JP2003243727A - Light emitting apparatus - Google Patents

Abstract

(57) [Summary] [Object] An excellent light emitting characteristic is obtained in a light emitting device in which two or more different emission wavelengths are combined and emitted, and in a light emitting device in which the emission wavelength from an LED chip is converted and a different emission wavelength is emitted. A light emitting device is provided. A light-emitting device comprising: a light-emitting element; and a coating layer formed of a binder containing a fluorescent substance that emits light of a different wavelength by absorbing at least a part of light from the light-emitting element, The binder is at least S
i, Al, Ga, Ti, Ge, P, B, Zr, Y or an oxide containing at least one element selected from the group consisting of alkaline earth metals; , And a region Y in which the fine particles are scattered.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting device used for a light source for illumination, an LED display, a backlight light source, a traffic light, a lighting switch, various sensors and various indicators.

[0002]

2. Description of the Related Art Today, semiconductors capable of emitting blue light with high brightness
A nitride semiconductor (In _xGa_yAl
_1-xyL using N, 0 ≦ x ≦ 1, 0 ≦ y ≦ 1)
ED chips have been put to practical use.

Further, by disposing at least a part of the blue light emitted from the LED chip on the LED chip and arranging a YAG: Ce phosphor which is a fluorescent substance capable of emitting yellow light, a white system is obtained. A light emitting diode capable of emitting light has also been put into practical use.

Furthermore, in recent years, a nitride semiconductor capable of emitting ultraviolet light has been developed. By disposing a fluorescent substance that absorbs light emitted from this LED chip and converts it into another emission wavelength. A lot of researches have been conducted on light emitting diodes that emit light having a wavelength different from that of LED chips.

In such a light emitting diode which emits a light emission wavelength different from the light emission wavelength from the LED chip, since the wavelength is converted by the phosphor constituting the fluorescent substance, the light emitting characteristics greatly change depending on the existence state of the phosphor. To do.

In addition, as in the present invention, L
A light emitting diode which emits a light emission wavelength different from the light emission wavelength from the ED chip has a coating layer containing a phosphor, but when the coating layer containing a phosphor is formed, the light emitting diode is a solid phosphor only. Can't form on top. Therefore, a layer is formed by using a binder as a binder.

[0007]

However, this coating layer has various characteristics and properties depending on the materials of the binder and the phosphor, the amount of the phosphor contained in the binder, the film forming conditions of the coating layer, and the like. Affects the light emission characteristics of the light emitting device.

For example, in order to increase the conversion efficiency of light, it is attempted to form the coating layer by increasing the ratio of the phosphor contained in the coating layer. At that time, since the proportion of the binder contained in the coating layer becomes small, the phosphor particles are not sufficiently bound and peeled off,
If the light is not sufficiently converted or if the light is partially peeled off, uneven light emission may occur.

On the contrary, the ratio of the phosphor contained in the coating layer is reduced to form a coating layer in which the phosphor does not easily peel off. At that time, since the proportion of the phosphor is small, even if an emission wavelength from the LED chip is to be emitted with a different wavelength, the proportion of the phosphor is small. L without conversion
The emission wavelength from the ED chip is emitted. This is not a problem in the light emitting device made for the purpose of emitting both the emission wavelength from the LED chip and the different emission wavelength converted by the phosphor, but the emission wavelength from the LED chip is
This is a big problem for a light-emitting device that is manufactured for the purpose of converting and emitting all by a phosphor. In that case, it is not desirable that the light of the emission wavelength from the LED chip leaks.

Further, when the ratio of the phosphor contained in the coating layer is decreased, in other words, when the ratio of the binder is increased, the phosphor particles are not evenly arranged in the coating layer. Therefore, the emission wavelength sufficiently converted by the phosphor is again absorbed by the phosphor, leading to a decrease in the energy of light, and a part of the light emitted due to the small amount of the phosphor is the phosphor. The light emission wavelength from the LED chip is emitted without being converted.

As described above, the first emission wavelength emitted from the LED chip and a part of the first emission wavelength are absorbed by the phosphor, and the second emission wavelength different from the first emission wavelength is emitted. The two emission wavelengths are combined to emit a different emission color such as white, and the first emission wavelength emitted from the LED chip is absorbed by the phosphor,
As a problem of a light emitting device that emits only a second light emission wavelength different from the light emitting wavelength of 1, there are various problems in obtaining a light emitting device having a good light emitting characteristic and a light emitting device having a good yield. These problems are due to the presence state of the phosphor present in the coating layer,
Further, it is important how the binder used as the binder of the phosphor and the phosphor are present.

[0012]

In view of these problems, in the present invention, a light emitting device that emits two or more different emission wavelengths combined, or an actual emission wavelength emitted from an LED chip is converted and different emission wavelengths are converted. The present invention provides a light emitting device having excellent light emitting characteristics in a light emitting device that emits light. (1) A light emitting device comprising a light emitting element and a coating layer made of a binder containing a fluorescent substance that absorbs at least a part of light from the light emitting element and emits light of different wavelengths, The binder is at least S
i, Al, Ga, Ti, Ge, P, B, Zr, Y, S
n, Pb, or an oxide containing one or more elements selected from the group of alkaline earth metals, and the surface of the coating layer has a region X in which fine particles of the oxide are densely present, and And a region Y in which fine particles are scattered. (2) A light emitting device, comprising: a light emitting element; and a coating layer made of a binder containing a fluorescent substance that absorbs at least a part of light from the light emitting element and emits light of different wavelengths. The binder is a translucent resin containing fine particles of a diffusing material and / or filler, and the surface of the coating layer has a region X where the fine particles are densely present and a region Y where the fine particles are scattered. It is characterized by comprising and. (3) The scattered regions Y are on the surface of the phosphor particles. (4) In the scattered regions Y, phosphor particles are partially exposed. (5) The densely-existing region X is a gap between adjacent phosphor particles. (6) The light emitting device is characterized in that the light emitting layer is made of a nitride semiconductor.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. However, the embodiments described below exemplify a light emitting device for embodying the technical idea of the present invention, and the present invention does not limit the light emitting device to the following. Further, the size and positional relationship of members shown in each drawing are exaggerated for clarity.

FIG. 1 is a schematic sectional view showing an embodiment of a light emitting device of the present invention, FIG. 2 is a schematic sectional view of a part of the surface of the light emitting device enlarged, and FIG. It is the figure which looked at a part of surface of a device from the upper surface, and shows the state of field X and field Y typically.

The light emitting device of the present invention comprises a coating layer containing a phosphor on the light emitting surface of the LED chip. For example, when the LED chip is mounted as shown in FIG. 1, the entire light emitting surface of the LED chip is coated. It is covered with layers. This coating layer has a fluorescent substance and a binder,
As shown in FIGS. 2 and 3, the phosphor particles and the fine particles that constitute them, and the surfaces thereof are the phosphor particles that form the fluorescent substance and the fine particles that consist of the oxide that forms the binder,
It is formed as shown in the following (a) to (d). (A) It is composed of a region X in which fine particles are densely present and a region Y in which fine particles are scattered. (B) The region Y in which the fine particles are scattered is on the surface of the phosphor particles. (C) In the region Y where the fine particles are scattered, the phosphor particles are partially exposed. (D) The region X where the fine particles are densely present is a gap between the adjacent phosphor particles.

Here, light is refracted as it passes from one medium to another. Assuming that the emission wavelength from the LED chip is the first wavelength and the emission wavelength absorbed and emitted by the phosphor is the second wavelength for the fine particles of the present invention, FIG. As shown in the schematic view of (b), light is propagated in various directions depending on the existence state of fine particles.

First, FIG. 4 (a) in which fine particles are scattered.
At this time, the light incident on the fine particles is partially refracted when passing through the fine particles as shown in FIG. However, because they exist scatteredly, when all the light that passed through is added together and viewed macroscopically (B)
Light is extracted in the same direction as the incident direction.

However, when the fine particles are densely present in FIG. 4B, in other words, when the fine particles exist as clusters, the light incident on the cluster passes through the fine particles as shown in FIG. Refraction is repeated every time, and light is diffused in various directions. Therefore, when the light passing through the clusters is added together and viewed macroscopically, the result becomes as shown in (B), and the component of the light extracted in the same direction as the incident direction becomes small. The principle of such refraction of light is a phenomenon that occurs when the light transmission path in the fine particles is larger than the emission wavelength of the incident light, depending on the size of the fine particles. For example, blue light of 420 nm is incident. In this case, the light transmission path in the fine particles is 420
This is a phenomenon that occurs when the thickness is greater than or equal to nm. However, even when the light transmission path in the fine particles is smaller than the emission wavelength of the incident light, the light is not refracted when the fine particles are scattered but is transmitted as it is, but when the fine particles are densely formed, clusters are formed. Since the light transmission path of is larger than the emission wavelength of light and is refracted, the phenomenon of refraction particularly in the presence of fine particles appears as a significant difference.

Here, looking at the surface of the light emitting device of the present invention as shown in FIGS. 2 and 3, that is, the surface of the coating layer, the light emitted from the LED chip is (a) to (d).
The configuration is as follows.

First, from (a), in the region X where the fine particles are densely present, the light incident on the fine particles is refracted or refracted repeatedly and is diffused in various directions and extracted in the same direction as the incident light. The component of the reflected light becomes small. That is, in the region X where the particles are densely present on the surface of the coating layer, light is difficult to be emitted from the coating layer,
Most of the light further travels to the surface of the coating layer or inside the coating layer. In addition, a region Y in which fine particles are scattered
Then, the light incident on the particles is not refracted, or only a part is refracted, and the light is extracted in the same direction as the incident light
Light is emitted from the coating layer.

As a result, in the case of a light emitting device made for the purpose of converting all the emission wavelength (first wavelength) from the LED chip by the phosphor and emitting only the second wavelength different from the first wavelength, the fine particles are produced. First in area X where
When the light of the wavelength is incident, the first wavelength is difficult to be directly emitted from the surface of the coating layer, and most of the light travels to the surface or inside of the coating layer, and the second light is emitted to the region Y where the fine particles are scattered. When the light of the wavelength is incident, the second wavelength is emitted from the surface of the coating layer to the outside. Therefore, it is possible to obtain a light emitting device having a coating layer in which the first wavelength is less likely to be emitted from the surface and the second wavelength is likely to be emitted from the surface.

The wavelength of light emitted from the LED chip (first
Of the light emitted from the surface of the coating layer in the case of a light emitting device made for the purpose of emitting both the emission wavelength) and the different emission wavelength (second wavelength) converted by the phosphor.
Component of the second wavelength can be conveniently controlled, and when the component of the second wavelength is weak in the light emitted from the coating layer, the second component is present in the region X where the fine particles are densely present. When the second wavelength is made to enter the region Y where the fine particles are scattered, the component of the second wavelength can be strengthened.

Further, from (b), the region Y where the fine particles are scattered on the surface of the coating layer is on the surface of the phosphor particles, so that the light of the second wavelength is efficiently emitted to the outside. Thus, it is possible to obtain a light emitting device for either of the above two purposes.

Further, from (c), since the phosphor particles are exposed in a part of the region Y where the fine particles are scattered on the surface of the coating layer, they are not refracted by the fine particles, and It is possible to obtain the light emitting device for any of the above two purposes, which is capable of emitting the light of the second wavelength to the outside without being diffused and further strengthening the component of the second light.

Further, from (d), the region X where the particles are densely present on the surface of the coating layer is between the phosphor particles, that is, in the gap between the adjacent phosphor particles, so that the LED chip is In the light emitting device made for the purpose of converting all the emission wavelength (first wavelength) from the fluorescent substance by the phosphor to emit only the second wavelength different from the first wavelength, the coating is performed without being absorbed by the phosphor particles. Since the light of the first wavelength that is about to be emitted from the surface of the layer increases, the effect of advancing the light of the first wavelength to the surface of the coating layer and the inside thereof becomes large, and the emission wavelength from the LED chip (first Wavelength) and a different emission wavelength (second wavelength) converted by the phosphor, the first wave which becomes strong when emitted from the surface of the coating layer to the outside in the light emitting device. It is possible to weaken the light components.

Incidentally, a comparative example to the present invention will be described with reference to FIGS. 5 and 6. FIG. 5 shows a coating when the ratio of the phosphors contained in the coating layer is small, and as one index showing this, the number of the phosphor particles (M) and the fine particles (N) has a relation of M << N. It is a schematic cross section of a layer surface. When the coating layer has a small number of phosphor particles as a whole, the above-mentioned problem occurs, but here, the number of phosphor particles is the same as the number of phosphors contained in the coating layer shown in the present invention, When the ratio of the fine particles N is large and the number of the fine particles contained in the coating layer has the relation of M << N shown in the present invention, the fine particles are densely present on the entire surface of the coating layer. That is, the fine particles are densely present also on the phosphor particles, and the light of the second wavelength emitted from the phosphor also advances to the surface or inside of the coating layer, and the light of the second wavelength is also emitted to the outside. It is hard to be done. In addition, FIG. 6 shows that when the ratio of the phosphor contained in the coating layer is high, one index representing this is when the number of phosphor particles (M) and fine particles (N) has a relationship of M >> N. It is a schematic cross section of the coating layer surface. Here, the number of phosphor particles is the same as the number of phosphors contained in the coating layer shown in the present invention, the proportion of fine particles N is small, and the number of fine particles contained in the coating layer is M
When >> N, on the surface of the coating layer,
Fine particles are scattered all over the surface. That is, fine particles are scattered even in the gaps between adjacent phosphor particles, and when a light emitting device that emits only the second wavelength is produced, the first wavelength is emitted or the first wavelength is emitted. When a light-emitting device that emits both the first wavelength and the second wavelength to the outside is produced, the light component of the first wavelength is strongly emitted, which makes it difficult to emit the desired light. I will end up. Therefore, it is not preferable in the case as shown in FIGS.

Here, in the present invention, the surface of the coating layer refers to the shape of the surface itself which is seen when the coating layer is formed on the LED chip when viewed from the front, and the particles are scattered. The region refers to a region where the probability that fine particles exist per unit area is less than 100% when viewed two-dimensionally from the surface of the coating layer, and a region where fine particles exist as a single layer when viewed three-dimensionally. A single layer means that there is a gap between the fine particles when viewed from the surface of the coating layer, so the probability that the fine particles exist is less than 100%, which is the same as the two-dimensional structure. ing. When the region where there is a gap between the fine particles is in the form of fluorescent particles, the fluorescent particles will be partially exposed on the surface. Further, the region X where the fine particles are densely present is a region in which the probability that the fine particles are present per unit area is 100% when viewed two-dimensionally from the surface of the coating layer,
A region where the fine particles exist as a layer of at least two or more as viewed three-dimensionally is a region where the fine particles are formed of a laminate. Two
The above layers mean that when viewed from the surface of the coating layer, the particles in the lower layer are present in the gaps between the particles, and the probability of existence of particles is 100%. The same thing as the configuration described above.

Further, FIGS. 1 to 6 used in the present invention are merely schematic sectional views and schematic surface views, and the shape of the phosphor particles and the shape of the fine particles made of oxide, and the number of the phosphor particles and the fine particles are Does not match. However,
In the present invention, the size of the phosphor particles or fine particles is defined by the particle size, for example, the average particle size. At least FIGS. 1 to 6 use the particle size of one embodiment of the present invention. The average particle size defined in the present embodiment is obtained by observing the surface of the coating layer surface with an electron microscope or the like, measuring each observed particle size, and taking the average value thereof. Further, in another embodiment of the present invention, the particle size of the phosphor is a value obtained by a volume-based particle size distribution curve, and the volume-based particle size distribution curve is a particle size distribution of the phosphor by a laser diffraction / scattering method. Is obtained. Specifically, in an environment of a temperature of 25 ° C. and a humidity of 70%, a phosphor is dispersed in an aqueous solution of sodium hexametaphosphate having a concentration of 0.05%, and a laser diffraction particle size distribution analyzer (SALD-2000A) is used. It was obtained by measuring in a particle size range of 0.03 μm to 700 μm. Here, the particle-based phosphors actually used have different sizes (major axis and minor axis) for each particle even if the particle diameters are made uniform by sieving, and the fluorescent materials are aggregated with each other to cause fluorescence. It may form a cluster of body particles. Therefore, in the present specification, the size of the phosphor particles is represented by an average particle size, and the average particle size means the maximum diameter of aggregates of the phosphor particles, and the phosphor particles in a state of one particle not aggregated. The average value of the maximum diameter (major axis) and the maximum diameter (major axis) of the smaller phosphor particles is meant.

The structure of the light emitting device of the present invention will be described in detail below. [Binder] The constitution of the present invention is to change the ratio (ratio) of the phosphor and the binder in the coating material when forming the coating layer, the forming method, and the temperature conditions and the forming speed when forming the coating layer. Can be formed with.

The binder used in the present invention is at least Si, Al, Ga, Ti, Ge, P, B, Zr,
It has an oxide containing one or more elements selected from the group of Y, Sn, Pb or alkaline earth metals. As one of the specific main materials of the binder, SiO ₂ , Al ₂ O
₃ , MSiO ₃ (where M is Zn, Ca, M
Examples thereof include g, Ba, Sr, Zr, Y, Sn and Pb. A transparent inorganic member containing a phosphor is preferably used. The phosphors are bound to each other by these translucent inorganic members, and the phosphors are further deposited in layers on the LED chip or the support to be bound. In the present invention,
At least Si, Al, Ga, Ti, Ge, P, B, Z
The oxide containing at least one element selected from the group of r, Y, Sn, Pb or alkaline earth metals is at least Si, Al, Ga, Ti, Ge, P, B, Zr, Y, S.
It is produced using an organometallic compound containing one or more elements selected from the group of n, Pb or alkaline earth metals. If an organic metal compound that is liquid at room temperature is used, it is possible to easily adjust the viscosity in consideration of workability and prevent the formation of coagulated substances such as organometallic compounds by adding an organic solvent, thus improving workability. Can be made. Further, since such an organometallic compound easily causes a chemical reaction such as hydrolysis, at least Si, Al,
Forming a coating layer in which a phosphor is bound by an oxide containing at least one element selected from the group of Ga, Ti, Ge, P, B, Zr, Y, Sn, Pb, or an alkaline earth metal. It is possible. for that reason,
The method using an organometallic compound is different from other methods in which a coating layer is formed on an LED under a high temperature of 350 ° C. or higher or under static electricity, and can be easily performed without deteriorating the performance of the LED as a light emitting element. A coating layer can be formed on the LED chip, which improves the manufacturing yield. Here, the organometallic compound is a molecule containing a carbon-metal bond, that is, a compound containing an alkyl group or an aryl group bonded to a metal. In particular, in the embodiment of the present invention, an alkyl silicate that produces an inorganic substance containing SiO ₂ as a main component or an aluminum alcoholate that produces an inorganic substance containing Al ₂ O ₃ as a main component is used.

The binder is at least S.
i, Al, Ga, Ti, Ge, P, B, Zr, Y, S
an oxide containing one or more elements selected from the group of n, Pb or alkaline earth metals, and at least Si, A
l, Ga, Ti, Ge, P, B, Zr, Y, Sn, Pb
Alternatively, it preferably has a hydroxide containing one or more elements selected from the group of alkaline earth metals. In this way, by using a binder containing an inorganic substance as a main component, the binder does not undergo color deterioration even under light with a short wavelength such as ultraviolet light to blue light or high output light. It is possible to form a highly reliable light emitting device as compared with the case of using the resin.

Particularly by using these binders,
This oxide or hydroxide becomes fine particles, and a single layer or two or more layers can be formed in the fine particle state to suitably bind the phosphor.

When a light-transmissive resin is used as the binder, specific examples of the light-transmissive resin that is preferably used include transparent resins and glass having excellent weather resistance such as glass, epoxy resin, silicone resin and acrylic resin. Are preferably used. In the present invention, by using a diffusing material or a filler, or a resin containing a diffusing material and a filler, as the resin, the diffusing material or the filler forms fine particles. [Diffusion Agent] When the diffusion material is used in the present invention, barium titanate, titanium oxide, aluminum oxide, silicon oxide or the like is preferably used as a specific diffusion agent. As a result, a light emitting device having good directional characteristics can be obtained. Here, in the present specification, the term “diffusing agent” refers to a median particle diameter of 1 nm or more and 5
It is less than μm. The diffusing agent having a size of 1 μm or more and less than 5 μm is preferable because it can diffuse light from the light emitting element and the fluorescent substance in a good diffused manner, and can suppress color unevenness that tends to occur when a fluorescent substance having a large particle size is used. In addition, the half width of the emission spectrum can be narrowed, and a light emitting device with high color purity can be obtained. On the other hand, a diffusing agent having a size of 1 nm or more and less than 1 μm has a low interference effect on the wavelength of light emitted from the light emitting element, but can increase the resin viscosity without lowering the luminous intensity. As a result, when the resin is sealed in the recess of the package by potting or the like, it becomes possible to disperse the fluorescent substance in the resin in the syringe almost uniformly and maintain that state, which is relatively difficult to handle. Even when a fluorescent substance having a large diameter is used, it is possible to produce with a good yield. As described above, the action of the diffusing agent in the present invention varies depending on the particle size range, and the diffusing agent can be selected or combined according to the method of use. [Filler] By using a filler in the present invention, the chromaticity variation of the light emitting device is improved by the light scattering action, and the thermal shock resistance of the translucent resin can be increased. As a result, even when used under high temperature, it is possible to prevent disconnection of the wire electrically connecting the light emitting element and the external electrode, peeling between the bottom surface of the light emitting element and the bottom surface of the recess of the package, and the like, and high reliability. A light emitting device is obtained. Further, the fluidity of the resin can be adjusted to be constant for a long time, the sealing member can be formed in a desired place, and mass production can be performed with high yield. [Light Emitting Element] The LED chip used as the light emitting element used in the present invention can be used in various types of light emitting diodes such as SMD type light emitting diode, display, 8-segment type and shell type. Each configuration of the LED chip used will be described in detail.

The LED chip used as a light emitting element in the present embodiment is one capable of exciting a phosphor. The LED chip, which is a light emitting element, has GaAs, InP, GaAlAs, InG on the substrate by the MOCVD method or the like.
aAlP, InN, AlN, GaN, InGaN, Al
A semiconductor such as GaN or InGaAlN is formed as a light emitting layer. Examples of the structure of the semiconductor include a homo structure having a MIS junction, a PIN junction and a PN junction, a hetero structure, or a double hetero structure. Various emission wavelengths can be selected depending on the material of the semiconductor layer and the degree of mixed crystal thereof. Further, the semiconductor active layer may be formed as a thin film in which a quantum effect is generated, and may have a single quantum well structure or a multiple quantum well structure. Preferably, a nitride-based compound semiconductor (general formula In _i Ga _j Al _k N, where 0 ≦ i, 0, which can efficiently emit a relatively short wavelength that can efficiently excite a phosphor)
≦ j, 0 ≦ k, i + j + k = 1).

When a gallium nitride compound semiconductor is used, sapphire, spinel, SiC, S are used as the semiconductor substrate.
Materials such as i, ZnO and GaN are preferably used. It is more preferable to use a sapphire substrate in order to form gallium nitride having good crystallinity. When growing a semiconductor film on a sapphire substrate, it is preferable to form a buffer layer of GaN, AlN or the like, and to form a gallium nitride semiconductor having a PN junction thereon. In addition, GaN selectively grown on a sapphire substrate using SiO ₂ as a mask.
The single crystal itself can also be used as the substrate. In this case, the light emitting element and the sapphire substrate can be separated by removing SiO ₂ by etching after forming each semiconductor layer. The gallium nitride-based compound semiconductor exhibits N-type conductivity in a state where it is not doped with impurities. In the case of forming a desired N-type gallium nitride semiconductor such as improving the luminous efficiency, Si, Ge, Se, N
It is preferable to introduce Te, C and the like as appropriate. On the other hand, when forming a P-type gallium nitride semiconductor, P-type dopants such as Zn, Mg, Be, Ca, Sr, and Ba are doped.

The gallium nitride-based compound semiconductor is difficult to become P-type by only doping with a P-type dopant, so that after the P-type dopant is introduced, it is annealed by heating in a furnace, low-speed electron beam irradiation, plasma irradiation or the like to make it a P-type. It is preferable. As a specific layer structure of the light emitting element, an N-type contact layer which is a gallium nitride semiconductor, an aluminum nitride / gallium semiconductor is provided on a sapphire substrate having a buffer layer formed of gallium nitride, aluminum nitride, or the like at low temperature or silicon carbide. A laminated N-type clad layer, an active layer that is an indium gallium nitride semiconductor doped with Zn and Si, a P-type clad layer that is an aluminum nitride / gallium semiconductor, and a P-type contact layer that is a gallium nitride semiconductor. Are preferred. LED
L having a sapphire substrate for forming chips
In the case of an ED chip, after the exposed surfaces of the P-type semiconductor and the N-type semiconductor are formed by etching or the like, each electrode having a desired shape is formed on the semiconductor layer by using a sputtering method, a vacuum evaporation method, or the like. In the case of a SiC substrate, the pair of electrodes can be formed by utilizing the conductivity of the substrate itself.

When light is emitted from the light emitting device of the present invention, the main emission wavelength of the LED chip is preferably 350 nm or more and 530 nm or less in consideration of the complementary color with the phosphor.

In particular, in the case where the light emitting diode of the present invention emits white light, the main light emission peak of the light emitting element is 400 nm in consideration of the complementary color relationship with the fluorescent substance, deterioration of the resin, and the like.
The above is preferably 530 or less, and more preferably 420 nm.
The above is 490 nm or less. In order to improve the efficiency of each of the light emitting element and the fluorescent material, 450 nm or more and 475
It is more preferable to use a light emitting device having a main emission peak in the range of nm or less. [Phosphor] The phosphor used in the present invention means a phosphor that emits light by being excited by at least light emitted from the LED chip. In the present embodiment, a phosphor that is excited by ultraviolet light to generate light of a predetermined color can also be used as the phosphor, and as a specific example,
For example, (1) Ca ₁₀ (PO ₄ ) ₆ FCl: Sb, Mn (2) M ₅ (PO ₄ ) ₃ Cl: Eu (where M is Sr,
(3) BaMg ₂ Al ₁₆ O ₂₇ : Eu (4) BaMg ₂ Al ₁₆ O ₂₇ : Eu, Mn (5) 3.5MgO · 0.5MgF ₂ · GeO ₂ : Mn (6) Y ₂ O ₂ S: Eu (7) Mg ₆ As ₂ O ₁₁ : Mn (8) Sr ₄ Al ₁₄ O ₂₅ : Eu (9) (Zn, Cd) S: Cu (10) SrAl _{2 O 4: Eu (11) Ca} 10 (PO 4) 6 ClBr: Mn, Eu (12) Zn 2 GeO 4: Mn (13) Gd 2 O 2 S: Eu, and _{(14) La 2 O 2 S} : Eu Etc.

Further, these phosphors may be used alone or in a mixture in a coating layer consisting of one layer. Further, they may be used alone or as a mixture in a coating layer formed by laminating two or more layers.

When the light emitted by the LED chip and the light emitted by the phosphor have a complementary color relationship, white light can be emitted by mixing the respective lights. Specifically, when the light from the LED chip and the light of the phosphor that is excited and emitted by the LED chip correspond to the three primary colors of light (red, green, and blue), or the blue light emitted by the LED chip, respectively. Examples thereof include light and yellow light of a phosphor that is excited by the light and emits light.

The emission color of the light-emitting device can be adjusted by variously adjusting the ratio of the phosphor to various resins acting as a binder for the phosphor, an inorganic member such as glass, the sedimentation time of the phosphor, and the shape of the phosphor. Also, by selecting the emission wavelength of the LED chip, it is possible to provide an arbitrary white color tone such as a light bulb color. When the light emitting device is provided with a sealing resin that protects the light emitting element and the lead electrode from the external environment, it is preferable that the light from the LED chip and the light from the phosphor are efficiently transmitted through the sealing resin. As such a sealing resin, for example, a transparent resin having excellent weather resistance such as an epoxy resin, a urea resin, a silicone resin, or glass is preferably used.

Phosphor used in the present embodiment
Is a yttrium-aluminum-garnet-based phosphor
And a phosphor capable of emitting red light, particularly a nitride phosphor
A combination of and can be used. these
The YAG-based phosphor and the nitride-based phosphor of
It may be contained in the coating layer or composed of a plurality of layers.
You may contain separately in the coating layer formed.
Hereinafter, each phosphor will be described in detail. (Yttrium / Aluminum / Garnet phosphor)
Yttrium aluminum used in the present embodiment
・ Garnet type phosphor (YAG type phosphor) means Y and A
l, and includes Lu, Sc, La, Gd, Tb, Eu and
And at least one element selected from Sm and Ga and
And a kind of element selected from In, and a rare earth element
Fluorescence activated with at least one element selected from
The body, visible light and ultraviolet rays emitted from the LED chip
It is a phosphor that emits light when excited by. Especially this embodiment
2 with different composition activated by Ce or Pr
More than one type of YAG-based phosphor can also be used. An example
For example, YAlO_Three: Ce, Y_ThreeAl₅O₁₂Y: Ce
(YAG: Ce) and Y_FourAl _TwoO₉: Ce, and even this
And the like. In addition, Ba, Sr, Mg,
At least one of Ca and Zn may be contained,
By further containing Si, the reaction of crystal growth
It is also possible to suppress the above and arrange the particles of the fluorescent substance. here
Therefore, the YAG-based phosphor activated with Ce is interpreted in a broad sense.
The yttrium or part of it, L
selected from the group consisting of u, Sc, La, Gd and Sm
Replaced by at least one element, or
What is Ba, Tl, Ga, In?
Includes a fluorophore that is substituted by either or both
Used in a broad sense. More specifically, the general formula (Y_zGd
_1-z) ₃Al_FiveO₁₂: Ce (where 0 <z ≦ 1)
Photoluminescent phosphor or general formula (Re_1-aS
m_a)₃Re ’_FiveO₁₂: Ce (however, 0 ≦ a <1, 0 ≦ b
≦ 1, Re is a small amount selected from Y, Gd, La and Sc.
At least one, Re 'is selected from Al, Ga and In.
Is at least one. ) Photolumine indicated by
It is a fluorescent phosphor.

Blue light emitted from a light emitting device using a nitride compound semiconductor in the light emitting layer, and green and red light emitted from a phosphor whose body color is yellow to absorb blue light. Alternatively, if yellowish light and more greenish and reddish light are displayed in a mixed color, a desired white emission color display can be performed. In order to cause this color mixing, the light emitting device preferably contains the phosphor powder or bulk in various resins such as epoxy resin, acrylic resin or silicone resin, and inorganic substances such as silicon oxide and aluminum oxide. The phosphor-containing material can be used in various ways such as a dot-shaped material or a layer-shaped material formed so thin as to allow light from the LED chip to pass therethrough. It is possible to provide an arbitrary color tone such as an incandescent lamp color including white by adjusting the ratio of the phosphor and the resin, coating and filling amount, and selecting the emission wavelength of the light emitting element.

Further, by arranging two or more kinds of phosphors respectively with respect to the incident light from the light emitting element, a light emitting device capable of emitting light efficiently can be obtained. That is, on a light emitting element having a reflection member, a color conversion member containing an absorption wavelength on the long wavelength side and containing a phosphor capable of emitting light at a long wavelength, and an absorption wavelength on the longer wavelength side than that, The reflected light can be effectively used by laminating a color conversion member capable of emitting light with a long wavelength.

When the YAG type phosphor is used, the irradiance is (Ee) = 0.1 W · cm ⁻² or more and 1000 W · c or more.
It is possible to obtain a light emitting device having high efficiency and sufficient light resistance even when the light emitting device is arranged in contact with or close to an LED chip of m ⁻² or less.

The YAG-based phosphor capable of emitting green light, which is the yttrium-aluminum oxide-based phosphor activated by cerium used in the present embodiment, has a garnet structure, and thus is strong against heat, light and moisture. The peak wavelength of the excitation absorption spectrum can be set to around 420 nm to 470 nm. Also, the emission peak wavelength λp is 510n.
It has a broad emission spectrum that is near m and has a skirt around 700 nm. On the other hand, even a YAG-based phosphor that is a yttrium-aluminum oxide-based phosphor activated by cerium and capable of emitting red light has a garnet structure and is resistant to heat, light, and moisture, and has a peak wavelength of an excitation absorption spectrum of 420 nm. To about 470 nm. Further, it has a broad emission spectrum in which the emission peak wavelength λp is in the vicinity of 600 nm and the tail is extended to the vicinity of 750 nm.

By substituting a part of Al with Ga in the composition of the YAG-based phosphor having a garnet structure, the emission spectrum is shifted to the short wavelength side, and a part of Y of the composition is G.
By substituting d and / or La, the emission spectrum shifts to the long wavelength side. If the substitution of Y is less than 20%, the green component is large and the red component is small. On the other hand, when the ratio is 80% or more, the reddish component increases, but the brightness sharply decreases. Similarly, regarding the excitation absorption spectrum, by replacing a part of Al with Ga in the composition of the YAG-based phosphor having a garnet structure, the excitation absorption spectrum shifts to the short wavelength side, and the composition Y Substituting a part of Gd and / or La for the excitation absorption spectrum shifts to the long wavelength side. The peak wavelength of the excitation absorption spectrum of the YAG-based phosphor is preferably on the shorter wavelength side than the peak wavelength of the emission spectrum of the light emitting element. With this configuration,
When the current applied to the light-emitting element is increased, the peak wavelength of the excitation absorption spectrum almost matches the peak wavelength of the emission spectrum of the light-emitting element, so that the chromaticity shift occurs without lowering the excitation efficiency of the phosphor. It is possible to form a light emitting device in which

Such a phosphor is composed of Y, Gd, Ce and L.
An oxide or a compound that easily becomes an oxide at high temperature is used as a raw material of a, Al, Sm, and Ga, and they are sufficiently mixed in a stoichiometric ratio to obtain a raw material. Or Y, Gd, C
e, La, and Sm are mixed by mixing a coprecipitated oxide obtained by firing a solution obtained by coprecipitating oxalic acid with a solution obtained by dissolving a rare earth element of stoichiometric ratio in an acid, aluminum oxide, and gallium oxide. Get the raw materials. An appropriate amount of a fluoride such as ammonium fluoride is mixed in this as a flux, packed in a crucible, and fired in the air at a temperature range of 1350 to 1450 ° C for 2 to 5 hours to obtain a fired product. Ball mill,
It can be obtained by washing, separating, drying and finally sieving. Further, in the method for manufacturing a phosphor according to another embodiment, a mixture of a mixed raw material obtained by mixing the raw materials of the phosphor and a flux is subjected to a first firing step in the air or a weak reducing atmosphere, and in a reducing atmosphere. It is preferable to perform the firing in two stages, which comprises the second firing step performed in 1. Here, the weak reducing atmosphere refers to a weak reducing atmosphere that is set to contain at least the amount of oxygen required in the reaction process for forming a desired phosphor from the mixed raw material. By performing the first firing step until the structure formation of the phosphor is completed, it is possible to prevent the phosphor from being blackened and to prevent the light absorption efficiency from decreasing. The reducing atmosphere in the second firing step means a reducing atmosphere that is stronger than the weak reducing atmosphere. By firing in two stages in this way, a phosphor having a high absorption efficiency of the excitation wavelength can be obtained. Therefore, when a light emitting device is formed with the phosphor thus formed, the amount of the phosphor required to obtain a desired color tone can be reduced, and a light emitting device with high light extraction efficiency can be formed. You can

The yttrium-aluminum oxide-based phosphor activated with two or more kinds of cerium having different compositions is
They may be mixed and used, or may be arranged independently. When arranging each phosphor independently,
It is preferable to arrange a phosphor that easily absorbs and emits light from the light emitting element on the shorter wavelength side and a phosphor that easily absorbs and emits light on the longer wavelength side. This enables efficient absorption and emission of light. (Nitride Phosphor) The first phosphor used in the present invention contains N, and at least one element selected from Be, Mg, Ca, Sr, Ba, and Zn, and C and S.
A nitride-based phosphor containing at least one element selected from i, Ge, Sn, Ti, Zr, and Hf and activated with at least one element selected from rare earth elements. The nitride-based phosphor used in the present embodiment refers to a phosphor that emits light when excited by absorbing visible light, ultraviolet rays, and light emitted from the YAG-based phosphor emitted from the LED chip. Particularly, the phosphor according to the present invention is Sr-Ca-Si-N: E to which Mn is added.
u, Ca-Si-N: Eu, Sr-Si-N: Eu, S
r-Ca-Si-ON: Eu, Ca-Si-ON:
Eu, Sr-Si-O-N: Eu-based silicon nitride. The basic constituent elements of this phosphor are represented by the general formula L _X S
i _Y N _{(2 / 3X + 4 / 3Y)} : Eu or L _X Si
_{Y O Z N (2 / 3X} + 4 / 3Y-2 / 3Z): Eu (L
Is Sr, Ca, or Sr and Ca. ). In the general formula, X and Y are X = 2, Y = 5, or X =
It is preferred that 1 and Y = 7, but any can be used. Specifically, the basic constituent elements, Mn is added _{(Sr X Ca 1-X)} 2 Si 5 N 8: Eu, Sr 2 S
i ₅ N ₈ : Eu, Ca ₂ Si ₅ N ₈ : Eu, Sr _X Ca
_1-X Si ₇ N ₁₀ : Eu, SrSi ₇ N ₁₀ : Eu,
Although it is preferable to use a phosphor represented by CaSi ₇ N ₁₀ : Eu, Mg, S, etc. are included in the composition of this phosphor.
At least one selected from the group consisting of r, Ca, Ba, Zn, B, Al, Cu, Mn, Cr and Ni may be contained. However, the present invention is not limited to this embodiment and examples. L is either Sr, Ca, or Sr and Ca. The compounding ratio of Sr and Ca can be changed as desired. By using Si for the composition of the phosphor, it is possible to provide a cheap phosphor having good crystallinity.

Europium Eu, which is a rare earth element, is used as the emission center. Europium mainly has divalent and trivalent energy levels. The phosphor of the present invention uses Eu ²⁺ as an activator with respect to the matrix alkaline earth metal-based silicon nitride. Eu ²⁺ is easily oxidized and trivalent Eu ₂
It is commercially available with a composition of O ₃ . However, commercially available Eu ₂ O
_In No. ₃ , O is largely involved and it is difficult to obtain a good phosphor. Therefore, it is preferable to use Eu ₂ O ₃ after removing O from the system. For example, it is preferable to use europium simple substance or europium nitride. However, this is not the case when Mn is added.

Mn, which is an additive, promotes the diffusion of Eu ²⁺ and improves the luminous efficiency such as luminous brightness, energy efficiency and quantum efficiency. Mn is contained in the raw material, or is contained in the raw material during the manufacturing process, or is burned together with the raw material. However, Mn is not contained in the basic constituent elements after firing, or even if it is contained, only a small amount remains as compared with the initial content. This is probably because Mn was scattered during the firing process. The phosphor contains Mg, Sr, Ca, Ba, Zn, B in the basic constituent elements or together with the basic constituent elements.
It contains at least one selected from the group consisting of Al, Cu, Mn, Cr, O and Ni. These elements have actions such as increasing the particle size and increasing the emission brightness. Also, B, Al, Mg, Cr and N
i has an effect of suppressing afterglow.

Such a nitride phosphor absorbs a part of the blue light emitted by the LED chip and emits light in the yellow to red region. The nitride-based phosphor is used together with the YAG-based phosphor in the light-emitting device having the above-mentioned structure to obtain LE.
Provided is a light emitting device which emits warm white light by mixing blue light emitted from a D chip and yellow to red light from a nitride-based phosphor. The phosphor added in addition to the nitride-based phosphor preferably contains a yttrium-aluminum oxide phosphor which is activated by cerium. This is because the chromaticity can be adjusted to a desired level by containing the yttrium aluminum oxide fluorescent substance. The cerium-activated yttrium-aluminum oxide fluorescent material absorbs part of the blue light emitted by the LED chip and emits light in the yellow region. Here, the blue light emitted by the LED chip,
The yellow light of the yttrium-aluminum oxide fluorescent substance is mixed to emit a pale white light. Therefore, the yttrium-aluminum oxide phosphor and the phosphor that emits red light are mixed together in a translucent coating layer and combined with the blue light emitted by the LED chip to obtain a white color mixture. A light emitting device that emits light can be provided. Particularly preferred is a white light emitting device whose chromaticity is located on the locus of black body radiation in the chromaticity diagram. However, in order to provide a light emitting device having a desired color temperature, the amount of phosphor of the yttrium-aluminum oxide phosphor and the amount of phosphor of red light emission can be appropriately changed. The light-emitting device that emits white-color mixed light is attempting to improve the special color rendering index R9. A conventional light emitting device that emits white light only by a combination of a blue light emitting element and a yttrium aluminum oxide phosphor activated by cerium has a special color rendering index R9 close to 0 near a color temperature Tcp = 4600K. The redness component was insufficient. Therefore, it has been a problem to be solved to increase the special color rendering index R9. However, by using the red-emitting phosphor with the yttrium aluminum oxide phosphor in the present invention, the special color rendering index near the color temperature Tcp = 4600K. R9 can be increased to around 40.

Next, the phosphor ((Sr _X Ca
_The method for producing _1-X ) ₂ Si ₅ N ₈ : Eu) will be described, but the present invention is not limited thereto. The above phosphor contains M
It contains n and O.

The raw materials Sr and Ca are crushed. Raw material S
R and Ca are preferably used alone, but compounds such as imide compounds and amide compounds can also be used. The raw materials Sr and Ca include B, Al, Cu and M.
It may contain g, Mn, Al ₂ O ₃ , or the like. The raw materials Sr and Ca are pulverized in a glove box in an argon atmosphere. Sr and Ca obtained by crushing are
The average particle size is preferably about 0.1 μm to 15 μm, but is not limited to this range. The purity of Sr and Ca is preferably 2N or more, but not limited to this. Metal Ca, metal S for better mixing
It is also possible to use at least one or more of r and metal Eu as an alloy material after nitriding and crushing.

The raw material Si is crushed. The raw material Si is
It is preferable to use a simple substance, but it is also possible to use a nitride compound, an imide compound, an amide compound, or the like.
For example, Si ₃ N ₄ , Si (NH ₂ ) ₂ , Mg ₂ Si, or the like. Although the purity of the raw material Si is preferably 3N or more, Al ₂ O ₃ , Mg, metal boride (Co ₃ B,
Ni ₃ B, CrB), manganese oxide, H ₃ BO ₃ , B ₂
Compounds such as O ₃ , Cu ₂ O and CuO may be contained. Si is crushed in a glove box in an argon atmosphere or a nitrogen atmosphere, similarly to the raw materials Sr and Ca. The average particle size of the Si compound is about 0.1 μ
It is preferably m to 15 μm.

Next, the raw materials Sr and Ca are nitrided in a nitrogen atmosphere. The reaction formulas are shown in the following formulas 1 and 2, respectively.

3Sr + N ₂ → Sr ₃ N ₂ ... (Equation 1) 3Ca + N ₂ → Ca ₃ N ₂ ... (Equation 2) Sr and Ca are added in a nitrogen atmosphere at 600 to 900 ° C. 5
Nitriding for hours. Sr and Ca may be mixed and nitrided, or may be individually nitrided. This allows S
A nitride of r and Ca can be obtained. The Sr and Ca nitrides are preferably highly pure, but commercially available ones can also be used.

The raw material Si is nitrided in a nitrogen atmosphere. This reaction formula is shown in Formula 3 below.

3Si + 2N ₂ → Si ₃ N ₄ (Equation 3) Silicon Si is also nitrided in a nitrogen atmosphere at 800 to 1200 ° C. for about 5 hours. Thereby, silicon nitride is obtained. The silicon nitride used in the present invention is preferably highly pure, but commercially available ones can also be used.

The Sr, Ca or Sr-Ca nitride is crushed. A nitride of Sr, Ca, and Sr-Ca is crushed in a glove box in an argon atmosphere or a nitrogen atmosphere. Similarly, Si nitride is crushed. Similarly, the Eu compound Eu ₂ O ₃ is pulverized. As the compound of Eu, europium oxide is used, but metal europium, europium nitride and the like can also be used. In addition, as the raw material Z, an imide compound or an amide compound can be used. Europium oxide is
A high-purity product is preferable, but a commercially available product can also be used. The average particle size of the crushed alkaline earth metal nitride, silicon nitride and europium oxide is about 0.1 μm.
To 15 μm is preferable.

In the above raw materials, Mg, Sr, Ca, B
At least one selected from the group consisting of a, Zn, B, Al, Cu, Mn, Cr, O and Ni may be contained. Further, the above elements such as Mg, Zn and B can be mixed by adjusting the blending amount in the following mixing step. These compounds can be added to the raw materials alone, but are usually added in the form of compounds. This class of _{compounds, H 3 BO 3, Cu 2} O 3, MgC
l ₂ , MgO · CaO, Al ₂ O ₃ , metal boride (C
rB, Mg ₃ B ₂ , AlB ₂ , MnB), B ₂ O ₃ , C
Examples include u ₂ O and CuO.

After the above pulverization, Sr, Ca, Sr
-Ca nitride, Si nitride, Eu compound Eu ₂ O
Mix ₃ and add Mn. Since these mixtures are easily oxidized, in an Ar atmosphere or a nitrogen atmosphere,
Mix in the glove box.

Finally, a mixture of Sr, Ca, Sr-Ca nitride, Si nitride, and Eu compound Eu ₂ O ₃ is fired in an ammonia atmosphere. Firing the, Mn is added _{(Sr X Ca 1-X)} 2 Si 5 N 8: it is possible to obtain a phosphor represented by Eu. The reaction formula of the basic constituent elements by this firing is shown below.

[0064]

[Chemical 1]

However, the composition of the intended phosphor can be changed by changing the mixing ratio of each raw material.

For firing, a tubular furnace, a small furnace, a high frequency furnace, a metal furnace or the like can be used. The firing temperature is 120
Although firing can be performed in the range of 0 to 1700 ° C,
A firing temperature of 1400 to 1700 ° C is preferred. For the firing, it is preferable to use one-step firing in which the temperature is gradually raised and the firing is performed at 1200 to 1500 ° C. for several hours.
It is also possible to use a two-stage firing (multi-stage firing) in which the first-stage firing is performed at 00 to 1000 ° C., and the second stage is fired at 1200 to 1500 ° C. by gradually heating. The phosphor raw material is preferably fired using a crucible made of boron nitride (BN) or a boat. Besides the crucible made of boron nitride, a crucible made of alumina (Al ₂ O ₃ ) can be used.

By using the above manufacturing method, it is possible to obtain the desired phosphor.

In the present embodiment, a nitride-based phosphor is particularly used as a phosphor that emits reddish light. In the present invention, the YAG-based phosphor and the red-based light described above are used. A light emitting device including a phosphor capable of emitting light can also be used. Such a phosphor that can emit red light is a phosphor that is excited by light having a wavelength of 400 to 600 nm to emit light, and is, for example, Y ₂ O ₂ S: E.
u, La ₂ O ₂ S: Eu, CaS: Eu, SrS: E
u, ZnS: Mn, ZnCdS: Ag, Al, ZnCd
S: Cu, Al, etc. are mentioned. As described above, the color rendering of the light emitting device can be improved by using the phosphor capable of emitting red light together with the YAG phosphor.

Two or more kinds of the phosphors formed as described above may be present in the coating layer consisting of one layer on the surface of the light emitting device, or one kind or two kinds respectively in the coating layer consisting of two layers. There may be two or more types. By doing so, white light is obtained by mixing the colors of light from different phosphors. In this case, it is preferable that the average particle diameter and the shape of the respective phosphors are similar in order to mix the light emitted from the respective phosphors better and reduce the color unevenness. Further, in consideration of the fact that the nitride-based phosphor absorbs a part of the light whose wavelength is converted by the YAG phosphor, the nitride-based phosphor is arranged at a position closer to the recess side surface than the YAG-based phosphor. It is preferable to form the coating layer so that By configuring in this way,
The color rendering property can be improved as compared with the case where the YAG-based phosphor and the nitride-based phosphor are mixed and contained in the coating layer. [Coating Layer] Further, as the method for forming the coating layer of the present invention, various commonly used methods such as potting, stencil printing and spin coating can be used, but in the present invention, particularly by spray coating described below. By using the forming method, it is possible to form the coating layer having the configurations (a) to (d) described above. In addition, since the coating layer formed by binding the phosphors can be formed on the entire surface of the light emitting device, that is, on the upper surface, the side surface, and the corner portion with substantially the same film thickness, the phosphors are uniformly dispersed on the entire surface of the light emitting device. Can be placed. This makes it possible to convert the wavelength of light emitted from the entire surface of the light emitting element, that is, from the upper surface, the side surface, and the corner portion with extremely high efficiency, and take it out to the outside.

The formation method by spray coating in the present embodiment means that the coating liquid (coating material) containing the phosphor is rotated in a mist and spiral shape based on the information of the light emitting element while the light emitting element is heated. It is characterized by spraying while making the spiral diameter increase as it approaches the surface of the light emitting element from the injection start point above the light emitting element, and further from the injection start point above the light emitting element to the light emitting element. It is characterized in that the rotation speed of the coating liquid is reduced as it approaches the surface. Also, this heated state means that the light emitting element is placed on a heater at 50 ° C.
It is desirable to set the temperature to 300 ° C. or lower.

[0071]

EXAMPLES Examples of the present invention will be described in detail below. Needless to say, the present invention is not limited to the examples shown below. (Embodiment 1) FIG. 1 is a schematic sectional view showing a light emitting device in this embodiment. In the light emitting device according to the present embodiment as shown in FIG. 1, the LED chip 102 mounted on the lead electrode is coated with a coating liquid by spray coating and then dried to form a coating layer 101. Is covered by. Here, the coating liquid is a solution in which the phosphor Y ₃ Al ₅ O ₁₂ Y: Ce is contained together with ethylene glycol as an organic solvent, using ethyl silicate containing 10 wt% of SiO ₂ component as a raw material. In addition, the phosphor Y ₃ Al ₅ O ₁₂ Y: C
e is an average particle diameter of 3 to 10 μm that emits fluorescence by wavelength-converting at least a part of the light emitted from the LED chip 102.
It is a particulate phosphor. Furthermore, the LED chip 102
The positive and negative electrodes are connected to the lead electrode by a conductive wire, and the lead electrode is connected to an external electrode to emit light capable of exciting the phosphor. As described above, the light emitting device has the LED chip 102.
It is possible to emit a mixed color light of the light emitted from the and the fluorescence of the phosphor excited by the light emission. Furthermore, FIG.
As shown in FIG. 3, the coating layer 101 formed according to the present example has phosphor particles 1 having an average particle diameter of 3 to 10 μm.
Areas 04 around which fine particles 105 having an average particle diameter of several nanometers, which are mainly composed of oxides or hydroxides produced by hydrolysis of ethyl silicate, are densely present, and areas Y are scattered and present. And is formed by fixing the phosphor particles 104 with a binder.

With the light emitting device configured as described above,
The excitation efficiency of the phosphor can be improved. Also, L
The mixed color light of the light emitted from the ED chip 102 and the fluorescent light generated by exciting the phosphor by the light from the LED chip 102 is efficiently extracted from the light emitting device. Further, since the light is scattered by the fine particles, the wavelength conversion efficiency of the phosphor and the light extraction efficiency of the entire light emitting device can be improved. (Embodiment 2) In this embodiment, a light emitting device in which a phosphor is fixed using a silicon resin containing aluminum oxide as a diffusing agent as a binder is formed. The phosphor in this example is a nitride-based phosphor (Sr _0.7 C
a _0.3 ) ₂ Si ₅ N ₈ : Eu and YAG phosphor Y
₃ (Al _0.8 Ga _0.2 ) ₅ O ₁₂ : Ce. By including these phosphors in combination in the coating layer, the light emitting device can emit reddish mixed color light (color temperature 2500K to 3500K). The other is
A light emitting device is formed in the same manner as in Example 1. As shown in FIG. 3, the coating layer 101 formed according to this example is generated by the hydrolysis of aluminum oxide fine particles 105 and ethyl silicate around phosphor particles 104 having an average particle diameter of 3 to 10 μm. It has a region X in which fine particles 105 having an average particle diameter of several nm and containing oxides or hydroxides as a main component are densely present, and regions Y in which they are scattered,
The phosphor particles 104 are formed by being fixed by a binder.

With the light emitting device configured as described above,
The excitation efficiency of various fluorescent substances can be improved. Further, the light emission of the LED chip 102 and the LED chip 10
Light mixed with fluorescent light generated by exciting the above two kinds of phosphors by the light from 2 is efficiently extracted from the light emitting device. Further, since the light is scattered by the fine particles, the wavelength conversion efficiency of the phosphor and the light extraction efficiency of the entire light emitting device can be improved.

[0074]

As described above, the light emitting device of the present invention emits light by combining two or more different emission wavelengths in the present invention, or emits different emission wavelengths by converting the actual emission wavelength. In the light emitting device according to the present invention, a light emitting device having excellent light emitting characteristics can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an embodiment of a light emitting device of the present invention.

FIG. 2 is a schematic cross-sectional view of a part of the surface of the coating layer of the light emitting device of FIG.

FIG. 3 is a schematic view showing a part of the surface of the coating layer of FIG. 2 in an enlarged view from the upper surface.

FIG. 4 is a schematic diagram illustrating an embodiment of a light emitting device of the present invention.

FIG. 5 is a schematic cross-sectional view showing a comparative example for explaining the light emitting device of the present invention.

FIG. 6 is a schematic cross-sectional view showing a comparative example for explaining the light emitting device of the present invention.

[Explanation of symbols]

101 ... coating layer, 102 ... LED chip, 103 ... Sealing resin, 104 ... Phosphor particles, 105 ... Fine particles.

─────────────────────────────────────────────────── ─── Continued Front Page (51) Int.Cl. ⁷ Identification Code FI Theme Coat (Reference) C09K 11/64 C09K 11/64

Claims (6)

[Claims] 1. A light emitting device comprising a light emitting element and a coating layer made of a binder containing a fluorescent substance that absorbs at least a part of light from the light emitting element and emits light having a different wavelength. The binder is at least Si, Al, Ga, T
i, Ge, P, B, Zr, Y, Sn, Pb or an oxide containing one or more elements selected from the group of alkaline earth metals, and the surface of the coating layer is A light emitting device comprising a region X in which fine particles are densely present and a region Y in which the fine particles are scattered and present. 2. A light emitting device comprising: a light emitting element; and a coating layer made of a binder containing a fluorescent substance that absorbs at least part of light from the light emitting element and emits light of different wavelengths. The binder is a light-transmitting resin containing fine particles of a diffusing material and / or a filler, and the fine particles on the surface of the coating layer are densely present areas X and scattered areas Y. And a light-emitting device. 3. The light emitting device according to claim 1, wherein the scattered regions Y are present on the surface of the phosphor particles. 4. The light emitting device according to claim 1, wherein phosphor particles are partially exposed in the scattered regions Y. 5. The light emitting device according to claim 1, wherein the densely-existing regions X are gaps between adjacent phosphor particles. 6. The light emitting device according to claim 1, wherein the light emitting element has a light emitting layer made of a nitride semiconductor.