JP2004179644A - Phosphor lamination and light source using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a phosphor lamination, in which two types of phosphor layers are laid on a semiconductor light-emitting element, such as an LED or an LD to enhance color rendering properties, with enhanced luminous efficiency and reduced the deterioration of the phosphor layers by adjusting the mixture of a diffusing agent, a binder resin, and a phosphor in each phosphor layer, and to provide a white light-emitting device or the like, using the phosphor lamination. <P>SOLUTION: In this phosphor lamination, a first phosphor layer and a second phosphor layer which includes a phosphor emitting a fluorescent light of a wavelength shorter than that of the fluorescent light emitted by the phosphor in the first phosphor layer are laid on a semiconductor light-emitting element such as an LED or an LD. In the lamination structure, where the first phosphor layer is positioned closer to the semiconductor light-emitting element than the second phosphor layer, the blending quantity or the refractive index of the diffusing agent and/or the binder resin in the first and second phosphor layers is adjusted. <P>COPYRIGHT: (C)2004,JPO

Description

  The present invention relates to a phosphor laminated structure having a semiconductor light emitting element (such as a light emitting diode or a laser diode) and a light source using the same.

  In this specification, the LED or LD chip itself is called a “light emitting element” or “semiconductor light emitting element” and includes an optical device such as an LED or LD chip, a phosphor laminated on the chip, and an electrode. The entire light-emitting device will be referred to as “light-emitting device” and “light source”.

  A light source that emits white-colored mixed light has advantages such as low voltage drive, small size, light weight, durability, and long life, and as a next-generation energy-saving illumination source, as well as in-vehicle display light sources and mobile phone display units. It is in the limelight as a backlight.

For example, in a method of providing a phosphor layer on a semiconductor light emitting device and using it as a light source that emits white mixed color light, a part of light emitted from a blue light emitting device is wavelength-converted by the phosphor, and the remaining blue light emission and phosphor A method for obtaining white light by mixing colors with light emitted from a light source, and a method for obtaining white light using a phosphor that emits red (R), green (G), and blue (B) using an ultraviolet light emitting element as a light emitting element. And have been proposed. In the former, YAG activated with cerium is used as the phosphor, but the spectrum formed by color mixture has relatively little red region component, and color rendering is sufficient for use in fields that require a red component. There is a problem that is not. Therefore, the latter method of obtaining white light using phosphors that emit RGB is recommended because it is relatively easy to obtain white light with excellent color rendering. However, since white is formed by the RGB ratio, there is a problem that uneven color tends to occur unless the ratio is correct and uniform. Such “unevenness” of light emission has been found to occur in the coating and resin curing processes due to differences in specific gravity and particle size of each of the RGB phosphors. A structure for forming a phosphor having a certain thickness on a smooth surface has been proposed (see, for example, Patent Document 1).
JP 2000-31532 A

  However, the conventional structural improvement measures are not drastic. That is, even if the phosphor layer thickness can be formed uniformly, the occurrence of color unevenness based on the non-uniformity of the distribution in the phosphor layer cannot be solved.

  Therefore, the inventors of the present invention laminating phosphor layers as a result of intensive studies to eliminate color unevenness based on film thickness and non-uniformity in the phosphor layers when laminating a plurality of phosphor layers. In the case of the structure, it has been found that by adjusting the diffusion efficiency of each layer, not only the color unevenness but also the overall brightness can be achieved.

  Accordingly, a first object of the present invention is to provide a phosphor laminate structure that can eliminate uneven color in the case of laminating phosphor layers and can improve the overall luminance.

  Furthermore, the second object of the present invention is to improve luminance without deterioration of quality due to color unevenness when a plurality of phosphor layers are laminated on a semiconductor light emitting device capable of emitting blue or ultraviolet light. It is to provide a light source capable of achieving the above.

  The first object is to laminate a plurality of phosphor layers made of a phosphor, a diffusing agent, and a binder resin on a semiconductor light emitting element, and the first phosphor layer closer to the semiconductor light emitting element The phosphor layered structure includes a phosphor that emits fluorescence having a wavelength longer than that of the second phosphor layer far from the semiconductor light emitting element, and the first phosphor layer includes the second phosphor layer. The phosphor layered structure is characterized in that it contains a diffusing agent having the same or higher refractive index as the diffusing agent contained in the body layer, and the amount of the diffusing agent is larger than that of the second phosphor layer. The first phosphor layer covers at least a part of the semiconductor light emitting element, and the second phosphor layer covers the first phosphor layer and at least a part of the semiconductor light emitting element. It is preferable to do.

  By increasing the diffusion effect of the diffusing material in the first phosphor layer having a large wavelength conversion width as compared with that of the second phosphor layer, there is no color unevenness and the luminance and efficiency can be improved. is there. Although the details of its function are unknown, it seems that efficient wavelength conversion not only in the first layer but also in the second layer can be achieved by increasing the diffusion efficiency of the first layer having a large wavelength conversion width. .

Specifically, the diffusing agent is at least one selected from oxides composed of SiO ₂ , Al ₂ O ₃ , TiO ₂ , B ₂ O ₃ , Zr ₂ O ₃ , Y ₂ O ₃ and CaCO _3. Preferably there is. It has been found that the oxide diffusing material is familiar with the phosphor, and in particular does not accelerate the deterioration of the silicon nitride phosphor defined below.

  In the phosphor layered structure of the present invention, when the types of diffusing agents in the first and second phosphor layers are different, the refractive index of the diffusing agent in the first phosphor layer is the second fluorescence layer. It is good to mix | blend so that it may become larger than the refractive index of the diffusing agent in a body layer. This is because the absolute amount of the diffusing material can be reduced and efficient wavelength conversion can be expected.

  In the phosphor laminate structure of the present invention, when the diffusing agent in the first and second phosphor layers is the same type, the blending amount of the diffusing agent in the first phosphor layer is the second It becomes more than the compounding quantity of the diffusing agent in the phosphor layer. By using the same kind of diffusing material, it is easy to adjust the diffusion efficiency of the first layer and the second layer.

  As the binder resin used in the phosphor laminate structure of the present invention, it is preferable to use an epoxy resin, an acrylic resin, an imide resin, a silicone resin, or a urea resin. Although it is convenient for manufacturing to use the same binder resin for the first layer and the second layer, the types of binder resins for forming the first and second phosphor layers may be different. In that case, the refractive index of the binder resin forming the first phosphor layer is preferably larger than the refractive index of the binder resin forming the second phosphor layer. This is because light reflection at the interface can be reduced.

  The effective refractive index of the diffusing material in the first and second phosphor layers depends on the refractive index difference between the binder resin and the diffusing material. Therefore, when the types of the binder resins are the same, the diffusion effect of the first layer and the second layer can be adjusted by adjusting the amount of the diffusing material in the first phosphor layer. The refractive index difference between the binder resin and the diffusing agent is made larger than the refractive index difference between the binder resin and the diffusing agent forming the second phosphor layer together with the adjustment or independently of the quantitative adjustment. Thus, the diffusion efficiency of the first layer and the second layer can be adjusted. On the other hand, when the types of binder resins forming the first and second phosphor layers are different, the refractive index of the binder resin forming the first phosphor layer forms the second phosphor layer. The refractive index difference between the binder resin forming the first phosphor layer and the diffusing agent is larger than the refractive index of the binder resin, and the refractive index difference between the binder resin forming the second phosphor layer and the diffusing material. By making it larger, the diffusion efficiency of the first layer and the second layer can be adjusted. In short, in order to obtain a predetermined function and effect according to the present invention, the average refractive index composed of the diffusing agent and the binder resin in the first and second phosphor layers is the diffusing agent in the second phosphor layer. It is necessary to adjust so that it may become larger than the average refractive index of binder resin.

When the second object of the present invention is applied to a semiconductor light emitting device capable of emitting blue light, in a light source formed by laminating a plurality of phosphor layers composed of a phosphor, a diffusing agent, and a binder resin,
The first phosphor layer closer to the semiconductor light emitting element includes a silicon nitride phosphor, and at least a phosphor emitting fluorescence having a longer wavelength than the second phosphor layer farther from the semiconductor light emitting element. The light source includes an aluminum garnet-based phosphor, and the first phosphor layer includes a diffusing agent having a refractive index equal to or larger than that of the diffusing agent included in the second phosphor layer, and the blending amount thereof is the first This is achieved by a configuration with more than two phosphor layers.

When applied to a semiconductor light emitting device capable of emitting ultraviolet light, in a light source formed by laminating a plurality of phosphor layers composed of a phosphor, a diffusing agent, and a binder resin,
The first phosphor layer closer to the semiconductor light emitting element includes an ultraviolet excited red light emitting phosphor, the second phosphor layer includes an ultraviolet excited green light emitting phosphor, and the third phosphor. The layer comprises an ultraviolet excited blue emitting phosphor;
The first phosphor layer includes a larger amount of a diffusing agent having a refractive index equal to or larger than that of the diffusing agent contained in the second phosphor layer, and the second phosphor layer includes the third phosphor. This can be achieved by a structure containing more diffusing agents having the same or higher refractive index as the diffusing agent contained in the layer.

  In the light source having the phosphor laminated structure of the present invention, color unevenness is eliminated by adjusting the diffusion effect of the phosphor layers to be laminated, and a high yield is achieved. In addition, by adjusting the diffusion effect of the phosphor layers to be laminated, the luminance can be improved as compared with the case where the phosphor diffusion effect is not adjusted.

  As described above, the phosphor laminate structure according to the present invention and the light source using the phosphor laminate structure have a structure in which a phosphor layer made of a phosphor, a diffusing agent, and a binder resin is laminated on a semiconductor light emitting device. The first phosphor layer includes a phosphor that emits fluorescence with a long wavelength, and the second phosphor layer includes a phosphor that emits fluorescence with a short wavelength, and the first phosphor layer includes In the laminated structure arranged closer to the light emitting element than the second phosphor layer, the amount of the diffusing agent in the first phosphor layer is larger than the amount in the second phosphor layer. In addition, the refractive index of the diffusing agent and / or binder resin in the first phosphor layer is blended so as to be larger than the refractive index of the diffusing agent in the second phosphor layer. That is, it is possible to improve luminance and efficiency. Moreover, self-absorption can be suppressed and the light of a fluorescent substance can be taken out efficiently.

Hereinafter, a light emitting device, a phosphor, a diffusing agent, and a binder resin according to the present invention will be described with reference to embodiments and examples of the present invention. However, the present invention is not limited to this embodiment and example.
<Light-emitting device 1>
FIG. 1 is a diagram showing a light emitting device 1 according to the present invention. The light emitting device 1 includes a semiconductor layer 2 that can emit blue light stacked on the sapphire substrate 1, a lead frame that is conductively connected by wires extending from electrodes formed on the semiconductor layer 2, and the sapphire substrate 1. The silicon nitride phosphor layer 14a, the YAG: Ce-based phosphor layer 14b, the laminated phosphor layers 14a and 14b, and the lead frame 13 provided so as to cover the outer periphery of the semiconductor light emitting device composed of the semiconductor layer 2. And an epoxy resin 15 covering the outer peripheral surface of the substrate.

  The first emission spectrum of the blue light emitted from the light emitting device 1 is first irradiated onto the first silicon nitride phosphor layer 14a, part of which is absorbed and emits a wavelength-converted second emission spectrum. . The second emission spectrum is applied to the second YAG: Ce phosphor layer 14b, but is transmitted without being absorbed by the second YAG: Ce phosphor layer 14b. On the other hand, a part of the first emission spectrum transmitted through the silicon nitride phosphor layer 14a is irradiated to the second YAG: Ce phosphor layer 14b, and a part thereof is absorbed and wavelength-converted third. The emission spectrum is emitted. Therefore, the light emitting device emits white with high color rendering properties by combining the first blue spectrum, the second red spectrum, and the third yellow spectrum.

<Light-emitting device 2>
FIG. 2 is a diagram showing a light emitting device 2 according to the present invention. The light emitting device 2 includes a semiconductor layer 2 stacked on the sapphire substrate 1 and capable of emitting near-ultraviolet light, a lead frame conductively connected by wires extending from electrodes formed on the semiconductor layer 2, and the sapphire substrate 1. An ultraviolet-excited red light-emitting phosphor layer 24a, an ultraviolet-excited green light-emitting phosphor layer 24b, an ultraviolet-excited blue light-emitting phosphor layer 24c provided so as to cover the outer periphery of the semiconductor light-emitting element composed of the semiconductor layer 2, and the laminated fluorescence The body layers 24 a to 24 c and the epoxy resin 15 covering the outer peripheral surface of the lead frame 13 are configured.

  The first emission spectrum that emits near-ultraviolet light by the light emitting device 2 is first irradiated to the first red light emitting phosphor layer 24a, a part of which is absorbed, and emits a wavelength-converted second emission spectrum. The second emission spectrum is applied to the second green light emitting phosphor layer 24b, but is transmitted without being absorbed by the second green light emitting phosphor layer 24b. On the other hand, a part of the first emission spectrum transmitted through the red-emitting phosphor layer 24a is irradiated to the second green-emitting phosphor layer 24b, and a part thereof is absorbed and wavelength-converted third emission spectrum. Is emitted. The third emission spectrum is applied to the third blue light emitting phosphor layer 24b, but is transmitted without being absorbed by the third blue light emitting phosphor layer 24b. On the other hand, a part of the first emission spectrum transmitted through the red light-emitting phosphor layer 24a and the green light-emitting phosphor layer 24b is irradiated to the third blue light-emitting phosphor layer 24c, and a part thereof is absorbed, thereby converting the wavelength. The emitted fourth emission spectrum is emitted. Therefore, the light emitting device emits white with high color rendering properties by combining the second red spectrum, the third green spectrum, and the fourth blue spectrum.

<Semiconductor light emitting device>
As a light source excitation LED, a known single or multiple quantum well blue LED having InGaN as a light emitting layer and a known single or multiple quantum well near UV LED having AlInGaN, GaN or AlGaN as a light emitting layer Can be used.

<Phosphor>
The phosphor used in this embodiment absorbs part of visible light and ultraviolet light emitted from the light emitting element, and emits light having a wavelength different from the wavelength of the absorbed light. The phosphor in the present embodiment is fixed by a binder resin and contained in the phosphor layer, and an insulating adhesive for fixing the LED chip to the package (for example, epoxy resin, silicone resin, glass, etc.) (Translucent inorganic member). In addition, the phosphor layer according to the present embodiment is provided as a cap that covers the surface of the mold member 5, and is spaced from the surface of the mold member or the light emitting element, and a sheet-like phosphor is formed in the mold member. It can also be provided as a layer.
The phosphor used in the present embodiment is a phosphor that emits light that has been wavelength-converted and excited by light emitted from at least the semiconductor light emitting layer of the LED chip, together with a binder that fixes the phosphor. The wavelength conversion member is used.
The phosphor according to the present invention is preferably composed of phosphor particles having an average particle diameter of 3 μm or more and particles having a particle diameter of 2 μm or less as measured by particle size distribution in a volume distribution of 10% or less. The average particle size is preferably 5 μm or more and 15 μm or less, and more preferably the average particle size is 10 μm or more and 12 μm or less. It is possible to suppress formation variation when forming the phosphor layer, and high luminance with little alignment variation can be obtained.

(RGB phosphor)
For example, europium-activated barium represented by BaMgAl ₁₀ O ₁₇ : Eu, which is composed of grown particles having a substantially hexagonal shape as a regular crystal growth shape and capable of emitting blue light by ultraviolet irradiation, and emits light in a blue region. Magnesium aluminate-based phosphor, composed of growing particles having a substantially spherical shape as a regular crystal growth shape, emits light in a blue region (Ca, Sr, Ba) ₅ (PO ₄ ) ₃ Cl: Eu Europium-activated calcium halophosphate phosphor, which is composed of growing particles having a substantially cubic shape as a regular crystal growth shape, and emits light in a blue region (Ca, Sr, Ba) ₂ B ₅ O ₉ Cl: Eu Europium activated alkaline earth chloroborate phosphor,
Europium composed of fractured particles having a fracture surface and emitting in the blue-green region (Sr, Ca, Ba) Al ₂ O ₄ : Eu or (Sr, Ca, Ba) ₄ Al ₁₄ O ₂₅ : Eu Examples include activated alkaline earth aluminate phosphors.
Europium activation represented by (Mg, Ca, Sr, Ba) Si ₂ O ₂ N ₂ : Eu composed of fractured particles having a fracture surface and capable of emitting green light by ultraviolet irradiation. Europium-activated alkaline earth magnesium silicate composed of alkaline earth silicon oxynitride phosphor, broken particles having a fracture surface, and emitting green light (Ba, Ca, Sr) ₂ SiO ₄ : Eu System phosphors.
Europium represented by (Mg, Ca, Sr, Ba) ₂ Si ₅ N ₈ : Eu composed of broken particles having a red fracture surface as a phosphor capable of emitting red light by ultraviolet irradiation. The activated alkaline earth silicon nitride phosphor is composed of growing particles having a substantially spherical shape as a regular crystal growth shape, and emits light in the red region (Y, La, Gd, Lu) ₂ O ₂ S: Eu And europium-activated rare earth oxycalyugenite-based phosphors.

(Aluminum / garnet phosphor)
The aluminum garnet phosphor used in the present embodiment includes Al and at least one element selected from Y, Lu, Sc, La, Gd, Tb, Eu, and Sm, and Ga and In. A phosphor activated by at least one element selected from rare earth elements and excited by visible light or ultraviolet light emitted from a semiconductor light emitting device. is there. For example, in addition to the YAG phosphor described above, Tb _2.95 Ce _0.05 Al ₅ O ₁₂ , Y _2.90 Ce _0.05 Tb _0.05 Al ₅ O ₁₂ , Y _2.94 Ce _0.05 Pr _{0.01 Al 5 O 12, Y 2.90} Ce 0.05 Pr 0.05 Al 5 O 12 and the like. Among these, in the present embodiment, two or more yttrium / aluminum oxide phosphors containing Y and activated by Ce or Pr and having different compositions are used.

Specific examples of the phosphor include yttrium, aluminum, and garnet phosphors activated with cerium (hereinafter, sometimes referred to as “YAG phosphors”). In particular, at the time of high luminance and long-term use _{(Re 1-x Sm x)} 3 (Al 1-y Ga y) 5 O 12: Ce (0 ≦ x <1,0 ≦ y ≦ 1, where, Re Is at least one element selected from the group consisting of Y, Gd, and La).
_{(Re 1-x Sm x)} 3 (Al 1-y Ga y) 5 O 12: Ce phosphor, for garnet structure, heat, resistant to light and moisture, the peak of the excitation spectrum can be like in the vicinity of 470nm Can do. In addition, the emission peak is in the vicinity of 530 nm, and a broad emission spectrum that extends to 720 nm can be provided.

Two or more kinds of phosphors may be mixed as the phosphor in the light emitting device in this embodiment. That, Al, Ga, Y, the content of La and Gd and Sm are two or more kinds of _{(Re 1-x Sm x)} 3 (Al 1-y Ga y) 5 O 12: by mixing Ce phosphor RGB wavelength components can be increased. At present, there are variations in the emission wavelength of the semiconductor light emitting device, so that two or more kinds of phosphors can be mixed and adjusted to obtain a desired white mixed color light or the like. Specifically, by adjusting the amount of phosphors with different chromaticity points according to the emission wavelength of the semiconductor light-emitting element, light can be emitted from any point on the chromaticity diagram connected between the phosphors and the light-emitting element. Can be made.

Blue light emitted from a semiconductor light emitting device using a nitride compound semiconductor in the light emitting layer, green light emitted from a phosphor whose body color is yellow to absorb blue light, and as necessary When a mixed color display with red light is displayed, a desired white light emission color display can be performed. In order to cause this color mixture, the light emitting device can contain phosphor powder and bulk in various resins such as epoxy resin, acrylic resin or silicone resin, and translucent inorganic materials such as silicon oxide and aluminum oxide. Such phosphors can be used in various ways depending on applications such as dot-like and layer-like ones that are formed thin enough to transmit light from the semiconductor light-emitting element. By adjusting the ratio, coating, and filling amount of the phosphor and the translucent inorganic substance and selecting the emission wavelength of the light emitting element, it is possible to provide an arbitrary color tone such as a light bulb color including white.
When a YAG phosphor is used, high efficiency is sufficient even when it is placed in contact with or close to a semiconductor light emitting device having an irradiance of (Ee) = 0.1 W · cm ^{−2 to} 1000 W · cm ^−2. A light-emitting device having light resistance can be obtained.

The cerium-activated yttrium / aluminum oxide phosphor used in the present embodiment is a YAG phosphor capable of emitting green light, and is strong against heat, light and moisture due to the garnet structure, and is excited and absorbed. The peak wavelength of the spectrum can be in the vicinity of 420 nm to 470 nm. In addition, with a broad emission spectrum that tails off to around 700nm is in the vicinity of the emission peak wavelength λ _p even 510nm. On the other hand, even YAG phosphors capable of emitting red light, which are yttrium / aluminum oxide phosphors activated by cerium, have a garnet structure and are resistant to heat, light and moisture, and the peak wavelength of the excitation absorption spectrum is 420 nm. To about 470 nm. Also, having a broad emission spectrum emission peak wavelength lambda _p is tails to around 750nm is in the vicinity of 600 nm.

  Of the composition of YAG phosphors with a garnet structure, the emission spectrum is shifted to the short wavelength side by substituting part of Al with Ga, and part of Y of the composition is replaced with Gd and / or La. By doing so, the emission spectrum shifts to the long wavelength side. In this way, it is possible to continuously adjust the emission color by changing the composition. Therefore, an ideal condition for converting white light emission by using blue light emission of the nitride semiconductor is provided such that the intensity on the long wavelength side is continuously changed by the composition ratio of Gd. If the substitution of Y is less than 20%, the green component is large and the red component is small, and if it is 80% or more, the redness component is increased but the luminance is drastically decreased. Similarly, the excitation absorption spectrum is shifted to the short wavelength side by substituting part of Al with Ga in the composition of the YAG phosphor having a garnet structure. By substituting a part of Gd and / or La, the excitation absorption spectrum is shifted to the longer wavelength side. The peak wavelength of the excitation absorption spectrum of the YAG 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 input to the light emitting element is increased, the peak wavelength of the excitation absorption spectrum substantially matches the peak wavelength of the emission spectrum of the light emitting element, so that the excitation efficiency of the phosphor is not reduced. Thus, a light emitting device in which the occurrence of chromaticity deviation is suppressed can be formed.

  Such phosphors use oxides or compounds that easily become oxides at high temperatures as raw materials for Y, Gd, Ce, La, Al, Sm, Pr, Tb and Ga, and they are added in a stoichiometric ratio. Mix thoroughly to obtain the raw material. Or a coprecipitated oxide obtained by calcining a solution obtained by coprecipitation of oxalic acid with a solution obtained by dissolving a rare earth element of Y, Gd, Ce, La, Sm, Pr, and Tb in an acid at a stoichiometric ratio with acid; Aluminum and gallium oxide are mixed to obtain a mixed raw material. An appropriate amount of fluoride such as ammonium fluoride is mixed with this as a flux and packed in a crucible, fired in air at a temperature range of 1350 to 1450 ° C. for 2 to 5 hours to obtain a fired product, and then the fired product in water. It can be obtained by ball milling, washing, separating, drying and finally passing through a sieve. Further, in the method for manufacturing a phosphor in another embodiment, a first firing step in which a mixture composed of a mixture of phosphor materials and a flux is mixed in the atmosphere or in a weak reducing atmosphere, and in a reducing atmosphere. It is preferable to perform the baking in two stages, which includes the second baking step performed in step (b). Here, the weak reducing atmosphere refers to a weak reducing atmosphere set to include at least the amount of oxygen necessary in the reaction process of forming a desired phosphor from the mixed raw material. By performing the first firing step until the formation of the phosphor structure is completed, blackening of the phosphor can be prevented and a decrease in light absorption efficiency can be prevented. In addition, the reducing atmosphere in the second firing step refers to a reducing atmosphere stronger than the weak reducing atmosphere. By firing in two stages in this way, a phosphor with high absorption efficiency at the excitation wavelength can be obtained. Therefore, when a light emitting device is formed with the phosphor thus formed, the amount of the phosphor necessary for obtaining a desired color tone can be reduced, and a light emitting device with high light extraction efficiency can be formed. Can do.

  Two or more kinds of yttrium / aluminum oxide phosphors activated by cerium having different compositions may be mixed and used. Moreover, it is good also as a multilayer structure which contains only 1 type of fluorescent substance in each layer. In the case of a multilayer structure, it is preferable to arrange in order of a phosphor layer that easily absorbs and emits light from the light emitting element on a shorter wavelength side, and a phosphor layer that easily absorbs and emits light on a longer wavelength side. This makes it possible to efficiently absorb and emit light.

(Nitride phosphor)
The fluorescent material in the present embodiment contains N and at least one element selected from Be, Mg, Ca, Sr, Ba, and Zn, and C, Si, Ge, Sn, Ti, Zr, and Hf And a nitride-based phosphor activated with at least one element selected from rare earth elements. In addition, the nitride-based phosphor used in the present embodiment refers to a phosphor that is excited and emits light by absorbing visible light, ultraviolet light, and light emitted from the YAG-based phosphor emitted from the semiconductor light-emitting element. . For example, Ca—Ge—N: Eu, Z system, Sr—Ge—N: Eu, Z system, Sr—Ca—Ge—N: Eu, Z system, Ca—Ge—O—N: Eu, Z system, Sr—Ge—O—N: Eu, Z system, Sr—Ca—Ge—ON: Eu, Z system, Ba—Si—N: Eu, Z system, Sr—Ba—Si—N: Eu, Z Type, Ba-Si-ON: Eu, Z type, Sr-Ba-Si-ON: Eu, Z type, Ca-Si-CN: Eu, Z type, Sr-Si-CN : Eu, Z system, Sr-Ca-Si-CN: Eu, Z system, Ca-Si-C-O-N: Eu, Z system, Sr-Si-C-O-N: Eu, Z system Sr—Ca—Si—C—O—N: Eu, Z series, Mg—Si—N: Eu, Z series, Mg—Ca—Sr—Si—N: Eu, Z series, Sr—Mg—Si— N: Eu, Z-based, Mg-Si-O- : Eu, Z series, Mg-Ca-Sr-Si-ON: Eu, Z series, Sr-Mg-Si-ON: Eu, Z series, Ca-Zn-Si-CN: Eu, Z-based, Sr-Zn-Si-CN: Eu, Z-based, Sr-Ca-Zn-Si-CN: Eu, Z-based, Ca-Zn-Si-CN- Eu: Z System, Sr—Zn—Si—C—O—N: Eu, Z system, Sr—Ca—Zn—Si—C—O—N: Eu, Z system, Mg—Zn—Si—N: Eu, Z system Mg-Ca-Zn-Sr-Si-N: Eu, Z system, Sr-Zn-Mg-Si-N: Eu, Z system, Mg-Zn-Si-O-N: Eu, Z system, Mg- Ca-Zn-Sr-Si-ON: Eu, Z system, Sr-Mg-Zn-Si-ON: Eu, Z system, Ca-Zn-Si-Sn-CN: Eu, Z system , Sr-Zn-Si-S -CN: Eu, Z system, Sr-Ca-Zn-Si-Sn-CN: Eu, Z system, Ca-Zn-Si-Sn-C-O-N: Eu, Z system, Sr- Zn—Si—Sn—C—O—N: Eu, Z series, Sr—Ca—Zn—Si—Sn—C—O—N: Eu, Z series, Mg—Zn—Si—Sn—N: Eu, Z-based, Mg-Ca-Zn-Sr-Si-Sn-N: Eu, Z-based, Sr-Zn-Mg-Si-Sn-N: Eu, Z-based, Mg-Zn-Si-Sn-O-N : Eu, Z series, Mg-Ca-Zn-Sr-Si-Sn-ON: Eu, Z series, Sr-Mg-Zn-Si-Sn-ON: Various combinations such as Eu, Z series A phosphor can be manufactured. Z, which is a rare earth element, preferably contains at least one of Y, La, Ce, Pr, Nd, Gd, Tb, Dy, Ho, Er, and Lu, but Sc, Sm, Tm, Yb may be contained. These rare earth elements are mixed in the raw material in the form of oxides, imides, amides, etc. in addition to simple substances. Rare earth elements mainly have a stable trivalent electron configuration, while Yb, Sm, etc. have a divalent configuration, and Ce, Pr, Tb, etc. have a tetravalent electron configuration. When the rare earth element of the oxide is used, the involvement of oxygen affects the light emission characteristics of the phosphor. In other words, the emission luminance may be reduced by containing oxygen. On the other hand, there are also advantages such as shortening the afterglow. However, when Mn is used, the particle size becomes large, and the emission luminance can be improved.

For example, La is used as a coactivator. Since lanthanum oxide (La ₂ O ₃ ) is a white crystal and is quickly replaced with carbonate when left in the air, it is stored in an inert gas atmosphere.
For example, Pr is used as a coactivator. Praseodymium oxide (Pr ₆ O ₁₁ ) is a non-stoichiometric oxide, unlike ordinary rare earth oxide Z ₂ O _3, and burns praseodymium oxalate, hydroxide, carbonate, etc. in the air 800 When heated to 0 ° C., it is obtained as a black powder having a composition of Pr ₆ O ₁₁ . Pr ₆ O ₁₁ is a starting material for synthesizing a praseodymium compound, and a high-purity one is also commercially available.

In particular, the phosphor according to the present invention includes Mn-added Sr—Ca—Si—N: Eu, Ca—Si—N: Eu, Sr—Si—N: Eu, Sr—Ca—Si—O—N: Eu, Ca-Si-ON: Eu, Sr-Si-ON: Eu-based silicon nitride. The basic constituent elements of this phosphor are represented by the general formula L _X Si _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 any one of Sr and Ca.) In the general formula, X and Y are preferably X = 2, Y = 5, or X = 1, 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 Si 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, CaSi 7 N 10: it is preferable to use a phosphor represented by Eu, during the composition of the phosphor, Mg, At least one selected from the group consisting of Sr, 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 any one of Sr, Ca, Sr and Ca. The mixing ratio of Sr and Ca can be changed as desired.
By using Si for the composition of the phosphor, it is possible to provide an inexpensive phosphor with good crystallinity.

Europium Eu, which is a rare earth element, is used for the emission center. Europium mainly has bivalent and trivalent energy levels. The phosphor of the present invention uses Eu ²⁺ as an activator with respect to the base alkaline earth metal silicon nitride. Eu ²⁺ is easily oxidized and is commercially available with a trivalent Eu ₂ O ₃ composition. However, in commercially available Eu ₂ O ₃ , O is greatly involved and it is difficult to obtain a good phosphor. Therefore, it is preferable to use a material obtained by removing O from Eu ₂ O ₃ out of the system. For example, it is preferable to use europium alone or europium nitride. However, this is not the case when Mn is added.
_{Sr 2 Si 5 N 8: Eu} , Pr, Ba 2 Si 5 N 8: Eu, Pr, Mg 2 Si 5 N 8: Eu, Pr, Zn 2 Si 5 N 8: Eu, Pr, SrSi 7 N 10: Eu _{, Pr, BaSi 7 N 10:} Eu, Ce, MgSi 7 N 10: Eu, Ce, ZnSi 7 N 10: Eu, Ce, Sr 2 Ge 5 N 8: Eu, Ce, Ba 2 Ge 5 N 8: Eu, _{Pr, Mg 2 Ge 5 N 8} : Eu, Pr, Zn 2 Ge 5 N 8: Eu, Pr, SrGe 7 N 10: Eu, Ce, BaGe 7 N 10: Eu, Pr, MgGe 7 N 10: Eu, Pr _{, ZnGe 7 N 10: Eu,} Ce, Sr 1.8 Ca 0.2 Si 5 N 8: Eu, Pr, Ba 1.8 Ca 0.2 Si 5 N 8: Eu, Ce, Mg 1.8 Ca 0 _.2 Si ₅ N ₈ : Eu, Pr, Zn _1.8 Ca _0.2 Si ₅ N ₈ : Eu, Ce, Sr _0.8 Ca _0.2 Si ₇ N ₁₀ : Eu, La, Ba _0.8 Ca _0.2 Si ₇ N _{10: Eu, La, Mg 0.8} Ca 0.2 Si 7 N 10: Eu, Nd, Zn 0.8 Ca 0.2 Si 7 N 10: Eu, Nd, Sr 0.8 Ca 0.2 Ge 7 _{N 10: Eu, Tb, Ba} 0.8 Ca 0.2 Ge 7 N 10: Eu, Tb, Mg 0.8 Ca 0.2 Ge 7 N 10: Eu, Pr, Zn 0.8 Ca 0.2 Ge ₇ N ₁₀ : Eu, Pr, Sr _0.8 Ca _0.2 Si ₆ GeN ₁₀ : Eu, Pr, Ba _0.8 Ca _0.2 Si ₆ GeN ₁₀ : Eu, Pr, Mg _0.8 Ca _{0.2 Si 6 GeN 10: Eu, Y} , Zn 0.8 Ca 0.2 Si _{GeN 10: Eu, Y, Sr} 2 Si 5 N 8: Pr, Ba 2 Si 5 N 8: Pr, Sr 2 Si 5 N 8: Tb, BaGe 7 N 10: Ce , etc. can be manufactured without limitation.

Mn as an additive promotes diffusion of Eu ²⁺ and improves luminous efficiency such as luminous luminance, energy efficiency, and quantum efficiency. Mn is contained in the raw material, or Mn alone or a Mn compound is contained in the manufacturing process and fired together with the raw material. However, Mn is not contained in the basic constituent elements after firing, or even if contained, only a small amount remains compared to the initial content. This is probably because Mn was scattered in the firing step.

  The phosphor includes Mg, Ga, In, Li, Na, K, Re, Mo, Fe, Sr, Ca, Ba, Zn, B, Al, Cu, in the basic constituent element or together with the basic constituent element. It contains at least one selected from the group consisting of Mn, Cr, O and Ni. These elements have actions such as increasing the particle diameter and increasing the luminance of light emission. Further, B, Al, Mg, Cr and Ni have an effect that afterglow can be suppressed.

Such a nitride-based phosphor absorbs part of the blue light emitted by the semiconductor light emitting device and emits light in the yellow to red region. Using a nitride-based phosphor together with a YAG-based phosphor in the light-emitting device having the above-described configuration, the blue light emitted from the semiconductor light-emitting element and the yellow to red light by the nitride-based phosphor are mixed to produce a warm color system. Provided is a light emitting device that emits a white mixed color light. It is preferable that the phosphor added in addition to the nitride-based phosphor contains an yttrium / aluminum oxide phosphor activated with cerium. This is because it can be adjusted to a desired chromaticity by containing the yttrium aluminum oxide phosphor. The yttrium / aluminum oxide phosphor activated by cerium absorbs part of the blue light emitted by the semiconductor light emitting element and emits light in the yellow region. Here, the blue light emitted by the semiconductor light emitting element and the yellow light of the yttrium / aluminum oxide fluorescent material emit light blue-white by mixing colors. Therefore, the yttrium / aluminum oxide phosphor and the phosphor emitting red light are mixed together in a translucent coating member and combined with the blue light emitted by the semiconductor light emitting element to produce a white-based material. A light emitting device that emits mixed color 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. This light-emitting device that emits white-based mixed color light improves the special color rendering index R9. A white light emitting device consisting only of a combination of a conventional blue light emitting element and an yttrium aluminum oxide phosphor activated by cerium has a special color rendering index R9 of almost 0 at a color temperature T _cp = 4600K, and is reddish Insufficient ingredients. Therefore, increasing the special color rendering index R9 has been a problem to be solved. In the present invention, a special color rendering evaluation is performed in the vicinity of the color temperature T _cp = 4600K by using a phosphor emitting red light together with an yttrium aluminum oxide phosphor. The number R9 can be increased to around 40.

Next, the phosphor according to the present invention: is described a method of manufacturing the _{((Sr X Ca 1-X} ) 2 Si 5 N 8 Eu), but is not limited to this manufacturing method. The phosphor contains Mn and O.
Raw materials Sr and Ca are pulverized. The raw materials Sr 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 may contain B, Al, Cu, Mg, Mn, MnO, Mn ₂ O ₃ , Al ₂ O ₃ and the like. The raw materials Sr and Ca are pulverized in a glove box in an argon atmosphere. Sr and Ca obtained by pulverization preferably have an average particle diameter of about 0.1 μm to 15 μm, but are not limited to this range. The purity of Sr and Ca is preferably 2N or higher, but is not limited thereto. In order to improve the mixed state, at least one of the metal Ca, the metal Sr, and the metal Eu can be alloyed, nitrided, pulverized, and used as a raw material.

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

Next, the raw materials Sr and Ca are nitrided in a nitrogen atmosphere. This reaction formula is shown in the following formula 1 and formula 2, respectively.
3Sr + N ₂ → Sr ₃ N ₂ (Formula 1)
3Ca + N ₂ → Ca ₃ N ₂ (Formula 2)
Sr and Ca are nitrided in a nitrogen atmosphere at 600 to 900 ° C. for about 5 hours. Sr and Ca may be mixed and nitrided, or may be individually nitrided. Thereby, a nitride of Sr and Ca can be obtained. Sr and Ca nitrides are preferably of high purity, but commercially available ones can also be used.

The raw material Si is nitrided in a nitrogen atmosphere. This reaction formula is shown in the following formula 3.
3Si + 2N ₂ → Si ₃ N ₄ (Formula 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.

Sr, Ca or Sr—Ca nitride is pulverized. Sr, Ca, and Sr—Ca nitrides are pulverized in a glove box in an argon atmosphere or a nitrogen atmosphere. Similarly, Si nitride is pulverized. Similarly, the Eu compound Eu ₂ O ₃ is pulverized. Europium oxide is used as the Eu compound, 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 preferably highly purified, but commercially available products can also be used. The average particle size of the alkaline earth metal nitride, silicon nitride and europium oxide after pulverization is preferably about 0.1 μm to 15 μm.

The raw material may contain at least one selected from the group consisting of Mg, Sr, Ca, Ba, Zn, B, Al, Cu, Mn, Cr, O, and Ni. In addition, 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 alone to the raw material, but are usually added in the form of compounds. Such compounds include H ₃ BO ₃ , Cu ₂ O ₃ , MgCl ₂ , MgO · CaO, Al ₂ O ₃ , metal borides (CrB, Mg ₃ B ₂ , AlB ₂ , MnB), B ₂ O ₃ , Cu ₂ O, CuO, and the like.

After the pulverization, Sr, Ca, Sr—Ca nitride, Si nitride, and Eu compound Eu ₂ O ₃ are mixed, and Mn is added. Since these mixtures are easily oxidized, they are mixed in a glove box in an Ar atmosphere or a nitrogen atmosphere.

Finally, a mixture of Sr, Ca, Sr—Ca nitride, Si nitride, and Eu compound Eu ₂ O ₃ is fired in an ammonia atmosphere. A phosphor represented by (Sr _X Ca _1-X ) ₂ Si ₅ N ₈ : Eu to which Mn is added can be obtained by firing. However, the composition of the target phosphor can be changed by changing the blending 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 can be in the range of 1200 to 1700 ° C, but the firing temperature is preferably 1400 to 1700 ° C. It is preferable to use a one-step baking in which the temperature is gradually raised and the baking is performed at 1200 to 1500 ° C. for several hours, but the first baking is performed at 800 to 1000 ° C. and the heating is gradually started from 1200. Two-stage firing (multi-stage firing) in which the second stage firing is performed at 1500 ° C. can also be used. The phosphor material is preferably fired using a boron nitride (BN) crucible or boat. Other boron nitride material quality of the crucible, alumina (Al 2 _{O 3)} can also be used materials of the crucible.
By using the above manufacturing method, it is possible to obtain a target phosphor.

In the embodiment of the present invention, a nitride-based phosphor is used as the phosphor that emits reddish light. In the present invention, the above-described YAG-based phosphor can emit red light. It is also possible to provide a light emitting device including a simple phosphor. Such a phosphor capable of emitting red light is a phosphor that emits light when excited by light having a wavelength of 400 to 600 nm. For example, Y ₂ O ₂ S: Eu, La ₂ O ₂ S: Eu. CaS: Eu, SrS: Eu, ZnS: Mn, ZnCdS: Ag, Al, ZnCdS: Cu, Al and the like. Thus, by using a phosphor capable of emitting red light together with a YAG phosphor, it is possible to improve the color rendering properties of the light emitting device.

  The phosphor capable of emitting red light typified by the aluminum garnet phosphor and the nitride phosphor formed as described above is disposed in the wavelength conversion member made of a single layer around the light emitting element. Two or more types may exist, and one type or two or more types may exist in the wavelength conversion member consisting of two layers. With such a configuration, it is possible to obtain mixed color light by mixing light from different types of phosphors. In this case, it is preferable that the average particle diameters and shapes of the phosphors are similar in order to better mix the light emitted from the phosphors and reduce color unevenness. Also, considering that the nitride-based phosphor absorbs part of the light that has been wavelength-converted by the YAG-based phosphor, the nitride-based phosphor is disposed closer to the light emitting element than the YAG-based phosphor. It is preferable to form the wavelength conversion member as described above. With this configuration, a part of the light wavelength-converted by the YAG phosphor is not absorbed by the nitride phosphor, and the YAG phosphor and the nitride phosphor are mixed. Compared with the case where it contains, the color rendering property of mixed-color light can be improved. The first phosphor layer containing the nitride phosphor covers at least a part of the semiconductor light emitting device, and the second phosphor layer containing the YAG phosphor is composed of the first phosphor layer and the semiconductor. It is preferable to have a phosphor layered structure that covers at least a part of the light emitting element. With this configuration, the excitation efficiency of the phosphor can be improved by the nitride phosphor and the YAG phosphor being directly excited by the light of the semiconductor light emitting device.

(Alkaline earth metal salt)
The light-emitting device in this embodiment mode uses alkaline earth activated by europium as a phosphor that absorbs part of light emitted from a light-emitting element and emits light having a wavelength different from the wavelength of the absorbed light. It can also have a metal silicate. The alkaline earth metal silicate is preferably an alkaline earth metal orthosilicate represented by the following general formula.
(2-x-y) SrO · x (Ba, Ca) O · (1-a-b-c-d) SiO 2 · aP 2 O 5 bAl 2 O 3 cB 2 O 3 dGeO 2: yEu 2+ ( Equation Medium, 0 <x <1.6, 0.005 <y <0.5, 0 <a, b, c, d <0.5.)
(2-x-y) BaO · x (Sr, Ca) O · (1-a-b-c-d) SiO 2 · aP 2 O 5 bAl 2 O 3 cB 2 O 3 dGeO 2: yEu 2+ ( Equation (Inside, 0.01 <x <1.6, 0.005 <y <0.5, 0 <a, b, c, d <0.5.)
Here, preferably, at least one of the values of a, b, c and d is greater than 0.01.

The light-emitting device in the present embodiment is a phosphor composed of an alkaline earth metal salt. In addition to the alkaline earth metal silicate described above, alkaline earth metal aluminate or Y activated by europium and / or manganese is used. (V, P, Si) O ₄ : Eu, or an alkaline earth metal-magnesium-disilicate represented by the following formula:
Me (3-xy) MgSi ₂ O ₃ : xEu, yMn (wherein 0.005 <x <0.5, 0.005 <y <0.5, Me represents Ba and / or Sr and / or Or Ca.)

Next, the manufacturing process of the phosphor made of alkaline earth metal silicate in the present embodiment will be described.
For the production of alkaline earth metal silicates, the stoichiometric amounts of the starting materials alkaline earth metal carbonate, silicon dioxide and europium oxide are intimately mixed according to the selected composition, and the phosphor is produced. In a conventional solid reaction, the desired phosphor is converted at a temperature of 1100 ° C. and 1400 ° C. under a reducing atmosphere. At this time, it is preferable to add less than 0.2 mol of ammonium chloride or other halide. If necessary, part of silicon can be replaced with germanium, boron, aluminum, and phosphorus, and part of europium can be replaced with manganese.

One of the phosphors as described above, ie, alkaline earth metal aluminates activated with europium and / or manganese, Y (V, P, Si) O ₄ : Eu, Y ₂ O ₂ S: Eu ³⁺ By combining one or these phosphors, as shown in the following table as an example, it is possible to obtain an emission color having a desired color temperature and high color reproducibility.

(Other phosphors)
In this embodiment, a phosphor that is excited by ultraviolet light and generates light of a predetermined color can be used as a phosphor. 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 at least one selected from Sr, Ca, Ba, Mg)
(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, (14) La ₂ O ₂ S: Eu, and the like.
In addition, these phosphors may be used alone in a single-layer wavelength conversion member, or may be used as a mixture. Furthermore, these phosphors may be used alone or in combination in each layer in the wavelength conversion member in which two or more layers are laminated.

<Diffusion agent>
By blending a diffusing agent in the phosphor layer, it is possible to obtain a phosphor layer in which the blending amount of the phosphor in the phosphor layer is reduced and the emission luminance is increased. Moreover, directivity can be relaxed.
As the diffusing agent, inorganic diffusing agents such as silicon dioxide, titanium oxide, aluminum oxide, calcium carbonate, zinc oxide, and barium titanate are preferable. Organic diffusing agents such as epoxy resins, phenol formalin resins, benzoguanamine resins, melamine resins, acrylic resins, polycarbonate resins, polyethylene resins, polypropylene resins, and guanamine resins may be used.
The average particle size is preferably 1 μm or more and 10 μm.
In an embodiment of the present invention, the diffusing agent in the phosphor layer is blended more in the first phosphor layer than in the second phosphor layer. The blending amount of the binder resin and the diffusing agent is preferably (binder resin) :( diffusing agent) = 10: 0.1 to 10: 2.

In another embodiment of the present invention, when different diffusing agents are blended in the first and second phosphor layers, the refractive index of the diffusing agent in the first phosphor layer is in the second phosphor layer. It mix | blends so that it may become larger than the refractive index of this diffusing agent. Specifically, when the diffusing agent in the first phosphor layer is Al ₂ O ₃ , the combination is such that the diffusing agent in the second phosphor layer is SiO ₂ having a refractive index smaller than that. can do. However, it is sufficient that the refractive index of the diffusing agent in the first phosphor layer is larger than the refractive index of the diffusing agent in the second phosphor layer, and the present invention is not limited to this combination.

<Binder resin>
In an embodiment of the present invention, the types of binder resins forming the first and second phosphor layers are different, and the refractive index of the binder resin forming the first phosphor layer is the second phosphor layer. It is blended so as to be larger than the refractive index of the binder resin that forms the film. The binder resin forming the first phosphor layer may be an epoxy resin and the binder resin forming the second phosphor layer may be a silicone resin. However, the refractive index of the binder resin that forms the first phosphor layer may be larger than the refractive index of the binder resin that forms the second phosphor layer, and the present invention is not limited to this combination.

<Mold member>
The mold member is a member for protecting the phosphor layer and the LED chip from external force or moisture from the external environment and efficiently emitting light from the light emitting element to the outside. As a specific material constituting such a mold member, transparent resin having excellent weather resistance such as epoxy resin, urea resin, silicone resin, and translucency generated by sol-gel method using metal alkoxide as a starting material. An inorganic member, glass or the like is preferably used. In particular, the mold member in this embodiment is preferably a transparent resin having high permeability to ceramic.
When LED chips are arranged at a high density, it is more preferable to use an epoxy resin, a silicone resin, or a combination thereof in consideration of disconnection of the conductive wire due to thermal shock. Further, a diffusing agent may be contained in the mold member in order to further increase the viewing angle. As specific diffusing agents, barium titanate, titanium oxide, aluminum oxide, silicon oxide, and the like, and mixtures thereof are preferably used. Moreover, an organic or inorganic coloring dye or coloring pigment can be contained for the purpose of cutting an undesired wavelength. Furthermore, a phosphor can be contained.

Examples according to the present invention will be described in detail below. In addition, this invention is not limited to the Example shown below.
FIG. 1 shows a schematic view of a light emitting device formed in an embodiment according to the present invention. In this example, the silicon nitride-based phosphor contained in the first phosphor layer is (Sr _0.7 Ca _0.3 ) ₂ Si ₅ N ₈ : Eu (hereinafter referred to as “phosphor 1”). .) The YAG: Ce-based phosphor contained in the second phosphor layer is Y ₃ (Al _0.8 Ga _0.2 ) ₅ O ₁₂ : Ce (hereinafter referred to as “phosphor 2”). is there.

  As shown in FIG. 1, the recess and the pair of positive and negative lead electrodes are formed by injection molding using a thermoplastic resin as a material. The semiconductor light emitting element 2 capable of emitting light in the blue region is bonded and fixed in the recess with an insulating adhesive. In this embodiment, the semiconductor light emitting elements placed in the recesses are each one chip, but a plurality of chips may be placed in the respective recesses. The semiconductor light emitting element 2, the positive electrode, and the negative electrode are wire-bonded to the positive electrode and the negative electrode of the lead electrode, respectively, using a conductive wire.

  The material for forming the first phosphor layer 14a in which the phosphor 1 is contained in the silicone resin is adjusted, and the adjusted material is disposed and cured so as to cover the semiconductor light emitting element 2 placed in the recess. .

  Subsequently, the formation material of the second phosphor layer 14b in which the phosphor 2 is contained in the silicone resin is adjusted, and the adjusted material is used so that the semiconductor light emitting element 2 and the first phosphor layer 14a are covered. Place and cure.

In addition, in order to make the average refractive index of the diffusing agent and the binder resin in the first phosphor layer higher than the average refractive index of the diffusing agent and the binder resin in the second phosphor layer, Al ₂ O ₃ is blended in the phosphor layer, and SiO ₂ is blended in the second phosphor layer. The combination of the diffusing agent and the binder resin in the first and second phosphor layers is set so that the average refractive index of the first phosphor layer is larger than the average refractive index in the second phosphor layer. It is only necessary to have this combination.

  The conductive wire, the phosphor layers 14a and 14b, and the semiconductor light emitting element 2 are sealed by the mold member 15 in which the diffusing agent is contained in the silicone resin.

FIG. 2 shows a schematic diagram of a light emitting device formed in an embodiment according to the present invention. In this embodiment, the ultraviolet-excited red light-emitting phosphor contained in the first phosphor layer is YO ₂ S ₂ : Eu, YVO ₄ : Eu, Gd ₂ O ₃ : Eu, (Y, Gd) BO ₃ : Eu, YBO ₃ : Eu (hereinafter referred to as “phosphor 1”), and the ultraviolet-excited green light-emitting phosphor contained in the second phosphor layer is ZnS: Cu, Ag, Zn ₂ SiO ₄ : Mn, BaAl ₁₂ O ₁₉ : Mn, BaMgAl ₁₆ O ₂₆ : Eu, Mn (hereinafter referred to as “phosphor 2”), the ultraviolet-excited blue light-emitting phosphor contained in the third phosphor layer is BaMgAl ₁₀ O ₁₇ : Eu, CaWO ₄ : Pb, Y ₂ SiO ₅ : Ce (hereinafter referred to as “phosphor 3”).

  As shown in FIG. 2, the recess and the pair of positive and negative lead electrodes are formed by injection molding using a thermoplastic resin as a material. The semiconductor light emitting element 2 capable of emitting ultraviolet light is adhered and fixed in the recess with an insulating adhesive. In this embodiment, each semiconductor light emitting element placed in the recess is one chip, but a plurality of chips may be placed in the recess. The semiconductor light emitting element 2, the positive electrode, and the negative electrode are wire-bonded to the positive electrode and the negative electrode of the lead electrode, respectively, using a conductive wire.

  The material for forming the first phosphor layer 24a in which the phosphor 1 is contained in the silicone resin is adjusted, and the adjusted material is arranged so that the semiconductor light emitting elements 1 and 2 placed in the recesses are covered. Harden.

  Then, the formation material of the 2nd fluorescent substance layer 24b which made the fluorescent substance 2 contain in the silicone resin was adjusted, the semiconductor light-emitting devices 1 and 2 and the 1st fluorescent substance layer 24a which were mounted in the recessed part. Place and cure the prepared material so that is covered.

  Furthermore, the formation material of the 3rd fluorescent substance layer 24c which made the fluorescent substance 3 contain the silicone resin was adjusted, the semiconductor light emitting elements 1 and 2 mounted in the recessed part, the 1st fluorescent substance layer 24a, The adjusted material is placed and cured so that the second phosphor layer 24b is covered.

  Also, a diffusing agent is blended so that the average refractive index of the diffusing agent and binder resin in the first phosphor layer is higher than the average refractive index of the diffusing agent and binder resin in the second phosphor layer. Keep it.

  The conductive wire, the phosphor layers 24a to 24c, and the semiconductor light emitting elements 1 and 2 are sealed by the mold member 15 in which the diffusing agent is contained in the silicone resin.

  FIG. 3 to FIG. 12 are a schematic cross-sectional view and a top view showing the light-emitting device according to the present example and the forming process thereof. Hereinafter, a light emitting device and a method for forming the same according to the present embodiment will be described with reference to the drawings.

  As shown in FIG. 10, the light emitting device according to this example includes a first phosphor layer 36 a and a second phosphor layer 36 b around the light emitting element flip-chip mounted on the submount 32. The first phosphor layer 36a covers at least a part of the main surface on the emission observation surface side of the translucent sapphire substrate 1, and the second phosphor layer 36b includes the first phosphor layer 36a and the light emission. The side of the element is covered. Here, the flip chip mounting is a mounting method in which the electrodes of the light emitting element are mechanically and electrically connected by facing and bonding to the conductive pattern of a support substrate such as a submount via a conductive member called a bump. Say. Hereinafter, a method of forming the light emitting device according to this example will be described.

  The submount substrate is provided with a conductive member 31 on one surface thereof to form a conductive pattern 31 for insulating and separating the positive electrode and the negative electrode. The conductive member is preferably made of aluminum, silver, gold, or an alloy thereof having high reflectivity. The material for the submount substrate is preferably aluminum nitride with respect to a material having substantially the same thermal expansion coefficient as that of the semiconductor light emitting device, for example, a nitride semiconductor light emitting device. By using such a material, the thermal stress generated between the submount and the light emitting element is relieved, and the electrical connection between the submount and the light emitting element via the bump can be maintained. Reliability can be improved. Alternatively, the material of the submount substrate is preferably silicon that can form a protective element (zener diode) and is inexpensive. The submount that functions as a Zener diode has a p-type semiconductor region having a positive electrode and an n-type semiconductor region having a negative electrode, and is in reverse parallel to the p-side electrode and the n-side electrode of the light-emitting element. Connected to. That is, the n-side electrode and the p-side electrode of the light emitting element are electrically connected to the p-type semiconductor region and the n-type semiconductor region of the submount by the bumps, respectively. Further, the positive and negative electrodes provided on the submount 32 are connected to an external electrode such as a lead electrode by a conductive wire 44. In this way, by giving the submount the function of a Zener diode, when an excessive voltage is applied between the positive and negative lead electrodes, if the voltage exceeds the Zener voltage of the Zener diode, the voltage between the positive and negative electrodes of the light emitting element Is held at the zener voltage and never exceeds this zener voltage. Therefore, it is possible to prevent an excessive voltage from being applied between the light emitting elements, protect the light emitting elements from the excessive voltage, and prevent the occurrence of element destruction and performance deterioration.

  In order to improve the reliability of the light emitting device, it is preferable that an underfill is filled in the gap formed between the positive and negative electrodes of the light emitting element and the insulating portion. The underfill material is, for example, a thermosetting resin such as an epoxy resin. In order to relieve the thermal stress of underfill, aluminum nitride, aluminum oxide, a composite mixture thereof, or the like may be further mixed into the epoxy resin. The amount of underfill is an amount that can fill a gap formed between the positive and negative electrodes of the light emitting element and the submount.

  As shown in FIG. 3, both the positive and negative electrodes of the light emitting element are fixed opposite to the positive and negative electrodes of the conductive pattern. That is, the p-side electrode and the n-side electrode of the light emitting element are fixed via the bumps 33 so as to face both the positive and negative electrodes formed on the same surface side of the submount. First, bumps made of Au are formed on both the positive and negative electrodes of the submount. Next, the electrode of the light emitting element and the electrode of the submount are opposed to each other through the bump, and the bump is welded by applying a load, heat, and ultrasonic waves, and the electrode of the light emitting element and the electrode of the submount are joined. . In addition to Au, eutectic solder (Au—Sn), Pb—Sn, lead-free solder, and the like can be used as the bump material.

  As in this example, by using a composite element of a light-emitting element and a submount mounted on a flip chip, light extraction efficiency of the light-emitting device is improved because light can be extracted from the light-transmitting substrate side of the light-emitting element. A highly reliable light-emitting device can be obtained by using a submount as a Zener diode. In addition, a light-emitting device with high heat dissipation can be obtained.

  As shown in FIG. 4, the first screen plate 34a is disposed on the submount substrate from the translucent substrate side of the light emitting element. The first screen plate 34a is configured to mask other than the main surface on the light emission observation surface side of the translucent substrate. In place of the screen plate, a metal mask may be disposed at a position where the phosphor layer is not desired to be formed, such as a ball bonding position of the conductive wire 44 or a parting line formation position.

  Hereinafter, a method for forming the phosphor layer in this example will be described. First, a material for forming the first phosphor layer 36a in which a nitride phosphor is contained in a silicone resin is adjusted. Here, the composition of the nitride-based phosphor and the diffusing agent contained in the forming material is the same as in Example 1. As shown in FIG. 5, the material for forming the phosphor layer containing the nitride-based phosphor is at least one of the main surfaces of the light-transmitting substrate in the light-emitting element on the side where the semiconductor is not stacked. Screen printing is performed using a squeegee 35 so as to cover the portion. FIG. 6 is a schematic cross-sectional view showing a state in which the material for forming the first phosphor layer 36a is disposed on the main surface on the light emission observation surface side of the light-transmitting substrate of the light-emitting element.

  Next, the material for forming the second phosphor layer 36b in which the YAG phosphor is contained in the silicone resin is adjusted. Here, the compositions of the YAG phosphor and the diffusing agent contained in the forming material are the same as those in Example 1. As shown in FIG. 7, the second screen plate 34 b is disposed on the submount substrate from the direction in which the first phosphor layer forming material is disposed. Here, the second screen plate 34b is different from the first screen plate 34a in the mask interval, and is configured such that at least the side surfaces of the light emitting element and the first phosphor layer forming material are not masked. Further, as shown in FIG. 8, the material for forming the second phosphor layer 36b containing the YAG phosphor includes the material for forming the first phosphor layer 36a and the side direction of the light emitting element. Screen printed to cover.

  FIG. 9 is a schematic cross-sectional view showing a state in which the second phosphor layer forming material is disposed so as to cover the first phosphor layer forming material and the side surface direction of the light emitting element. As shown in FIG. 9, the second screen plate 34 b is removed and the first and second phosphor layer forming materials are cured. Here, the materials for forming the first and second phosphor layers may be cured separately. That is, after the material for forming the first phosphor layer is cured, the material for forming the second phosphor layer may be screen-printed and cured. By forming in this way, sagging of the first phosphor layer forming material can be prevented, and the first phosphor layer can be reliably arranged in the direction of the main surface of the sapphire substrate on the emission observation surface side. Finally, by cutting the submount substrate so that at least one light emitting element is placed on the submount along the parting line, an element having a phosphor layer formed around the light emitting element is obtained.

  By forming the first and second phosphor layers as in this embodiment, the portion of the phosphor layer containing the YAG phosphor that covers the first phosphor layer is nitride-based fluorescence. The light that has been wavelength-converted by the body is reflected to the emission observation surface side without being absorbed, and at least part of the light from the light-emitting element that has been transmitted through the first phosphor layer without being wavelength-converted is absorbed. Flashes. On the other hand, the portion of the phosphor layer containing the YAG phosphor that covers the side surface direction of the light emitting element is directly excited by light from the light emitting element without interposing a layer containing the nitride phosphor. Therefore, the light emission from the YAG phosphor excited by the light from the light emitting element and the light emission from the nitride phosphor similarly excited by the light from the light emitting element are mixed in color, so the excitation efficiency of the phosphor is increased. The color rendering property can be improved as compared with the conventional light emitting device.

  FIG. 11 is a schematic top view of the light emitting device in this example, and FIG. 12 is a cross-sectional view taken along line A-A ′ of the light emitting device shown in FIG. 11. The light emitting device in this embodiment has a pair of positive and negative lead electrodes 43a and 43b for supplying electric power to the semiconductor element, a package 41 for housing the semiconductor element, and a light distribution characteristic of light emitted from the light emitting element. And a sealing member 47 filled between the concave portion of the package 41 and the lens.

  The package 41 in this embodiment is integrally molded so that a part of the metal base 45 and the lead electrodes 43a and 43b are covered with the molding resin by injection molding using the molding resin as a material. In addition, the metal base 45 has a concave bottom surface 42 for mounting a semiconductor element and is made of a metal having good thermal conductivity, so that the heat dissipation of the light emitting device can be improved. In this embodiment, the submount 32 on which the semiconductor light emitting element is mounted is fixed to the concave bottom surface 42 of the package with silver paste, as shown in FIGS. The conductive wire 44 connects the conductive pattern 31 of the submount 32 to the lead electrodes 43a and 43b exposed in the vicinity of the recess bottom surface 42 of the package. The material of the sealing member 47 can be the same material as the mold member described above. The sealing member 47 in this embodiment has a multilayer structure composed of a gel-like silicone resin that covers the periphery of the conductive wire and a rubber-like silicone resin that bonds the gel-like silicone resin and the lens 48 together. ing. In this manner, by covering the conductive wire with a flexible gel-like silicone resin, disconnection of the conductive wire can be prevented and a highly reliable light-emitting device can be obtained.

  As another aspect of the present embodiment, a back electrode having the same polarity as any one of a pair of positive and negative electrodes provided on the submount can be provided on the submount. At this time, the back electrode of the submount is opposed to the bottom surface of the recess that is electrically connected to the lead electrode, and is fixed through a conductive adhesive. By using a submount having a back electrode in this manner, the number of conductive wires can be reduced, and a highly reliable light-emitting device without wire breakage can be obtained.

  The light source having the phosphor laminated structure according to the present invention has advantages such as low voltage drive, small size and light weight, durability, and long life, and is used as a next-generation energy-saving illumination source, as well as an in-vehicle display light source and a mobile phone. It can be used as a backlight of a display portion.

Schematic of a light-emitting device comprising a blue LED as a light source, a first layer made of silicon nitride phosphor, and a second layer made of YAG phosphor activated by cerium, Schematic diagram of a light emitting device comprising an ultraviolet LED as a light source, a first layer composed of an ultraviolet excited red light emitting phosphor, a second layer composed of an ultraviolet excited green light emitting phosphor, and a third layer composed of an ultraviolet excited blue light emitting phosphor; Typical sectional drawing which shows one Example of the fluorescent substance laminated structure concerning this invention, Typical sectional drawing which shows one Example of the fluorescent substance laminated structure concerning this invention, Typical sectional drawing which shows one Example of the fluorescent substance laminated structure concerning this invention, Typical sectional drawing which shows one Example of the fluorescent substance laminated structure concerning this invention, Typical sectional drawing which shows one Example of the fluorescent substance laminated structure concerning this invention, Typical sectional drawing which shows one Example of the fluorescent substance laminated structure concerning this invention, Typical sectional drawing which shows one Example of the fluorescent substance laminated structure concerning this invention, Typical sectional drawing which shows one Example of the fluorescent substance laminated structure concerning this invention, The typical top view showing one example of the light-emitting device concerning the present invention, It is typical sectional drawing which shows one Example of the light-emitting device concerning this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sapphire substrate 2 Semiconductor layer 13, 13a, 13b Lead frame 14a Silicon nitride fluorescent substance 14b YAG: Ce system fluorescent substance 15 Silicone resin Mold member 24a Ultraviolet excitation red light emission fluorescent substance 24b Ultraviolet excitation green light emission fluorescent substance 24c Ultraviolet excitation blue light emission Phosphor 31 Conductive pattern 32 Submount 33 Bump 34a First screen plate 34b Second screen plate 35 Squeegee 36a First phosphor layer forming material 36b First phosphor layer forming material 41 Package 42 Recess bottom surface 43a, 43b Lead electrode 44 Conductive wire 45 Metal base 46 Semiconductor element 47 Sealing member 48 Lens

Claims (13)

A plurality of phosphor layers made of a phosphor, a diffusing agent, and a binder resin are laminated on a semiconductor light emitting element, and the first phosphor layer closer to the semiconductor light emitting element is far from the semiconductor light emitting element. A phosphor layered structure including a phosphor that emits fluorescence having a wavelength longer than that of the second phosphor layer,
The first phosphor layer includes a diffusing agent having a refractive index equal to or larger than that of the diffusing agent contained in the second phosphor layer, and the blending amount thereof is larger than that of the second phosphor layer. A phosphor laminate structure. The first phosphor layer covers at least a part of the semiconductor light emitting element, and the second phosphor layer covers the first phosphor layer and at least a part of the semiconductor light emitting element. Item 6. The phosphor laminated structure according to Item 1.
The diffusing agent is at least one selected from the group consisting of SiO ₂ , Al ₂ O ₃ , Zr ₂ O ₃ , and Y ₂ O ₃ , TiO ₂ , B ₂ O ₃ , and CaCO _3. 3. The phosphor laminated structure according to 1 or 2.   The kind of diffusing agent in the first and second phosphor layers is different, and the refractive index of the diffusing agent in the first phosphor layer is larger than the refractive index of the diffusing agent in the second phosphor layer. The phosphor laminated structure according to claim 1.   The types of binder resins that form the first and second phosphor layers are different, and the refractive index of the binder resin that forms the first phosphor layer is the refraction of the binder resin that forms the second phosphor layer. The phosphor layered structure according to claim 1, wherein the phosphor layered structure has a larger ratio.   The phosphor laminated structure according to claim 1, wherein the binder resin is selected from the group consisting of an epoxy resin, an acrylic resin, an imide resin, a silicone resin, and a urea resin.   The diffusing agent in the first and second phosphor layers is the same, and the blending amount of the diffusing agent in the first phosphor layer is greater than the blending amount of the diffusing agent in the second phosphor layer. The phosphor layered structure according to claim 1, wherein the phosphor layered structure is increased.   The type of binder resin forming the first and second phosphor layers is the same, and the difference in refractive index between the binder resin forming the first phosphor layer and the diffusing agent is the second phosphor layer. The phosphor laminated structure according to claim 1, wherein a difference in refractive index between the binder resin and the diffusing agent forming the phosphor is larger.   The types of binder resins that form the first and second phosphor layers are different, and the refractive index of the binder resin that forms the first phosphor layer is the same as that of the binder resin that forms the second phosphor layer. The refractive index difference between the binder resin forming the first phosphor layer and the diffusing agent is larger than the refractive index difference between the binder resin forming the second phosphor layer and the diffusing material. The phosphor layered structure according to claim 1, wherein:   The kind of diffusing agent and / or binder resin in the first and second phosphor layers is different, and the average refractive index of the diffusing agent and binder resin in the first phosphor layer is in the second phosphor layer. The phosphor multilayer structure according to claim 1, wherein the phosphor has a larger refractive index than the average refractive index of the diffusing agent and binder resin. In a light source formed by laminating a plurality of phosphor layers made of a phosphor, a diffusing agent, and a binder resin on a semiconductor light emitting element capable of emitting blue light,
The first phosphor layer closer to the semiconductor light emitting element is a silicon nitride-based phosphor, and the phosphor emitting fluorescence having a longer wavelength than the second phosphor layer farther from the semiconductor light emitting element is A light source that is at least an aluminum garnet phosphor,
The first phosphor layer includes a diffusing agent having a refractive index equal to or larger than that of the diffusing agent contained in the second phosphor layer, and the blending amount thereof is larger than that of the second phosphor layer. Light source.   The first phosphor layer covers at least a part of the main surface of the semiconductor light emitting device, and the second phosphor layer covers the first phosphor layer and the side surface direction of the semiconductor light emitting device. The light source according to claim 11. In a light source formed by laminating a plurality of phosphor layers made of a phosphor, a diffusing agent, and a binder resin on a semiconductor light emitting device capable of emitting ultraviolet rays,
The first phosphor layer closer to the semiconductor light emitting element includes an ultraviolet excited red light emitting phosphor, the second phosphor layer includes an ultraviolet excited green light emitting phosphor, and the third phosphor. The layer comprises an ultraviolet excited blue emitting phosphor;
The first phosphor layer includes a diffusing agent equivalent to or larger in refractive index than the diffusing agent contained in the second phosphor layer than the second phosphor layer, and the second phosphor layer includes: A light source comprising a diffusing agent equivalent to or having a larger refractive index than the diffusing agent contained in the third phosphor layer, as compared with the third phosphor layer.

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