JP3645422B2 - Light emitting device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a light emitting device, and more particularly to a light emitting device in which a light emitting element such as a semiconductor light emitting element and a wavelength conversion means such as a phosphor are combined.
[0002]
[Prior art]
2. Description of the Related Art A light-emitting device that combines a semiconductor light-emitting element such as an LED (light emitting diode) and a phosphor is attracting attention as a light-emitting device that is inexpensive and has a long life and is being widely used. In particular, white light-emitting devices are expected to be used in various ways as light-emitting devices that replace fluorescent lamps or as light sources for display devices.
[0003]
FIG. 6 is a schematic cross-sectional view showing a conceptual configuration of a conventional white light-emitting device. That is, in the conventional light emitting device, the blue light emitting LED 111 is mounted on the cup portion of the lead frame 116 and the periphery thereof is molded with the resin 112. The LED 111 is appropriately wired by a wire 114. A phosphor 117 is applied on the resin 112. Further, the periphery thereof is sealed with a sealing resin 113.
[0004]
In the light emitting device of FIG. 6, a part of the blue light of the primary light emitted from the blue light emitting LED 111 is absorbed by the phosphor 117, and yellow light is emitted as the secondary light. That is, white light is generated by the blue light emitted from the LED 111 and the yellow light emitted from the phosphor 117.
[0005]
[Problems to be solved by the invention]
However, as a result of the inventor's trial production and evaluation, it has been found that the conventional light emitting device as shown in FIG. 6 has the following problems. That is,
(1) There is a large variation in white balance between devices.
(2) The change in white balance due to the change in the supplied current value is large.
(3) The change in white balance due to fluctuations in ambient temperature is large.
(4) A change in white balance due to a change with time of the LED 111 is large.
[0006]
These problems are all caused by the essential characteristics of the blue light emitting LED 111 used as the semiconductor light emitting element. That is, the composition of indium gallium nitride (InGaN) used as the light emitting layer of the blue light emitting LED 111 is difficult to strictly control, and the emission wavelength tends to fluctuate for each growth wafer. Further, it has a characteristic that the emission wavelength varies relatively greatly depending on the current and temperature supplied to the LED. Furthermore, when the light emission operation is continued by supplying current, the emission wavelength tends to fluctuate.
[0007]
In this way, when the wavelength of the blue light emitted from the blue light emitting LED 111 fluctuates, the intensity balance with the yellow light emitted from the phosphor 17 is lost, and the chromaticity coordinates are greatly shifted. As a result, it has been found that there arises a problem that the white balance of the output white light changes greatly.
[0008]
As a method for solving this problem, there is a method using a phosphor that emits light of three colors of R (red), G (green), and B (blue). However, in this case, it is necessary to precisely adjust the blending ratio of the three types of phosphors, and there is a drawback that it is not easy to mix with a predetermined balance. Further, when the phosphors are mixed and applied, there is a drawback that it is difficult to realize a desired uniform mixing form due to the influence of separation caused by the difference in specific gravity of the respective phosphor particles.
[0009]
The present invention has been made based on recognition of such unique problems. That is, an object of the present invention is to provide a light-emitting device having a stable light-emitting characteristic by reliably and easily adjusting a light mixing ratio to a desired balance.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, a light emitting device of the present invention includes a light emitting element that emits ultraviolet light as light of a first wavelength, and absorbs light of the first wavelength to emit light of a second wavelength. First wavelength converting means that absorbs part of the light of the second wavelength and emitting light of the third wavelength, and the light of the second wavelength. The light emitting device is configured to emit white light by emitting light other than the part of the light and the light of the third wavelength.
[0011]
Here, the second wavelength is longer than the first wavelength, the third wavelength is longer than the second wavelength, and the second wavelength converting means is configured to By not substantially absorbing light, the balance between the second wavelength light and the third wavelength light can be extremely stabilized.
[0012]
In a preferred embodiment of the present invention, the first wavelength converting means is a phosphor, and the second wavelength converting means is a phosphor.
[0013]
Further, the light having the first wavelength is ultraviolet light, the light having the second wavelength is blue light, and the light having the third wavelength is yellow light. White light with a very stable white balance can be obtained.
[0014]
The light-emitting element is a semiconductor light-emitting element made of a nitride semiconductor, whereby a high-luminance light-emitting device can be realized.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view illustrating a conceptual configuration of a light emitting device according to an embodiment of the present invention. That is, the light-emitting device shown in the figure is generally called a “vertical LED”, and the light-emitting element 11 is mounted on the cup portion of the lead frame 16 and the periphery thereof is molded with the resin 12. The resin 12 is preferably made of a material that absorbs less light emitted from the light emitting element 11. The light emitting elements 11 are appropriately wired by wires 14. A first wavelength conversion unit 18 and a second wavelength conversion unit 17 are provided on the resin 12. Further, the periphery thereof is sealed with a sealing resin 13.
[0016]
Here, the first wavelength conversion means 18 absorbs the light of the first wavelength emitted from the light emitting element 11 and converts it to the light of the second wavelength longer than that. For example, when an LED that emits ultraviolet light is used as the light emitting element 11, a phosphor that emits blue secondary light when excited by the ultraviolet light can be obtained.
[0017]
On the other hand, the second wavelength conversion means 17 absorbs the secondary light having the second wavelength emitted from the first wavelength conversion means 18 and converts it into secondary light having a longer third wavelength. . As the second wavelength conversion means 17, for example, a phosphor that is excited by blue light emitted from the phosphor 18 and emits yellow secondary light can be used. Here, the phosphor 17 is characterized in that the absorptance with respect to the light of the first wavelength emitted from the light emitting element 11 is low. That is, the phosphor 17 desirably has an absorption peak in the wavelength region of the secondary light emitted from the phosphor 18.
[0018]
If it demonstrates along the above-mentioned specific example, in the light-emitting device of this invention, the ultraviolet light of the primary light discharge | released from the ultraviolet light emission LED11 will be absorbed by the fluorescent substance 17, and blue light will be discharge | released as secondary light. . A part of the blue light is absorbed by the phosphor 17, and yellow light is emitted as secondary light. The phosphor 17 has a low absorptance with respect to the ultraviolet light emitted from the LED 11, and does not substantially cause wavelength conversion. The blue light emitted from the phosphor 18 and the yellow light emitted from the phosphor 17 cause white light emission.
[0019]
As an example of the phosphor that can be used in the present invention, as the blue light emitting phosphor 18 excited by ultraviolet light, for example, Toshiba model 801EJ is available. The specific gravity of 801EJ is 4.2. On the other hand, as the yellow light emitting phosphor 17 excited by blue light, YAG (Ce), that is, (Y _1-a Gd _a ) _Three (Al _1-b Ga _b ) _Five O ₁₂ : There is Ce. The specific gravity of YAG (Ce) is also about 4.2.
[0020]
The following method can be mentioned as an example of how to form the layers of the phosphors 17 and 18.
(1) Cast 801EJ. That is, the phosphor is dispersed in a solvent, applied to the surface of the resin 12 and heated to cure and cure. In this way, a layer of the blue phosphor 18 can be formed. Next, similarly, YAG (Ce) is cast thereon. This series of methods can be used regardless of the magnitude relationship of the specific gravity of the phosphor.
(2) A solvent in which 801EJ is dissolved and a solvent in which YAG (Ce) is dissolved are dropped onto the surface of the resin 12. At this time, in consideration of the specific gravity of the phosphor particles, the viscosity of the solvent and the curing speed, the 801EJ is designed to be a layer below YAG (Ce) by phase separation.
According to the present invention, the primary light emitted from the LED 11 is wavelength-converted only by the phosphor 18 and converted into blue light. The phosphor 17 does not substantially convert the wavelength of the ultraviolet light emitted from the LED 11. This feature makes it possible to obtain an extremely stable white balance.
[0021]
Here, it is assumed that both the phosphor 17 and the phosphor 18 convert the wavelength of the ultraviolet light emitted from the LED 11. In such a case, as described above with reference to FIG. 6, when the emission wavelength of the LED 11 varies, there arises a problem that the white balance varies. This is because it is technically impossible to make the wavelength dependency of the absorption rate of the phosphor 17 and that of the phosphor 18 the same. When the wavelength of the primary light emitted from the LED 11 fluctuates as a result of the difference between the absorption spectra of the two, the balance of the light components absorbed by the phosphor 17 and the phosphor 18 changes and is converted and emitted. This is because the balance of the secondary light to be changed also changes.
[0022]
On the other hand, according to the present invention, the primary light emitted from the LED 11 is wavelength-converted only by the phosphor 18 and converted into blue light. The phosphor 17 does not substantially convert the wavelength of the ultraviolet light emitted from the LED 11. Even if the emission wavelength of the LED 11 varies due to various factors as described above with reference to FIG. 6, the wavelength of the blue light emitted from the phosphor 18 does not vary. A part of the blue light is converted into yellow light by the phosphor 17. That is, according to the present invention, the balance between the blue light and the yellow light emitted to the outside from the light emitting device depends only on the mixing ratio of the phosphor 17 and the phosphor 18, and the light emission wavelength and light emission intensity of the LED 11 are dependent on each other. There is no dependence and it is extremely stable.
[0023]
As described above, according to the present invention, both the blue light and the yellow light extracted to the outside have a very stable wavelength spectrum, and the resulting white balance of the white light is extremely stable.
[0024]
In addition, when using three-color phosphors, precise adjustment of the blending ratio is required, and it is not easy to reproduce white balance, but according to the present invention, only two-color phosphors are used. Therefore, it is much easier to adjust the blending ratio of the phosphors.
[0025]
Examples of the ultraviolet light emitting LED 11 that can be used in the present invention include indium nitride, aluminum, and gallium In. _x Al _y Ga _1-xy A nitride semiconductor light emitting device having N (0 ≦ x <1, 0 ≦ y <1) as an active layer can be given.
[0026]
In this application, “nitride semiconductor” means B _x In _y Al _z Ga _(1-xyz) N (O ≦ x ≦ 1, O ≦ y ≦ 1, O ≦ z ≦ 1) III-V group compound semiconductor, and further, as a group V element, in addition to N, phosphorus (P) or arsenic (As ) And other mixed crystals.
[0027]
FIG. 2 is a schematic cross-sectional view showing a conceptual configuration of the semiconductor light emitting element. The laminated structure of the light emitting element in FIG. Note that the doping material, film thickness, and the like may be changed as appropriate.
(1) Sapphire substrate 131
(2) GaN buffer layer 132
(3) n-type GaN contact layer 133 having a thickness of 4 μm
(4) n-type AlGaN cladding layer 134 having a thickness of 200 μm
(5) InGaN active layer 135 with a film thickness of 50 μm. Here, the active layer may be doped, or the active layer may be a multilayer film such as a multiple quantum well (MQW).
(6) p-type AlGaN cladding layer 136 having a thickness of 200 μm
(7) p-type GaN contact layer 137 with a thickness of 50 μm
The stacked structure described above is partially etched from the surface to the n-type contact layer 133 as shown in the figure, and an n-side electrode 141 is provided. A p-side electrode 143 having transparency is provided on the p-type contact layer 137. Further, bonding pads 142 and 144 are connected to the respective electrodes, and the surface of the element is covered with protective films 145 and 146.
[0028]
Note that the material of the substrate 131 is not limited to sapphire, and other examples include spinel, MgO, and ScAlMgO. _Four LaSrGaO _Four , (LaSr) (AlTa) O _Three Insulating substrates such as SiC and conductive substrates such as SiC, Si, GaAs, and GaN can be used in the same manner to obtain the respective effects. Here, ScAlMgO _Four In the case of a substrate, the (0001) plane, (LaSr) (AlTa) O _Three In the case of a substrate, it is desirable to use the (111) plane.
[0029]
The LED 11 illustrated in FIG. 2 emits ultraviolet light having a wavelength of about 370 to 375 nm with high emission intensity when the composition of the active layer 135 in the group III element of indium (In) is about 2 to 3%. . A white light emitting device combining such an LED, a blue light emitting phosphor excited by ultraviolet light, and a yellow light emitting phosphor excited by blue light is extremely excellent in uniformity and stability of white balance. That is, since the emission wavelength of the phosphor is constant regardless of the intensity and wavelength of the light that excites the phosphor, the wavelength of the light emitting device is constant even if the characteristics of the semiconductor light emitting element vary. For this reason, variations in white balance due to elements, variations in white balance due to current and temperature, or changes in white balance due to element degradation do not occur.
[0030]
Here, in the light emitting device illustrated in FIG. 1, the sealing resin 13 is made of a material having a high absorption rate with respect to ultraviolet rays in order to prevent leakage of ultraviolet rays emitted from the light emitting elements 11 to the outside. It is desirable.
[0031]
In the present embodiment, as a white light emitting device, a device using an ultraviolet light emitting semiconductor light emitting element, a blue light emitting phosphor excited by ultraviolet light, and a yellow light emitting phosphor excited by blue light is given as a specific example. However, the present invention is not limited to this.
[0032]
For example, a light-emitting semiconductor light-emitting element that emits light in a purple wavelength band as a light-emitting element, a blue-green light-emitting phosphor that is excited by violet light as a first phosphor, and a blue-green light that is excited as a second phosphor Even in a light emitting device using each of the red light emitting phosphors, extremely uniform and stable white light can be obtained. Further, the light emitting element used in the present invention is not necessarily a semiconductor light emitting element. That is, in addition to semiconductor light emitting elements such as LEDs and semiconductor lasers, EL (electro-luminescent) elements and other various light emitting elements may be used.
[0033]
Furthermore, it can apply similarly about the light-emitting device which emits light other than white, and can obtain the same hardening. That is, light emission without change in chromaticity coordinates using a first phosphor that emits light when excited by light from the light emitting element and a second phosphor that emits light when excited by light from the first phosphor. A device can be realized.
[0034]
Next, a second embodiment of the present invention will be described.
FIG. 3 is a schematic cross-sectional view showing a light emitting device according to a second embodiment of the present invention. That is, the light-emitting device in the figure is generally called an SMD (Surface Mounted Device) lamp. That is, the wiring pattern 26 is formed on the surface of the mounting substrate 25, and the semiconductor light emitting element 11 is mounted thereon. The light emitting element 11 is appropriately connected to the wiring pattern 26 by a wire 24. The semiconductor light emitting element 11 is a light emitting element that emits light in the ultraviolet region.
[0035]
The phosphors used in the present embodiment are also a blue light emitting phosphor 28 excited by ultraviolet light and a yellow light emitting phosphor 27 excited by blue light. In the figure, 22 is a resin, and a yellow light emitting phosphor 27 excited by blue light is applied on the resin, and a blue light emitting phosphor 28 excited by ultraviolet light is further applied thereon. . Further, the periphery thereof is sealed with a sealing resin 23. The inner resin 22 is formed of a material that absorbs less ultraviolet light.
[0036]
In the present embodiment, the yellow light emitting phosphor 27 is provided closer to the light emitting element 11 than the blue light emitting phosphor 28. In the case of such an arrangement, the ultraviolet light emitted from the light emitting element 11 is transmitted without being absorbed by the yellow light emitting phosphor 27, reaches the blue light emitting phosphor 28 and is absorbed, and is converted into blue light. Is done. Of the blue light, the component emitted toward the inside of the light emitting device is absorbed by the yellow light emitting phosphor 27 and converted into yellow light. That is, also in the present embodiment, white light composed of blue light and yellow light can be extracted outside. Further, the white balance depends on only the ratio between the phosphors 27 and 28 as described above in the first embodiment, and does not depend on the variation in the emission wavelength or emission intensity of the light emitting element 11. . As a result, extremely stable and uniform white light can be obtained.
[0037]
Examples of the phosphors 27 and 28 that can be used in the present embodiment can be the same as those described above with reference to the first embodiment. That is, as the blue light emitting phosphor 28 excited by ultraviolet light, there is the above-mentioned Toshiba model 801EJ. The specific gravity of 801EJ is 4.2. Further, as the yellow light-emitting phosphor 27 excited by blue light, YAG (Ce), that is, (Y _1-a Gd _a ) _Three (Al _1-b Ga _b ) _Five O ₁₂ : There is Ce. Here, YAG (Ce) has an absorption peak in the wavelength region of blue light. That is, while the absorption rate for blue light is extremely high, the absorption rate for light in the ultraviolet region emitted from the light emitting element 11 is extremely low. Accordingly, the primary light emitted from the light emitting element 11 is not substantially absorbed by the yellow phosphor 27, but is transmitted to reach the blue phosphor 28.
[0038]
The method of applying these phosphors 27 and 28 can be the same as that described above with respect to the first embodiment. Ie:
(1) Cast YAG (Ce). That is, the phosphor is dispersed in a solvent, applied to the surface of the resin 22 and heated to cure and cure. In this way, a layer of the blue phosphor 27 can be formed. Next, in the same manner, 801EJ is cast thereon. This series of methods can be used regardless of the magnitude relationship of the specific gravity of the phosphor.
(2) A solvent in which 801EJ is dissolved and a solvent in which YAG (Ce) is dissolved are dropped onto the surface of the resin 12. At this time, in consideration of the specific gravity of the phosphor particles, the viscosity of the solvent and the curing speed, the YAG (Ce) is designed to be a layer below 801EJ by phase separation.
[0039]
Next, a third embodiment of the present invention will be described.
FIG. 4 is a schematic cross-sectional view illustrating a light emitting device according to a third embodiment of the present invention. The light-emitting device shown in the figure is also called a “vertical LED”. The present embodiment is characterized in that a phosphor is applied to the surface of the light emitting element 11.
[0040]
That is, the ultraviolet light emitting element 11 is mounted on the cup portion of the lead frame 36 by the adhesive 30. A blue light-emitting phosphor 38 that is excited by ultraviolet light is applied to the surface of the light-emitting element 11, and a yellow light-emitting phosphor 37 that is excited by blue light is further applied thereon.
[0041]
Also in the present embodiment, the blue light-emitting phosphor 28 is excited by the ultraviolet light emitted from the light-emitting element 11 to emit blue light, and a part of this blue light is absorbed by the yellow light-emitting phosphor 27 to become yellow light. Converted. And the white light which consists of blue light and yellow light can be taken out.
[0042]
In the present embodiment, by directly applying the phosphors 37 and 38 to the surface of the light emitting element 11, the wavelength is converted in the very vicinity of the light emitting element 11, and white light with high emission luminance can be obtained. Furthermore, since this white light emission source can be brought close to a point light source, light having a predetermined radiation shape can be easily obtained by optical means. For example, parallel rays can be easily formed by forming the resin 33 in a lens shape.
[0043]
Further, in the present embodiment, since no resin exists between the light emitting element 11 and the phosphors 37 and 38, the absorption loss of ultraviolet light due to such a resin can be eliminated. In addition, since many phosphors generally have insulating properties, there is no fear of being electrically short-circuited even when directly applied to the surface of the light emitting element 11 as in this embodiment. In addition, since the material of the blue fluorescent substance 38 and the yellow fluorescent substance 37 used in this embodiment and its coating method can be the same as that of each embodiment mentioned above, detailed description is abbreviate | omitted.
[0044]
Further, the order of applying the phosphors may be reversed to that illustrated in FIG. 4, first, the yellow phosphor may be applied to the surface of the light emitting element 11, and further the blue phosphor may be applied thereon.
[0045]
Next, a fourth embodiment of the present invention will be described.
FIG. 5 is a schematic cross-sectional view showing a light emitting device according to a fourth embodiment of the present invention. The light emitting device shown in FIG. 1 is generally called a “7-segment display”.
In the figure, reference numeral 11 denotes an ultraviolet light emitting semiconductor light emitting element, which is mounted on a substrate 45. A blue light-emitting phosphor 48 excited by ultraviolet light and a yellow light-emitting phosphor 47 excited by blue light are mixed and coated on the element 11. 49 is a shielding member, and 43 is a sealing resin. In the present embodiment, there is an advantage that it is not necessary to consider the ultraviolet light absorption of the resin 43. In FIG. 5, electrode patterns and wires for wiring are omitted for convenience.
[0046]
Even if the blue light-emitting phosphor 47 and the yellow light-emitting phosphor 48 are mixed and used as in this embodiment, the same effects as those of the above-described embodiments can be obtained. When three color phosphors are used as in a conventional light emitting device, separation occurs when the solvent is cured due to the difference in specific gravity of the phosphors, resulting in uneven color development. On the other hand, when only two color phosphors are mixed as in this embodiment, separation when the solvent is hard to cure does not easily occur, and color unevenness is unlikely to occur. In particular, when the specific gravity of the phosphor 47 and the phosphor 48 is the same, for example, when 801EJ is used as the blue light-emitting phosphor 48 and YAG (Ce) is used as the yellow light-emitting phosphor 47, the separation is suppressed. This is effective in that uniform color development can be easily obtained.
[0047]
The embodiments of the present invention have been described above with reference to specific examples. However, it is not limited to these specific examples of the present invention. That is, the present invention provides a light-emitting element, a first phosphor that converts the wavelength of light emitted from the light-emitting element, and light from the light-emitting element is not substantially absorbed, and is emitted from the first phosphor. A light-emitting device provided with a second phosphor that converts the wavelength of the emitted secondary light has the same effects, and the specific configuration of each element is appropriately determined by those skilled in the art. Can be selected and implemented.
[0048]
Furthermore, in each of the specific examples described above, the case where two types of phosphors are provided has been described, but in addition to this, three or more types of phosphors may be used. For example, a first phosphor that converts primary light from a light emitting element into secondary light, a second phosphor that converts the wavelength of the secondary light and emits secondary light having different wavelengths, and a third phosphor It is good also as what comprised this fluorescent substance.
[0049]
【The invention's effect】
The present invention is implemented in the form described above, and has the effects described below.
[0050]
That is, according to the present invention, a light emitting device that emits primary light having a first wavelength, a first phosphor that absorbs the primary light and emits secondary light having a second wavelength, and A second phosphor that absorbs the secondary light of the second wavelength and emits the secondary light of the third wavelength, and the second phosphor has a low absorptance with respect to the first wavelength, By constructing it so that it does not substantially convert the wavelength, the balance of the obtained light spectrum is extremely stabilized, and even if the wavelength or intensity of the primary light emitted from the light emitting element changes, the obtained light spectrum changes. To be eliminated.
[0051]
For example, when a white light emission is obtained by using a semiconductor light emitting device having ultraviolet light emission, a blue light emitting phosphor excited by ultraviolet light, and a yellow light emitting phosphor excited by blue light, for example, There are merits like
(1) Variations in mounted light emitting elements, that is, variations in white balance due to individual differences are eliminated.
(2) The white balance change due to the current change is eliminated.
(3) A change in white balance due to a change in temperature is eliminated.
(4) The change in white balance due to deterioration of the mounted light emitting element is eliminated.
[0052]
In addition, as a method of emitting white light using fluorescence, by using phosphors of only two colors,
(5) Easy adjustment of phosphor blending ratio
You can also get the benefits.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating a conceptual configuration of a light emitting device according to an embodiment of the present invention.
FIG. 2 is a schematic cross-sectional view showing a conceptual configuration of a semiconductor light emitting element used in a light emitting device of the present invention.
FIG. 3 is a schematic cross-sectional view showing a light emitting device according to a second embodiment of the invention.
FIG. 4 is a schematic cross-sectional view showing a light emitting device according to a third embodiment of the invention.
FIG. 5 is a schematic cross-sectional view showing a light emitting device according to a fourth embodiment of the invention.
FIG. 6 is a schematic cross-sectional view showing a conceptual configuration of a conventional white light emitting device.
[Explanation of symbols]
11 Light emitting element
12, 22 resin
13, 23, 33, 43 Sealing resin
14, 24, 34 Wire
15, 36 Lead frame
16, 36 Lead frame
17, 27, 37, 47 Yellow light emitting phosphor excited by blue light emission
18, 28, 38, 48 Blue phosphor
25 substrates
26 Wiring pattern
30 Adhesive
22 Resin
23 Resin mold
24 Lead frame
25 metal post
26 Metal stem
27 Yellow-emitting phosphor excited by blue light emission
28 Blue-emitting phosphor excited by ultraviolet emission
45 substrates
49 Shading member
111 Light Emitting Element
112 resin
113 Sealing resin
114 Wire
115, 116 lead frame
117 Yellow phosphor
131 Sapphire substrate
132 GaN buffer layer
133 n-type GaN layer
134 n-type AlGaN layer
135 Active layer
136 p-type AlGaN layer
137 p-type GaN layer
141 n-side electrode
142 Bonding pads
143 p-side electrode
144 Bonding pad
145 SiO ₂ Protective film
146 SiO ₂ Protective film

Claims (5)

A light emitting element which emits ultraviolet light as light of a first wavelength,
First wavelength converting means for absorbing light of the first wavelength and emitting light of the second wavelength;
A second wavelength converting means for absorbing a part of the second wavelength light and emitting a third wavelength light;
And emitting white light by emitting light other than the part of the light of the second wavelength and light of the third wavelength. The second wavelength is longer than the first wavelength;
The third wavelength is longer than the second wavelength;
2. The light emitting device according to claim 1, wherein the second wavelength converting means does not substantially absorb the light of the first wavelength. The first wavelength converting means is a phosphor,
The light emitting device according to claim 1, wherein the second wavelength conversion unit is a phosphor. Before Stories light of the second wavelength is blue light,
The light emitting device according to claim 1, wherein the light having the third wavelength is yellow light.   The light emitting device according to claim 1, wherein the light emitting element is a semiconductor light emitting element made of a nitride semiconductor.

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