ₂ O ₄ :Eu”. and "Ca _1-x Sr _x Al ₂ O ₄ :Eu", "Sr _1-x Ba _x Al ₂ O ₄ : Eu", and "Ca _1-x Ba _x Al ₂ O ₄ : Eu", "Ca _{1-xy Sr x} Bay Al ₂ O ₄ :Eu" (where 0<x<1, 0<y<1, 0<x+y<1) and all inclusive shall be as shown in

<Sintered phosphor>
A sintered phosphor according to an 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 the fluoride inorganic binder, and the composite retains the phosphor mainly by sintering the crystalline inorganic binders. It is a composite in which a compound inorganic binder is integrated by physical and/or chemical bonding. The fluoride inorganic binder used preferably has at least heat resistance and high thermal conductivity.

Techniques for confirming the thermal conductivity of the sintered phosphor according to the present embodiment include measurement methods using a constant 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 increases due to irradiation with strong excitation light, which tends to deteriorate the phosphor and surrounding members. Therefore, the above range is preferable.

The method for producing the sintered phosphor is not particularly limited. For example, a nitride phosphor and a fluoride inorganic binder particle are used as main raw materials, and a mixture of these is compacted and sintered to produce a sintered phosphor that is a composite. can be manufactured. More specifically, it preferably includes any of the following steps.
(Step 1) A step of stirring and mixing nitride phosphor (or garnet phosphor and nitride phosphor) and inorganic binder particles, press-molding, and sintering the compact (Step 2) Nitride phosphor A process of stirring and mixing the body (or garnet-based phosphor and nitride phosphor) and inorganic binder particles, and sintering simultaneously with pressure pressing

Although the sintered phosphor may be used as it is manufactured, it is usually sliced into a predetermined thickness, and further processed into a plate of a predetermined thickness by grinding and polishing to obtain a plate-like sintered phosphor. can get. Grinding and polishing conditions are not particularly limited, but for example, polishing is performed with a #800 diamond grindstone at a grindstone rotation speed of 80 rpm, a work rotation speed of 80 rpm, and 50 g/cm ² , and processed into a plate shape. The final thickness of the sintered phosphor has a lower limit of usually 30 μm or more, preferably 50 μm or more, more preferably 100 μm or more, and an upper limit of usually 2000 μm or less, preferably 1000 μm or less, more preferably 800 μm or less. It is preferably 500 μm or less. If the thickness of the sintered phosphor plate is less than this range, it is likely to break, while if it exceeds this range, it becomes difficult for light to pass through.
Furthermore, after polishing the surface as appropriate, uneven processing may be performed by appropriate wet etching treatment, dry wet etching treatment, or the like.

The sintered phosphor plate can be processed into an arbitrary shape suitable for combination with a light source by dicing or the like. For example, it may have a disk shape or a rectangular plate shape. In the case of a rectangle, the size is not particularly limited and can be appropriately set according to the light source. is 5 cm or less.

From the viewpoint of heat dissipation, the sintered phosphor is preferably fixed so as to have a large contact area with the internal members having higher thermal conductivity. Only a part of the body may be adhered, or a method that does not adhere and fix by placing it so as to drop it into the counterbore is also available. Also, a heat radiation member for releasing heat from 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, Cy- When plotted in a CE diagram, it is preferable that Cy is in the range of 0.25 or more and 0.45 or less and CE≧100×Cy+120 is satisfied.
Cy is y in the CIE color system, and the Cy-CE diagram with this as the x-axis and the conversion efficiency CE as the y-axis shows the transition of the conversion efficiency when the chromaticity of the emitted light changes. By satisfying the above range, it can be said that the sintered phosphor is capable of maintaining high conversion efficiency with respect to changes in the chromaticity of light emitted from the sintered phosphor. It is more preferable to satisfy CE≧100×Cy+125.
In order to satisfy the above range, the voids in the sintered phosphor should be reduced, the grain size in the sintered phosphor should be reduced, etc. Furthermore, the temperature rise during sintering and the sintering time Such adjustments are effective.

<Nitride phosphor>
Nitride phosphors are characterized by absorbing at least the excitation light emitted from the light emitting element, converting the wavelength of the excited light, and emitting light of a wavelength different from that of the light emitting element. _The type of phosphor is not particularly limited as long as it contains nitrogen in the phosphor composition. ₅ N ₈ ), nitride phosphors containing calcium and silicon in the crystal phase (specifically SCASN, CASN, CASON), nitride phosphors containing strontium, silicon and aluminum in the crystal phase (specifically , SCASN), nitride phosphors containing calcium, silicon, and aluminum in the crystal phase (specifically, SCASN, CASN, CASON), barium, and nitride phosphors containing silicon in the crystal phase (specifically, BSON ).
Another class of nitride phosphors is 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.
Furthermore, specifically, for example,
β-sialon which can be represented by the following general formula: Si6 _{-zAlzOzN8-z : Eu (} where 0<z<4.2),
_{LSN represented} by the following general _formula ; .3, 5.4 ≤ y ≤ 6.6, 10 ≤ n ≤ 12.)
CASN represented by the following general formula: CaAlSiN ₃ :Eu,
SCASN can be represented by the following general formula: (Ca,Sr,Ba,Mg) _AlSiN3 :Eu and/or (Ca,Sr,Ba)AlSi(N,O) ₃ :Eu,
CASON which can be represented by the following general formula: ( _CaAlSiN3 ) _{1-x ( Si2N2O} ) _x :Eu (where 0<x<0.5),
CaAlSi ₄ N ₇ ; 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),
_Sr2Si5N8 can be represented by the following general formula: ₍ Sr, Ca, Ba) _{2AlxSi5 - xOxN8 - x} :Eu (where _0≤x≤2 )
_{BSON which} can be _represented by the following _{general formula :} , except for Lu), 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 represent the following formula: 0.03≦x≦0.9, 0.9≦y≦2.95, and x+y+z=3).
Among these phosphors, from the viewpoint of not decreasing the brightness when made into a sintered phosphor, a nitride phosphor containing no oxygen as a constituent element (including oxygen that is unavoidably mixed), that is, LSN, Nitride phosphors such as CaAlSiN ₃ , SCASN, Sr ₂ Si ₅ N ₈ , β-sialon and BSON are preferably used.

The volume fraction of the nitride phosphor with respect to the total volume of the sintered phosphor is generally 1% or more and 50% or less. If the volume fraction of the nitride phosphor is too low, it is necessary to increase the thickness of the phosphor layer in order to control the chromaticity to an arbitrary value, resulting in a decrease in translucency. This is because the light transmittance is also lowered due to a decrease in the

<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 a compound other than a fluoride inorganic binder, but is preferably a crystalline compound. The fluoride inorganic binder preferably transmits part of the excitation light emitted from the light emitting element or at least 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 that of the phosphor. Furthermore, it is preferable that the material withstands heat generated by strong excitation light irradiation and has heat dissipation properties. Also, by using a fluoride inorganic binder, the moldability of the sintered phosphor is improved.
Specific examples of fluoride inorganic binders include CaF ₂ (calcium fluoride), MgF ₂ (magnesium fluoride), BaF ₂ (barium fluoride), SrF ₂ (strontium fluoride), LaF ₃ (lanthanum fluoride ), YF ₃ (yttrium fluoride), alkaline earth metals such as AlF ₃ (aluminum fluoride), fluorides of rare earth metals, fluorides of typical metals, and complexes thereof One or more types can be mentioned. Especially preferred is _CaF2 .
The fluoride inorganic binder is formed by physically and/or chemically bonding particles having the same composition as the fluoride inorganic binder.

The total volume fraction of the nitride phosphor and 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.
Further, 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.

The volume median diameter of the fluoride binder particles, which is the raw material of the fluoride inorganic binder, is 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. Also, it is usually 15 μm or less, preferably 10 μm or less, more preferably 5 μm or less. When the fluoride inorganic binder particles are within the above range, the sintering temperature can be reduced, and deactivation of the nitride phosphor due to reaction between the nitride phosphor and the inorganic binder can be suppressed, A decrease in the internal quantum efficiency of the sintered phosphor can be suppressed. The volume median diameter can be measured, for example, by the Coulter counter method described above, and other typical devices 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, Inc.) or the like.

The ratio nb/np of the refractive index nb of the fluoride inorganic binder particles to the refractive index np of the nitride phosphor is 1 or less, preferably 0.8 or less, more preferably 0.6 or less. It is also usually a value greater than zero. If the refractive index ratio is greater than 1, the light extraction efficiency after sintering tends to decrease. Therefore, the above range is preferable.

The fluoride inorganic binder particles preferably have a low melting point. By using fluoride inorganic binder particles with a low melting point, it is possible to reduce the sintering temperature, suppress the deactivation of the nitride phosphor due to the reaction between the nitride phosphor and the inorganic binder, A decrease in the internal quantum efficiency of the sintered phosphor can be suppressed. Specifically, the melting point is preferably 1500° C. or less. 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 comprising a sintered phosphor and a gallium nitride-based light-emitting element.
The light-emitting device according to the present embodiment includes at least a blue semiconductor light-emitting element (blue light-emitting diode or blue semiconductor laser) and a wavelength conversion member for converting the wavelength of blue light. The sintered phosphor according to the embodiment of the present invention 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 between them, or a space may be provided. As shown in FIG. 1 as a schematic diagram, it is preferable to have a structure having a space between the semiconductor light emitting element 1 and the sintered phosphor 3 .

<Light emitting element>
Gallium nitride-based materials are currently widely used to fabricate light-emitting devices such as semiconductor light-emitting devices (LEDs) and semiconductor lasers (LDs). A sapphire substrate is mainly used to form an n-type layer and a p-type layer in the c(+) direction ([0001] axis direction), and an InGaN-based quantum well light-emitting layer is fabricated between the n-type layer and the p-type layer. . In order to improve the light extraction efficiency, a vertical structure type LED with a peeled sapphire substrate and a flip-chip type LED that does not use wires are also manufactured.

A light-emitting device using a sapphire substrate has the problem that threading dislocations inevitably occur due to lattice constant mismatch between the sapphire substrate and the gallium nitride-based material. Therefore, when light of high light density and large luminous flux is required, a light-emitting element manufactured using a self-supporting gallium nitride substrate is used in order to ensure characteristics and reliability.

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

The blue semiconductor light-emitting element 1 normally emits excitation light with a peak wavelength of 425 nm to 475 nm, and preferably emits excitation light with a peak wavelength of 430 nm to 470 nm. The number of blue semiconductor light-emitting elements 1 can be appropriately set according to the intensity of excitation light required by the device.
On the other hand, instead of the blue semiconductor light emitting device 1, a violet semiconductor light emitting device can be used. A violet semiconductor light-emitting element normally emits excitation light with a peak wavelength of 390 nm to 425 nm, preferably excitation light with a peak wavelength of 395 to 415 nm.

The blue semiconductor light emitting element 1 is mounted on the chip mounting surface 2a of the wiring board 2. As shown in FIG. 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 shown that the sintered phosphor 3 is placed on the wiring board 2, but this is not the only option. good.

For example, in FIG. 1, the wiring board 2 and the sintered phosphor 3 are arranged with the frame 4 interposed therebetween. The frame 4 may be tapered in order to give directivity to the light. Moreover, the frame 4 may be a reflective material.
From the viewpoint of improving the luminous efficiency of the light-emitting device 10, the wiring board 2 preferably has excellent electrical insulation, good heat dissipation, and high reflectance. It is also possible to provide a reflector with a high reflectance on the surface on which the blue semiconductor light emitting element 1 does not exist, or on at least part of the inner surface of another member that connects the wiring board 2 and the sintered phosphor 3 .

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

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-based phosphor may be used as the phosphor. Moreover, it is preferable that the sintered phosphor 3 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. In this way, the sintered phosphor 3 and the phosphor contained in the sintered phosphor are heated by the heat emitted by the blue semiconductor light emitting device 1 due to the distance between the sintered phosphor 3 and the blue semiconductor light emitting device 1 . 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, and particularly preferably 1.0 mm or more, while it is preferably 1.0 m or less, and more preferably 500 mm or less. , 100 mm or less are particularly preferred.

The light emitting device according to this embodiment is preferably a light emitting device that emits white light. A light-emitting device that emits white light preferably has a deviation duv of -0.0200 to 0.0200 from the black body radiation locus of the light emitted from the light-emitting device.
A light-emitting device that emits white light in this manner is preferably provided in a lighting device. In the light emitting device according to the present embodiment, it is desirable that temperature changes in luminous flux, chromaticity, etc. during light emission are small. By using sintered phosphors using LSN and LYSN as phosphors, it is possible to provide a light-emitting device in which a decrease in conversion efficiency is suppressed to about 10% even in a 200° C. environment.

In the light-emitting device according to the present embodiment, the reduction in conversion efficiency after driving for 1000 hours at a region temperature of 200° C. or higher in the region of the sintered phosphor perpendicular to the light emitting surface of the light source in the direction of light emission is 10%. % is preferred. In addition, in the region of the sintered phosphor that is perpendicular to the light emitting surface of the light source in the light emitting direction, the change in chromaticity point after driving for 1000 hours at a region temperature of 200 ° C. or higher is 5/1000 or less. is preferred. A light-emitting device within such a range is preferable because it is a highly reliable light-emitting device in which luminance does not decrease even after long-term use at high temperature and color shift is small.
In the sintered phosphor 3 shown in FIG. 10, a dashed line 6 indicates a region perpendicular to the light emitting surface of the blue semiconductor light emitting element 1, which is the light source, in the light emitting direction. This region is a region where the intensity of light emitted from a light source such as a semiconductor light emitting device or a laser is high, and is the region where deterioration of the sintered phosphor is most likely to occur. In the present embodiment, even in the region where deterioration of the sintered phosphor is most likely to occur, the reduction in conversion efficiency after driving for 1000 hours at a region temperature of 200 ° C. or higher is less than 10%, and the chromaticity It is possible to provide a high-performance light-emitting device with a point variation of 5/1000 or less.

<Lighting device>
Another embodiment of the present invention is a lighting device comprising the above light emitting device.
As described above, since a high total luminous flux is emitted from the light emitting device, a lighting fixture with a high total luminous flux can be obtained. The luminaire preferably has a diffusion member that covers the sintered phosphor in the light emitting device so that the color of the sintered phosphor is inconspicuous when the light is turned off.

<Image display device>
Another embodiment of the present invention is an image display device comprising the above 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 it is preferably used together with a color filter. For example, when a color image display device using a color liquid crystal display element is used as the image display device, the light emitting device is used as a backlight, and an optical shutter using liquid crystal and a color filter having red, green, and blue pixels are used. can be combined to form an image display device.

<Vehicle indicator light>
Another embodiment of the present invention is a vehicle indicator light comprising the above light emitting device.
It is preferable that the light-emitting device used for the vehicle indicator lamp is a light-emitting device that emits white light. A light-emitting device that emits white light has a deviation duv of -0.0200 to 0.0200 from the blackbody radiation locus of light color and a color temperature of 5000 K or more and 30000 K or less. is preferably
The vehicular indicator lamps include lights provided in a vehicle for the purpose of giving some kind of indication to other vehicles, people, etc., such as headlamps, side lamps, back lamps, turn signals, brake lamps, and fog lamps of the vehicle.

Specific embodiments of the present invention will now 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 from a sintered phosphor was produced by irradiating blue light emitted from an LED chip (peak wavelength 450 nm) capable of emitting light with an emission surface intensity of 2 W/mm ² . ^The emission spectrum from the device was observed using a 1 m integrating sphere (manufactured by Labspher) and a spectrometer MC-9800 (manufactured by Otsuka Electronics). Degree coordinates and luminous flux (lumen) 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 emitting light was fabricated by arranging four LED chips (peak wavelength 450 nm) capable of emitting light with a light emitting surface intensity of 1 W/mm ² and combining sintered phosphors with a minimum square size of 2 mm. did. The emission spectrum from the device was observed using a 1 m integrating sphere (manufactured by Labspher) and a spectrometer MC-9800 (manufactured by Otsuka Electronics), and the color temperature, chromaticity coordinates, and color temperature when excited while changing the light emitting surface intensity. Lumen 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 emitting light with a light emitting surface intensity of 1 W/mm ² were arranged, and a sintered phosphor with a square size of 3 mm was combined to produce a light emitting device capable of emitting light. The device was driven for up to 1,000 hours and changes in lumen and chromaticity coordinates were measured. In order to examine the characteristics of the sintered phosphor, only the sintered phosphor was taken out from the apparatus and incorporated into another apparatus, and the emission spectrum was observed using a 1 m integrating sphere manufactured by Labspher and a spectrometer MC-9800 manufactured by Otsuka Electronics.

[Manufacturing method of sintered phosphor]
(Production example 1)
10.0 g of CaF ₂ powder (Kojundo Chemical Laboratory) was used as the fluoride inorganic binder material of the sintered phosphor, and LSN phosphor (La ₃ Si ₆ N ₁₁ :Ce) was used as the phosphor in the sintered body. were weighed and mixed so that the concentration of the phosphor was 5% by volume. 50 g of alumina beads of 3 mmΦ were added to these powders, dry-mixed for 6 hours by a ball mill, sieved (sieve with an opening of 90 μm), and used as a phosphor raw material for sintering.

After setting 2.0 g of this raw material in a uniaxial press die (made of stainless steel, Φ20 mm) consisting of an upper punch, a lower punch, and a cylindrical die, a press pressure of 30 MPa is applied, and after holding for 5 minutes, pellets of Φ20 mm and a thickness of 3 mm got
The obtained pellets were vacuum laminated packed, introduced into a cold isostatic pressing (CIP) device (Nikkiso Rubber Press), and pressurized at 300 MPa for 1 minute. After that, it is introduced into a firing furnace (tubular furnace) (Irie Seisakusho tubular furnace IRH), heated to 1200 ° C. at 10 ° C./min, held for 60 min, and then cooled in the furnace to produce a sintered body with a diameter of 20 mm and a thickness of 3 mm. Obtained.

The obtained sintered phosphor having a diameter of 20 mm and a thickness of 5 mm was cut with a diamond cutter into pieces having a thickness of about 0.5 mm. . Also, a sintered phosphor was produced by cutting the plate-shaped sintered phosphor into a size of □3 mm.

(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 so that the concentration was 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 device}
<Example 1>
(Conversion efficiency of sintered phosphor portion)
As shown in Fig. 6, a vertical structure type LED (1 mm square) is mounted in a package via AuSn eutectic solder, and manufactured at the same position as the package reflector (a position about 0.35 mm away from the LED chip surface). The sintered phosphor of Example 1 was installed and the optical properties were evaluated.

Also, as shown in FIG. 7, a vertical structure type LED (□ 1 mm) was mounted on the package in 2-series and 2-parallel via AuSn eutectic solder. A sample holder is installed (see FIG. 9), and the sintered phosphor of Production Example 1 is installed on a φ2 mm diaphragm formed at the position where the LED emission density is highest on the sample holder, and sintering for the light intensity of the LED The properties of the phosphor were confirmed.

As shown in Table 1 and FIG. 3, the sintered phosphor of the present invention can maintain high conversion efficiency even at light densities at which problems such as deformation and cracking tend to occur with organic binders. Therefore, the light-emitting device of the present invention is excellent in durability and heat resistance.

<Example 2>
(Optical Characteristics of Sintered Phosphor Portion)
As shown in Fig. 6, a vertical structure type LED (square 1 mm) was mounted in a package via AuSn eutectic solder, and a 2 mm thick aluminum foil was placed on the reflector of the package (at a position approximately 0.35 mm from the surface of the LED chip). (see Fig. 9), and the sintered phosphor of Production Example 1 was placed on a φ2 mm diaphragm formed at the position of the sample holder where the LED emission density is the highest, and the optical characteristics were evaluated. did.
The results are shown in FIG. When the chromaticity point Cy when excited by blue light with a wavelength of 450 nm and the conversion efficiency CE (Lm/W) of the sintered phosphor are plotted in the Cy-CE diagram, there is a correlation between CE and Cy near Cy = 0.35. can be seen. The sintered phosphor used in this embodiment exhibits 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 (square 1 mm) were mounted in a package in two series and two parallel via AuSn eutectic solder, and a thickness of about 2.5 mm was mounted on the surface of the LED chip. A sample holder made of 2 mm alumina was placed (see FIG. 9), and the sintered phosphor of Production Example 1 was placed on a diaphragm of φ2.8 mm formed at a position of the sample holder where the LED emission density is highest. The LED package was placed on an aluminum heat sink (100×100×40 mm) via heat conductive grease.

(Reliability test of sintered phosphor part)
As shown in Fig. 6, a vertical structure type LED (square 1 mm) was mounted in a package via AuSn eutectic solder, and a 2 mm thick aluminum foil was placed on the reflector of the package (at a position approximately 0.35 mm from the surface of the LED chip). A sintered phosphor taken out from the light-emitting device was placed on a φ2mm diaphragm formed at the position of the sample holder where the LED emission density is highest (see Fig. 9), and optical evaluation was performed. did.
In the light emitting device for continuous lighting, the temperature of each part after 10 minutes with a current of 1,000 mA per LED is shown in Table 2 below. A lighting test up to 1,000 hours was conducted under these conditions. PKG is a package.

As shown in Table 2 and FIG. 5, the chromaticity point Cx: less than -1/1000, Cy: about -3/1000, and luminous flux maintenance factor: about 93%.

<Example 4>
(Temperature characteristics of sintered phosphor part)
As shown in FIG. 11, by installing a light source outside the oven and guiding the light to the sintered phosphor produced in Production Example 1, Production Example 2, or Production Example 3 installed inside the oven using an optical fiber. , the optical characteristics of only the sintered phosphor portion were evaluated when the temperature was changed. The reflected light spectrum of the sintered phosphor was measured using the apparatus shown in FIG. 11(a) (reflection measurement). Using the apparatus of FIG. 11(b), the transmitted light spectrum of the sintered phosphor was measured (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 Changes in the emission spectrum were measured when the thickness was about 1.1 mm. Assuming that the luminous efficiency before the temperature rise is 1, the results of the luminous flux maintenance factor after the temperature rise are shown in FIG. The sintered phosphors labeled LSN and LYSN and used in this embodiment had a luminous flux maintenance factor of about 95% at 150° C. compared to room temperature and 80% or more at 250° C. compared to room temperature.
In addition, the same LSN phosphor as used in Production Example 1 was used as a sintered phosphor, an unprocessed one (powder), or a resin-encapsulated sintered phosphor (a phosphor in a highly heat-resistant resin). Embedding), the luminous flux maintenance factor was evaluated when the temperature was changed under the same conditions. The results are shown in FIG. 13(a). Furthermore, the change in chromaticity coordinates was evaluated when the temperature was changed. The results are shown in FIGS. 13(b) and 13(c).
As shown in FIG. 13, even if the same phosphor is used, by processing it into the sintered phosphor used in this embodiment, there is a tendency to improve the luminous flux maintenance factor and the chromaticity point change.

<Example 5>
(Heat conduction of sintered phosphor part)
As shown in FIG. 14, a phosphor sheet produced by embedding the sintered phosphor produced in Production Example 1 or the same LSN phosphor as that used in Production Example 1 in silicone resin (resin-encapsulated phosphor sheet) ) was laminated directly above a thin GaN type/square 1 mm size LED, and the optical characteristics were evaluated and the temperature was measured. Optical properties were evaluated by measuring 10 seconds after lighting using an integrating sphere total luminous flux measurement system. For temperature measurement, a thermography was used to read the value of the light-emitting part about 30 seconds after lighting.
The results are shown in FIGS. 15(a) and (b). From FIG. 15(a), it can be seen that the sintered phosphor does not lower the relative luminous flux even if the current IF increases compared to the case of resin sealing (phosphor sheet). Also, from FIG. 15(b), it can be seen that the sintered phosphor suppresses the temperature rise as compared with the case of resin sealing (phosphor sheet).

10 Light-emitting device 1 Blue semiconductor light-emitting element 2 Wiring substrate 2a Chip mounting surface 3 Plate-like sintered phosphor 4 Frame 5 Sample holder 6 Area vertically above light emission direction LED Semiconductor light-emitting element PKG Package

Claims (9)

Equipped with a nitride phosphor that does not contain oxygen as a constituent element (including oxygen that is unavoidably mixed) , a sintered phosphor containing a crystalline fluoride inorganic binder, and a gallium nitride LED or laser as a light source. ,
The crystal system of the fluoride inorganic binder is cubic,
A light-emitting device, wherein the sintered phosphor absorbs at least part of the 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; Z is an activator satisfying 2.7≦x≦3.3, 5.4≦y≦6.6, and 10≦n≦12) , CaAlSiN ₃ , SCASN represented by the following general formula: (Ca, Sr, Ba, Mg) AlSiN ₃ :Eu and/or (Ca, Sr, Ba) AlSiN ₃ :Eu, and Sr ₂ Si ₅ N ₈ represented by the following general formula; (Sr, Ca , _{Ba ) 2Si5N8} : Eu . 3. A light emitting device according to claim 1 or 2, wherein the sintered phosphor is rectangular. For the sintered phosphor, Cy- 4. The light-emitting device according to claim 1, which satisfies CE≧100×Cy+120 when Cy is in the range of 0.25 to 0.45 when plotted in a CE diagram. A decrease in conversion efficiency of the sintered phosphor is less than 10% when driven for 1000 hours at a region temperature of 200 ° C. or higher in a region perpendicular to the light emitting surface of the light source in the light emitting direction. The light-emitting device according to any one of claims 1 to 4, wherein A change in chromaticity point when driven for 1000 hours at a region temperature of 200° C. or higher in a region of the sintered phosphor perpendicular to the light emitting surface of the light source in the light emitting direction is 5/1000 or less. A light-emitting device according to any one of claims 1 to 5, characterized in that. 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 any one of claims 1 to 6. A vehicle indicator lamp comprising the light emitting device according to any one of claims 1 to 6.

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