JP2007158298A - Light-emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light-emitting device which emits white light of high efficiency and low color temperature. <P>SOLUTION: In the light emitting device, a wavelength conversion part emitting a secondary light, having a wavelength longer than the wavelength of a primary light by absorbing a part of the primary light from an light emitting element includes one or more kinds of yellow light-emitting phosphors and one or more kinds of red light-emitting phosphors. The yellow light-emitting phosphor includes divalent europium inactivated silicate phosphors, represented by 2(M11-aEua)O-SiO2 (M1 comprises at least Sr, and is one or a plurality of elements selected out from among Mg, Ca and Ba including Sr, (a) is 0.005≤a≤0.10; and when a composition of M1 and Eu added together is 1, a composition of Sr is 0.5 or larger). The red light-emitting phosphor includes divalent europium inactivated nitride phosphors, represented by (M21-bEub)M3SiN3 (M2 is at least one element selected out from among Mg, Ca Sr and Ba, M3 is at least one element selected out from among Al, Ga, In, Sc, Y, La, Gd and Lu, (b) is 0.001≤b≤0.05). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a light-emitting device including a semiconductor light-emitting element that emits primary light and a wavelength conversion unit that includes a phosphor that absorbs the primary light and emits secondary light, and in particular, white light having high efficiency and low color temperature. The present invention relates to a light emitting device that can emit light.

  Light-emitting devices that combine such semiconductor light-emitting elements and wavelength conversion units are attracting attention as next-generation light-emitting devices that are expected to have low power consumption, small size, high brightness, and a wide range of color reproducibility. It is active.

  As the primary light emitted from the light emitting element, one having a wavelength in the blue range from the long wavelength side of ultraviolet rays, that is, in the range of about 380 nm to 480 nm is usually used. In addition, wavelength conversion units using various phosphors suitable for use in converting such primary light into secondary light have also been proposed.

  Furthermore, recently, with respect to this type of light emitting device, light emission at various color temperatures (warm white to light bulb color) has been desired due to diversification of color sense as well as efficiency (brightness).

In the present existing white light emitting device, a blue light emitting element (peak wavelength, around 450 nm) and activated by trivalent cerium which is excited by the blue light and emits yellow light (Y, Gd) ₃ ( Combinations with Al, Ga) ₅ O ₁₂ phosphors or (Sr, Ba, Ca) ₂ SiO ₄ phosphors activated with divalent europium are mainly used.

  However, in these light emitting devices, it is very difficult to obtain light having a color temperature of 4000 K or less. For example, if a color temperature of 3000 K is to be reproduced, a deviation (duv) described later becomes around +0.04, Only very yellowish white light can be obtained, and it is difficult to obtain a clear color temperature of 3000K.

Therefore, for this type of light emitting device, there is an urgent need to develop a product that can emit clear low color temperature light in order to meet market needs.
JP 2004-186278 A JP 2003-124527 A JP 2001-127346 A JP 2005-109085 A

Regarding this type of light emitting device, in (Example 2-2) in Japanese Patent Application Laid-Open No. 2004-186278 of Patent Document 1, (Ca _0.15 Eu _0.06 ) (Si, Al) ₁₂ (O, N) ₁₆ phosphor is 350 It describes that it has an excitation peak at ˜500 nm and exhibits an emission peak at 550 to 650 nm. Furthermore, various examples in Patent Document 1 describe excitation and emission characteristics of various phosphors. However, Patent Document 1 basically focuses on improving the color rendering of red, and does not mention white light with a low color temperature.

  FIG. 14 in Japanese Patent Application Laid-Open No. 2003-124527 of Patent Document 2 shows a blue LED (wavelength 460 nm) and a GO-phosphor (sialon activated by divalent europium emitting yellow-orange) 0.5 The color coordinates of the mixture with GO-phosphor at a mixing rate of ˜9% are shown. Patent Document 2 describes that a colored LED having a desired color is realized and color coordinates on a connecting line from blue, pink to yellow-orange are achieved. However, this Patent Document 2 does not mention a specific low color temperature white light.

  Japanese Patent Application Laid-Open No. 2001-127346 of Patent Document 3 discloses a combination of a blue light-emitting element, a yellow light-emitting phosphor (YAG phosphor), and a red light-emitting phosphor (CuS phosphor: emission near a wavelength of 630 nm). In addition, it is described that the color rendering property can be increased thereby, and that the color tone is broadened because it contains light of three colors of blue, yellow, and red. However, the CuS phosphor reacts with moisture, is easily oxidized, is chemically unstable, and Patent Document 3 does not mention specific low color temperature white light.

  Japanese Patent Application Laid-Open No. 2005-109085 of Patent Document 4 discloses an LED chip that emits ultraviolet light, an α-type silicon nitride phosphor that emits yellow visible light when excited by ultraviolet light emitted from the LED chip, and a blue system. A white light emitting diode is described in combination with an oxide phosphor that emits visible light. Even in the case of Patent Document 4, it is difficult to obtain a product with a low color temperature, which is completely different from the conventional white light emitting device.

On the other hand, (Y, Gd) ₃ (Al, Ga) ₅ O activated by a blue light emitting element (peak wavelength is around 450 nm) and trivalent cerium which is excited by the blue light and emits yellow light. _{When 12} phosphors are used, white light can be emitted with high efficiency only when the peak wavelength of the primary light from the light emitting element is around 450 nm, and the peak wavelength of the primary light is 380 nm. Cannot be applied over the entire wavelength region in the range from 480 nm to 480 nm.

  As a result of sufficiently investigating and examining the problems in the prior art as described above, the present invention uses a specific phosphor that emits light with high efficiency by light within a range of 380 nm to 480 nm from a semiconductor light emitting device. Another object of the present invention is to provide a light emitting device that emits white light with high efficiency and low color temperature.

A light-emitting device according to an aspect of the present invention includes a light-emitting element that emits primary light, and a wavelength conversion unit that absorbs part of the primary light and emits secondary light including a wavelength equal to or greater than the wavelength. The wavelength conversion unit includes one or more yellow light-emitting phosphors and one or more red light-emitting phosphors, and the yellow light-emitting phosphors are represented by the general formula: 2 (M1 _1-a Eu _a ) O.SiO _2. (In the formula, M1 includes at least Sr and is composed of one or more elements selected from Mg, Ca and Ba including Sr, and a is a number satisfying 0.005 ≦ a ≦ 0.10. And a divalent europium-activated silicate phosphor substantially represented by the following formula: Sr composition is 0.5 or more when the combined composition of M1 and Eu is 1. The body has the general formula: (M2 _1-b Eu _b ) M3SiN ₃ (wherein M2 is Mg, Ca, S at least one element selected from r and Ba; M3 represents at least one element selected from Al, Ga, In, Sc, Y, La, Gd and Lu; and b is 0.001 ≦ b ≦ And a divalent europium-activated nitride phosphor substantially represented by the formula (1).

  In this case, the light emitting element is formed of a gallium nitride semiconductor, and the peak wavelength of the primary light emitted from the light emitting element may be in the range of 430 nm to 480 nm.

A light-emitting device according to another aspect of the present invention includes a light-emitting element that emits primary light, and a wavelength conversion unit that absorbs part of the primary light and emits secondary light including a wavelength equal to or greater than the wavelength. The wavelength conversion unit includes one or more blue light-emitting phosphors, one or more yellow light-emitting phosphors, and one or more red light-emitting phosphors, and the blue light-emitting phosphor has a general formula: (M4 , Eu) ₁₀ (PO ₄ ) ₆ · Cl ₂ (wherein M4 is an alkaline earth metal element and represents at least one element selected from Mg, Ca, Sr and Ba). Divalent europium activated halophosphate phosphor, general formula: c (M5, Eu) O.dAl ₂ O ₃ (wherein M5 is a divalent metal element, Mg, Ca, Sr, Ba and And at least one element selected from Zn, c and d are c> 0, d> 0, and 0.1 ≦ c / d ≦ 1.0 is a number satisfying) substantially bivalent with europium activated aluminate phosphor represented by, and the general _{formula: c (M5, Eu e,} Mn f ) O.dAl ₂ O ₃ (wherein M5 is a divalent metal element and represents at least one element selected from Mg, Ca, Sr, Ba and Zn, and c, d, e and f are c) > 0, d> 0, 0.1 ≦ c / d ≦ 1.0, and 0.001 ≦ f / e ≦ 0.2). It contains at least one selected from manganese-activated aluminate phosphors, and the yellow light-emitting phosphor has the general formula: 2 (M1 _1-a Eu _a ) O.SiO ₂ (wherein M1 contains at least Sr) And one or a plurality of elements selected from Mg, Ca and Ba including Sr, and a is 0 0.005 ≦ a ≦ 0.10, and the composition of Sr is 0.5 or more when the combined composition of M1 and Eu is 1, the divalent europium substantially represented by The red light emitting phosphor includes an activated silicate phosphor, and has a general formula: (M2 _1-b Eu _b ) M3SiN ₃ (wherein M2 is at least one element selected from Mg, Ca, Sr and Ba) M3 represents at least one element selected from Al, Ga, In, Sc, Y, La, Gd and Lu, and b is a number satisfying 0.001 ≦ b ≦ 0.05. A divalent europium activated nitride phosphor substantially represented is included.

  In this case, the light emitting element is formed of a gallium nitride semiconductor, and the peak wavelength of the primary light emitted from the light emitting element is preferably in the range of 380 nm to 420 nm.

  M3 in the above phosphor composition may be at least one element selected from Al, Ga and In. Moreover, it is preferable that the multiple types of phosphors included in the wavelength conversion unit are stacked in the order of phosphors that emit secondary light having a longer wavelength along the optical path of the primary light emitted from the light emitting element. Thus, by making the wavelength conversion part into a laminated structure, it is possible to prevent the phosphor that emits the secondary light having the long wavelength from being excited by absorbing the light emitted from the phosphor that emits the secondary light having the short wavelength. This makes it possible to avoid a light emission loss of particularly short wavelength light during wavelength conversion.

The light emitting device as described above can emit white light having a color temperature of 4000K or less. When the color temperature of white light from the light emitting device exceeds 4000K, a conventional blue light emitting element (peak wavelength is around 450 nm) and trivalent cerium that emits yellow light when excited by the blue light. Even in combination with activated (Y, Gd) ₃ (Al, Ga) ₅ O ₁₂ phosphor or (Sr, Ba, Ca) ₂ SiO ₄ phosphor activated with divalent europium, Clear white light with a small deviation (duv) can be obtained.

  In the light emitting device having the wavelength conversion unit including the phosphor according to the present invention as described above, the light emitted from the light emitting element is efficiently absorbed to emit white light with high efficiency, and clear white light without yellowing is obtained. be able to.

  A light-emitting device of the present invention includes a light-emitting element that emits primary light, a wavelength conversion unit that absorbs a part of the primary light and emits secondary light having a wavelength longer than the wavelength of the primary light, and Is basically provided. The wavelength conversion unit in the light emitting device of the present invention includes one or more yellow light emitting phosphors and one or more red light emitting phosphors.

The yellow light-emitting phosphor used for the wavelength conversion unit in the light-emitting device of the present invention is
General formula: 2 (M1 _1-a Eu _a ) O.SiO ₂
Is a divalent europium activated silicate phosphor substantially represented by

  In the above general formula, M1 is an alkaline earth metal, and preferably contains at least Sr and is composed of one or more elements selected from Mg, Ca and Ba including Sr.

  In the above general formula, the value of a is 0.005 ≦ a ≦ 0.10, and preferably 0.01 ≦ a ≦ 0.05. When the value of a is less than 0.005, there is a problem that sufficient brightness cannot be obtained, and when the value of a exceeds 0.10, there is a problem that the brightness is greatly reduced. In the above general formula, when the total composition of M1 and Eu is 1, the composition of Sr is 0.5 or more.

  Further, the particle size (average particle size, ventilation method) of the yellow light-emitting phosphor in the wavelength conversion part of the light emitting device of the present invention is not particularly limited, but is preferably in the range of 6 to 15 μm. More preferably, it is in the range of 8 to 13 μm. If the particle size of the yellow light-emitting phosphor is less than 6 μm, crystal growth is insufficient and the brightness tends to decrease greatly. If it exceeds 15 μm, it is difficult to control sedimentation in ordinary resins. It is because it tends to become.

Moreover, the red light emitting phosphor used for the wavelength conversion unit in the light emitting device of the present invention,
General formula: (M2 _1-b Eu _b ) M3SiN ₃
Is a divalent europium activated nitride phosphor substantially represented by

  In the above general formula, M2 is an alkaline earth metal and represents at least one element selected from Mg, Ca, Sr and Ba. In the above general formula, M3 is a trivalent metal element and represents at least one element selected from Al, Ga, In, Sc, Y, La, Gd, and Lu.

  In the above general formula, the value of b is 0.001 ≦ b ≦ 0.05, and preferably 0.005 ≦ b ≦ 0.02. When the value of b is less than 0.001, there is a problem that sufficient brightness cannot be obtained. When the value of b exceeds 0.05, there is a problem that the brightness is greatly reduced due to concentration quenching or the like. is there.

  Further, the particle diameter (average particle diameter, aeration method) of the red light emitting phosphor in the wavelength conversion part of the light emitting device of the present invention is not particularly limited, but is preferably in the range of 3 to 10 μm. More preferably, it is in the range of 4 to 7 μm. When the particle size of the red light emitting phosphor is less than 3 μm, crystal growth is insufficient and the brightness tends to be greatly reduced. On the other hand, when a particle having a particle size exceeding 10 μm is prepared, abnormally grown coarse particles are likely to be generated, which is not practical.

  In the light emitting device of the present invention, as the red light emitting phosphor, a divalent europium activated nitride phosphor in which M3 is at least one element selected from Al, Ga and In in the above general formula It is preferable to use. By using the divalent europium activated nitride phosphor as a red light emitting phosphor, it is possible to emit red light with higher efficiency.

  In the light emitting device of the present invention, the plurality of phosphors used in the wavelength conversion unit are stacked in the order of phosphors having a long wavelength of secondary light from the primary light incident side to the emission side of the wavelength conversion unit. It is preferable that By being laminated in this manner, the visible light emitted from the phosphor layer is hardly absorbed by the phosphor layer laminated thereon and can be effectively taken out to the outside. A light-emitting device can be provided. Specifically, the phosphors are stacked in the order of red light emitting phosphors and yellow light emitting phosphors (and blue light emitting phosphors) from the primary light incident side to the emission side of the wavelength conversion unit. It is preferable that

  The wavelength conversion unit in the light emitting device of the present invention contains the above-described yellow light emitting phosphor and red light emitting phosphor, absorbs a part of the primary light emitted from the light emitting element, and has a wavelength equal to or greater than the wavelength of the primary light. The medium is not particularly limited as long as it can emit secondary light having a wavelength of λ. As the medium (transparent resin), for example, an epoxy resin, a silicone resin, a urea resin, or the like can be used.

In addition to the phosphor and the medium described above, the wavelength conversion unit is a suitable additive such as SiO ₂ , TiO ₂ , ZrO ₂ , Al ₂ O ₃ , and Y ₂ O ₃ as long as the effects of the present invention are not impaired. Of course, it may be contained.

  As the light-emitting element used in the light-emitting device of the present invention, a gallium nitride (GaN) -based semiconductor can be preferably used from the viewpoint of efficiency. From the viewpoint of efficiently emitting light from the light emitting device of the present invention, the light emitting element used in the light emitting device of the present invention emits primary light having a peak wavelength in the range of 430 nm to 480 nm (more preferably 460 nm to 480 nm). It is preferable. When the peak wavelength of the primary light emitted from the light emitting element is less than 430 nm, the color rendering is deteriorated, and there is a possibility that it does not meet the object of the present invention. On the other hand, if it exceeds 480 nm, the brightness in white tends to be reduced, which tends to be impractical.

  The present invention also provides a light emitting device including a wavelength conversion unit further including one or more blue light emitting phosphors in addition to the one or more yellow light emitting phosphors and one or more red light emitting phosphors. To do. In this case, as the blue light emitting phosphor, the following divalent europium activated halophosphate phosphor, divalent europium activated aluminate phosphor, and divalent europium and manganese activated aluminate fluorescence At least one selected from the body is preferable.

The divalent europium activated halophosphate phosphor used as the blue light-emitting phosphor in the present invention is:
General formula: (M4, Eu) ₁₀ (PO ₄ ) ₆ · Cl ₂
Is substantially represented by Here, in the above general formula, M4 is an alkaline earth metal and represents at least one element selected from Mg, Ca, Sr and Ba.

In addition, the divalent europium activated aluminate phosphor used as the blue light-emitting phosphor in the present invention,
General formula: c (M5, Eu) O.dAl ₂ O ₃
Is substantially represented by Here, in the above general formula, M5 is a divalent metal element and represents at least one element selected from Mg, Ca, Sr, Ba and Zn.

  In the above general formula, the ratio (c / d) between the divalent metal element and Al is 0.1 ≦ c / d ≦ 1.0. With other compositions, a satisfactory blue light-emitting phosphor is obtained. The characteristics cannot be obtained. In the above general formula, c> 0 and d> 0.

In addition, the divalent europium and manganese activated aluminate phosphor used as the blue light-emitting phosphor in the present invention,
General _{formula: c (M5, Eu e,} Mn f) O · dAl 2 O 3
Is substantially represented by In the above general formula, M5 is a divalent metal element and represents at least one element selected from Mg, Ca, Sr, Ba and Zn, as described above.

  The ratio (c / d) of the divalent metal element to Al is preferably 0.1 ≦ c / d ≦ 1.0. With other compositions, satisfactory characteristics as a blue light-emitting phosphor are obtained. I can't get it. Further, the ratio (e / f) between europium and manganese is preferably 0.001 ≦ e / f ≦ 0.2, and if it is less than 0.001, the contribution of light emission of manganese is not recognized. When it exceeds 2, the brightness in white decreases, which is not practical. In the above general formula, c> 0 and d> 0.

  The particle size of the blue light-emitting phosphor in the wavelength conversion part of the light-emitting device of the present invention is not particularly limited, but in the case of a divalent europium-activated halophosphate phosphor, 3.0 to 9 It is preferably within a range of 0.0 μm, and more preferably within a range of 4.5 to 6.5 μm. When the particle diameter of the divalent europium activated halophosphate phosphor is less than 3.0 μm, crystal growth is insufficient and the brightness tends to be greatly reduced. On the other hand, when a particle having a particle diameter exceeding 9.0 μm is prepared, abnormally grown coarse particles are likely to be generated, which tends to be impractical. In the case of a divalent europium activated aluminate phosphor or a divalent europium and manganese activated aluminate phosphor, it is preferably in the range of 2.0 to 7.0 μm, 3.0 More preferably, it is in the range of ˜5.0 μm. If the particle size of the divalent europium activated aluminate phosphor or the divalent europium and manganese activated aluminate phosphor is less than 2.0 μm, crystal growth is insufficient and the brightness is greatly reduced. Tend to. On the other hand, when a particle having a particle diameter exceeding 7.0 μm is prepared, abnormally grown coarse particles are likely to be generated and tend to be impractical.

  In addition to the yellow light-emitting phosphor and the red light-emitting phosphor described above, in a light emitting device including a wavelength conversion unit further including a blue light-emitting phosphor, those suitable as the yellow light-emitting phosphor and the red light-emitting phosphor are The same as described above. Also in the light emitting device of such an aspect, the plurality of phosphors used in the wavelength conversion unit are arranged in the order of phosphors having a long wavelength of secondary light from the light incident side to the emission side of the wavelength conversion unit. It is preferable that they are laminated. Also, the same medium as described above can be suitably used as the medium used for forming the wavelength conversion section.

  From the viewpoint of efficiency, gallium nitride (GaN) is used as a light emitting device used in a light emitting device including a wavelength conversion unit further including a blue light emitting phosphor in addition to the yellow light emitting phosphor and the red light emitting phosphor described above. A system semiconductor can be preferably used.

  In addition to the yellow light-emitting phosphor and the red light-emitting phosphor, the light-emitting element used in the light-emitting device including the wavelength conversion unit further including the blue light-emitting phosphor is from the viewpoint of efficiently emitting the blue light-emitting phosphor. In addition, it is preferable to emit primary light having a peak wavelength in the range of 380 nm to 420 nm, and it is more preferable to emit primary light in the range of 395 nm to 410 nm. When the peak wavelength of the primary light emitted from the light emitting element is less than 380 nm, the deterioration of the resin or the like cannot be ignored, and there is a possibility that it is not practical. On the other hand, if it exceeds 420 nm, the emission intensity of the blue light-emitting phosphor is greatly reduced, which may be impractical.

  In addition, the light emitting device of the present invention preferably emits white light having a correlated color temperature of 4000 K or less. Here, the correlated color temperature refers to that specified in JIS-Z8725.

  The yellow light-emitting phosphor, red light-emitting phosphor and blue light-emitting phosphor used in the light-emitting device of the present invention may be those prepared by a conventionally known appropriate method, or those commercially available. Of course, it may be used. In addition, the wavelength conversion unit in the light emitting device of the present invention disperses the above-described yellow light emitting phosphor and red light emitting phosphor (and sometimes the blue light emitting phosphor) in an appropriate resin, and under appropriate conditions. It can be produced by molding, and its production method is not particularly limited.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated in detail, this invention is not limited to these.

Example 1
FIG. 1 is a schematic longitudinal sectional view showing a light emitting device of Example 1 according to the present invention. The light emitting device 10 includes a light emitting element 11 that emits primary light, and a wavelength converter 12 that absorbs at least a part of the primary light and emits secondary light having a wavelength equal to or greater than the wavelength of the primary light. ing. The wavelength converter 12 includes a red light emitting phosphor 13 and a yellow light emitting phosphor 14 dispersed in a resin.

In Example 1, a gallium nitride (GaN) -based semiconductor having an emission peak wavelength at 450 nm was used as the light emitting layer of the light emitting element 11. In the wavelength conversion unit 12, 2 (Sr _0.93 Ba _0.05 Eu _0.02 ) O · SiO ₂ is used as the yellow light-emitting phosphor 14, and (Ca _0.98 Eu _0.02 ) AlSiN ₃ is used as the red light-emitting phosphor 13.

  That is, the wavelength conversion part 12 is produced by mixing these yellow light-emitting phosphors 14 and red light-emitting phosphors 13 in a ratio of 1: 0.2 and dispersing them in a predetermined resin. Thus, the characteristics of the light emitting device 10 incorporating the light emitting element 11 and the wavelength conversion unit 12 are evaluated, and the evaluation results are shown in Table 1.

On the other hand, the light-emitting device of Comparative Example 1 is the same as Example 1 except that the composition of the yellow light-emitting phosphor 14 is changed to (Y _0.50 Gd _0.35 Ce _0.15 ) ₃ Al ₅ O ₁₂ in the wavelength converter 12. Was also made. The characteristics of the light emitting device of Comparative Example 1 were also evaluated, and the evaluation results are also shown in Table 1.

  As is apparent from Table 1, it can be seen that the light emitting device of Example 1 can obtain clear white light without yellowing as compared with Comparative Example 1 corresponding to the conventional product. That is, in the first embodiment, the deviation (duv) is much smaller than that in the first comparative example.

Here, Tc represents the correlated color temperature of the light emission color of the light emitting device, and duv represents the light emission on the deviation (U * V * W * chromaticity diagram (CIE1964 uniform color space)) of the light emission chromaticity point from the black body radiation locus. Represents the length of the perpendicular drawn from the chromaticity point of the color to the blackbody radiation locus). If duv is 0.01 or less, it is said that it is perceived as uncolored white like a normal tungsten filament bulb.

  In Table 1, although the brightness of the light emitting device of Example 1 is lower than that of Comparative Example 1, the composition range of the phosphor in the present invention so as to produce the same Tc-duv value as Comparative Example 1. In the case of adjusting the brightness, it is possible to obtain a brightness approximately equal to or higher than that of Comparative Example 1.

  On the other hand, in the case of Comparative Example 1, no matter how the phosphor composition range is adjusted, it is not possible to make the Tc-duv equivalent to that of Example 1.

(Example 2)
FIG. 2 is a schematic longitudinal sectional view of the light emitting device of Example 2 according to the present invention. The light emitting device includes a light emitting element 11 that emits primary light, and a wavelength conversion unit 20 that absorbs at least part of the primary light and emits secondary light having a wavelength equal to or greater than the wavelength of the primary light. Yes. The wavelength conversion unit 20 includes a resin layer 21 including a dispersed red light emitting phosphor and a resin layer 22 including a dispersed yellow light emitting phosphor. The resin layer 21 containing the red light emitting phosphor is disposed in the vicinity of the light emitting element 11, and the resin layer 22 containing the yellow light emitting phosphor is laminated thereon.

In Example 2, a gallium nitride (GaN) -based semiconductor having an emission peak wavelength at 450 nm was used as the light emitting layer of the light emitting element 11. In the wavelength conversion unit 20, 2 (Sr _0.900 Ba _0.075 Ca _0.010 Eu _0.015 ) O · SiO ₂ is used as the yellow light-emitting phosphor, and (Ca _0.97 Sr _0.01 Eu _0.02 ) (Al _0.98 Ga _0.02 ) as the red light-emitting phosphor. ) SiN ₃ was used.

  That is, the yellow light-emitting phosphor and the red light-emitting phosphor are dispersed in separate resins, respectively, and the resin layer 21 including the red light-emitting phosphor and the resin layer 22 including the yellow light-emitting phosphor are arranged in this order. The wavelength conversion part 22 was produced by laminating. Thus, the characteristics of the light-emitting device incorporating the light-emitting element 11 and the wavelength conversion unit 20 are evaluated, and the evaluation results are shown in Table 2.

  On the other hand, the light emitting device of Reference Example 1 was used under the same conditions as in Example 2 except that the yellow light emitting phosphor and red light emitting phosphor of Example 2 were mixed and dispersed in the same resin layer. Was made. The characteristics of the light emitting device of Reference Example 1 were also evaluated, and the evaluation results are also shown in Table 2.

  As is clear from Table 2, clear white light without yellowing is also obtained in the light emitting device of Example 2. As is clear from comparison with Reference Example 1, the brightness of the light-emitting device is also significantly improved by laminating a resin layer containing a phosphor having a longer secondary light wavelength in order from the side closer to the light-emitting element 11. I understand that

(Example 3)
In Example 3 according to the present invention, a gallium nitride (GaN) -based semiconductor having an emission peak wavelength at 435 nm was used as the light emitting layer of the light emitting element. In the wavelength conversion section, 2 (Sr _0.90 Ba _0.07 Ca _0.01 Eu _0.02 ) O.SiO ₂ is used as the yellow light emitting phosphor, and (Ca _0.985 Eu _0.015 ) (Al _0.99 In _0.01 ) SiN ₃ is used as the red light emitting phosphor. Was used. These yellow light-emitting phosphors and red light-emitting phosphors were mixed at a predetermined ratio and dispersed in the same resin layer, whereby a wavelength conversion unit was produced. The characteristics of the light emitting device of Example 3 incorporating such a light emitting element and a wavelength conversion unit were evaluated, and the evaluation results are shown in Table 3.

On the other hand, except that a gallium nitride (GaN) based semiconductor having a peak wavelength at 460 nm is used as the light emitting layer of the light emitting element and the yellow light emitting phosphor is changed to (Y _0.45 Gd _0.42 Ce _0.13 ) ₃ Al ₅ O _12. A light emitting device of Comparative Example 2 was fabricated under the same conditions as in Example 3. The characteristics of the light emitting device of Comparative Example 2 were also evaluated, and the evaluation results are also shown in Table 3.

  As is apparent from Table 3, it can be seen that the light emitting device of the third embodiment can obtain clear white light without yellowing as compared with the comparative example 2 corresponding to the conventional product.

Example 4
FIG. 3 is a schematic longitudinal sectional view of the light emitting device of Example 4 according to the present invention. The light emitting device includes a light emitting element 30 that emits primary light, and a wavelength conversion unit 31 that absorbs at least part of the primary light and emits secondary light having a wavelength equal to or greater than the wavelength of the primary light. Yes. The wavelength conversion unit 31 includes a resin layer 21 including a dispersed red light emitting phosphor, a resin layer 22 including a dispersed yellow light emitting phosphor, and a resin layer 32 including a dispersed blue light emitting phosphor. Including. Then, a resin layer 21 containing a red light emitting phosphor is disposed in the vicinity of the light emitting element 30, and a resin layer 22 containing a yellow light emitting phosphor and a resin layer 32 containing a blue light emitting phosphor are sequentially formed thereon. Are stacked.

In Example 4, a gallium nitride (GaN) -based semiconductor having an emission peak wavelength at 380 nm was used as the light emitting layer of the light emitting element 30. The wavelength conversion unit 31 includes (Ba _0.50 Sr _0.35 Eu _0.15 ) MgAl ₁₀ O _{17 as} a blue light emitting phosphor, 2 (Sr _0.900 Ba _0.075 Ca _0.010 Eu _0.015 ) O · SiO ₂ as a yellow light emitting phosphor, (Ca _0.97 Sr _0.01 Eu _0.02 ) (Al _0.98 Ga _0.02 ) SiN ₃ was used as a red light emitting phosphor. That is, the blue light-emitting phosphor, the yellow light-emitting phosphor, and the red light-emitting phosphor are dispersed in separate resins, respectively, and the resin layer 21 including the red light-emitting phosphor from the light emitting element side, the yellow light-emitting phosphor, The wavelength conversion part 31 was produced by laminating | stacking in order of the resin layer 22 containing a light emission fluorescent substance, and the resin layer 32 containing a blue-type light emission fluorescent substance. Thus, the characteristic was evaluated about the light-emitting device of the present Example 4 incorporating the light-emitting element 30 and the wavelength conversion unit 31, and the evaluation results are shown in Table 4.

  On the other hand, under the same conditions as in Example 4, except that the yellow light-emitting phosphor, red light-emitting phosphor, and blue light-emitting phosphor of Example 4 were mixed and dispersed in the same resin layer. A light emitting device of Reference Example 2 was produced. The characteristics of the light emitting device of Reference Example 2 were also evaluated, and the evaluation results are also shown in Table 4.

  As is clear from Table 4, the light emitting device of Example 4 can obtain clear white light without yellowishness. Further, as apparent from comparison with Reference Example 3, the brightness of the light emitting device can be improved by laminating a resin layer containing a phosphor having a longer secondary light wavelength in order from the light emitting element 30 in order. It turns out that it improves remarkably.

(Examples 5 to 10)
Although it is similar to Example 1, the light emission device of Examples 5-10 and Comparative Examples 3-8 by this invention was produced by changing the light emission peak wavelength of a light emitting element, and the composition of a fluorescent substance variously. Various characteristics of these light emitting devices are evaluated, and the evaluation results are summarized in Table 5.

  As is clear from Table 5, in the light emitting devices of Examples 5 to 10 according to the present invention, clear white light without yellowing can be obtained as compared with Comparative Examples 3 to 8 corresponding to conventional products. .

  In addition, the light emission peak wavelength of the light emitting element of each above-mentioned Example is not necessarily limited to the value shown in those Examples, and in Examples 1-3 and 5-8, it exists in the range of 430-480 nm. In Examples 4, 9, and 10, it may be in the range of 380 to 420 nm.

  Further, the phosphor is not limited to the composition range described in each of the above-described embodiments, and may be within the composition range of each constituent element described in the column of “Means for Solving the Problems”. .

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  As described above, according to the present invention, by using a specific phosphor that emits light with high efficiency by light in the range of 380 nm to 480 nm from a semiconductor light emitting device, white light with high efficiency and low color temperature can be obtained. A light emitting device that emits light can be provided.

It is a typical longitudinal cross-sectional view of the principal part in the light-emitting device of Example 1 by this invention. It is a typical longitudinal cross-sectional view of the principal part in the light-emitting device of Example 2 by this invention. It is a typical longitudinal cross-sectional view of the principal part in the light-emitting device of Example 4 by this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Light-emitting device, 11 Light-emitting element, 12 Wavelength conversion part, 13 Red light emission fluorescent substance, 14 Yellow light emission fluorescent substance, 20 Wavelength conversion part, 21 Resin layer containing red light emission fluorescent substance, 22 Yellow light emission fluorescent substance A resin layer containing 30 light emitting elements, 31 a wavelength conversion part, 32 a resin layer containing a blue light emitting phosphor.

Claims (7)

A light emitting element that emits primary light, and a wavelength conversion unit that absorbs part of the primary light and emits secondary light including a wavelength equal to or greater than the wavelength of the primary light,
The wavelength conversion unit includes one or more yellow light-emitting phosphors and one or more red light-emitting phosphors,
The yellow light-emitting phosphor is
General formula: 2 (M1 _1-a Eu _a ) O.SiO ₂
(In the formula, M1 includes at least Sr and is composed of one or more elements selected from Mg, Ca and Ba including Sr, and a is a number satisfying 0.005 ≦ a ≦ 0.10. Yes, the composition of Sr is 0.5 or more when the combined composition of M1 and Eu is 1.
A divalent europium activated silicate phosphor substantially represented by:
The red light emitting phosphor is
General formula: (M2 _1-b Eu _b ) M3SiN ₃
(Wherein M2 represents at least one element selected from Mg, Ca, Sr and Ba, and M3 represents at least one element selected from Al, Ga, In, Sc, Y, La, Gd and Lu. And b is a number satisfying 0.001 ≦ b ≦ 0.05)
And a divalent europium activated nitride phosphor substantially represented by the formula:   2. The light emitting device according to claim 1, wherein the light emitting element is formed of a gallium nitride based semiconductor, and a peak wavelength of the primary light emitted from the light emitting element is in a range of 430 nm to 480 nm. A light emitting element that emits primary light, and a wavelength conversion unit that absorbs part of the primary light and emits secondary light including a wavelength equal to or greater than the wavelength of the primary light,
The wavelength conversion unit includes one or more blue light-emitting phosphors, one or more yellow light-emitting phosphors, and one or more red light-emitting phosphors,
The blue light emitting phosphor is
General formula: (M4, Eu) ₁₀ (PO ₄ ) ₆ · Cl ₂
(In the formula, M4 is an alkaline earth metal element and represents at least one element selected from Mg, Ca, Sr and Ba)
A divalent europium-activated halophosphate phosphor substantially represented by:
General formula: c (M5, Eu) O.dAl ₂ O ₃
(Wherein M5 is a divalent metal element and represents at least one element selected from Mg, Ca, Sr, Ba and Zn, and c and d are c> 0, d> 0, and 0.1 ≦ c / d ≦ 1.0 is satisfied)
In divalent europium-activated aluminate phosphor substantially represented, and the general _{formula: c (M5, Eu e,} Mn f) O · dAl 2 O 3
(Wherein, M5 is a divalent metal element and represents at least one element selected from Mg, Ca, Sr, Ba and Zn, and c, d, e and f are c> 0, d> 0, 0.1 ≦ c / d ≦ 1.0 and 0.001 ≦ f / e ≦ 0.2)
At least one selected from divalent europium and manganese-activated aluminate phosphors substantially represented by:
The yellow light-emitting phosphor is
General formula: 2 (M1 _1-a Eu _a ) O.SiO ₂
(In the formula, M1 includes at least Sr and is composed of one or more elements selected from Mg, Ca and Ba including Sr, and a is a number satisfying 0.005 ≦ a ≦ 0.10. Yes, the composition of Sr is 0.5 or more when the combined composition of M1 and Eu is 1.
A divalent europium activated silicate phosphor substantially represented by:
The red light emitting phosphor is
General formula: (M2 _1-b Eu _b ) M3SiN ₃
(Wherein M2 represents at least one element selected from Mg, Ca, Sr and Ba, and M3 represents at least one element selected from Al, Ga, In, Sc, Y, La, Gd and Lu. And b is a number satisfying 0.001 ≦ b ≦ 0.05)
And a divalent europium activated nitride phosphor substantially represented by the formula:   4. The light emitting device according to claim 3, wherein the light emitting element is formed of a gallium nitride based semiconductor, and a peak wavelength of the primary light emitted from the light emitting element is in a range of 380 nm to 420 nm. .   5. The light emitting device according to claim 1, wherein M3 is at least one element selected from Al, Ga and In.   The plurality of types of phosphors included in the wavelength conversion unit are stacked in the order of phosphors emitting secondary light having a longer wavelength along the optical path of the primary light emitted from the light emitting element. The light emitting device according to claim 1.   The light-emitting device according to claim 1, wherein the light-emitting device emits white light having a color temperature of 4000 K or less.

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