JP6075712B2 - Light emitting device - Google Patents

Light emitting device Download PDF

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JP6075712B2
JP6075712B2 JP2013061353A JP2013061353A JP6075712B2 JP 6075712 B2 JP6075712 B2 JP 6075712B2 JP 2013061353 A JP2013061353 A JP 2013061353A JP 2013061353 A JP2013061353 A JP 2013061353A JP 6075712 B2 JP6075712 B2 JP 6075712B2
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phosphor
excitation light
fluorescence
dispersed
plate
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研吾 森安
研吾 森安
井上　正樹
正樹 井上
蕪木　清幸
清幸 蕪木
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Ushio Denki KK
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本発明は、発光デバイスに関し、特に、励起光により蛍光を放射する発光デバイスに係わるものである。   The present invention relates to a light emitting device, and more particularly to a light emitting device that emits fluorescence by excitation light.

従来から、プロジェクター等の用途に、レーザ光を励起光として蛍光体に照射することによって、緑色の蛍光を放射する発光デバイスが知られている。
このような発光デバイスの一例として、特開２０１２−１９９０７５号公報（特許文献１）が知られていて、その概要が図６に示されている。
図において、ガラス粉末と蛍光体粉末を焼結させた蛍光体層２１を反射体２２の上に貼り付け、さらに発光効率向上のため、所定の入射角範囲内の励起光を透過し、範囲外の励起光を反射するとともに、蛍光を透過させる波長選択反射層２３を設けたものである。 2. Description of the Related Art Conventionally, light emitting devices that emit green fluorescence by irradiating phosphors with laser light as excitation light are known for applications such as projectors.
As an example of such a light emitting device, Japanese Patent Application Laid-Open No. 2012-199075 (Patent Document 1) is known, and an outline thereof is shown in FIG.
In the figure, a phosphor layer 21 obtained by sintering glass powder and phosphor powder is pasted on a reflector 22, and further, excitation light within a predetermined incident angle range is transmitted to increase the luminous efficiency. The wavelength selective reflection layer 23 that reflects the excitation light and transmits the fluorescence is provided.

ところで、上記従来技術における蛍光体層２１はガラス粉末と蛍光体粉末を焼結させた焼結体であるために、熱伝導が悪くて十分な冷却効果が得られず、蛍光体層２１が高温化して温度消光が発生しやすい、といった問題があった。
また、蛍光体層２１が焼結体であるために、その表面には凹凸があって誘電体多層膜からなる波長選択反射層２３を形成することが困難であった。
また、この蛍光体層２１で発生した蛍光が全反射によって蛍光体層内に閉じ込められ、この閉じ込められた蛍光は外部に放射されることがなく、そのため発光効率が低下する、といった問題があった。 By the way, since the phosphor layer 21 in the prior art is a sintered body obtained by sintering glass powder and phosphor powder, the heat conduction is poor and a sufficient cooling effect cannot be obtained, and the phosphor layer 21 has a high temperature. There is a problem that temperature quenching is likely to occur.
In addition, since the phosphor layer 21 is a sintered body, it has been difficult to form the wavelength selective reflection layer 23 formed of a dielectric multilayer film with irregularities on the surface thereof.
Further, there is a problem that the fluorescence generated in the phosphor layer 21 is confined in the phosphor layer by total reflection, and the confined fluorescence is not radiated to the outside, so that the light emission efficiency is lowered. .

特開２０１２−１９９０７５号公報JP 2012-199075 A

この発明が解決しようとする課題は、励起光が入射し、蛍光を放射する蛍光体を有し、高熱伝導材料からなるヒートシンクを介して当該蛍光体の熱を排熱する発光デバイスにおいて、蛍光体の熱伝導性を高めて、ヒートシンクによる冷却を効果的なものとして温度消光が発生することを防止し、更には、発生した蛍光が蛍光体内に閉じ込められることなく、効率的に外部に放射できて発光効率の高い発光デバイスを提供することである。   A problem to be solved by the present invention is a light emitting device that has a phosphor that emits fluorescence and emits fluorescence, and that dissipates the heat of the phosphor through a heat sink made of a highly heat conductive material. In order to prevent the occurrence of temperature quenching by improving the thermal conductivity of the heat sink and effectively cooling the heat sink, the generated fluorescence can be efficiently emitted outside without being trapped in the phosphor. The object is to provide a light emitting device with high luminous efficiency.

上記課題を解決するために、この発明に係る発光デバイスは、蛍光体が、バルク状の結晶から成り、当該蛍光体の内部には蛍光を散乱する散乱体が分散されていることを特徴とする。
また、前記蛍光体の励起光入射面と蛍光出射面とが同一面であることを特徴とする。
また、前記蛍光体の励起光入射面と蛍光出射面とが反対側面であることを特徴とする。
また、前記蛍光体の励起光入射面には、前記励起光の反射を防止する反射防止層が設けられていることを特徴とする。
また、前記蛍光体と、前記ヒートシンクとの間には、蛍光を反射する反射層が設けられていることを特徴とする。 In order to solve the above-described problems, the light-emitting device according to the present invention is characterized in that the phosphor is made of a bulk crystal, and a scatterer that scatters fluorescence is dispersed inside the phosphor. .
Further, the excitation light incident surface and the fluorescence emission surface of the phosphor are the same surface.
Further, the excitation light incident surface and the fluorescence emission surface of the phosphor are opposite side surfaces.
Moreover, an antireflection layer for preventing reflection of the excitation light is provided on the excitation light incident surface of the phosphor.
In addition, a reflective layer that reflects fluorescence is provided between the phosphor and the heat sink.

また、前記蛍光体は、前記励起光入射面に近い側に分散された散乱体の数密度が、奥側に分散された散乱体の数密度に比べて低いことを特徴とする。
また、前記蛍光体は、密接配置された複数の板状蛍光体からなり、前記励起光入射側の板状蛍光体に分散された散乱体の数密度が、奥側の板状蛍光体に分散された散乱体の数密度に比べて低いことを特徴とする。
また、前記蛍光体は、密接配置された複数の板状蛍光体からなり、前記励起光入射側および前記蛍光出射側の板状蛍光体に分散された散乱体の数密度が、これらに挟まれた板状蛍光体に分散された散乱体の数密度に比べて低いことを特徴とする。 Further, the phosphor is characterized in that the number density of scatterers dispersed on the side closer to the excitation light incident surface is lower than the number density of scatterers dispersed on the back side.
The phosphor comprises a plurality of closely arranged plate-like phosphors, and the number density of scatterers dispersed in the plate-like phosphor on the excitation light incident side is dispersed in the plate-like phosphor on the back side. It is characterized in that it is lower than the number density of the scatterers formed.
The phosphor is composed of a plurality of plate-like phosphors arranged closely, and the number density of scatterers dispersed in the plate-like phosphor on the excitation light incident side and the fluorescence emission side is sandwiched between them. The number density of the scatterers dispersed in the plate-like phosphor is low.

この発明の発光デバイスによれば、蛍光体が、バルク状の結晶から成るので、粉末の蛍光体層や、樹脂やガラス中に分散させた従来の蛍光体層に比べて熱伝導率が高くなり、蛍光体に当接したヒートシンクへの熱伝導が良好となって、排熱効率が高められ、蛍光体の温度消光という不具合が回避される。
また、蛍光体内に粒子状の散乱体を分散混入することで、蛍光の進行方向をランダムに変化させ、蛍光が蛍光体の界面で全反射して内部に閉じ込められる光を低減させることが可能となって、光取り出し効率を高めることができる。
また、蛍光体の励起光入射面に励起光の反射防止層を設けることで、励起光が効率的に蛍光体に入射するようになり、励起光の利用効率を高めることができる。更に、この蛍光体がバルク状の結晶構造であるので、その表面に凹凸が形成されることもなく、反射防止層の接合性が良好なものとなる。
また、蛍光体のヒートシンクに接する面に反射層を設けることで、光取り出し効率を高めることができる。 According to the light emitting device of the present invention, since the phosphor is composed of bulk crystals, the thermal conductivity is higher than that of a powder phosphor layer or a conventional phosphor layer dispersed in resin or glass. The heat conduction to the heat sink in contact with the phosphor becomes good, the heat exhaust efficiency is increased, and the problem of temperature quenching of the phosphor is avoided.
In addition, by dispersing and dispersing particulate scatterers in the phosphor, it is possible to change the direction of fluorescence randomly, and to reduce the light that is totally reflected and confined inside the phosphor interface. Thus, the light extraction efficiency can be increased.
In addition, by providing an excitation light reflection preventing layer on the excitation light incident surface of the phosphor, the excitation light efficiently enters the phosphor, and the utilization efficiency of the excitation light can be increased. Furthermore, since this phosphor has a bulk crystal structure, the surface of the phosphor is not formed with irregularities, and the antireflection layer has good bondability.
In addition, the light extraction efficiency can be increased by providing a reflective layer on the surface of the phosphor that is in contact with the heat sink.

また、蛍光体は、励起光入射面に近い側に分散された散乱体の数密度が、奥側に分散された散乱体の数密度に比べて低いことにより、励起光が散乱体により散乱されることがなく、蛍光体の奥部まで進行できて、有効な蛍光変換ができる。
また、蛍光体は、密接配置された複数の板状蛍光体からなり、それぞれ分散された散乱体の数密度を異ならせた板状蛍光体を用意することで、励起光入射方向で散乱体の数密度を異ならせる構造が容易に得られる。 In addition, in the phosphor, excitation light is scattered by the scatterer because the number density of the scatterer dispersed on the side closer to the excitation light incident surface is lower than the number density of the scatterer dispersed on the back side. It is possible to proceed to the inner part of the phosphor without causing any trouble, and effective fluorescence conversion can be performed.
In addition, the phosphor is composed of a plurality of closely arranged plate-like phosphors, and by preparing plate-like phosphors with different numbers of dispersed scatterers, the scatterer is arranged in the excitation light incident direction. A structure with different number density can be easily obtained.

本発明の第１実施例を示す断面図。Sectional drawing which shows 1st Example of this invention. 本発明の第２実施例を示す断面図。Sectional drawing which shows 2nd Example of this invention. 本発明の第３実施例を示す断面図。Sectional drawing which shows 3rd Example of this invention. 本発明の第４実施例を示す断面図。Sectional drawing which shows 4th Example of this invention. 本発明の第５実施例を示す断面図。Sectional drawing which shows 5th Example of this invention. 従来技術の断面図。Sectional drawing of a prior art.

図１に本発明の第１実施例が示されており、蛍光体１は、蛍光材の多結晶または単結晶で形成されている。この蛍光体１は、例えば、Ｌｕ３Ａｌ５Ｏ１２結晶（以下ＬｕＡＧ結晶という）に発光元素として希土類を添加した材料を用いることができる。発光元素は、例えばＣｅ、Ｐｒ、Ｎｄ、Ｅｕ、Ｔｂなどがある。添加する発光元素によって、蛍光の波長を変えることも可能である。
一般的に、蛍光体は温度が上がると、温度消光を起こし、発光効率が低下するが、本発明における蛍光体は、バルク状の結晶から成るので粒子間の空間がほとんどなく熱伝導が優れており、従来のガラス粉末と蛍光体粉末を混合して焼結させたものと比較して、熱伝導率が大幅に向上し、排熱効率を大幅に高めて温度消光を抑制することができる。 FIG. 1 shows a first embodiment of the present invention. A phosphor 1 is formed of a polycrystalline or single crystal of a fluorescent material. For this phosphor 1, for example, a material in which a rare earth is added as a light emitting element to a Lu 3 Al 5 O 12 crystal (hereinafter referred to as LuAG crystal) can be used. Examples of the light emitting element include Ce, Pr, Nd, Eu, and Tb. It is also possible to change the fluorescence wavelength depending on the light emitting element to be added.
In general, when the temperature of the phosphor rises, temperature quenching occurs and the luminous efficiency decreases. However, the phosphor in the present invention is composed of bulk crystals, so there is almost no space between the particles and heat conduction is excellent. Therefore, compared with the conventional glass powder and phosphor powder mixed and sintered, the thermal conductivity is greatly improved, the exhaust heat efficiency is greatly increased, and the temperature quenching can be suppressed.

この蛍光体１には散乱体２が分散されて混入されている。
この散乱体２としては、蛍光体の焼結時に析出させたプレート状結晶の主成分と屈折率が異なる相や、焼結時に添加した不純物などを用いることができる。
例えば、蛍光体の母体材料（Ｌｕ３Ａｌ５Ｏ１２やＹ３Ａｌ５Ｏ１２など）を焼結して結晶化する際に、原材料の配合比率を調整することで、母体材料とは屈折率の異なる結晶相（例えばＬｕ２Ｏ３、Ｙ２Ｏ３、Ａｌ２Ｏ３を多く含む結晶相）を粒界に析出させ、散乱体として蛍光体の内部に設けることができる。
また、結晶中に微粒子（例えばＬｕ２Ｏ３、Ｙ２Ｏ３、Ａｌ２Ｏ３などの粒子）を添加することで、散乱体とすることもできる。 In this phosphor 1, scatterers 2 are dispersed and mixed.
As the scatterer 2, a phase having a refractive index different from that of the main component of the plate-like crystal deposited during the sintering of the phosphor, an impurity added during the sintering, or the like can be used.
For example, when sintering and crystallizing a phosphor base material (such as Lu 3 Al 5 O 12 or Y 3 Al 5 O 12 ), the refractive index of the base material is adjusted by adjusting the mixing ratio of the raw materials Crystal phases different from each other (for example, a crystal phase containing a large amount of Lu 2 O 3 , Y 2 O 3 , and Al 2 O 3 ) can be precipitated at grain boundaries and provided inside the phosphor as a scatterer.
Moreover, the addition of fine particles (particles such as Lu 2 O 3, Y 2 O 3, Al 2 O 3), may be a scatterer in the crystal.

この実施例では、励起光入射面と蛍光出射面とが同一面であって、つまり、蛍光体１の上面１ａから励起光Ｘが入射し、蛍光体１内で発生した蛍光Ｙも同じ上面１ａから出射される。
そして、この蛍光体１の下面１ｂには、金属などの高熱伝導材料からなるヒートシンク３を当接している。
また、蛍光体１の励起光入射面１ａには、励起光の反射を防止する反射防止層４が設けられており、この反射防止層４には、例えばＭｇＯ膜などからなるＡＲコートが用いられる。これにより、励起光の表面反射によるロスを低減できる。
前記したように、蛍光体１はプレート状の結晶体であるために、その表面に凹凸が形成されることがなく、前記反射防止層４が強固に接合される。なお、反射防止層４が形成される蛍光体１の表面は、予め研磨加工を施しておくことがより好ましい。 In this embodiment, the excitation light incident surface and the fluorescence emission surface are the same surface, that is, the excitation light X is incident from the upper surface 1a of the phosphor 1, and the fluorescence Y generated in the phosphor 1 is also the same upper surface 1a. It is emitted from.
A heat sink 3 made of a highly heat conductive material such as metal is in contact with the lower surface 1b of the phosphor 1.
Further, an antireflection layer 4 for preventing reflection of excitation light is provided on the excitation light incident surface 1a of the phosphor 1, and an AR coat made of, for example, an MgO film is used for the antireflection layer 4. . Thereby, the loss by the surface reflection of excitation light can be reduced.
As described above, since the phosphor 1 is a plate-like crystal, there is no unevenness on the surface thereof, and the antireflection layer 4 is firmly bonded. In addition, it is more preferable that the surface of the phosphor 1 on which the antireflection layer 4 is formed is previously polished.

また、蛍光体１の励起光入射面（蛍光出射面でもある）１ａとは励起光入射方向の反対側の面１ｂには、蛍光Ｙを反射する反射層５が設けられている。この反射層５には、例えば銀の蒸着膜が用いられる。これにより、蛍光体１から反射層５に至った蛍光はこの反射層５により再び蛍光体１内に戻されて有効活用される。なお、銀の蒸着膜を用いた場合、励起光Ｘも反射されるので、その有効利用が図られる。
こうして反射層５が設けられた蛍光体１は、該反射層５を介在させて、接合層６によってヒートシンク３に接合されている。これにより、励起光Ｘの照射によって蛍光体１で発生した熱は、ヒートシンク３に伝わって外部へ排熱される。
なお、ヒートシンク３との接合は図１では蛍光体１の底面１ｂのみであるが、励起光入射面（蛍光放射面）１ａ以外の面の全てがヒートシンク３と接していてもよい。 In addition, a reflection layer 5 that reflects the fluorescence Y is provided on the surface 1b opposite to the excitation light incident direction (also a fluorescence emission surface) 1a of the phosphor 1. For example, a silver deposition film is used for the reflective layer 5. Thereby, the fluorescence from the phosphor 1 to the reflection layer 5 is returned again into the phosphor 1 by the reflection layer 5 and effectively used. In addition, since the excitation light X is reflected when a silver vapor deposition film is used, the effective utilization is achieved.
The phosphor 1 thus provided with the reflection layer 5 is bonded to the heat sink 3 by the bonding layer 6 with the reflection layer 5 interposed therebetween. Thereby, the heat generated in the phosphor 1 by the irradiation of the excitation light X is transmitted to the heat sink 3 and is exhausted to the outside.
In FIG. 1, only the bottom surface 1b of the phosphor 1 is joined to the heat sink 3. However, all surfaces other than the excitation light incident surface (fluorescence emission surface) 1a may be in contact with the heat sink 3.

上記構成において、励起光Ｘが入射して蛍光体１内で発生した蛍光Ｙの一部は、蛍光体１の内面、もしくは反射層５で全反射を起こす開口にあるが、蛍光体１内部にランダムに存在する散乱体２によって散乱されて光線の向きが変えられので、全反射によって閉じ込められる光を低減させ、光取り出し効率を高めることができる。   In the above configuration, a part of the fluorescence Y generated in the phosphor 1 when the excitation light X is incident is in the inner surface of the phosphor 1 or the opening that causes total reflection in the reflection layer 5. Since the direction of the light beam is scattered by the scatterers 2 present at random, the light confined by the total reflection can be reduced, and the light extraction efficiency can be increased.

図２には、本発明の第２実施例が示されていて、蛍光体１に分散される散乱体２の数密度が、励起光入射方向における深さ方向で異なっている例である。
即ち、蛍光体１の励起光入射面１ａに近い部分における散乱体２の数密度が、奥側、つまり、反射層５形成面側における散乱体２の数密度に比べて低くなっている。
なお、ここでいう数密度とは、蛍光体１に含まれる散乱体２の単位体積あたりの個数を表している。
こうすることで、励起光Ｘが蛍光体１に入射したとき、入射方向の浅い部分で散乱体２によって散乱されてしまうことがなく、蛍光体１の奥部まで進行することができて、励起光Ｘによる蛍光変換を有効に行なうことができる。
また、併せて、蛍光体１内で発生した蛍光が、蛍光出射面でもある励起光入射面１ａの近傍で散乱されて出射されなくなるという事態を回避している。 FIG. 2 shows a second embodiment of the present invention, in which the number density of the scatterers 2 dispersed in the phosphor 1 is different in the depth direction in the excitation light incident direction.
That is, the number density of the scatterers 2 in the portion close to the excitation light incident surface 1a of the phosphor 1 is lower than the number density of the scatterers 2 on the back side, that is, the reflection layer 5 formation surface side.
Here, the number density represents the number of scatterers 2 included in the phosphor 1 per unit volume.
By doing so, when the excitation light X is incident on the phosphor 1, it is not scattered by the scatterer 2 in the shallow portion of the incident direction, and can travel to the inner part of the phosphor 1, and the excitation light X can be excited. Fluorescence conversion by light X can be performed effectively.
In addition, the situation where the fluorescence generated in the phosphor 1 is scattered and is not emitted in the vicinity of the excitation light incident surface 1a which is also the fluorescence emission surface is avoided.

図３には、本発明の第３実施例が示されていて、図２に示す第２実施例の散乱体２の数密度勾配をもった蛍光体を容易に作製できる実施例である。
この実施例では、蛍光体１が複数（この場合２つ）の板状蛍光体１１、１２からなり、互いに密接に積層配置されている。励起光入射側の板状蛍光体１１における散乱体２の数密度は、励起光入射方向の奥側、即ち、ヒートシンク３側の板状蛍光体１２における散乱体２の数密度よりも低くなっている。
こうすることで、蛍光体１に散乱体２の数密度の勾配を容易に付けることができる。
なお、板状蛍光体は２枚以上であってもよい。このとき、最も励起光入射側に位置する板状蛍光体には散乱体を全く含まないようにしてもよい。また、板状蛍光体は、単に重ねて設置してもよいし、密に貼り合わせてもよい。 FIG. 3 shows a third embodiment of the present invention, in which a phosphor having a number density gradient of the scatterer 2 of the second embodiment shown in FIG. 2 can be easily manufactured.
In this embodiment, the phosphor 1 is composed of a plurality of (in this case, two) plate-like phosphors 11 and 12, and they are closely stacked. The number density of the scatterers 2 in the plate-like phosphor 11 on the excitation light incident side is lower than the number density of the scatterers 2 in the plate-like phosphor 12 on the back side in the excitation light incident direction, that is, the heat sink 3 side. Yes.
In this way, the phosphor 1 can be easily given a gradient of the number density of the scatterers 2.
Two or more plate-like phosphors may be used. At this time, the plate-like phosphor positioned closest to the excitation light incident side may not include any scatterers. Further, the plate-like phosphors may be simply stacked and may be closely bonded.

以上の実施例では、励起光入射面と蛍光出射面が同一面であるものを示したが、これらが異なる面であってもよい。
図４には、本発明の第４実施例が示されていて、蛍光体１への励起光Ｘの入射面と、蛍光Ｙの出射面が異なり、互いに平行な反対側の平面となっている。
この実施例では、蛍光体２の上面１ａが励起光入射面であって、この面１ａには励起光の反射防止層４が形成され、下面１ｂが蛍光出射面である。勿論この例でも蛍光体１には、散乱体２が分散して混入されている。
そして、励起光入射面１ａと蛍光出射面１ｂ以外の側面に反射層５、５が設けられていて、ヒートシンク３、３は、該反射層５を介して蛍光体１の側面に当接されている。 In the above embodiment, the excitation light incident surface and the fluorescence emission surface are the same surface, but they may be different surfaces.
FIG. 4 shows a fourth embodiment of the present invention. The incident surface of the excitation light X to the phosphor 1 and the emission surface of the fluorescence Y are different and are opposite planes parallel to each other. .
In this embodiment, the upper surface 1a of the phosphor 2 is an excitation light incident surface, the excitation light reflection preventing layer 4 is formed on the surface 1a, and the lower surface 1b is a fluorescence emission surface. Of course, also in this example, the scatterer 2 is dispersed and mixed in the phosphor 1.
Reflective layers 5 and 5 are provided on the side surfaces other than the excitation light incident surface 1 a and the fluorescence emission surface 1 b, and the heat sinks 3 and 3 are in contact with the side surfaces of the phosphor 1 through the reflective layer 5. Yes.

図５には、本発明の第５実施例が示されていて、図４の実施例における蛍光体１を複数の板状蛍光体によって構成したものである。
蛍光体１が、複数の密着配置された板状蛍光体１３、１４、１５からなる。励起光入射側に位置する板状蛍光体１３には励起光反射防止層４が設けられている。そして、該板状蛍光体１３と、蛍光出射側に位置する板状蛍光体１５における散乱体の数密度は、これらに挟まれた板状蛍光体１４における散乱体２の数密度よりも低く、この例では、板状蛍光体１３、１５には散乱体が含まれず、板状蛍光体１４にのみ散乱体２が分散された例が示されている。
もちろん、この例でも蛍光体１を構成する板状蛍光体の数は３枚に限定されない。
この場合も、励起光Ｘが励起光入射側の板状蛍光体１３内で散乱されることがないので、板状蛍光体１４にまで進行し、この間に発生した蛍光は分散体２によって分散されて蛍光出射側の板状蛍光体１５から出射される。このとき、蛍光Ｙが板状蛍光体１５内で散乱されて出射できなくなることもない。 FIG. 5 shows a fifth embodiment of the present invention, in which the phosphor 1 in the embodiment of FIG. 4 is composed of a plurality of plate-like phosphors.
The phosphor 1 is composed of a plurality of plate-like phosphors 13, 14, 15 arranged in close contact with each other. An excitation light reflection preventing layer 4 is provided on the plate-like phosphor 13 located on the excitation light incident side. The number density of the scatterers in the plate-like phosphor 13 and the plate-like phosphor 15 located on the fluorescence emission side is lower than the number density of the scatterers 2 in the plate-like phosphor 14 sandwiched between them. In this example, a scatterer is not included in the plate-like phosphors 13 and 15, and the scatterer 2 is dispersed only in the plate-like phosphor 14.
Of course, also in this example, the number of plate-like phosphors constituting the phosphor 1 is not limited to three.
Also in this case, since the excitation light X is not scattered in the plate-like phosphor 13 on the excitation light incident side, it proceeds to the plate-like phosphor 14, and the fluorescence generated during this time is dispersed by the dispersion 2. And is emitted from the plate-like phosphor 15 on the fluorescence emission side. At this time, the fluorescence Y is not scattered within the plate-like phosphor 15 and cannot be emitted.

本発明の効果を検証した実験を以下に述べる。
＜比較例＞
実験に用いた蛍光体１は、Ｃｅを元素割合で０．５％含むＬｕ３Ａｌ５Ｏ１２結晶（ＬｕＡＧ）の粉末を加圧条件下で焼結して結晶化し、表面に研磨加工を施した。
この蛍光体は、蛍光ピーク波長である５２０ｎｍにおける直線透過率が８３％の透明蛍光体（Ａ）であり、これを比較例とした。
＜本発明品＞
蛍光体は、比較例の蛍光体よりもＬｕを多く含む原料粉末を用い、粒界にＬｕ２Ｏ３を析出させて、直線透過率を７０％に低下させた散乱体混入蛍光体（Ｂ）である。 An experiment verifying the effect of the present invention will be described below.
<Comparative example>
The phosphor 1 used in the experiment was sintered by crystallizing a powder of Lu 3 Al 5 O 12 crystal (LuAG) containing 0.5% Ce in an element ratio under pressure, and the surface was polished. did.
This phosphor is a transparent phosphor (A) having a linear transmittance of 83% at 520 nm, which is the fluorescence peak wavelength, and this was used as a comparative example.
<Invention product>
The phosphor used was a raw material powder containing more Lu than the phosphor of the comparative example, and Lu 2 O 3 was precipitated at the grain boundaries to reduce the linear transmittance to 70% (B). It is.

上述の蛍光体（Ａ）（Ｂ）の寸法は共に３ｍｍ×４ｍｍ×１ｍｍであり、それぞれ３ｍｍ×４ｍｍの面の片方にフッ化マグネシウム薄膜を約８０ｎｍの膜厚で蒸着し、励起光の反射防止層４を形成した。
また、反射防止層４を設けた面と対向する側である３ｍｍ×４ｍｍの面には、銀粒子を蒸着し、蛍光の反射層５を形成した。
この蛍光体１の反射層５側をヒートシンク接合面とし、銀ペーストを用いて５０×５０×１０ｍｍのアルミニウム板（ヒートシンク３）に蛍光体１を接合した。 The dimensions of the phosphors (A) and (B) are 3 mm × 4 mm × 1 mm, and a magnesium fluoride thin film is deposited on one side of each 3 mm × 4 mm to a thickness of about 80 nm to prevent reflection of excitation light. Layer 4 was formed.
In addition, silver particles were vapor-deposited on the surface of 3 mm × 4 mm, which is the side facing the surface on which the antireflection layer 4 was provided, to form a fluorescent reflection layer 5.
The phosphor 1 was bonded to a 50 × 50 × 10 mm aluminum plate (heat sink 3) using a silver paste with the reflective layer 5 side of the phosphor 1 as a heat sink bonding surface.

上記のそれぞれの蛍光体（Ａ）（Ｂ）の励起光入射面に対して、波長４４７ｎｍのレーザ光を５００Ｗ/ｃｍ２の照度で照射し、蛍光体から放射される５２０ｎｍをピークとする蛍光の照度を測定した。その結果が表１に表されている。
＜表１＞

Figure 0006075712
その結果、表１に示すように、比較例に対して本発明品の蛍光の発光照度は３％高い値となった。これは、散乱体を混入することによって、全反射により蛍光体内部に閉じ込められる光が低減されたことによるものである。 The excitation light incident surface of each of the phosphors (A) and (B) is irradiated with a laser beam having a wavelength of 447 nm at an illuminance of 500 W / cm 2 , and the fluorescence emitted from the phosphor has a peak at 520 nm. The illuminance was measured. The results are shown in Table 1.
<Table 1>
Figure 0006075712
As a result, as shown in Table 1, the fluorescence emission intensity of the product of the present invention was 3% higher than that of the comparative example. This is because the light trapped inside the phosphor due to total reflection is reduced by mixing the scatterer.

以上説明したように、本発明に係る発光デバイスは、蛍光体がバルク状の結晶から成り、当該蛍光体の内部に蛍光を散乱する散乱体が分散されている構成としたことにより、蛍光体の熱伝導率が高くなり、該蛍光体に当接したヒートシンクへの熱伝導が良好となって、排熱効率が高められ、蛍光体の温度消光という不具合が回避される。
また、蛍光体内に分散された粒子状の散乱体によって、蛍光の進行方向をランダムに変化させ、蛍光が蛍光体の界面で全反射して内部に閉じ込められてしまうことがなくなり、光取り出し効率を高めることができるものである。 As described above, the light-emitting device according to the present invention has a configuration in which the phosphor is made of a bulk crystal and the scatterers that scatter fluorescence are dispersed inside the phosphor. The heat conductivity is increased, the heat conduction to the heat sink in contact with the phosphor is improved, the exhaust heat efficiency is increased, and the problem of temperature quenching of the phosphor is avoided.
In addition, the particle scatterers dispersed in the phosphor randomly change the direction of travel of the fluorescence, so that the fluorescence is not totally reflected and confined inside the phosphor interface, thereby improving the light extraction efficiency. It can be raised.

１ 蛍光体
１ａ 上面
１ｂ 下面
１１〜１５ 板状蛍光体
２ 散乱体
３ ヒートシンク
４ 励起光反射層
５ 蛍光反射層
６ 接合層
Ｘ 励起光
Ｙ 蛍光


DESCRIPTION OF SYMBOLS 1 Phosphor 1a Upper surface 1b Lower surface 11-15 Plate-like phosphor 2 Scattering body 3 Heat sink 4 Excitation light reflection layer 5 Fluorescence reflection layer 6 Junction layer X Excitation light Y Fluorescence


Claims (3)

励起光が入射し、蛍光を放射する蛍光体を有し、ヒートシンクを介して当該蛍光体の熱を排熱する発光デバイスにおいて、
前記蛍光体は、バルク状の結晶から成り、当該蛍光体の内部には蛍光を散乱する散乱体が分散されてなり、
前記蛍光体の励起光入射面と蛍光出射面とが同一面であるとともに、
前記蛍光体は、前記励起光入射面に近い側に分散された散乱体の数密度が、奥側に分散された散乱体の数密度に比べて低いことを特徴とする発光デバイス。 In a light emitting device that includes a phosphor that emits excitation light and emits fluorescence, and exhausts heat of the phosphor through a heat sink.
The phosphor is made of a bulk crystal, and a scatterer that scatters fluorescence is dispersed inside the phosphor.
The excitation light incident surface and the fluorescence emission surface of the phosphor are the same surface,
In the phosphor, the number density of scatterers dispersed on the side closer to the excitation light incident surface is lower than the number density of scatterers dispersed on the back side. 前記蛍光体は、密接配置された複数の板状蛍光体からなり、前記励起光入射側の板状蛍光体に分散された散乱体の数密度が、奥側の板状蛍光体に分散された散乱体の数密度に比べて低いことを特徴とする請求項１に記載の発光デバイス。The phosphor comprises a plurality of closely arranged plate-like phosphors, and the number density of scatterers dispersed in the plate-like phosphor on the excitation light incident side is dispersed in the plate-like phosphor on the back side. The light emitting device according to claim 1, wherein the light emitting device is lower than the number density of the scatterers. 励起光が入射し、蛍光を放射する蛍光体を有し、ヒートシンクを介して当該蛍光体の熱を排熱する発光デバイスにおいて、
前記蛍光体は、バルク状の結晶から成り、当該蛍光体の内部には蛍光を散乱する散乱体が分散されてなり、
前記蛍光体の励起光入射面と蛍光出射面とが反対側面であるとともに、
前記蛍光体は、密接配置された複数の板状蛍光体からなり、前記励起光入射側および前記蛍光出射側の板状蛍光体に分散された散乱体の数密度が、これらに挟まれた板状蛍光体に分散された散乱体の数密度に比べて低いことを特徴とする発光デバイス。 In a light emitting device that includes a phosphor that emits excitation light and emits fluorescence, and exhausts heat of the phosphor through a heat sink.
The phosphor is made of a bulk crystal, and a scatterer that scatters fluorescence is dispersed inside the phosphor.
The excitation light entrance surface and the fluorescence exit surface of the phosphor are opposite sides,
The phosphor is composed of a plurality of closely arranged plate-like phosphors, and the number density of scatterers dispersed in the plate-like phosphors on the excitation light incident side and the fluorescence emission side is sandwiched between them Light-emitting device characterized by being lower than the number density of scatterers dispersed in a phosphor-like material.
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