JP2011003786A - Light emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light emitting device which has high light emitting intensity by using a phosphor efficiently excited by an ultraviolet ray or short-wavelength visible light to emit light.SOLUTION: The light emitting device 10 is equipped with: a semiconductor light emitting element 18 that emits the ultraviolet ray or the short-wavelength visible light; a first phosphor which is excited by the ultraviolet ray or the short-wavelength visible light to emit visible light; a second phosphor which is excited by the ultraviolet ray or the short-wavelength visible light to emit visible light, which is complimentary to the visible light emitted from the first phosphor; and a third phosphor which is excited by the ultraviolet ray or the short-wavelength visible light to emit visible light, and has a peak wavelength between the peak wavelength in the visible light emitted from the first phosphor and the peak wavelength in the visible light emitted from the second phosphor. White light is obtained by additive color mixture of the lights from each phosphor.

Description

  The present invention relates to a light emitting device using a phosphor, and for example, relates to a light emitting device using a phosphor that is efficiently excited and emitted by ultraviolet light or short wavelength visible light.

  Various light-emitting elements configured to obtain light of a desired color by combining a light-emitting element and a phosphor that is excited by light generated by the light-emitting element and generates light having a wavelength region different from that of the light-emitting element. The device is known.

  In particular, in recent years, as a white light emitting device with long life and low power consumption, semiconductor light emitting diodes such as light emitting diodes (LED) and laser diodes (LD) that emit ultraviolet light or short wavelength visible light, and phosphors using these as light sources for excitation A light-emitting device configured to obtain white light by combining the above is drawing attention.

  As a specific example of such a white light emitting device, there is known a method of combining a plurality of phosphors that emit violet light or ultraviolet light, and phosphors that are excited by violet light or ultraviolet light and emit light of a color such as blue or yellow. (See Patent Document 1).

JP 2009-38348 A

  However, the phosphor that emits yellow light used in the white light emitting device described above has a peak wavelength of the emission spectrum near 575 nm, does not coincide with the visibility curve, and has a maximum visibility. Also, the peak wavelength is shifted to the long wavelength side. Therefore, although the conversion efficiency as a single phosphor is good, the white light emitting device is required to be further improved from the viewpoint of luminous flux and light emission efficiency.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a light-emitting device having a high luminous flux using a phosphor that is efficiently excited and emitted by ultraviolet light or short-wavelength visible light. is there.

  In order to solve the above problems, a light-emitting device according to an aspect of the present invention includes a light-emitting element that emits ultraviolet light or short-wavelength visible light, and a first phosphor that emits visible light when excited by ultraviolet light or short-wavelength visible light. Excited by ultraviolet light or short-wavelength visible light and excited by ultraviolet light or short-wavelength visible light; a second phosphor that emits visible light complementary to the visible light emitted by the first phosphor; A third phosphor that emits visible light and has a peak wavelength between the peak wavelength of visible light emitted by the first phosphor and the peak wavelength of visible light emitted by the second phosphor; The light from each phosphor is additively mixed to obtain white light.

  Since the visible light emitted from the first phosphor and the visible light emitted from the second phosphor are complementary to each other, white light can be obtained. However, when one of the peak wavelengths of visible light is shifted to the shorter wavelength side than the peak wavelength of the visibility curve and the other is shifted to the longer wavelength side, the peak wavelength of the emission spectrum obtained by synthesizing these visible lights is , Deviated from the peak wavelength of the visibility curve. Therefore, according to this aspect, the third phosphor has a peak wavelength between the peak wavelength of visible light emitted from the first phosphor and the peak wavelength of visible light emitted from the second phosphor. Visible light having a peak wavelength closer to the peak wavelength of the visibility curve can be emitted. As a result, the emission spectrum obtained by synthesizing the visible light emitted by these three phosphors has a peak wavelength closer to the peak wavelength of the visibility curve than when only the first phosphor and the second phosphor are present. Thus, white light with a high luminous flux can be obtained.

The first phosphor has a general formula of M ¹ O ₂ .aM ² O.bM ³ X ₂ : M ⁴ _c (where M ¹ is at least 1 selected from the group consisting of Si, Ge, Ti, Zr and Sn) seed elements, ^{M 2} is Mg, Ca, Sr, at least one element selected from the group consisting of Ba and Zn, ^{M 3} is Mg, Ca, Sr, at least one selected from the group consisting of Ba, and Zn Element, X is at least one halogen element, M ⁴ is at least one element essential to Eu ²⁺ selected from the group consisting of rare earth elements and Mn, a is 0.1 ≦ a ≦ 1.3, b may be 0.1 ≦ b ≦ 0.25, and c may be 0.03 <c / (a + c) <0.8.) Alternatively, the general formula _{^{M 1 O 2 · a (M}} 2 1-z, M 4 z) O · bM 3 X 2 :( However, ^{M 1} is selected from the group consisting of Si, Ge, Ti, Zr and Sn At least one element, M ² is at least one element selected from the group consisting of Mg, Ca, Sr, Ba and Zn, and M ³ is at least one selected from the group consisting of Mg, Ca, Sr, Ba and Zn X represents at least one halogen element, M ⁴ represents at least one element essential to Eu ²⁺ selected from the group consisting of rare earth elements and Mn, a is 0.7 ≦ a ≦ 1. 3, b may be 0.1 ≦ b ≦ 0.25, and z may be in the range of 0.01 <z <0.3. As a result, a first phosphor with better emission characteristics can be obtained.

  The third phosphor may emit green light. Specifically, the third phosphor may have a peak wavelength of its emission spectrum in a wavelength range of 490 to 560 nm. Thereby, it is possible to emit light having a peak wavelength closer to the peak wavelength of the visibility curve, and white light with a higher luminous flux can be obtained. The third phosphor may have a half width of its emission spectrum of 15 to 120 nm. When the full width at half maximum is moderately small, it is possible to synthesize an emission spectrum having a wavelength with high visibility with a smaller output. That is, light in a desired wavelength region can be obtained efficiently.

  Further, it has been newly found that the first phosphor represented by the general formula emits visible light having a high emission intensity by being efficiently excited in the ultraviolet or short wavelength visible light, particularly in the wavelength region near 400 nm. This phosphor may be used in a light emitting device.

  Further, from the viewpoint of color rendering properties of the light emitting device, the emission spectrum of the first phosphor preferably has a peak wavelength in a wavelength range of 560 to 590 nm and a half width of 100 nm or more.

  The emission spectrum of the second phosphor is not particularly limited as long as the second phosphor emits visible light having a complementary color relationship with the visible light emitted from the first phosphor. For the purpose of obtaining a light emitting device for white light, when the first phosphor emits yellow light, it is preferable to use a phosphor that emits blue light that is complementary color light. For the same purpose, from the viewpoint of color rendering properties, the emission spectrum of the second phosphor preferably has a peak wavelength in the wavelength range of 440 nm to 470 nm and a half width of 30 to 60 nm.

  The emission spectrum of the light-emitting element is not particularly limited as long as it emits at least ultraviolet light or short-wavelength visible light, but the peak wavelength of the emission spectrum is 350 nm to 430 nm from the viewpoint of the light emission efficiency of the light emitting device. It is preferable to be included in the range.

  Moreover, as a specific example of a light emitting element, various light sources, such as semiconductor light emitting elements, such as LED and LD, a light source for obtaining light emission from a vacuum discharge or thermoluminescence, an electron beam excitation light emitting element, can be used, for example. More preferably, by using a semiconductor light emitting element as the light emitting element, a light emitting device with a small size, power saving, and long life can be obtained. As a suitable example of such a semiconductor light emitting device, an InGaN-based LED or LD having good light emission characteristics in a wavelength region near 400 nm can be given.

  It should be noted that any combination of the above-described constituent elements and a representation obtained by converting the expression of the present invention between a method, an apparatus, a system, and the like are also effective as an aspect of the present invention.

  ADVANTAGE OF THE INVENTION According to this invention, the light-emitting device of a high luminous flux can be provided using the fluorescent substance which is efficiently excited and light-emitted with an ultraviolet-ray or short wavelength visible light.

It is a schematic sectional drawing of the light-emitting device concerning this Embodiment. It is a figure which shows the emission spectrum of the fluorescent substance 1 under 400 nm excitation. 2 is a diagram showing an excitation spectrum of phosphor 1. FIG. It is a figure which shows the emission spectrum of the fluorescent substance 2 under 400 nm excitation. It is a figure which shows the excitation spectrum of the fluorescent substance 2. It is a figure which shows the emission spectrum of the fluorescent substance 3 under 400 nm excitation. It is a figure which shows the excitation spectrum of the fluorescent substance 3. It is the figure which showed the emission spectrum (solid line) of the Example when a 700 mA drive current is applied to a light-emitting device, and the emission spectrum (dotted line) of a comparative example with the visibility curve.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and repeated descriptions are omitted as appropriate.

  FIG. 1 is a schematic cross-sectional view of the light emitting device according to the present embodiment. In the light emitting device 10 shown in FIG. 1, a pair of electrodes 14 (anode) and an electrode 16 (cathode) are formed on a substrate 12. A semiconductor light emitting element 18 is fixed on the electrode 14 by a mount member 20. The semiconductor light emitting element 18 and the electrode 14 are electrically connected by a mount member 20, and the semiconductor light emitting element 18 and the electrode 16 are electrically connected by a wire 22. A fluorescent layer 24 is formed on the semiconductor light emitting device.

  The substrate 12 is preferably formed of a material having no electrical conductivity but high thermal conductivity. For example, a ceramic substrate (aluminum nitride substrate, alumina substrate, mullite substrate, glass ceramic substrate), a glass epoxy substrate, or the like is used. be able to.

  The electrodes 14 and 16 are conductive layers formed of a metal material such as gold or copper.

  The semiconductor light emitting element 18 is an example of a light emitting element used in the light emitting device of the present invention. For example, an LED or LD that emits ultraviolet light or short wavelength visible light can be used. Specific examples include InGaN-based compound semiconductors. The emission wavelength range of the InGaN-based compound semiconductor varies depending on the In content. When the In content is large, the emission wavelength becomes long, and when it is small, the wavelength tends to be short. However, the InGaN-based compound semiconductor containing In at such an extent that the peak wavelength is around 400 nm is a quantum efficiency in light emission. Has been confirmed to be the highest.

  The mount member 20 is, for example, a conductive adhesive such as silver paste or gold-tin eutectic solder, and the lower surface of the semiconductor light emitting element 18 is fixed to the electrode 14. The electrode 14 is electrically connected.

  The wire 22 is a conductive member such as a gold wire, and is joined to the upper surface side electrode and the electrode 16 of the semiconductor light emitting element 18 by, for example, ultrasonic thermocompression bonding, and electrically connects both.

  In the fluorescent layer 24, each phosphor described later is sealed in a film shape (layer shape) covering the upper surface of the semiconductor light emitting element 18 with a binder member. The phosphor layer 24 is prepared, for example, by preparing a phosphor paste in which a phosphor is mixed in a liquid or gel binder member, and then applying the phosphor paste to the upper surface of the semiconductor light emitting element 18, and thereafter binding the phosphor paste. It is formed by curing the member. As the binder member, for example, a silicone resin or a fluorine resin can be used. Moreover, since the light-emitting device according to this embodiment uses ultraviolet light or short-wavelength visible light as an excitation light source, a binder member having excellent ultraviolet resistance is preferable.

  The fluorescent layer 24 may be mixed with substances having various physical properties other than the phosphor. A substance having a higher refractive index than the binder member, such as a metal oxide, a fluorine compound, or a sulfide, is mixed in the fluorescent layer 24, whereby the refractive index of the fluorescent layer 24 can be increased. As a result, total reflection that occurs when light generated from the semiconductor light emitting element 18 enters the fluorescent layer 24 is reduced, and an effect of improving the efficiency of capturing excitation light into the fluorescent layer 24 is obtained. Furthermore, the refractive index can be increased without reducing the transparency of the fluorescent layer 24 by making the particle size of the substance to be mixed nanosize. In addition, white powder having an average particle size of about 0.3 to 3 μm, such as alumina, zirconia, or titanium oxide, can be mixed in the fluorescent layer 24 as a light scattering agent. Thereby, uneven brightness and chromaticity in the light emitting surface can be prevented.

  Next, each phosphor used in the light emitting device according to the present embodiment will be described in detail.

(First phosphor)
The first phosphor can be obtained, for example, as follows. As the first phosphor, compounds represented by the following composition formulas (1) to (4) can be used as raw materials.
(1) M ¹ O ₂ (M ¹ represents a tetravalent element such as Si, Ge, Ti, Zr, or Sn.)
(2) M ² O (M ² represents a divalent element such as Mg, Ca, Sr, Ba, Zn, etc.)
(3) M ³ X ₂ (M ³ is a divalent element such as Mg, Ca, Sr, Ba, Zn, etc., and X is a halogen element.)
(4) M ⁴ (M ⁴ represents a rare earth element such as Eu ²⁺ and / or Mn.)

As a raw material of the composition formula (1), for example, SiO ₂ , GeO ₂ , TiO ₂ , ZrO ₂ , SnO _{2 and the} like can be used. As a raw material of the composition formula (2), for example, a carbonate, oxide, hydroxide, or the like of a divalent metal ion can be used. Examples of the raw material of the composition formula (3) include SrCl ₂ , SrCl ₂ .6H ₂ O, MgCl ₂ , MgCl ₂ .6H ₂ O, CaCl ₂ , CaCl ₂ .2H ₂ O, BaCl ₂ , BaCl ₂ .2H ₂ O. the _{ZnCl 2, MgF 2, CaF 2} , SrF 2, BaF 2, ZnF 2, MgBr 2, CaBr 2, SrBr 2, BaBr 2, ZnBr 2, MgI 2, CaI 2, SrI 2, BaI 2, ZnI 2 or the like Can be used. As a raw material of the composition formula (4), for example, Eu ₂ O ₃ , Eu ₂ (CO ₃ ) ₃ , Eu (OH) ₃ , EuCl ₃ , MnO, Mn (OH) ₂ , MnCO ₃ , MnCl ₂ .4H ₂ O , Mn (NO ₃ ) ₂ .6H ₂ O, or the like can be used.

In As the raw material in the composition formula (1), and essentially includes at least Si is ^{M 1,} Si, Ge, Ti, at least one element selected from the group consisting of Zr and Sn, the proportion of Si is more than 80 mol% Certain compounds are preferred. As a raw material of the composition formula (2), M ² is at least one element selected from the group consisting of Mg, Ca, Sr, Ba, and Zn, at least Ca and / or Sr essential, and Ca and / or The compound whose ratio of Sr is 60 mol% or more is preferable. As a raw material of the composition formula (3), M ³ is at least Sr essential, is at least one element selected from the group consisting of Mg, Ca, Sr, Mg, Ba and Zn, and Sr is 30 mol% or more. Some compounds are preferred. Further, as the raw material of the composition formula (3), a compound in which X is at least one halogen element in which at least Cl is essential and the proportion of Cl is 50 mol% or more is preferable. As a raw material of the composition formula (4), M ⁴ is preferably a rare earth element in which divalent Eu is essential, and may contain a rare earth element other than Mn or Eu.

The molar ratio of the raw materials of the composition formulas (1) to (4) is (1) :( 2) = 1: 0.1 to 1.0, (2) :( 3) = 1: 0.2 to 12. 0, (2) :( 4) = 1: 0.05-4.0, preferably (1) :( 2) = 1: 0.25-1.0, (2) :( 3) = 1 : 0.3-6.0, (2): (4) = 1: 0.05-3.0, more preferably (1) :( 2) = 1: 0.25-1.0, (2 ): (3) = 1: 0.3-4.0, (2) :( 4) = 1: 0.05-3.0 Weighed and put each weighed raw material in an alumina mortar about 30 Minute pulverization and mixing are performed to obtain a raw material mixture. This raw material mixture is put in an alumina crucible and baked in a reducing atmosphere electric furnace at a predetermined atmosphere (H ₂ : N ₂ = 5: 95) at a temperature of 700 ° C. or higher and lower than 1100 ° C. for 3 to 40 hours to obtain a baked product. . The first phosphor can be obtained by carefully washing the fired product with warm pure water and washing away excess chloride. The first phosphor is excited by ultraviolet light or short wavelength visible light and emits visible light.

  In addition, about the raw material (divalent metal halide) of a composition formula (3), it is preferable to weigh the excess amount beyond a stoichiometric ratio. This is because a part of the halogen element is vaporized and evaporated during firing, and is to prevent the occurrence of crystal defects in the phosphor due to the lack of the halogen element. Moreover, the raw material of the composition formula (3) added in excess is liquefied at the firing temperature and acts as a flux for the solid phase reaction, thereby promoting the solid phase reaction and improving the crystallinity.

  In addition, after baking the raw material mixture described above, the above-described excessively added raw material of the composition formula (3) is present as an impurity in the manufactured phosphor. Therefore, in order to obtain a phosphor having high purity and high emission intensity, it is necessary to wash away these impurities with warm pure water. The composition ratio shown in the general formula of the first phosphor of the present embodiment is the composition ratio after the impurities are washed away, and the raw material of the composition formula (3) that is added excessively and becomes impurities as described above. Is not taken into account in this composition ratio.

  In order to obtain a phosphor with high luminous efficiency in this embodiment, it is preferable to reduce the number of metal elements as impurities as much as possible. In particular, since transition metal elements such as Fe, Co, and Ni act as light emission inhibitors, use high-purity raw materials and mix impurities in the synthesis process so that the total of these elements is 500 ppm or less. It is preferable to prevent.

(Second phosphor)
The second phosphor can be obtained, for example, as follows. The second phosphor uses CaCO ₃ , MgCO ₃ , CaCl ₂ , CaHPO ₄ , and Eu ₂ O ₃ as raw materials, and the molar ratio of these raw materials is CaCO ₃ : MgCO ₃ : CaCl ₂ : CaHPO ₄ : Eu _2. O ₃ = 0.05 to 0.35: 0.01 to 0.50: 0.17 to 0.50: 1.00: 0.005 to 0.050 Weighed at a predetermined ratio and weighed Each raw material is put in an alumina mortar and pulverized and mixed for about 30 minutes to obtain a raw material mixture. This raw material mixture is put in an alumina crucible and fired at a temperature of 800 ° C. or higher and lower than 1200 ° C. for 3 hours in an N ₂ atmosphere containing ₂ to 5% of H ₂ to obtain a fired product. The second phosphor can be obtained by carefully washing the fired product with warm pure water and washing away excess chloride. The second phosphor emits visible light having a complementary color relationship with the visible light emitted from the first phosphor.

Note that the basis weight of CaCl ₂ in obtaining the aforementioned raw material mixture (molar ratio), with respect to the composition ratio of the second phosphor to be manufactured, an excess amount of more than 0.5mol than its stoichiometric ratio Is preferably weighed. Thereby, it is possible to prevent the occurrence of crystal defects in the second phosphor due to the lack of Cl ₂ .

(Third phosphor)
As the third phosphor, phosphors represented by the following general formulas (1) to (6) can be used.
(1) M ¹ ₂ SiO ₄ : Eu ²⁺ , RE (where M ¹ is at least one element selected from the group consisting of Ba, Sr, Ca and Mg, RE is a rare earth other than Eu and Mn At least one element selected from the group consisting of
_{(2) Ba 5-x-} y M y Si m O 5 + 2m: Eu 2+ x (M is at least one element selected from Ca and Sr, x, y, m is 0.001 ≦ x ≦ 0.3, 0 ≦ y ≦ 0.8, x + y <5, 2.5 <m <3.5)
(3) M ¹ _2-x M ² M ³ ₂ O ₇ : Eu ²⁺ _x (M ¹ is an alkaline earth element containing 70 mol% or more of Ba, M ² is Zn and Mn containing 90 mol% or more of Mg And at least one element selected from the group consisting of M ³ is a tetravalent metal element group containing 80 mol% or more of Si)
(4) MO.Si ₂ N ₂ O: Eu ²⁺ (M is at least one element selected from the group consisting of Ca, Sr and Ba)
(5) M ₃ Si ₆ O ₁₂ N ₂ : Eu (M is an alkaline earth element containing 80 mol% or more of Ba)
(6) M _1-a Mg _1-b Al ₁₀ O ₁₇ : Eu ²⁺ _a , Mn ²⁺ _b (M is Ba or Sra, b is 0.05 <a ≦ 1, 0.01 <b ≦ 0 .9)

  The third phosphor emits visible light (green). The green visible light has a peak wavelength between the peak wavelength of visible light (yellow) emitted from the first phosphor and the peak wavelength of visible light (blue which is a complementary color of yellow) emitted from the second phosphor. Have

  Determination of the crystal structure and the like of the first phosphor in the present embodiment was performed based on the analysis result of growing a single crystal of the base crystal. Since a detailed method is described in Japanese Patent Laid-Open No. 2009-38348, description thereof is omitted here.

  The light-emitting device configured as described above will be described in more detail with reference to the following examples. However, the following description of the light-emitting device, the manufacturing method, the chemical composition of the phosphor, and the like will be given below. The embodiment is not limited in any way.

First, the phosphor used in the light emitting device of this example will be described in detail.
<Phosphor 1>
The phosphor 1 is a phosphor represented by SiO ₂ · 1.0 (Ca _0.54 , Sr _0.36, Eu ²⁺ _0.1 ) O · 0.17SrCl ₂ , and the first phosphor described above. It is an example. The phosphor 1 has the general formula M ¹ O ₂ · a (M ² _1−z , M ⁴ _z ) O · bM ³ X ₂ , where M ¹ = Si, M ² = Ca / Sr (molar ratio 60 / 40), M ³ = Sr, X = Cl, M ⁴ = Eu ²⁺ , a = 1.0, b = 0.17, and a phosphor synthesized so that the content z of M ⁴ is 0.1. . The phosphor 1 is a phosphor in which cristobalite is generated in the phosphor by adding excessive SiO ₂ at the mixing ratio of the raw materials. The phosphor 1 is manufactured by first using SiO ₂ , Ca (OH) ₂ , SrCl ₂ .6H ₂ O, and Eu ₂ O ₃ with a molar ratio of SiO ₂ : Ca (OH) ₂ : SrCl _2.・ 6H ₂ O: Eu ₂ O ₃ = 1.1: 0.45: 1.0: 0.13 Weighed, each weighed raw material was put in an alumina mortar and pulverized and mixed for about 30 minutes. Got. This raw material mixture was put into an alumina crucible and fired at a predetermined atmosphere (H ₂ : N ₂ = 5: 95) at a temperature of 1030 ° C. for 5 to 40 hours in a reducing atmosphere electric furnace to obtain a fired product. The obtained fired product was carefully washed with warm pure water, and excess chloride was washed away to obtain phosphor 1.

<Phosphor 2>
The phosphor 2 is a phosphor represented by (Ca _4.67 Mg _0.5 ) (PO ₄ ) ₃ Cl: Eu _0.08 , and is an example of the second phosphor described above. The phosphor 2 is manufactured by first using the raw materials of CaCO ₃ , MgCO ₃ , CaCl ₂ , CaHPO ₄ , and Eu ₂ O ₃ with a molar ratio of CaCO ₃ : MgCO ₃ : CaCl ₂ : CaHPO ₄ : Eu _2. Weighed so that O ₃ = 0.42: 0.5: 3.0: 1.25: 0.04, and put each weighed raw material in an alumina mortar for about 30 minutes to obtain a raw material mixture. This raw material mixture was put in an alumina crucible and fired at a temperature of 800 ° C. or more and less than 1200 ° C. for 3 hours in an N ₂ atmosphere containing ₂ to 5% of H ₂ to obtain a fired product. The obtained fired product was carefully washed with warm pure water, and the phosphor 2 was obtained by washing away excess chloride.

<Phosphor 3>
The phosphor 3 is a phosphor represented by (Ba _1.4 Sr _0.45 ) ₂ SiO ₄ : Eu ²⁺ _0.15 , and is an example of the third phosphor described above. The phosphor 3 is manufactured by first using the raw materials of BaCO ₃ , SrCO ₃ , SiO ₂ , and Eu ₂ O ₃ with a molar ratio of BaCO ₃ : SrCO ₃ : SiO ₂ : Eu ₂ O ₃ = 1.4. : 0.45: 1: 0.075, each weighed raw material was placed in an alumina mortar and ground and mixed for about 30 minutes to obtain a raw material mixture. This raw material mixture was put in an alumina crucible and fired at a temperature of 1000 ° C. or higher and lower than 1300 ° C. for 2 to 8 hours in an N ₂ atmosphere containing ₂ to 5% of H ₂ to obtain a fired product. The obtained fired product was carefully washed with warm pure water, and the phosphor 3 was obtained by washing away excess chloride.

<Evaluation result of phosphor 1>
The phosphor 1 was measured for emission characteristics under 400 nm excitation. FIG. 2 is a diagram showing an emission spectrum of the phosphor 1 under 400 nm excitation. In addition, the vertical axis | shaft of the graph in FIG. 2 shows the relative light emission intensity (relative intensity) in each wavelength.

  As shown in FIG. 2, the phosphor 1 has an emission spectrum peak wavelength of around 579 nm and a half width of 100 nm or more. From this, it can be seen that the phosphor 1 can emit broad yellow visible light having high color rendering properties.

  FIG. 3 is a diagram showing an excitation spectrum of the phosphor 1. As shown in FIG. 3, it can be seen that the phosphor 1 has an excitation spectrum peak in the wavelength range of 350 to 430 nm. From this, it can be seen that the phosphor 1 is efficiently excited in the wavelength region near 400 nm. Further, FIG. 3 shows that the phosphor 1 hardly absorbs light in the wavelength region of 450 to 480 nm. From this, when the phosphor 1 is used in combination with another phosphor that emits light in the wavelength range of 450 to 480 nm, for example, when a white light emitting device is configured by combining the phosphor 1 and the blue light emitting phosphor. Since the blue phosphor does not absorb the light emitted, a light emitting device with high luminous efficiency and little color shift can be constructed.

<Evaluation result of phosphor 2>
The phosphor 2 was measured for light emission characteristics under 400 nm excitation. FIG. 4 is a diagram showing an emission spectrum of the phosphor 2 under 400 nm excitation. As shown in FIG. 4, the phosphor 2 has an emission spectrum peak wavelength around 460 nm and a wide half-value width of 38 nm. From this, it can be seen that the phosphor 2 can emit broad blue visible light having high color rendering properties. Further, by using the phosphor 2 and the phosphor 1 together, it is possible to realize a white light emitting device with high color rendering properties. FIG. 5 is a diagram showing an excitation spectrum of the phosphor 2. As shown in FIG. 5, it can be seen that the phosphor 2 is efficiently excited by light in the wavelength range of 380 to 430 nm.

<Evaluation result of phosphor 3>
The phosphor 2 was measured for light emission characteristics under 400 nm excitation. FIG. 6 is a diagram showing an emission spectrum of the phosphor 3 under 400 nm excitation. As shown in FIG. 6, it can be seen that the phosphor 3 has an emission spectrum peak wavelength around 520 nm and a full width at half maximum of about 70 nm. FIG. 7 is a diagram showing an excitation spectrum of the phosphor 3. As shown in FIG. 7, it can be seen that the phosphor 3 is efficiently excited by light in the wavelength range of 350 to 480 nm.

  Next, the configuration of the light emitting device according to the example will be described in detail.

<Configuration of light emitting device>
The light-emitting device according to the example uses the following specific configuration in the light-emitting device shown in FIG. The configuration of the light emitting device described below is common in the examples and comparative examples except for the type of phosphor used.

First, an aluminum nitride substrate was used as the substrate 12, and an electrode 14 (anode) and an electrode 16 (cathode) were formed on the surface using gold. As the semiconductor light emitting element 18, a 1 mm square LED having a light emission peak at 405 nm (SemiLEDs, Inc .: MvpLED ^™ SL-V-U40AC) is used. Then, the lower surface of the LED is adhered on the silver paste (Able Stick 84-1LMRIS4) dripped on the electrode 14 (anode) using a dispenser, and the silver paste is cured at 175 ° C. for 1 hour. I let you. Further, a Φ45 μm gold wire was used as the wire 22, and this gold wire was bonded to the upper surface side electrode of the LED and the electrode 16 (cathode) by ultrasonic thermocompression bonding. Further, a phosphor paste was prepared by mixing a mixture of various phosphors in a silicone resin (manufactured by Toray Dow Corning Silicone Co., Ltd .: JCR6140) as a binder member so as to be 20 vol%. And after apply | coating this fluorescent substance paste to the upper surface of the semiconductor light-emitting element 18 by 100 micrometer thickness, it is fixed by the step hardening for 40 minutes under an 80 degreeC environment, and then for 60 minutes under a 150 degreeC environment, and a fluorescent layer 24 was formed.

  Based on the configuration of the phosphor and the light emitting device described above, light emitting devices according to Examples and Comparative Examples were manufactured.

<Example>
In this example, phosphor 1 was used as the first phosphor, phosphor 2 was used as the second phosphor, and phosphor 3 was used as the third phosphor, and these were mixed. A light emitting device was fabricated using the phosphor paste. In this embodiment, a mixed phosphor in which phosphors 1, 2, and 3 are mixed at a volume ratio of 37: 56: 7 is used.

<Comparative example>
In the comparative example, the phosphor 1 was used as the first phosphor and the phosphor 2 was used as the second phosphor, and a light emitting device was fabricated using a phosphor paste in which these were mixed. In the comparative example, a mixed phosphor obtained by mixing phosphor 1 and phosphor 2 at a volume ratio of 40:60 is used.

<Evaluation of Examples>
The light emitting devices according to the examples and the comparative examples were made to emit light by supplying a current of 700 mA in an integrating sphere, and the luminous flux ratio and the spectral spectrum were measured with a spectroscope (manufactured by Instrument System: CAS140B-152). The measurement results will be described in detail below.

Table 1 shows the luminous flux ratio and chromaticity coordinates (cx, cy) when a driving current of 700 mA is applied to each light emitting device. The luminous flux ratio is shown as a relative value with a luminous flux of 100 when a driving current of 700 mA is applied to the light emitting device of the comparative example.

  Since the yellow visible light emitted from the phosphor 1 and the blue visible light emitted from the phosphor 2 are complementary to each other, white light can be obtained even with the light emitting device of the comparative example. However, the peak wavelength of each visible light is one (blue) is shifted to the shorter wavelength side than the peak wavelength of the visibility curve, and the other (yellow) is shifted to the longer wavelength side. The peak wavelength of the emission spectrum is shifted from the peak wavelength of the visibility curve.

  In contrast, the light emitting device of the example has a peak wavelength between the peak wavelength of visible light (yellow) emitted from the phosphor 1 and the peak wavelength of visible light (blue) emitted from the phosphor 2. A phosphor 3 that emits light (green) is provided. Therefore, when the light from each phosphor is synthesized, visible light having a peak wavelength closer to the peak wavelength (555 nm) of the visibility curve can be emitted. As a result, the emission spectrum obtained by synthesizing the visible light emitted by these three phosphors depends on the peak wavelength of the visibility curve as compared to the comparative example in which only the first phosphor and the second phosphor are present. It has a close peak wavelength, and white light with a high luminous flux can be obtained.

  Specifically, as shown in Table 1, it can be seen that the luminous ratio of the light emitting device of the example is improved by 12% compared to the light emitting device of the comparative example. Further, the chromaticity coordinates of the light emitted by the light emitting device of the embodiment are in the region of the white color specification (JIS-D-5500) of the vehicular lamp, and can be applied to a vehicular lamp that requires a high luminous flux. Recognize. In addition, it is preferable that the phosphor 3 has a peak wavelength of its emission spectrum in a wavelength range of 490 to 560 nm. Thereby, it becomes possible to emit light having a peak wavelength closer to the peak wavelength (555 nm) of the visibility curve, and white light with a higher luminous flux can be obtained.

  FIG. 8 is a diagram showing an emission spectrum (solid line) of an example and a light emission spectrum (dotted line) of a comparative example when a driving current of 700 mA is applied to the light emitting device, together with a visibility curve. In addition, the vertical axis | shaft of the graph in FIG. 8 shows the relative light emission intensity of an Example and a comparative example. As shown in FIG. 8, the peak wavelength of the light emitting device according to the example is closer to the peak wavelength of the visibility curve than the peak wavelength of the light emitting device according to the comparative example. In addition, the light emitting device according to the example shows a broad emission spectrum as compared with the light emitting device according to the comparative example, and it can be seen that the light emitting device has high color rendering.

  Further, in comparison with the case where white light is synthesized using three types of phosphors that emit red, blue, and green visible light, the light emitting device according to the present embodiment is a phosphor that emits red visible light. Instead of a fluorescent material that emits yellow visible light. Since the peak wavelength of the emission spectrum of yellow visible light is closer to the peak wavelength of the visibility curve compared to red visible light, yellow visible light is more visible than red visible light even if it emits the same energy. I feel bright. That is, the light emitting device according to this embodiment can obtain white light with a high luminous flux by additively mixing three colors of blue, yellow, and green visible light.

  The present invention has been described based on the embodiments and examples. This embodiment is an exemplification, and it will be understood by those skilled in the art that various modifications can be made to combinations of the respective constituent elements and processing processes, and such modifications are also within the scope of the present invention. is there.

  The light emitting device of the present invention can be used for various lamps, for example, lighting lamps, displays, vehicle lamps, traffic lights and the like. In particular, the white light emitting device according to the present invention can be expected to be applied to a lamp that requires high output white light such as a vehicle headlamp.

  DESCRIPTION OF SYMBOLS 10 Light-emitting device, 12 Substrate, 14,16 Electrode, 18 Semiconductor light emitting element, 20 Mount member, 22 Wire, 24 Fluorescent layer.

Claims (5)

A light emitting element emitting ultraviolet light or short wavelength visible light;
A first phosphor that emits visible light when excited by the ultraviolet or short wavelength visible light;
A second phosphor that emits visible light that is excited by the ultraviolet light or short-wavelength visible light and has a complementary color relationship with visible light emitted by the first phosphor;
Visible light having a peak wavelength between the peak wavelength of visible light that is excited by the ultraviolet light or short-wavelength visible light and emitted from the first phosphor and the peak wavelength of visible light that is emitted from the second phosphor. A third phosphor that emits light;
And a light emitting device configured to add white light from each phosphor to obtain white light. The first phosphor has a general formula of M ¹ O ₂ .aM ² O.bM ³ X ₂ : M ⁴ _c
(Where ^{M 1} is at least one element of Si, Ge, Ti, at least one element selected from the group consisting of Zr and Sn, ^{M 2} is selected from the group consisting of Mg, Ca, Sr, Ba and Zn , M ³ is at least one element selected from the group consisting of Mg, Ca, Sr, Ba and Zn, X is at least one halogen element, M ⁴ is Eu ²⁺ selected from the group consisting of rare earth elements and Mn. It represents at least one element that is essential, a is 0.1 ≦ a ≦ 1.3, b is 0.1 ≦ b ≦ 0.25, and c is 0.03 <c / (a + c) <0.8. The light-emitting device according to claim 1, wherein the light-emitting device is expressed by:   The light emitting device according to claim 1, wherein the third phosphor emits green light.   The light emitting device according to any one of claims 1 to 3, wherein the third phosphor has a peak wavelength of an emission spectrum in a wavelength range of 490 to 560 nm.   5. The light emitting device according to claim 1, wherein the third phosphor has a half width of an emission spectrum of 15 to 120 nm.