JP2006041096A - Light emission device and phosphor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light emission device which has small color slurring and color unevenness, and high light emission efficiency, and to provide a phosphor used therefor. <P>SOLUTION: The light emission device is equipped with an exciting light source and the phosphor which absorbs at least part of the light emitted by the exciting light source and converts it to a different wavelength. The phosphor is a rare-earth aluminate phosphor having (a) aluminum; (b) at least one kind selected from a group of yttrium, lutetium, scandium, lanthanum, gadolinium, terbium, europium, and samarium; (c) gallium at need; and (d) a rare-earth element and has a filled part and a cavity inside, the area rate of the cavity to the total of the filled part and cavity stands at the level of 0 to 20% in a section. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a light emitting device used for a display, a backlight light source, a display, an illuminated switch, various indicators, and the like, and a phosphor used therefor.

A light-emitting device using a light-emitting element emits light with a small color, high power efficiency, and vivid colors. Moreover, since it is a semiconductor element, there is no worry of a broken ball. In addition, it has excellent initial drive characteristics and is resistant to vibration and repeated on / off lighting.
Because of such excellent characteristics, light-emitting devices using semiconductor light-emitting elements such as LEDs (Light Emitting Diodes) and LDs (Laser Diodes) are used as various light sources.

There is a demand for multicolor light emitting devices in a wide range of fields such as lighting such as fluorescent lamps, in-vehicle lighting, displays, and backlights for liquid crystals. In particular, a light emitting device that emits white light (hereinafter referred to as “white light emitting device”) is required.
The light emission color of a white light emitting device using a semiconductor light emitting element is obtained by the principle of light color mixing. The blue light emitted from the light emitting element is incident on the YAG-based phosphor layer represented by the composition formula of Y ₃ Al ₅ O ₁₂ : Ce, and then repeatedly absorbed and scattered several times in the layer. After that, it is discharged to the outside. On the other hand, the blue light absorbed by the YAG phosphor acts as an excitation light source and emits yellow fluorescence. Then, blue light and yellow light are mixed and recognized as white by human eyes.

In Patent Document 1, wavelength conversion is performed for an electroluminescent element including a semiconductor element that emits ultraviolet light, blue light, or green light based on a transparent epoxy casting resin to which a luminescent material is added. An inorganic luminescent material pigment powder comprising a luminescent material pigment from the group of fluorescent materials having the general formula A ₃ B ₅ X ₁₂ : M is dispersed in this transparent epoxy casting resin, A wavelength-converting casting material is described in which the phosphor pigment has a particle size of ≦ 20 μm and an average particle diameter d ₅₀ ≦ 5 μm. And this provides a wavelength conversion casting material that can produce electroluminescent devices that emits a homogeneous mixed color and enables mass production with applicable technical costs and fully reproducible device characteristics It describes what you can do.
However, with this casting material, it has been impossible to improve luminous efficiency and color unevenness required for recent light emitting devices. There was also room for improvement in color misregistration.

Japanese National Patent Publication No. 11-500584

  An object of the present invention is to provide a light-emitting device with low color misregistration and uneven color and high luminous efficiency, and a phosphor used therefor.

  The present invention provides the following (1) to (7).

(1) an excitation light source;
A light-emitting device comprising: a phosphor that absorbs at least part of light emitted from the excitation light source and converts the light into a different wavelength;
The phosphor includes (a) aluminum,
(B) at least one selected from the group consisting of yttrium, lutetium, scandium, lanthanum, gadolinium, terbium, europium and samarium;
(C) gallium as necessary;
(D) a rare earth aluminate phosphor having a rare earth element;
The phosphor has a filling portion and a hollow portion inside the phosphor,
The light emitting device, wherein an area ratio of the hollow portion to the total of the filling portion and the hollow portion when the cross-section is performed on the phosphor is larger than 0% and smaller than 20%.

(2) The light emitting device according to (1), wherein the phosphor has three or more grain boundaries.

(3) The light emitting device according to the above (1) or (2), wherein the general formula of the phosphor is represented by the following formula.
_{(Ln 1-x, R x} ) 3 (Al 1-n, Ga n) 5 O 12
(Ln represents at least one selected from the group consisting of Y, Lu, Sc, La, Gd, Tb, Eu and Sm, R represents at least one rare earth element, and x represents 0.0001 ≦ x ≦ Represents a number satisfying 0.3, and n represents a number satisfying 0 ≦ n ≦ 0.5.)

(4) A light-emitting element whose light-emitting layer is a semiconductor, and a photoluminescence phosphor that absorbs part of the light emitted by the light-emitting element and emits light having a wavelength different from the wavelength of the absorbed light. In the light emitting device
(1) The light-emitting element is a blue light-emitting LED chip whose light-emitting layer is a gallium nitride semiconductor and whose emission spectrum has a peak wavelength in the range of 410 to 490 nm.
(2) The photoluminescent phosphor comprises: (a) aluminum;
(B) at least one selected from the group consisting of yttrium, lutetium, scandium, lanthanum, gadolinium, terbium, europium and samarium;
(C) gallium as necessary;
(D) a rare earth aluminate phosphor having a rare earth element;
The phosphor has a filling portion and a hollow portion inside the phosphor,
When the cross section of the phosphor is taken out, the area ratio of the cavity to the total of the filler and the cavity is a phosphor that is greater than 0% and less than 20%.
(3) Mixing of an emission spectrum having a peak wavelength in the range of 510 to 580 nm emitted from the phosphor and an emission spectrum having a peak wavelength in the range of 410 to 490 nm that is not absorbed by the phosphor from the LED chip The light emitting device emits white light having a continuous combined spectrum by overlapping both spectra.

(5) (a) aluminum;
(B) at least one selected from the group consisting of yttrium, lutetium, scandium, lanthanum, gadolinium, terbium, europium and samarium;
(C) gallium as necessary;
(D) a rare earth aluminate phosphor having a rare earth element;
The phosphor has a filling portion and a hollow portion inside the phosphor,
The rare earth aluminate phosphor, wherein an area ratio of the cavity portion to the total of the filling portion and the cavity portion when the cross section is taken out of the phosphor is greater than 0% and less than 20%.

(6) The rare earth aluminate phosphor according to (5), wherein the phosphor has three or more grain boundaries.

(7) The rare earth aluminate phosphor according to (5) or (6), wherein the general formula of the phosphor is represented by the following formula.
_{(Ln 1-x, R x} ) 3 (Al 1-n, Ga n) 5 O 12
(Ln represents at least one selected from the group consisting of Y, Lu, Sc, La, Gd, Tb, Eu and Sm, R represents at least one rare earth element, and x represents 0.0001 ≦ x ≦ Represents a number satisfying 0.3, and n represents a number satisfying 0 ≦ n ≦ 0.5.)

The light-emitting device described in (1) is a light-emitting device that includes an excitation light source and a phosphor that absorbs at least a part of light emitted from the excitation light source and converts the light into a different wavelength. And (b) at least one selected from the group consisting of yttrium, lutetium, scandium, lanthanum, gadolinium, terbium, europium, and samarium, (c) a gallium, if necessary, and (d) a rare earth element It is an aluminate phosphor, and the phosphor has a filling portion and a cavity portion inside, and the area ratio of the cavity portion to the total of the filling portion and the cavity portion when the cross section of the phosphor is taken out Is greater than 0% and less than 20%.
By having such a cavity, it is considered that light can be emitted with reduced loss of absorbed energy, and the light emission efficiency is improved. Moreover, since the space between the cavity and the filling portion serves as an interface and diffuses light, color shift and color unevenness are reduced.
In addition, by adopting the above configuration, the phosphor particles in the resin are not completely submerged and are uniformed, so that color misregistration and color unevenness are reduced.

  In the light emitting device according to (2), it is preferable that the phosphor has three or more grain boundaries. By having three or more grain boundaries, a light diffusion effect can be obtained, and color unevenness can be further reduced while maintaining high luminous efficiency.

(3) The light emitting device according to the general formula of the _{phosphor, (Ln 1-x, R} x) 3 (Al 1-n, Ga n) 5 O 12 (Ln is Y, Lu, Sc, La , Gd, Tb, Eu and Sm, R represents at least one rare earth element, x represents a number satisfying 0.0001 ≦ x ≦ 0.3, n Represents a number satisfying 0 ≦ n ≦ 0.5.

The light-emitting device described in (4) includes a light-emitting element whose light-emitting layer is a semiconductor and a photo that emits light having a wavelength different from the wavelength of the absorbed light by absorbing part of the light emitted by the light-emitting element. In the light emitting device including the luminescent phosphor, the light emitting element is a blue light emitting LED chip whose light emitting layer is a gallium nitride semiconductor and whose emission spectrum has a peak wavelength in the range of 410 to 490 nm. The body comprises (a) aluminum, (b) at least one selected from the group consisting of yttrium, lutetium, scandium, lanthanum, gadolinium, terbium, europium and samarium, and (c) gallium, if necessary, (d ) A rare earth aluminate phosphor having a rare earth element, the phosphor has a filling portion therein, The area ratio of the cavity portion to the total of the filling portion and the cavity portion when the cross section of the phosphor is provided is a phosphor larger than 0% and smaller than 20%. By mixing the emission spectrum having a peak wavelength in the range of 510 to 580 nm that emits light and the emission spectrum having a peak wavelength in the range of 410 to 490 nm that is not absorbed by the phosphor from the LED chip, both spectra overlap, Emits white light with a continuous composite spectrum.
With the above-described configuration, a light emitting device with small color shift and color unevenness and high light emission efficiency can be obtained.

The rare earth aluminate phosphor described in (5) includes (a) aluminum, (b) at least one selected from the group consisting of yttrium, lutetium, scandium, lanthanum, gadolinium, terbium, europium, and samarium; ) A rare earth aluminate phosphor having gallium and (d) a rare earth element as required, and the phosphor has a filling portion and a cavity inside thereof, and the phosphor was sectioned. The ratio of the area of the cavity to the total of the filler and cavity is greater than 0% and less than 20%.
By having such a cavity, it is considered that light can be emitted with reduced loss of absorbed energy, and the light emission efficiency is improved. Moreover, since the space between the cavity and the filling portion serves as an interface and diffuses light, color shift and color unevenness are reduced.
In addition, by adopting the above configuration, the phosphor particles in the resin are not completely submerged and are uniformed, so that color misregistration and color unevenness are reduced.

In the rare earth aluminate phosphor described in (6), the phosphor preferably has three or more grain boundaries. By having three or more grain boundaries, a light diffusion effect can be obtained, and color unevenness can be further reduced while maintaining high luminous efficiency.

In the rare earth aluminate phosphor according to (7), the general formula of the _{phosphor, (Ln 1-x, R} x) 3 (Al 1-n, Ga n) 5 O 12 (Ln is Y, Lu, Represents at least one selected from the group consisting of Sc, La, Gd, Tb, Eu and Sm, R represents at least one rare earth element, and x represents a number satisfying 0.0001 ≦ x ≦ 0.3. And n is preferably a number satisfying 0 ≦ n ≦ 0.5.

  Hereinafter, the light emitting device and the rare earth aluminate phosphor according to the present invention will be described in detail. However, the present invention is not limited to this embodiment.

The light-emitting device according to the present invention is a light-emitting device that includes an excitation light source and a phosphor that absorbs at least part of light emitted from the excitation light source and converts it to a different wavelength.
In the present invention, JIS Z8110 is taken into consideration for the relationship between color names and chromaticity coordinates.

(Excitation light source)
As the excitation light source, one having an emission peak wavelength from the ultraviolet to the short wavelength side of visible light is used. Any excitation light source having an emission peak wavelength in this range can be used even if it uses a semiconductor light emitting element, lamp, electron beam, plasma, EL or the like as an energy source, and is not particularly limited. It is preferable to use a semiconductor light emitting element.

(Light emitting device)
A light-emitting device according to Embodiment 1 of the present invention will be described with reference to FIG.
The light emitting device of the first embodiment includes a semiconductor layer 2 stacked on the sapphire substrate 1, and a lead frame 13 conductively connected by a conductive wire 14 extending from positive and negative electrodes 3 formed on the semiconductor layer 2. The phosphor 11 and the coating member 12 provided in the cup of the lead frame 13 a so as to cover the outer periphery of the light emitting element 10 composed of the sapphire substrate 1 and the semiconductor layer 2, and the mold that covers the outer peripheral surface of the lead frame 13. And a member 15.

  A semiconductor layer 2 is formed on the sapphire substrate 1, and positive and negative electrodes 3 are formed on the same plane side of the semiconductor layer 2. The semiconductor layer 2 is provided with a light emitting layer (not shown), and an emission peak wavelength output from the light emitting layer has an emission spectrum in the vicinity of 500 nm or less from the ultraviolet to the blue region.

The light-emitting element 10 is set on a die bonder, face-up to a lead frame 13a provided with a cup, and die-bonded (adhered). After die bonding, the lead frame 13 is transferred to a wire bonder, the negative electrode 3 of the light emitting element is wire bonded to the lead frame 13a provided with a cup with a gold wire, and the positive electrode 3 is wire bonded to the other lead frame 13b. .

Next, it transfers to a molding apparatus and inject | pours the fluorescent substance 11 and the coating member 12 in the cup of the lead frame 13 with the dispenser of a molding apparatus. The phosphor 11 and the coating member 12 are uniformly mixed in advance at a desired ratio. As the phosphor 11, at least one phosphor that is directly excited by the light emitting element 10 is used.
Next, after the phosphor 11 is injected, the phosphor 11 and the coating member 12 are cured.
Finally, after immersing the lead frame 13 in a mold mold in which the mold member 15 has been injected in advance, the mold is removed and the resin is cured to obtain a bullet-type light emitting device as shown in FIG.

Next, the light-emitting device of Embodiment 2 of this invention is demonstrated using FIG.
The light-emitting device of Embodiment 2 forms a surface-mount type light-emitting device. The light-emitting element 101 can be an ultraviolet light-excited nitride semiconductor light-emitting element. The light-emitting element 101 can also be a blue-light-excited nitride semiconductor light-emitting element.
Here, the light emitting element 101 excited by ultraviolet light will be described as an example. The light emitting element 101 uses a nitride semiconductor light emitting element having an InGaN semiconductor with an emission peak wavelength of about 370 nm as a light emitting layer. As a more specific LED element structure, an n-type GaN layer that is an undoped nitride semiconductor on a sapphire substrate, a GaN layer that is formed with an Si-doped n-type electrode and becomes an n-type contact layer, and an undoped nitride semiconductor A single quantum well structure includes an n-type GaN layer, an n-type AlGaN layer that is a nitride semiconductor, and then an InGaN layer that constitutes a light-emitting layer. On the light emitting layer, an AlGaN layer as a p-type cladding layer doped with Mg and a GaN layer as a p-type contact layer doped with Mg are sequentially laminated. (Note that a GaN layer is formed on the sapphire substrate at a low temperature to serve as a buffer layer. In addition, the p-type semiconductor is annealed at 400 ° C. or higher after film formation). Etching exposes the surface of each pn contact layer on the same side as the nitride semiconductor on the sapphire substrate. An n-electrode is formed in a strip shape on the exposed n-type contact layer, and a translucent p-electrode made of a metal thin film is formed on almost the entire surface of the p-type contact layer that remains without being cut. A pedestal electrode is formed on the p-electrode in parallel with the n-electrode using a sputtering method.

  Next, a Kovar package 105 having a concave portion at the central portion and a base portion having Kovar lead electrodes 102 inserted and fixed in an airtight manner on both sides of the concave portion is used. A Ni / Ag layer is provided on the surface of the package 105 and the lead electrode 102. The light emitting element 101 described above is die-bonded with an Ag—Sn alloy in the recess of the package 105. With this configuration, all the constituent members of the light emitting device can be made of an inorganic material, and the light emission from the light emitting element 101 is drastically reliable even if the light emitted from the light emitting element 101 is in the ultraviolet region or the short wavelength region of visible light. A light emitting device with high brightness can be obtained.

Next, each electrode of the die-bonded light emitting element 101 is electrically connected to each lead electrode 102 exposed from the bottom of the package recess by an Ag wire 104. After sufficiently removing moisture in the recess of the package, sealing is performed with a Kovar lid 106 having a glass window 107 at the center, and seam welding is performed. The glass window 107 constitutes the following color conversion member. The color conversion member contains the phosphor 108 of the present invention in a slurry composed of 90 wt% of nitrocellulose and 10 wt% of γ-alumina, and is applied to the back surface of the translucent window 107 of the lid 106, and is heated to 220 ° C. For 30 minutes. When the light-emitting device thus formed emits light, a light-emitting diode capable of emitting white light with high luminance can be obtained. As a result, it is possible to obtain a light emitting device that is extremely easy to adjust the chromaticity and has excellent mass productivity and reliability.
Hereafter, each structure of this invention is explained in full detail.

(Phosphor 11, 108)
The phosphors 11 and 108 include at least one phosphor that is directly excited. Direct excitation means excitation mainly by light from an excitation light source.For example, when an excitation light source having a main emission peak in the ultraviolet region is used, the luminous efficiency is the maximum value in the visible light region. That is 60% or more. On the other hand, the case of not being directly excited means that the primary light from a different phosphor excited by the light from the excitation light source becomes the excitation light source and is not excited by the light from the excitation light source. When excited by.

The phosphors 11 and 108 are rare earth aluminate phosphors according to the present invention.
The rare earth aluminate phosphor according to the present invention includes (a) aluminum, (b) at least one selected from the group consisting of yttrium, lutetium, scandium, lanthanum, gadolinium, terbium, europium and samarium, and (c) necessary Is a rare earth aluminate phosphor having gallium and (d) a rare earth element, and this phosphor has a filling portion and a cavity portion therein, and when the cross section of the phosphor is taken out The area ratio of the hollow portion to the sum of the filling portion and the hollow portion is greater than 0% and smaller than 20%.

The rare earth aluminate phosphor of the present invention has a filling part and a cavity part inside the phosphor, and the area of the cavity part with respect to the total of the filling part and the cavity part when the cross section of the phosphor is taken out The proportion needs to be greater than 0% and less than 20%.
In the present invention, the cross-section is performed as follows. A rare earth aluminate phosphor having an average particle diameter is selected from among a number of particles of the rare earth aluminate phosphor according to the present invention.
Here, the average particle size means the median particle size. The median particle size means a particle size at which the volume cumulative frequency of the particle size distribution of the secondary particles reaches 50%. The method for measuring the median particle size is not particularly limited. For example, the particle size distribution is measured by the laser diffraction scattering method, and the integrated distribution using the logarithm of the volume-based particle diameter is obtained. Can be measured as
The cross-section is performed up to the portion where the particle cross-sectional image of the selected rare earth aluminate phosphor has the maximum particle size. In addition, it is preferable to use the average value of the area ratio calculated | required from performing cross-section out several times (for example, 10 times).
The method for extracting the cross section is not particularly limited. For example, it can be carried out by a method of embedding in a resin and scraping the particle cross section, or a method of processing by FIB. The particle cross-sectional image is not particularly limited. For example, an SEM image, a SIM image, a TEM image, or a STEM image can be used.

When the cross section of the rare earth aluminate phosphor is taken out, the area ratio of the cavity portion to the total of the filling portion and the cavity portion is preferably 1% or more, more preferably 2% or more, , 18% or less is preferable, and 15% or less is more preferable.
If the cavity is too small, the loss of absorbed energy increases, and the particles are heavy and easily sink, resulting in color shift and color unevenness. If the cavity is too large, the absorbed energy cannot be converted into light sufficiently, and the particles are too light to float, resulting in color shift and color unevenness.
In the phosphor of the present invention, when there are a plurality of cavities, the cavities in the present invention mean the sum of the plurality of cavities.

The rare earth aluminate phosphor of the present invention preferably has three or more grain boundaries. The grain boundary in the present invention means a boundary between fine particles constituting a matrix portion of a material. It is more preferable to have 10 or more grain boundaries, more preferably 30 or more, more preferably 80 or less, and even more preferably 50 or less.
When there are too many grain boundaries, energy loss increases, and when there are too few grain boundaries, the effect of particle diffusion is reduced, resulting in color shift and color unevenness.

  The following (i)-(iii) are mentioned as a suitable aspect of the rare earth aluminate fluorescent substance of this invention.

(I) (a) aluminum; (b) at least one selected from the group consisting of yttrium, lutetium, scandium, lanthanum, gadolinium, terbium, europium, and samarium; and (c) gallium, if necessary, (d And) a rare earth aluminate phosphor having a rare earth element and having a composition ratio of (d) :( a) of 1: 0.5 to 1: 2.

  (Ii) A part or all of yttrium is replaced with at least one element selected from the group consisting of Lu, Sc, La, Gd, Pr, Tb and Sm, or a part or all of aluminum is replaced with Tl, A cerium-activated yttrium aluminum oxide-based phosphor having a fluorescent action that is substituted with either or both of Ga and In.

(Iii) the general formula _{(Y z Gd 1-z)} 3 Al 5 O 12: Ce (. Z is representing a number satisfying 0 <z ≦ 1), _{or, (A 1-a Sm a} ) 3 A '5 O ₁₂ : Ce (A represents at least one selected from the group consisting of Y, Lu, Sc, La, Gd, Pr and Tb, and A ′ represents at least one selected from the group consisting of Al, Ga and In. And a represents a number satisfying 0 ≦ a <1.)

The rare earth aluminate phosphor of the present invention preferably has a garnet structure in the crystal structure.
Hereinafter, the yttrium / aluminum / garnet phosphor (YAG phosphor) will be described in more detail.

  Yttrium / Aluminum / Garnet phosphor (YAG phosphor) is a general term for a garnet structure containing rare earth elements such as Y and Group III elements such as Al, and is activated by at least one element selected from rare earth elements. The phosphor is excited by blue light emitted from the light emitting element 10 and emits light.

The YAG-based phosphor, for _{example, (Ln 1-x Sm x} ) 3 (Al 1-y Ga y) 5 O 12: Ce (0 ≦ x <1,0 ≦ y ≦ 1, where, Ln is, Y And at least one element selected from the group consisting of Gd, La).
_{(Ln 1-x Sm x)} 3 (Al 1-y Ga y) 5 O 12: Ce phosphor, for garnet structure, heat, resistant to light and moisture, in particular, when used for a long time at a high intensity Is preferred. Further, the peak of the excitation spectrum can be set around 470 nm. The emission peak is in the vicinity of 530 nm, and a broad emission spectrum that extends to 720 nm is obtained.
In particular, YAG-based phosphor, Al, Ga, In, Y , La and Gd and the Sm content is two or more kinds of _{(Ln 1-x Sm x)} 3 (Al 1-y Ga y) 5 O 12 : RGB wavelength components can be increased by mixing Ce phosphors. At present, there are some variations in the emission wavelength of the semiconductor light emitting device, but by mixing two or more kinds of phosphors, a desired white mixed color light or the like can be obtained. That is, by combining phosphors having different chromaticity points according to the emission wavelength of the light emitting element, light at an arbitrary point on the chromaticity diagram connected between the phosphors and the light emitting element can be emitted. .

The aluminum / garnet phosphor contains Al and contains at least one element selected from Y, Lu, Sc, La, Gd, Tb, Eu and Sm, and one element selected from Ga and In. And a phosphor activated with at least one element selected from rare earth elements, and is a phosphor that emits light when excited by visible light or ultraviolet light.
In this type of phosphor having a garnet structure, the emission spectrum is shifted to the short wavelength side by substituting part of Al with Ga, and part of Y of the composition is replaced with Gd and / or La. Thus, the emission spectrum shifts to the longer wavelength side. In this way, it is possible to continuously adjust the emission color by changing the composition. Therefore, an ideal condition for converting white light emission using the blue light emission of the nitride semiconductor is provided such that the intensity on the long wavelength side is continuously changed by the composition ratio of Gd. If the Y substitution is less than 20%, the green component is large and the red component is small, and if it is 80% or more, the red component is increased, but the luminance is drastically decreased.

  Similarly, this type of phosphor having a garnet structure also has an excitation absorption spectrum that shifts the excitation absorption spectrum to the short wavelength side by substituting a part of Al with Ga. By substituting the part with Gd and / or La, the excitation absorption spectrum is shifted to the longer wavelength side. The peak wavelength of the excitation absorption spectrum of the phosphor is preferably shorter than the peak wavelength of the emission spectrum of the light emitting element. With this configuration, when the current input to the light emitting element is increased, the peak wavelength of the excitation absorption spectrum substantially matches the peak wavelength of the emission spectrum of the light emitting element, so that the excitation efficiency of the phosphor is not reduced. Occurrence of chromaticity deviation can be suppressed.

Specifically, in addition to the YAG phosphor described above, Tb _2.95 Ce _0.05 Al ₅ O ₁₂ , Y _2.90 Ce _0.05 Tb _0.05 Al ₅ O ₁₂ , Y _2.94 Ce _0.05 Pr _0.01 Al ₅ O ₁₂ , Y _2.90 Ce _0.05 Pr _0.05 Al ₅ O ₁₂ or the like. Of these, an yttrium-aluminum oxide phosphor containing Y and activated with Ce or Pr is preferable. In particular, it is preferable to use a combination of two or more phosphors having different compositions.

  For example, an yttrium / aluminum oxide phosphor activated with cerium can emit green or red light. Since the phosphor capable of emitting green light is garnet structure, it is resistant to heat, light and moisture, the peak wavelength of the excitation absorption spectrum is from 420 nm to 470 nm, and the emission peak wavelength λp is from 510 nm to 700 nm. It has a broad emission spectrum that draws a tail. The phosphor capable of emitting red light has a garnet structure, is resistant to heat, light and moisture, has a peak wavelength of excitation absorption spectrum of 420 nm to 470 nm, and an emission peak wavelength λp of 600 nm, which is 750 nm. It has a broad emission spectrum that stretches to the vicinity.

When the crystal structure of the rare earth aluminate phosphor of the present invention is a garnet structure, it becomes strong against heat, light and moisture, and the peak of the excitation spectrum can be made around 450 nm. In addition, the emission peak is near 580 nm and becomes a phosphor having a broad emission spectrum that extends to 700 nm.
Further, this phosphor can increase the excitation emission efficiency in a long wavelength region of 460 nm or more by containing Gd in the crystal. As the Gd content increases, the emission peak wavelength shifts to a longer wavelength, and the entire emission wavelength also shifts to the longer wavelength side. That is, when a strong reddish emission color is required, it can be achieved by increasing the amount of substitution of Gd. On the other hand, as the amount of Gd increases, the emission luminance of this fluorescent material by blue light tends to decrease. Furthermore, in addition to Ce, Tb, Cu, Ag, Au, Fe, Cr, Nd, Dy, Co, Ni, Ti, Eu, and the like can be contained if desired.
In the composition of the yttrium / aluminum / garnet phosphor having a garnet structure as the crystal structure, the emission wavelength can be shifted to the short wavelength side by replacing a part of Al with Ga. Further, by replacing part of Y in the composition with Gd, the emission wavelength can be shifted to the longer wavelength side.
When a part of Y is substituted with Gd, it is preferable that the substitution with Gd is less than 10%, and the Ce content (substitution) is 0.03 to 1.0. If the substitution with Gd is less than 20%, the green component is large and the red component is small. However, by increasing the Ce content, the red component can be supplemented and a desired color tone can be obtained without lowering the luminance. With such a composition, the temperature characteristics are improved.

The rare earth aluminate phosphor of the present invention has at least one YAlO ₃ : Ce selected from the group consisting of Y ₄ Al ₂ O ₉ : Ce, orthorhombic, cubic and hexagonal. Also good.

In the rare earth aluminate phosphor of the present invention, in the particle size distribution, when the particle sizes at which the volume accumulation frequency reaches 10%, 50% and 90% are D10, D50 and D90, respectively,
0.60 ≦ (D10 / D50) <0.80,
1.30 <(D90 / D50) ≦ 1.50 and 1.0 μm ≦ D50 ≦ 40 μm
It is preferable to satisfy all of the following.
When D10, D50, and D90 satisfy the above relational expression, variations in color tone can be reduced.
The measurement of the particle size distribution of the particles is not particularly limited. For example, it can be measured by a laser diffraction scattering method.

The rare earth aluminate phosphor of the present invention preferably has an aspect ratio of 0.78 or more and 1.00 or less. The aspect ratio is more preferably 0.85 or more. When the aspect ratio is within this range, reflection of excitation light is reduced and the sedimentation speed of the phosphor particles is made uniform.
In the present invention, the aspect ratio is obtained as follows.
The sample is photographed with a SEM at a magnification of 4000 times. As shown in FIG. 4, a plurality of particle images (for example, 20, 50, 100, etc.) are randomly extracted from the SEM photograph. Then, a (the longest diameter of the particle image) and b (the maximum diameter perpendicular to a) are obtained for each particle image, the value of b is divided by the value of a, and the average value of the values is defined as the aspect ratio. .

  The rare earth aluminate phosphor of the present invention preferably has a fluorine content of 5 ppm or more, more preferably 10 ppm or more, and preferably 50 ppm or less, more preferably 20 ppm or less. . When there is too much content of fluorine, resin degradation will be caused and luminescence output will fall. If the fluorine content is too small, the particles do not grow at the time of firing and the luminance is lowered.

The particle diameter of the phosphor 11 is preferably in the range of 1 μm to 20 μm, more preferably 2 μm to 8 μm. Particularly, 5 μm to 8 μm is preferable. A phosphor having a particle size smaller than 2 μm tends to form an aggregate. On the other hand, a phosphor having a particle size range of 5 μm to 8 μm has high light absorptivity and conversion efficiency. In this manner, the mass productivity of the light-emitting device is improved by including a phosphor having a large particle diameter and having optically excellent characteristics.
Here, the particle diameter means an average particle diameter obtained by the air permeation method. Specifically, in an environment with an air temperature of 25 ° C. and a humidity of 70%, a sample of 1 cm ³ is weighed and packed in a special tubular container. The value is converted into an average particle diameter. The average particle size of the phosphor used in the present invention is preferably in the range of 2 μm to 8 μm.
Moreover, it is preferable that the phosphor having this average particle diameter value is contained frequently. In addition, it is preferable that the particle size distribution is distributed in a narrow range, and in particular, particles having a particle size of 2 μm or less are preferable. As described above, by using a phosphor having a small variation in particle size and particle size distribution, color unevenness is further suppressed, and a light emitting device having a good color tone can be obtained.

Alkaline earth metal nitride phosphor (alkaline earth metal silicon nitride phosphor) and / or alkaline earth metal oxynitride phosphor (alkaline earth metal silicon oxynitride phosphor) together with the rare earth aluminate phosphor of the present invention By using the light emitting device, it is possible to obtain a light emitting device with less color unevenness and color misregistration and with improved color rendering properties without impairing the characteristics of high light emission efficiency.

As the alkaline earth metal oxynitride phosphor, a monoclinic or orthorhombic alkaline earth metal silicon nitride phosphor activated with at least Eu, for example, Ca ₂ Si ₅ N ₈ : Eu, Sr ₂ Si ₅ N ₈ : Eu, Ba ₂ Si ₅ N ₈ : Eu, (Ca, Sr) ₂ Si ₅ N ₈ : Eu, or the like is preferably used. Also, the following phosphors (1) to (4) can be used.
(1) An alkaline earth metal sulfide phosphor represented by (M1 _1-a Eu _a ) S.
Here, M1 is at least one selected from Mg, Ca, Ba, Sr, and Zn, and 0.0001 ≦ a ≦ 0.5.
_{(2) (M1 1-a} -b Eu a Mn b) alkaline earth metal sulfide phosphor represented by S.
Here, M1 is at least one selected from Mg, Ca, Ba, Sr, and Zn, and 0.0001 ≦ a ≦ 0.5 and 0.0001 ≦ b ≦ 0.5.
(3) An alkali metal tungstate phosphor such as LiEuW ₂ O ₈ . (4) An alkali metal borate phosphor activated with at least Eu.

The alkaline earth metal nitride _{phosphor, M 2 Si 5 N 8:} Eu, MSi 7 N 10: Eu, M 1.8 Si 5 O 0.2 N 8: Eu, M 0.9 Si 7 O 0 _.1 N ₁₀ : Eu (M is at least one selected from Sr, Ca, Ba, Mg, Zn). This nitride phosphor preferably contains B in order to improve the light emission luminance. Moreover, it is preferable that content of this B (boron) is 1 ppm or more and 10,000 ppm or less, and light emission luminance can be improved more effectively by containing boron in this range.

Furthermore, examples of the alkaline earth metal silicon oxynitride phosphor activated by at least Eu or Ce include a phosphor represented by (M1 _1-a Eu _a ) Si ₂ O ₂ N ₂ . Here, M1 is at least one selected from Mg, Ca, Ba, Sr, and Zn, and 0.0001 ≦ a ≦ 0.5. More specifically, BaSi ₂ O ₂ N ₂ : Eu, (Sr, Ca) Si ₂ O ₂ N ₂ : Eu, and the like.

As the alkaline earth metal oxynitride phosphor, an alkaline earth metal silicon oxynitride phosphor activated with at least Eu or Ce is preferable. For example, a phosphor represented by (M1 _1-a Eu _a ) Si ₂ O ₂ N ₂ can be given. Here, M1 is at least one selected from Mg, Ca, Ba, Sr, and Zn, and 0.0001 ≦ a ≦ 0.5. More specifically, BaSi ₂ O ₂ N ₂ : Eu, (Sr, Ca) Si ₂ O ₂ N ₂ : Eu, and the like.

The alkaline earth metal oxynitride phosphor uses a rare earth element as an activator, and includes at least one group II element selected from the group consisting of Be, Mg, Ca, Sr, Ba, Zn, and And at least one group IV element selected from the group consisting of C, Si, Ge, Sn, Ti, Zr, and Hf. Although the combination of elements is arbitrary, it is preferable to use the following composition. Oxynitride _{phosphor, L X M Y O Z N} ((2/3) X + (4/3) Y- (2/3) Z): R, _{or, L X M Y Q T O} Z N ( _{(2/3) X + (4/3) Y + T− (2/3) Z)} : R (L is at least one selected from the group consisting of Be, Mg, Ca, Sr, Ba, Zn. M is a Group II element, and M is a Group IV element that is at least one selected from the group consisting of C, Si, Ge, Sn, Ti, Zr, and Hf, Q is B, Al, Ga, It is at least one group III element selected from the group consisting of In, O is an oxygen element, N is a nitrogen element, R is a rare earth element, 0.5 <X < 1.5, 1.5 <Y <2.5, 0 <T <0.5, and 1.5 <Z <2.5.) X, Y and Z show high luminance in this range. Of these, oxynitride phosphors in which X, Y, and Z are represented by X = 1, Y = 2, and Z = 2 in the general formula are particularly preferable because they exhibit high luminance. However, it is not limited to the said range, Arbitrary things can also be used.

(Phosphor production method)
The production method of the rare earth aluminate phosphor of the present invention is not particularly limited, and can be produced, for example, as follows.

(1) Preparation of raw material mixture The compounds described later are mixed so that each constituent element has a predetermined composition ratio to obtain a raw material mixture of the phosphor. The compound used for the raw material mixture of the phosphor is selected according to the elements constituting the target composition.
The mixing method is not particularly limited, for example, a method of mixing powdery compounds as they are to obtain a raw material mixture; mixing in a slurry form using water and / or an organic solvent, and then drying to obtain a raw material mixture Method: A method in which an aqueous solution of the above-mentioned compound is mixed and precipitated, and the resulting precipitate is dried to obtain a raw material mixture; a method in which these are used in combination.

Below, the compound used for the raw material mixture of fluorescent substance is illustrated.
The compounds of Y, Lu, Sc, La, Gd, Pr, Tb, Eu, Sm, Al, Tl, Ga, Ce and In are not particularly limited, but for example, oxides, or oxides easily at high temperatures Compounds.
A raw material mixture having an aspect ratio of 0.75 or more and 1.00 or less is used.
The raw material mixture has a particle size distribution of 10%, 50% and 90% in the particle size distribution of the particles, where D10, D50 and D90 are D10, 2.5 to 4.0 μm , D50 is 4.0 to 5.5 μm, and D90 is 5.5 to 8.5 μm.
In order to obtain a raw material mixture having such a particle size distribution, a rough mortar, ball mill, vibration mill, jet mill, or the like can be used. Various classifiers can also be used.

(2) Firing and grinding of raw material mixture Next, the raw material mixture is fired. The firing temperature, time, atmosphere, and the like are not particularly limited, and can be appropriately determined according to the purpose.
The firing temperature is preferably 800 ° C. or higher. If the firing temperature is too low, unreacted raw materials may remain in the second fluorescent material, and the original characteristics of the second fluorescent material may not be utilized. Moreover, it is preferable that a calcination temperature is 2000 degrees C or less. If the firing temperature is too high, the particle size of the second fluorescent material may become too large and the characteristics may deteriorate.
In general, the firing time is preferably 1 to 20 hours. When the firing time is too short, the diffusion reaction between the raw material particles does not proceed. If the firing time is too long, firing after the diffusion reaction is almost completed is wasted, and coarse particles may be formed by sintering.

  The firing may be divided into a plurality of firing steps. For example, the first baking step can be performed at 800 to 1000 ° C. for 2 to 3 hours, and the second baking step can be performed at 1300 to 1600 ° C. for 2 to 3 hours.

The firing atmosphere is, for example, air, oxygen gas, a mixed gas of these with an inert gas such as nitrogen gas or argon gas, an atmosphere in which the oxygen concentration (oxygen partial pressure) is controlled, a weak oxidizing atmosphere, H ₂ , N _2. And reducing atmosphere. Among them, a reducing atmosphere such as H ₂ and N ₂ is preferable.
Here, the reducing atmosphere is a nitrogen atmosphere, a nitrogen-hydrogen atmosphere, an ammonia atmosphere, an inert gas atmosphere such as argon, or the like.

After firing, if desired, the powder may be pulverized using a rough mortar, ball mill, vibration mill, pin mill, jet mill or the like to obtain a powder having a desired particle size. It may be passed through a sieve.
By the manufacturing method described above, the rare earth aluminate phosphor of the present invention can be obtained.

(Coating member 12, 109)
The phosphors 11 and 108 can be attached using various coating members (binders) such as a resin that is an organic material and glass that is an inorganic material. The coating members 12 and 109 may have a role as a binder for fixing the phosphors 11 and 108 to the light emitting elements 10 and 101, the window portion 107, and the like. When an organic material is used as the coating member (binder), a transparent resin having excellent weather resistance such as an epoxy resin, an acrylic resin, or silicone is preferably used as a specific material. In particular, it is preferable to use silicone because it is excellent in reliability and the dispersibility of the phosphors 11 and 108 can be improved.

In addition, it is preferable to use an inorganic material that approximates the thermal expansion coefficient of the window portion 107 as the coating members (binders) 12 and 109 because the phosphor 108 can be adhered to the window portion 107 satisfactorily.
As a specific method of attaching the phosphor using a coating member, a precipitation method, a sol-gel method, a spray method, or the like can be used. For example, the phosphors 11 and 108 are mixed with silanol (Si (OEt) ₃ OH) and ethanol to form a slurry. After the slurry is discharged from the nozzle, the slurry is heated at 300 ° C. for 3 hours. SiO ₂ can be used to fix the phosphor at a desired location.

In addition, an inorganic binder can be used as the coating members (binders) 12 and 109.
The binder is so-called low-melting glass, is fine particles, has little absorption with respect to light in the ultraviolet to visible region, and is extremely stable in the coating members (binders) 12 and 109. preferable.

  In addition, when a phosphor having a large particle size is attached to the coating members (binders) 12 and 109, it can be obtained by a binder in which the particles are an ultrafine powder, for example, silica, alumina, or a precipitation method even if the melting point is high. It is preferable to use a fine-grained alkaline earth metal pyrophosphate or orthophosphate. These binders can be used alone or mixed with each other.

In order to sufficiently enhance the binding effect, the binder is preferably wet pulverized in a vehicle to form a slurry and used as a binder slurry. A vehicle is a high viscosity solution obtained by dissolving a small amount of a binder in an organic solvent or deionized water. For example, an organic vehicle can be obtained by adding 1 wt% of nitrocellulose as a binder to butyl acetate as an organic solvent.

The binder slurry thus obtained contains phosphors 11 and 108 to prepare a coating solution. The added amount of the slurry in the coating solution can be such that the total amount of the binder in the slurry is about 1 to 3% wt with respect to the amount of the phosphor in the coating solution. In order to suppress a decrease in the luminous flux maintenance factor, it is preferable that the amount of the binder added is small.
The coating liquid is applied to the back surface of the window portion 107. After that, hot air or hot air is blown to dry. Finally, baking is performed at a temperature of 400 ° C. to 700 ° C. to disperse the vehicle. As a result, the phosphor layer is adhered to the desired place with the binder.

(Light emitting element 10, 101)
In the present invention, the light-emitting elements 10 and 101 are preferably semiconductor light-emitting elements having a light-emitting layer capable of emitting a light emission wavelength capable of efficiently exciting the phosphor. Examples of the material of such a semiconductor light emitting device include various semiconductors such as BN, SiC, ZnSe, GaN, InGaN, InAlGaN, AlGaN, BAlGaN, and BInAlGaN. Similarly, these elements may contain Si, Zn, or the like as an impurity element to serve as a light emission center. In particular, a nitride semiconductor (for example, a nitride semiconductor containing Al or Ga, In or Ga, for example) is used as a light emitting layer material that can efficiently emit short wavelengths of visible light from the ultraviolet region that can excite the phosphors 11 and 108 efficiently. _{in X Al Y Ga 1-X} -Y N, 0 ≦ X, 0 ≦ Y as a nitride semiconductor containing, X + Y ≦ 1) can be mentioned as more preferable.

  Further, as a semiconductor structure, a homostructure having a MIS junction, a PIN junction, a pn junction, or the like, a heterostructure, or a double hetero configuration is preferably exemplified. Various emission wavelengths can be selected depending on the semiconductor layer material and the mixed crystal ratio. Further, the output can be further improved by adopting a single quantum well structure or a multiple quantum well structure in which the semiconductor active layer is formed in a thin film that produces a quantum effect.

When a nitride semiconductor is used for the light emitting elements 10 and 101, a material such as sapphire, spinel, SiC, Si, ZnO, GaAs, or GaN is preferably used for the semiconductor substrate.
In order to form a nitride semiconductor with good crystallinity with high productivity, it is preferable to use a sapphire substrate. A nitride semiconductor can be formed on the sapphire substrate by HVPE method, MOCVD method or the like. A buffer layer made of GaN, AlN, GaAIN or the like is grown at a low temperature on the sapphire substrate to form a non-single crystal, and a nitride semiconductor having a pn junction is formed thereon.

As an example of a light emitting element capable of efficiently emitting light in an ultraviolet region having a pn junction using a nitride semiconductor, SiO ₂ is formed in a stripe shape on the buffer layer substantially perpendicular to the orientation flat surface of the sapphire substrate. GaN is grown on the stripes using EHV (Epitaxial Lateral Over Grows GaN) using the HVPE method. Subsequently, a first contact layer formed of n-type gallium nitride, a first cladding layer formed of n-type aluminum nitride / gallium, a well layer of indium nitride / aluminum / gallium, and aluminum nitride / gallium are formed by MOCVD. An active layer having a multiple quantum well structure in which a plurality of barrier layers are stacked, a second cladding layer formed of p-type aluminum nitride / gallium, and a second contact layer formed of p-type gallium nitride are sequentially stacked. Examples include a double hetero configuration. The active layer may be formed into a ridge stripe shape and sandwiched between guide layers, and a resonator end face may be provided to provide a semiconductor laser device usable in the present invention.

  Nitride semiconductors exhibit n-type conductivity without being doped with impurities. When forming a desired n-type nitride semiconductor, for example, to improve luminous efficiency, it is preferable to appropriately introduce Si, Ge, Se, Te, C, etc. as an n-type dopant. On the other hand, when forming a p-type nitride semiconductor, it is preferable to dope p-type dopants such as Zn, Mg, Be, Ca, Sr, and Ba. Since nitride semiconductors are not easily converted to p-type by simply doping with a p-type dopant, it is preferable to reduce resistance by heating in a furnace or plasma irradiation after introducing the p-type dopant. When the sapphire substrate is not used, the contact layer is exposed by etching from the p-type side to the surface of the first contact layer. A light emitting element made of a nitride semiconductor can be formed by cutting the semiconductor wafer into chips after forming electrodes on each contact layer.

In order to form the light emitting device of the present invention with high productivity, it is preferable to form the phosphors 11 and 108 using a resin when the phosphors 11 and 108 are fixed to the light emitting elements 10 and 101. In this case, taking into consideration the emission wavelength from the phosphors 11 and 108 and the deterioration of the translucent resin, the light emitting elements 10 and 101 have an emission spectrum in the ultraviolet region, and the emission peak wavelength is 360 nm or more and 420 nm or less. And those having a wavelength of 450 nm to 470 nm are preferable.
Here, in the semiconductor light emitting devices 10 and 101 used in the present invention, the sheet resistance of the n-type contact layer formed at an impurity concentration of 10 ¹⁷ to 10 ²⁰ / cm ³ and the sheet resistance of the translucent p electrode are as follows: It is preferable to adjust so that Rp ≧ Rn. The n-type contact layer is preferably formed to a film thickness of, for example, 3 to 10 μm, more preferably 4 to 6 μm, and the sheet resistance is estimated to be 10 to 15Ω / □, so that Rp at this time is the sheet resistance value. It is good to form in a thin film so that it may have the above sheet resistance values. The translucent p-electrode may be formed of a thin film having a thickness of 150 μm or less.

  Further, when the translucent p-electrode is formed of a multilayer film or alloy composed of one kind selected from the group of gold and platinum group elements and at least one other element, it is contained. When the sheet resistance of the translucent p-electrode is adjusted by the content of the gold or platinum group element, stability and reproducibility are improved. Since gold or a metal element has a high absorption coefficient in the wavelength region of the semiconductor light emitting device used in the present invention, the smaller the amount of gold or platinum group element contained in the translucent p-electrode, the better the transparency. In the conventional semiconductor light emitting device, the relationship of sheet resistance is Rp ≦ Rn. However, in the present invention, Rp ≧ Rn, and therefore the translucent p-electrode is formed in a thin film as compared with the conventional one. However, thinning can be easily performed by reducing the content of gold or platinum group elements.

  As described above, in the semiconductor light emitting devices 10 and 101 used in the present invention, the sheet resistance RnΩ / □ of the n-type contact layer and the sheet resistance RpΩ / □ of the translucent p electrode have a relationship of Rp ≧ Rn. Preferably. It is difficult to measure Rn after forming the semiconductor light emitting devices 10 and 101, and it is practically impossible to know the relationship between Rp and Rn. However, from the state of the light intensity distribution during light emission, what Rp and You can know if it is related to Rn.

  When the translucent p-electrode and the n-type contact layer have a relationship of Rp ≧ Rn, providing a p-side pedestal electrode in contact with the translucent p-electrode and having an extended conductive portion further improves external quantum efficiency. Can be achieved. There is no limitation on the shape and direction of the extended conductive portion, and when the extended conductive portion is on the satellite, it is preferable because the area for blocking light is reduced, but a mesh shape may be used. Further, the shape may be a curved shape, a lattice shape, a branch shape, or a hook shape in addition to the straight shape. At this time, since the light shielding effect increases in proportion to the total area of the p-side pedestal electrode, it is preferable to design the line width and length of the extended conductive portion so that the light shielding effect does not exceed the light emission enhancing effect.

(Light emitting element 10, 101)
As the light-emitting elements 10 and 101, a light-emitting element that emits blue light different from the above-described ultraviolet light-emitting element can be used. The light emitting elements 10 and 101 that emit blue light are preferably group III nitride compound light emitting elements. The light-emitting elements 10 and 101 include, for example, an n-type GaN layer in which Si is undoped, an n-type contact layer made of n-type GaN in which Si is doped, an undoped GaN layer, and multiple quanta on a sapphire substrate 1. Light emitting layer with a well structure (GaN well layer / InGaN well layer quantum well structure), p-clad layer made of p-type GaN made of Mg-doped p-type GaN, p-type made of p-type GaN doped with Mg It has a laminated structure in which contact layers are sequentially laminated, and electrodes are formed as follows. However, a light emitting element different from this configuration can also be used.

The p ohmic electrode is formed on almost the entire surface of the p-type contact layer, and the p pad electrode is formed on a part of the p ohmic electrode.
The n-electrode is formed in the exposed portion by removing the undoped GaN layer from the p-type contact layer by etching to expose a part of the n-type contact layer.
In the present embodiment, the light emitting layer having a multiple quantum well structure is used. However, the present invention is not limited to this, and for example, a single quantum well structure using InGaN may be used. GaN doped with Zn may be used.

  The light emitting layers of the light emitting elements 10 and 101 can change the main light emission peak wavelength in the range of 420 nm to 490 nm by changing the In content. The emission peak wavelength is not limited to the above range, and those having an emission peak wavelength in the range of 360 nm to 550 nm can be used.

(Coating member 12, 109)
The coating member 12 (light transmissive material) is provided in the cup of the lead frame 13 and is used by mixing with the phosphor 11 that converts the light emission of the light emitting element 10. Specific materials for the coating member 12 include transparent resins, silica sol, glass, inorganic binders, and the like that are excellent in temperature characteristics and weather resistance, such as epoxy resins, urea resins, and silicone resins. Further, a diffusing agent, barium titanate, titanium oxide, aluminum oxide or the like may be contained together with the phosphor. Moreover, you may contain a light stabilizer and a coloring agent.

(Lead frame 13)
The lead frame 13 includes a mount lead 13a and an inner lead 13b.
The mount lead 13a is for placing the light emitting element 10 thereon. The upper portion of the mount lead 13a has a cup shape, and the light emitting element 10 is die-bonded in the cup, and the outer peripheral surface of the light emitting element 10, that is, the cup is covered with the phosphor 11 and the coating member 12. A plurality of light emitting elements 10 can be arranged in the cup, and the mount lead 13 a can be used as a common electrode of the light emitting elements 10. In this case, sufficient electrical conductivity and connectivity with the conductive wire 14 are required. Die bonding (adhesion) between the light emitting element 10 and the cup of the mount lead 13a can be performed with a thermosetting resin or the like. Examples of the thermosetting resin include an epoxy resin, an acrylic resin, and an imide resin. In addition, Ag-ace, carbon paste, metal bumps, or the like can be used for die-bonding and electrical connection with the mount lead 13a by the face-down light emitting element 10 or the like. An inorganic binder can also be used.

  The inner lead 13b is intended to be electrically connected to the conductive wire 14 extending from the electrode 3 of the light emitting element 10 disposed on the mount lead 13a. The inner lead 13b is preferably disposed at a position away from the mount lead 13a in order to avoid a short circuit due to electrical contact with the mount lead 13a. In the case where the plurality of light emitting elements 10 are provided on the mount lead 13a, it is necessary that the conductive wires be arranged so as not to contact each other. The inner lead 13b is preferably made of the same material as the mount lead 13a, and iron, copper, iron-containing copper, gold, platinum, silver, or the like can be used.

(Conductive wire)
The conductive wire 14 is for electrically connecting the electrode 3 of the light emitting element 10 and the lead frame 13. The conductive wire 14 preferably has good ohmic properties, mechanical connectivity, electrical conductivity, and thermal conductivity with the electrode 3. Specific materials for the conductive wire 14 are preferably metals such as gold, copper, platinum, and aluminum, and alloys thereof.

(Mold member)
The mold member 15 is provided to protect the light emitting element 10, the phosphor 11, the coating member 12, the lead frame 13, the conductive wire 14, and the like from the outside. In addition to the purpose of protection from the outside, the mold member 15 also has the purposes of widening the viewing angle, relaxing the directivity from the light emitting element 10, and converging and diffusing the emitted light. In order to achieve these objects, the mold member can have a desired shape. Further, the mold member 15 may have a structure in which a plurality of layers are stacked in addition to the convex lens shape and the concave lens shape. As a specific material of the mold member 15, a material excellent in translucency, weather resistance, and temperature characteristics such as epoxy resin, urea resin, silicone resin, silica sol, and glass can be used. The mold member 15 can contain a diffusing agent, a colorant, an ultraviolet absorber, and a phosphor. As the diffusing agent, barium titanate, titanium oxide, aluminum oxide or the like is preferable. In order to reduce the resilience of the material with the coating member 12, it is preferable to use the same material in consideration of the refractive index.

(Other preferred forms)
The light-emitting device of Embodiment 3 is a cap-type light-emitting device as shown in FIG. The light emitting element 10 uses a light emitting element having a main light emission peak in an ultraviolet light region of 365 nm.

  The light emitting device is configured by covering the surface of the mold member 15 with a cap 16 made of a light transmissive resin in which a phosphor (not shown) is dispersed.

  A cup for mounting the light emitting element 10 is provided on the top of the mount lead 13a, and the light emitting element 10 is die-bonded on the bottom surface of the substantially central part of the cup. In the light emitting device, the phosphor 11 is provided so as to cover the light emitting element 10 on the upper portion of the cup. This is because the phosphor 11 is not provided on the light emitting element 10 so that it is not directly affected by the heat generated from the light emitting element 10.

The cap 16 has the phosphor uniformly dispersed in the light transmissive resin. The light-transmitting resin containing this phosphor is molded into a shape that fits into the shape of the mold member 15 of the light-emitting device. Alternatively, a manufacturing method in which a light-transmitting resin containing a phosphor is placed in a predetermined mold, and then the light emitting device is pushed into the mold and molded is also possible. Specific materials for the light transmissive resin of the cap 16 include transparent resins, silica sol, glass, inorganic binders, and the like that are excellent in temperature characteristics and weather resistance such as epoxy resins, urea resins, and silicone resins. In addition to the above, thermosetting resins such as melamine resins and phenol resins can be used. In addition, thermoplastic resins such as polyethylene, polypropylene, polyvinyl chloride, and polystyrene, thermoplastic rubbers such as styrene-butadiene block copolymer, segmented polyurethane, and the like can also be used. Further, a diffusing agent, barium titanate, titanium oxide, aluminum oxide or the like may be contained together with the phosphor. Moreover, you may contain a light stabilizer and a coloring agent. The phosphor used for the cap 16 is the rare earth aluminate phosphor of the present invention (Y _0.8 Gd _0.2 ) ₃ Al ₅ O ₁₂ : Ce and Ca ₁₀ (PO ₄ ) ₆ Cl ₂ : Eu. , BaSi ₂ O ₂ N ₂ : Eu, (Sr, Ca) ₂ Si ₅ N ₈ : Eu, and other phosphors are used. The phosphor 11 used in the cup of the mount lead 13a is a phosphor such as Ca ₁₀ (PO ₄ ) ₆ Cl ₂ : Eu. However, since a phosphor is used for the cap 16, Ca ₁₀ (PO ₄ ) ₆ Cl ₂ : Eu or the like may be contained in the cap 16, and only the coating member 12 may be contained in the cup of the mount lead 13 a.

In the light emitting device configured as described above, light emitted from the light emitting element 10 excites Ca ₁₀ (PO ₄ ) ₆ Cl ₂ : Eu or the like of the phosphor 11. (Y _0.8 Gd _0.2 ) ₃ Al ₅ O ₁₂ : Ce, which is the rare earth aluminate phosphor of the present invention, is excited by blue light emitted from Ca ₁₀ (PO ₄ ) ₆ Cl ₂ : Eu. Thereby, white light is emitted from the surface of the cap 16 to the outside by the mixed color light of the phosphor 11.

  Hereinafter, the rare earth aluminate phosphor according to the present invention will be described with reference to examples. However, the present invention is not limited to these examples.

[Example 1]
Aspect ratio is 0.92, D10 is 5.0 μm, D50 is 7.3 μm and D90 is 10.4 μm (Y _0.90 Ce _0.05 Gd _0.05 ) ₂ O ₃ 29.72 g, Al ₂ O ₃ 21 .88 g, 0.01 g of H ₃ BO ₃ and 0.03 g of AlF ₃ were mixed and baked at 1400 ° C. for 4 hours in a reducing atmosphere. By grinding, a rare earth aluminate phosphor having a composition formula of (Y _0.90 Ce _0.09 Gd _0.01 ) ₃ Al ₅ O ₁₂ was obtained.

[Example 2]
The aspect ratio is 0.82, D10 is 4.5 μm, D50 is 6.7 μm, and D90 is 9.3 μm (Y _0.90 Ce _0.05 Gd _0.05 ) ₂ O ₃ 29.72 g, Al ₂ O ₃ 21 .88 g and 0.52 g of BaF ₂ were mixed and baked at 1400 ° C. for 4 hours in a reducing atmosphere. By grinding, a rare earth aluminate phosphor having a composition formula of (Y _0.90 Ce _0.05 Gd _0.05 ) ₃ Al ₅ O ₁₂ was obtained.

[Comparative Example 1]
Y ₂ O ₃ to 669 g, the CeO ₂ 12g, 538.5g of Al ₂ O _3, the 2.44g and H ₃ BO ₃ and AlF ₃ were mixed 1.22 g, 4 hours firing at 1400 ° C. in a reducing atmosphere did. By grinding, a rare earth aluminate phosphor having a composition formula of Y _2.965 Ce _0.035 Al ₅ O ₁₂ was obtained.

1. Properties of rare earth aluminate phosphors (1) Composition analysis The rare earth aluminate phosphors obtained in the examples were dissolved in nitric acid, and each element other than halogen elements and oxygen was contained by plasma emission spectroscopy (ICP) analysis. The quantity was quantified. Further, the rare earth aluminate phosphor obtained in a predetermined amount was put into pure water and stirred to obtain a supernatant aqueous solution. The halogen element in the supernatant aqueous solution was quantified by an ion meter using an anion selective electrode as an indicator electrode.

(2) Measurement of aspect ratio With respect to the rare earth aluminate phosphor obtained in the examples, a photograph of a particle image was taken with an SEM at a magnification of 4000 times. As shown in FIG. 4, a plurality of particle images (for example, 20, 50, 100, etc.) were randomly extracted from the SEM photograph. Then, for each particle image, a (the longest diameter of the particle image) and b (the maximum diameter perpendicular to a) are obtained, the value of b is divided by the value of a, and the average value of the values is defined as the aspect ratio. .

(3) Measurement of particle size distribution The rare earth aluminate phosphors obtained in the examples were measured by a laser diffraction scattering method to obtain D10 / D50, D90 / D50 and D50.

(4) Measurement of area ratio From the number of particles of rare earth aluminate phosphors obtained in the examples, each medium-sized rare earth aluminate phosphor was selected. A cross-section was performed by a focused ion beam processing observation apparatus up to a portion where the particle cross-sectional image (SIM image) of the selected rare earth aluminate phosphor had the maximum particle size. The ratio of the area of the space portion of the particle cross-sectional image to the total of the outer shell portion and the space portion was calculated from the SIM image.

The results are shown in Table 1.
Compared with the rare earth aluminate phosphor obtained in Comparative Example 1, the rare earth aluminate phosphor obtained in Examples 1 and 2 has less color shift and color unevenness when used in a light emitting device, and has high luminous efficiency. there were.

  The light emitting device according to the present invention can be used for various power sources such as signals, lighting, displays, indicators, and backlights of mobile phones.

It is sectional drawing which shows the structure of the light-emitting device of Embodiment 1 which concerns on this invention. (A) It is a top view which shows the structure of the light-emitting device of Embodiment 2 which concerns on this invention. (B) It is sectional drawing which shows the structure of the light-emitting device of Embodiment 2 which concerns on this invention. It is sectional drawing which shows the structure of the light-emitting device of Embodiment 3 which concerns on this invention. It is a schematic diagram which shows the evaluation method of the aspect ratio by a SEM photograph.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2 Semiconductor layer 3 Electrode 4 Bump 10 Light emitting element 11 Phosphor 12 Coating member 13 Lead frame 13a Mount lead 13b Inner lead 14 Conductive wire 15 Mold member 101 Light emitting element 102 Lead electrode 103 Insulating sealing material 104 Conductive wire 105 Package 106 Lid 107 Window 108 Phosphor 109 Coating member 201 Substrate 202 Underlayer 203 N-type layer 203a Exposed surface 204 Active layer 205 P-side carrier confinement layer 206 First p-type layer 207 Current diffusion layer 208 P-side contact layer 209 Light emission Part 210 p-side electrode 210a electrode branch 210b p-side pad electrode 211a n-side electrode 211b n-side pad electrode

Claims (7)

An excitation light source;
A light-emitting device comprising: a phosphor that absorbs at least part of light emitted from the excitation light source and converts the light into a different wavelength;
The phosphor includes (a) aluminum,
(B) at least one selected from the group consisting of yttrium, lutetium, scandium, lanthanum, gadolinium, terbium, europium and samarium;
(C) gallium as necessary;
(D) a rare earth aluminate phosphor having a rare earth element;
The phosphor has a filling portion and a hollow portion inside the phosphor,
The light emitting device, wherein an area ratio of the hollow portion to the total of the filling portion and the hollow portion when the cross-section is performed on the phosphor is larger than 0% and smaller than 20%.   The light emitting device according to claim 1, wherein the phosphor has three or more grain boundaries. 3. The light emitting device according to claim 1, wherein a general formula of the phosphor is represented by the following formula.
_{(Ln 1-x, R x} ) 3 (Al 1-n, Ga n) 5 O 12
(Ln represents at least one selected from the group consisting of Y, Lu, Sc, La, Gd, Tb, Eu and Sm, R represents at least one rare earth element, and x represents 0.0001 ≦ x ≦ Represents a number satisfying 0.3, and n represents a number satisfying 0 ≦ n ≦ 0.5.) A light emitting device comprising: a light emitting element whose light emitting layer is a semiconductor; and a photoluminescence phosphor that absorbs part of the light emitted by the light emitting element and emits light having a wavelength different from the wavelength of the absorbed light. In
(1) The light-emitting element is a blue light-emitting LED chip whose light-emitting layer is a gallium nitride semiconductor and whose emission spectrum has a peak wavelength in the range of 410 to 490 nm.
(2) The photoluminescent phosphor comprises: (a) aluminum;
(B) at least one selected from the group consisting of yttrium, lutetium, scandium, lanthanum, gadolinium, terbium, europium and samarium;
(C) gallium as necessary;
(D) a rare earth aluminate phosphor having a rare earth element;
The phosphor has a filling portion and a hollow portion inside the phosphor,
When the cross section of the phosphor is taken out, the area ratio of the cavity to the total of the filler and the cavity is a phosphor that is greater than 0% and less than 20%.
(3) Mixing of an emission spectrum having a peak wavelength in the range of 510 to 580 nm emitted from the phosphor and an emission spectrum having a peak wavelength in the range of 410 to 490 nm that is not absorbed by the phosphor from the LED chip The light emitting device emits white light having a continuous combined spectrum by overlapping both spectra. (A) aluminum;
(B) at least one selected from the group consisting of yttrium, lutetium, scandium, lanthanum, gadolinium, terbium, europium and samarium;
(C) gallium as necessary;
(D) a rare earth aluminate phosphor having a rare earth element;
The phosphor has a filling portion and a hollow portion inside the phosphor,
The rare earth aluminate phosphor, wherein an area ratio of the cavity portion to the total of the filling portion and the cavity portion when the cross section is taken out of the phosphor is greater than 0% and less than 20%. The rare earth aluminate phosphor according to claim 5, wherein the phosphor has three or more grain boundaries. The rare earth aluminate phosphor according to claim 5 or 6, wherein the general formula of the phosphor is represented by the following formula.
_{(Ln 1-x, R x} ) 3 (Al 1-n, Ga n) 5 O 12
(Ln represents at least one selected from the group consisting of Y, Lu, Sc, La, Gd, Tb, Eu and Sm, R represents at least one rare earth element, and x represents 0.0001 ≦ x ≦ Represents a number satisfying 0.3, and n represents a number satisfying 0 ≦ n ≦ 0.5.)

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