JP3747026B2

JP3747026B2 - Red light emitting phosphor and light emitting device using the same

Info

Publication number: JP3747026B2
Application number: JP2002338454A
Authority: JP
Inventors: 良吉松; 尚史吉田
Original assignee: NEC Lighting Ltd
Current assignee: Hotalux Ltd
Priority date: 2002-11-21
Filing date: 2002-11-21
Publication date: 2006-02-22
Anticipated expiration: 2022-11-21
Also published as: JP2004168946A

Description

【０００１】
【発明の属する技術分野】
本発明は赤色発光螢光体およびそれを用いた発光素子に関し、特に、紫外線励起により赤色発光する螢光体、及び、紫外線発光ダイオードと赤色、緑色、青色の発光螢光体とを組み合わせた白色発光ダイオードなどの可視光発光素子に関する。
【０００２】
【従来の技術】
白色発光ダイオードとしては、（Ｙ、Ｇｄ）₃（Ａｌ、Ｇａ）₅Ｏ₁₂の組成式で知られるＹＡＧ系酸化物母体格子中にＣｅをドープした螢光体（以下、ＹＡＧ：Ｃｅ螢光体と記す）を、窒化物半導体を用いた青色発光ダイオードを包囲する封止樹脂中に分散させたもの（例えば、特許文献１〜特許文献３参照）や、非粒子状性の螢光体層を青色ＬＥＤ上に成膜したもの（例えば、特許文献４参照）が知られている。これらは、ディスプレイ用バックライトやＬＥＤ表示器などに使用されている。しかし、上記構成の白色発光ダイオードでは、色再現性が悪く、演色性が低いために、紫外線発光ダイオードと青色、緑色、赤色発光螢光体を組み合わせた３波長型の白色発光ダイオードが開発されている。そのような白色発光ダイオードの一例が下記の特許文献５に開示されている。
【０００３】
特許文献５に開示されている白色発光ダイオードは、図２に示すように、透明基板（前面パネル）１上にドーム状に形成された透明樹脂３の中に紫外線発光ダイオード５を埋設している。透明樹脂３には赤色、緑色、青色の３種の螢光体粉末２が混入されており、透明樹脂３の表面４はミラーとして作用するようミラー加工が施されている。特許文献５においては、赤色発光螢光体として、Ｙ₂Ｏ₂Ｓ：Ｅｕ³⁺などが挙げられ、ＩｎＧａＮまたはＧａＮからなる紫外線発光ダイオード５を励起光源としている。
【０００４】
【特許文献１】
特許第２９００９２８号明細書（〔０００８〕、図２）
【特許文献２】
特許第２９２７２７９号明細書（〔００５６〕〜〔００６０〕、図１）
【特許文献３】
特許第２９９８６９６号明細書（〔０００６〕、図２）
【特許文献４】
特開平１１−４６０１５号公報（〔００４２〕〜〔００４４〕、図１）
【特許文献５】
特表２０００−５０９９１２号公報（第５頁〜７頁、図１）
【０００５】
【発明が解決しようとする課題】
上記特許文献５で用いられた紫外線発光ダイオードは、発光波長が３７０ｎｍから４１０ｎｍの間で高い発光効率を有し、とくに３７０ｎｍ〜３９０ｎｍ付近の波長で最も高い発光効率を示す。しかし、この波長範囲の紫外光励起により効率よく発光する螢光体はなく、問題となっている。
【０００６】
本発明は、より効率よく紫外線を吸収し、高効率で赤色発光し、従来に比べて高輝度な赤色発光螢光体を提供することを目的としている。
【０００７】
また、本発明は、紫外線発光ダイオードの最大ピーク波長を効率よく吸収し、波長６００ｎｍ以上の赤色発光を効率よく発光する螢光体を紫外線発光ダイオードと組み合わせて、高効率・高輝度な可視光発光素子を提供することを目的とする。さらに、本発明による赤色発光螢光体と、青色発光螢光体と、緑色発光螢光体とを紫外線発光ダイオードと組み合わせて照明用などの白色発光素子を提供することを目的とする。
【０００８】
【課題を解決するための手段】
本発明の赤色発光螢光体は、紫外線発光ダイオードを励起源とした場合に、その最大ピーク波長を効率よく吸収し、高輝度で赤色発光する赤色発光螢光体であって、少なくともリチウム、イットリウム、硼素および酸素を含み、さらに、ユーロピウムを付活剤として含んでいることを特徴とする。
【０００９】
この赤色発光螢光体は、一般式、ＬｉＹ_2-x-yＥｕ_xＢｉ_yＢＯ₅（但し、０．０１≦ｘ≦１．０、０．００１≦ｙ≦０．２）で示される組成を有し、紫外発光を効率よく吸収し、効率よく赤色発光する。組成値ｘ＝０．２、ｙ＝０．０２の螢光体においては発光強度特性が波長５９２ｎｍ、６１４ｎｍ、６２９ｎｍに発光ピークを有する。
【００１０】
本発明の発光素子は、紫外線を発光する紫外線発光ダイオードと、前記紫外線発光ダイオードから発せられた光により励起されて発光する螢光体とを有する発光素子において、前記螢光体が、一般式、ＬｉＹ_2-x-yＥｕ_xＢｉ_yＢＯ₅（但し、０．０１≦ｘ≦１．０、０．００１≦ｙ≦０．２）で表される上記本発明の赤色発光螢光体を少なくとも含むことを特徴としている。
【００１１】
則ち、本発明の発光素子は、紫外線発光ダイオードと組み合わせる螢光体が本発明の赤色発光螢光体ＬｉＹ_2-x-yＥｕ_xＢｉ_yＢＯ₅（但し、０．０１≦ｘ≦１．０、０．００１≦ｙ≦０．２）のみの場合は赤色発光素子となり、本発明の赤色発光螢光体に加えて、さらに緑色発光螢光体、青色発光螢光体を含んでいると白色或いは中間色の発光素子となる。
【００１２】
本発明の発光素子に用いた赤色発光螢光体は、波長３７０ｎｍ〜３８０ｎｍ付近の紫外線による励起・発光効率がよいので、波長３７０ｎｍ〜３８０ｎｍ付近の紫外線を発光する紫外線発光ダイオードを用いるのが望ましい。
【００１３】
【発明の実施の形態】
（第１の実施の形態）
以下、本発明の実施の形態について図面を参照して詳細に説明する。本実施の形態として、３７０ｎｍ〜３８０ｎｍ付近の波長で最も高い発光効率を示すＩｎＧａＮまたはＧａＮからなる紫外線発光ダイオードを励起光源とする場合に、３７０ｎｍ〜３８０ｎｍ付近の波長を効率よく吸収できる赤色発光螢光体を種々検討した結果、Ｌｉを添加した硼酸塩を母体材料とし、ユーロピウムを付活剤とすることにより、上記条件を満たすことを見出した。とくに、下記の一般式
ＬｉＹ_2-x-yＥｕ_xＢｉ_yＢＯ₅
但し、０．０１≦ｘ≦１．０、０．００１≦ｙ≦０．２
で示される赤色発光螢光体が好ましいことが確認できた。
【００１４】
組成値ｘ＝０．２、ｙ＝０．０２の場合の螢光体、ＬｉＹ_1.78Ｅｕ_0.2Ｂｉ_0.02ＢＯ₅についての発光強度特性を励起強度特性と共に図１に示す。同図から明らかなように、この組成による赤色発光螢光体は、波長３００ｎｍ〜４００ｎｍで大きな励起強度があり、波長３７０ｎｍを中心にその前後（３００ｎｍ〜４００ｎｍ、とくに３６０ｎｍ〜３８０ｎｍでブロードな吸収）の紫外光を最も効率よく吸収し、励起・発光することが分かる。発光強度特性は発光波長６１４ｎｍをメインピークとし、発光波長５９３ｎｍおよび６２５ｎｍをサブピークとする特性を有している。
【００１５】
また、上記組成の赤色発光螢光体（ＬｉＹ_1.78Ｅｕ_0.2Ｂｉ_0.02ＢＯ₅）と従来の赤色発光螢光体（Ｙ₂Ｏ₂Ｓ：Ｅｕ³⁺）との波長３７０ｎｍ光励起での発光特性を比較すると、下記表１に示すように、輝度の点において、本実施形態の赤色発光螢光体は従来の赤色発光螢光体の１．２倍以上の輝度を示すことが分かる。さらに、ＣＩＥ色度座標において、従来の赤色発光螢光体よりも赤色としての色純度が良くなっていることが分かる。
【００１６】
【表１】

【００１７】
次に、本発明の赤色発光螢光体の製造方法について述べる。本発明の赤色発光螢光体は、出発原料を窒素ガス雰囲気中で焼成するなどして、固相反応法もしくは共沈法により作製することができる。一例として、上記組成（ｘ＝０．２、ｙ＝０．０２）の赤色発光螢光体ＬｉＹ_1.78Ｅｕ_0.2Ｂｉ_0.02ＢＯ₅の製造方法を例にとると、先ず、出発原料に純度９９．９９％以上のＬｉ₂ＣＯ₃試薬とＬａ₂Ｏ₃試薬と純度９９．９９％以上のＨ₃ＢＯ₃ないしＢ₂Ｏ₃試薬および純度９９．９％以上のＥｕ₂Ｏ₃試薬および純度９９．９９％のＢｉ₂Ｏ₃試薬を上記の組成比となるように調合する。すなわち、Ｌｉ₂ＣＯ₃、Ｙ₂Ｏ₃、Ｂ₂Ｏ₃、Ｅｕ₂Ｏ₃およびＢｉ₂Ｏ₃をＬｉ、Ｙ、Ｂ、Ｅｕ、Ｂｉのモル比が１：１．７８：１：０．２：０．０２になるように調合する。その後に、これらを乾式混合し、約８００℃〜１１００℃で数時間（約３時間程度）焼成することにより、上記組成（ｘ＝０．２、ｙ＝０．０２）の赤色発光螢光体を作製することができる。
【００１８】
一般式、ＬｉＹ_2-x-yＥｕ_xＢｉ_yＢＯ₅（但し、０．０１≦ｘ≦１．０、０．００１≦ｙ≦０．２）で表される本発明の赤色発光螢光体において、組成値ｘの値がその下限である０．０１を下回ると、十分な発光強度が得られなくなる。一方、組成値ｘの値がその上限である１．０を越えると、濃度消光による発光強度の低下が生じ、実用性がなくなる。また、組成値ｙの値がその下限である０．００１を下回ると、十分な発光強度が得られなくなる。一方、組成値ｙの値がその上限である０．２を越えると、Ｂｉによる再吸収による発光強度の低下が生じ、実用性がなくなる。このような理由により、本発明の組成値ｘ、ｙは、０．０１≦ｘ≦１．０、０．００１≦ｙ≦０．２に決定されている。
【００１９】
（第２の実施の形態）
本実施形態における発光素子は、図２に示す従来の構造と同様に、透明基板１の上にドーム状に形成されたエポキシ等の透明樹脂３の中に紫外線発光ダイオード５を埋設している。透明樹脂３には螢光体粉末２として本発明の螢光体ＬｉＹ_2-x-yＥｕ_xＢｉ_yＢＯ₅（但し、０．０１≦ｘ≦１．０、０．００１≦ｙ≦０．２）が分散されており、紫外線励起により赤色発光する赤色発光素子として機能する。具体的には第１の実施形態で示した組成の螢光体ＬｉＹ_1.78Ｅｕ_0.2Ｂｉ_0.02ＢＯ₅を用いた。透明樹脂３の表面４はミラーとして作用するようミラー加工（例えば、Ａｌ膜コーティング）が施されて、効率良く光出力が取り出せる構造になっている。
【００２０】
本発明の螢光体は、赤色発光螢光体であるので、白色として光を放出させる発光素子にする場合は、図２に示す構造において、透明樹脂３に赤色、緑色、青色の３種類の螢光体粉末２を混入した構成にする。この時、３種類の螢光体粉末のうち、赤色発光螢光体粉末として本発明の螢光体を採用すれば、従来に比してより高輝度の白色光発光素子が実現できる。ここで、緑色発光螢光体としては、従来から用いられているもの、例えば、上記特許文献５に開示のＺｎＳ：ＣｕやＢａＭｇＡｌ₁₀Ｏ₁₇：Ｅｕ、Ｍｎなどが採用できる。同様に、青色発光螢光体も従来から用いられているもの、例えば、特許文献５に開示のＢａＭｇＡｌ₁₀Ｏ₁₇：Ｅｕ、Ｓｒ₅（ＰＯ₄）₃Ｃｌ：Ｅｕ、ＺｎＳ：Ａｇなどが採用可能である。
【００２１】
尚、上記例は赤色、緑色、青色の３種類の螢光体を混合して白色発光素子としたが、３種類の螢光体の混合比を変えたり、２種類の螢光体の組み合わせ（例えば、本発明の赤色発光螢光体と青色発光螢光体を組み合わせた紫色発光等）にして中間色の発光素子としてもよい。
【００２２】
紫外線発光ダイオードは、本発明の赤色発光螢光体を効率よく励起・発光せしめる波長の紫外線を発光するものであればどのような材料、構造のものでもよいが、本発明の赤色発光螢光体の特性上、波長３７０ｎｍ〜３８０ｎｍ付近の光を発光するものであればさらに望ましい。一例として、本実施形態では、サファイア基板上にｎ型ＧａＮクラッド層、ＩｎＧａＮ量子井戸層とＧａＮ障壁層を交互に積層したＭＱＷ活性層、ｐ型ＡｌＧａＮクラッド層、ｐ型ＧａＮコンタクト層を順次積層した多層構造のものを用いた。電極はｎ型ＧａＮクラッド層とｐ型ＧａＮコンタクト層にそれぞれ設けている。
【００２３】
本実施形態の発光素子は、透明基板１の上の、螢光体を分散したドーム状透明樹脂３の中に紫外線発光ダイオード５を埋設した図２と同様の構造としたが、ステム或いはリードフレームに紫外線発光ダイオードを固着し、螢光体粉末を混入した透明樹脂でモールドした構造、或いは、螢光体粉末を混入した窓を有するケース内に紫外線発光ダイオードを封止した構造、紫外線発光ダイオードの出射面前方に螢光体（或いは螢光体を含有する透明体）を配置した構造、紫外線発光ダイオードの光出射面表面に螢光体を含有する被膜を形成し、この紫外線発光ダイオードをケースに収めた構造等、紫外線発光ダイオードから発せられた紫外線で螢光体が励起されて発光する構造であればどのような構造でもよい。
【００２４】
【発明の効果】
本発明による赤色発光螢光体は、紫外線、特に波長３７０ｎｍ前後の紫外発光を効率よく吸収し、高輝度で赤色発光する。この赤色発光螢光体を波長変換剤とし、紫外線発光ダイオードと組み合わせて、従来に比べて高輝度な可視光発光素子が得られた。
【図面の簡単な説明】
【図１】実施形態における赤色発光螢光体の発光強度特性及び励起強度特性を示す図。
【図２】発光ダイオードの構成例を示す図。
【符号の説明】
１透明基板
２螢光体粉末
３透明樹脂
４透明樹脂表面（ミラー面）
５紫外線発光ダイオード[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a red light emitting phosphor and a light emitting device using the same, and in particular, a phosphor that emits red light by ultraviolet excitation, and a white color that combines an ultraviolet light emitting diode and red, green, and blue light emitting phosphors. The present invention relates to a visible light emitting element such as a light emitting diode.
[0002]
[Prior art]
As a white light emitting diode, a phosphor (hereinafter referred to as YAG: Ce phosphor) in which Ce is doped in a YAG-based oxide matrix lattice known by a composition formula of (Y, Gd) ₃ (Al, Ga) ₅ O _12. Are dispersed in a sealing resin surrounding a blue light emitting diode using a nitride semiconductor (for example, see Patent Documents 1 to 3) or a non-particulate phosphor layer. A film formed on a blue LED (for example, see Patent Document 4) is known. These are used for display backlights, LED displays, and the like. However, since the white light emitting diode having the above structure has poor color reproducibility and low color rendering, a three-wavelength white light emitting diode that combines an ultraviolet light emitting diode and a blue, green, and red light emitting phosphor has been developed. Yes. An example of such a white light emitting diode is disclosed in Patent Document 5 below.
[0003]
As shown in FIG. 2, the white light emitting diode disclosed in Patent Document 5 has an ultraviolet light emitting diode 5 embedded in a transparent resin 3 formed in a dome shape on a transparent substrate (front panel) 1. . The transparent resin 3 is mixed with three kinds of phosphor powders 2 of red, green and blue, and the surface 4 of the transparent resin 3 is mirrored so as to act as a mirror. In Patent Document 5, Y ₂ O ₂ S: Eu ³⁺ is ^exemplified as a red light emitting phosphor, and an ultraviolet light emitting diode 5 made of InGaN or GaN is used as an excitation light source.
[0004]
[Patent Document 1]
Japanese Patent No. 2900928 ([0008], FIG. 2)
[Patent Document 2]
Japanese Patent No. 2927279 ([0056] to [0060], FIG. 1)
[Patent Document 3]
Japanese Patent No. 29998696 ([0006], FIG. 2)
[Patent Document 4]
Japanese Patent Laid-Open No. 11-46015 ([0042] to [0044], FIG. 1)
[Patent Document 5]
JP 2000-509912A (pages 5-7, FIG. 1)
[0005]
[Problems to be solved by the invention]
The ultraviolet light-emitting diode used in Patent Document 5 has a high emission efficiency when the emission wavelength is between 370 nm and 410 nm, and particularly shows the highest emission efficiency at a wavelength in the vicinity of 370 nm to 390 nm. However, there is no phosphor that efficiently emits light by excitation with ultraviolet light in this wavelength range, which is a problem.
[0006]
An object of the present invention is to provide a red light-emitting phosphor that absorbs ultraviolet rays more efficiently, emits red light with high efficiency, and has higher luminance than conventional ones.
[0007]
In addition, the present invention efficiently absorbs the maximum peak wavelength of an ultraviolet light-emitting diode, and combines a phosphor that efficiently emits red light with a wavelength of 600 nm or more with an ultraviolet light-emitting diode to produce high-efficiency and high-luminance visible light An object is to provide an element. It is another object of the present invention to provide a white light emitting element for illumination or the like by combining a red light emitting phosphor, a blue light emitting phosphor and a green light emitting phosphor according to the present invention with an ultraviolet light emitting diode.
[0008]
[Means for Solving the Problems]
The red light-emitting phosphor of the present invention is a red light-emitting phosphor that efficiently absorbs the maximum peak wavelength and emits red light with high luminance when an ultraviolet light-emitting diode is used as an excitation source, and at least lithium and yttrium. , Boron and oxygen, and europium as an activator.
[0009]
This red light emitting phosphor has a composition represented by the general formula: LiY _2-xy Eu _x Bi _y BO ₅ (where 0.01 ≦ x ≦ 1.0, 0.001 ≦ y ≦ 0.2). In addition, it absorbs ultraviolet light efficiently and emits red light efficiently. In the phosphor having the composition values x = 0.2 and y = 0.02, the emission intensity characteristics have emission peaks at wavelengths of 592 nm, 614 nm, and 629 nm.
[0010]
The light-emitting element of the present invention is a light-emitting element having an ultraviolet light-emitting diode that emits ultraviolet light and a phosphor that emits light by being excited by light emitted from the ultraviolet light-emitting diode. At least the red light emitting phosphor of the present invention represented by LiY _2-xy Eu _x Bi _y BO ₅ (where 0.01 ≦ x ≦ 1.0, 0.001 ≦ y ≦ 0.2). It is characterized by.
[0011]
Sokuchi, the light emitting device of the present invention, the red emitting phosphor of the phosphor to be combined with ultraviolet light emitting diodes present invention _{_{_{LiY 2-xy Eu x Bi y}}} BO 5 ( where, 0.01 ≦ x ≦ 1.0, In the case of only 0.001 ≦ y ≦ 0.2), a red light emitting element is obtained, and in addition to the red light emitting phosphor of the present invention, a green light emitting phosphor and a blue light emitting phosphor are included. It becomes a light emitting element of an intermediate color.
[0012]
Since the red light emitting phosphor used in the light emitting device of the present invention has good excitation and emission efficiency due to ultraviolet light having a wavelength of about 370 nm to 380 nm, it is desirable to use an ultraviolet light emitting diode that emits ultraviolet light having a wavelength of about 370 nm to 380 nm.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
(First embodiment)
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the present embodiment, when an ultraviolet light emitting diode made of InGaN or GaN that exhibits the highest light emission efficiency at a wavelength in the vicinity of 370 nm to 380 nm is used as an excitation light source, red light emission fluorescence that can efficiently absorb a wavelength in the vicinity of 370 nm to 380 nm As a result of various studies on the body, it was found that the above condition was satisfied by using a borate to which Li was added as a base material and europium as an activator. In particular, the following general formula LiY _2-xy Eu _x Bi _y BO ₅
However, 0.01 ≦ x ≦ 1.0, 0.001 ≦ y ≦ 0.2
It was confirmed that a red light emitting phosphor represented by
[0014]
FIG. 1 shows emission intensity characteristics of the phosphor, LiY _1.78 Eu _0.2 Bi _0.02 BO _{5 with} composition values x = 0.2 and y = 0.02, together with excitation intensity characteristics. As is clear from the figure, the red light-emitting phosphor having this composition has a large excitation intensity at a wavelength of 300 nm to 400 nm, and around that wavelength (around 300 nm to 400 nm, particularly 360 nm to 380 nm). It can be seen that the ultraviolet light is absorbed most efficiently and excited and emitted. The light emission intensity characteristics have a light emission wavelength of 614 nm as a main peak and light emission wavelengths of 593 nm and 625 nm as sub-peaks.
[0015]
In addition, the emission characteristics of the red light-emitting phosphor having the above composition (LiY _1.78 Eu _0.2 Bi _0.02 BO ₅ ) and the conventional red light-emitting phosphor (Y ₂ O ₂ S: Eu ³⁺ ) are compared by light excitation at a wavelength of 370 nm. Then, as shown in Table 1 below, in terms of luminance, it can be seen that the red light emitting phosphor of the present embodiment exhibits a luminance of 1.2 times or more that of the conventional red light emitting phosphor. Furthermore, it can be seen that, in the CIE chromaticity coordinates, the color purity as red is better than the conventional red light emitting phosphor.
[0016]
[Table 1]

[0017]
Next, a method for producing the red light emitting phosphor of the present invention will be described. The red light emitting phosphor of the present invention can be produced by a solid phase reaction method or a coprecipitation method, for example, by firing a starting material in a nitrogen gas atmosphere. As an example, taking a production method of the red light emitting phosphor LiY _1.78 Eu _0.2 Bi _0.02 BO _{5 having} the above composition (x = 0.2, y = 0.02) as an example, first, the purity of the starting material is 99.99. % Li ₂ CO ₃ reagent and La ₂ O ₃ reagent and H ₉ BO ₃ to B ₂ O ₃ reagent with a purity of 99.99% and Eu ₂ O ₃ reagent with a purity of 99.9% and purity 99.99% % Bi ₂ O ₃ reagent is prepared so as to achieve the above composition ratio. That is, Li ₂ CO ₃ , Y ₂ O ₃ , B ₂ O ₃ , Eu ₂ O ₃ and Bi ₂ O ₃ have a molar ratio of Li, Y, B, Eu, Bi of 1: 1.78: 1: 0. 2: Prepare to be 0.02. Thereafter, they are dry-mixed and fired at about 800 ° C. to 1100 ° C. for several hours (about 3 hours), whereby a red light emitting phosphor having the above composition (x = 0.2, y = 0.02). Can be produced.
[0018]
In the red light emitting phosphor of the present invention represented by the general formula, LiY _2-xy Eu _x Bi _y BO ₅ (where 0.01 ≦ x ≦ 1.0, 0.001 ≦ y ≦ 0.2), When the value of the composition value x is below the lower limit of 0.01, sufficient light emission intensity cannot be obtained. On the other hand, if the composition value x exceeds 1.0, which is the upper limit, the emission intensity decreases due to concentration quenching, and the practicality is lost. On the other hand, if the composition value y is less than the lower limit of 0.001, sufficient light emission intensity cannot be obtained. On the other hand, if the composition value y exceeds the upper limit of 0.2, the emission intensity is reduced due to reabsorption by Bi, and the practicality is lost. For these reasons, the composition values x and y of the present invention are determined to be 0.01 ≦ x ≦ 1.0 and 0.001 ≦ y ≦ 0.2.
[0019]
(Second Embodiment)
In the light emitting device according to the present embodiment, an ultraviolet light emitting diode 5 is embedded in a transparent resin 3 such as an epoxy formed on a transparent substrate 1 in the same manner as the conventional structure shown in FIG. The transparent resin 3 includes the phosphor LiY _2-xy Eu _x Bi _y BO ₅ of the present invention as the phosphor powder 2 (where 0.01 ≦ x ≦ 1.0, 0.001 ≦ y ≦ 0.2). Are dispersed, and function as a red light-emitting element that emits red light by ultraviolet excitation. Specifically, the phosphor LiY _1.78 Eu _0.2 Bi _0.02 BO ₅ having the composition shown in the first embodiment was used. The surface 4 of the transparent resin 3 is subjected to mirror processing (for example, Al film coating) so as to act as a mirror, so that light output can be extracted efficiently.
[0020]
Since the phosphor of the present invention is a red light-emitting phosphor, in the case of a light-emitting element that emits light as white, in the structure shown in FIG. 2, the transparent resin 3 has three types of red, green, and blue. The phosphor powder 2 is mixed. At this time, if the phosphor of the present invention is adopted as the red light-emitting phosphor powder among the three types of phosphor powders, a white light-emitting element with higher brightness than the conventional one can be realized. Here, as the green light emitting phosphor, those conventionally used, for example, ZnS: Cu, BaMgAl ₁₀ O ₁₇ : Eu, Mn and the like disclosed in Patent Document 5 can be adopted. Similarly, blue light emitting phosphors conventionally used, for example, BaMgAl ₁₀ O ₁₇ : Eu, Sr ₅ (PO ₄ ) ₃ Cl: Eu, ZnS: Ag, etc. disclosed in Patent Document 5 can be adopted. It is.
[0021]
In the above example, three types of phosphors of red, green, and blue are mixed to form a white light emitting element. However, the mixing ratio of the three types of phosphors is changed, or a combination of two types of phosphors ( For example, a light emitting element having an intermediate color may be formed by using a red light emitting phosphor and a blue light emitting phosphor of the present invention.
[0022]
The ultraviolet light-emitting diode may be of any material and structure as long as it emits ultraviolet light having a wavelength that efficiently excites and emits the red light-emitting phosphor of the present invention. In view of the above characteristics, it is more desirable to emit light having a wavelength in the vicinity of 370 nm to 380 nm. As an example, in this embodiment, an n-type GaN cladding layer, an MQW active layer in which an InGaN quantum well layer and a GaN barrier layer are alternately stacked, a p-type AlGaN cladding layer, and a p-type GaN contact layer are sequentially stacked on a sapphire substrate. A multilayer structure was used. Electrodes are provided on the n-type GaN cladding layer and the p-type GaN contact layer, respectively.
[0023]
The light emitting device of this embodiment has the same structure as that of FIG. 2 in which the ultraviolet light emitting diode 5 is embedded in the dome-shaped transparent resin 3 on which the phosphor is dispersed on the transparent substrate 1, but the stem or the lead frame A structure in which an ultraviolet light emitting diode is fixed and molded with a transparent resin mixed with phosphor powder, or a structure in which an ultraviolet light emitting diode is sealed in a case having a window mixed with phosphor powder, A structure in which a phosphor (or a transparent body containing a phosphor) is disposed in front of the emission surface, a coating film containing the phosphor is formed on the light emission surface of the ultraviolet light emitting diode, and the ultraviolet light emitting diode is used as a case. Any structure may be used as long as the phosphor is excited by the ultraviolet light emitted from the ultraviolet light emitting diode and emits light.
[0024]
【The invention's effect】
The red light emitting phosphor according to the present invention efficiently absorbs ultraviolet light, particularly ultraviolet light having a wavelength of around 370 nm, and emits red light with high luminance. By using this red light-emitting phosphor as a wavelength conversion agent and combining it with an ultraviolet light-emitting diode, a visible light-emitting element having higher luminance than conventional ones was obtained.
[Brief description of the drawings]
FIG. 1 is a graph showing emission intensity characteristics and excitation intensity characteristics of a red light emitting phosphor in an embodiment.
FIG. 2 is a diagram showing a configuration example of a light-emitting diode.
[Explanation of symbols]
1 Transparent substrate 2 Phosphor powder 3 Transparent resin 4 Transparent resin surface (mirror surface)
5 UV light emitting diode

Claims

Formula, LiY2-x-yEuxBiyBO5 (where, 0.01 ≦ x ≦ 1.0, 0.001 ≦ y ≦ 0.2) is represented by, it characterized that you are excited red emission by ultraviolet red light-emitting phosphor.

Red light emitting phosphor of claim 1 Symbol mounting, characterized in that efficiently excited and emits light by ultraviolet rays in the vicinity of a wavelength 370Nm～380nm.

Luminance characteristics to wavelength 592 nm, 614 nm, according to claim 1 or claim 2 red light emitting phosphor according to characterized in that it has an emission peak at 629 nm.

In a light emitting device having an ultraviolet light emitting diode that emits ultraviolet light and a phosphor that emits light when excited by light emitted from the ultraviolet light emitting diode, the phosphor is represented by the general formula LiY2-x-yEuxBiBO5 (however, , 0.01 ≦ x ≦ 1.0, 0.001 ≦ y ≦ 0.2), at least a red light-emitting phosphor.

In a light emitting device having an ultraviolet light emitting diode that emits ultraviolet light and a phosphor that emits light by being excited by light emitted from the ultraviolet light emitting diode, the phosphor is a phosphor that emits red light by ultraviolet excitation, and The phosphor includes three types of phosphors, a green light-emitting phosphor and a blue light-emitting phosphor, and the red light-emitting phosphor has the general formula LiY2-x-yEuxBiBO5 (where 0.01 ≦ x ≦ 1.0, 0.001 ≦ y ≦ 0.2) A light emitting element characterized by being a red light emitting phosphor.

Light emitting device according to claim 4 or claim 5, wherein the ultraviolet light emitting diode is characterized in that emits ultraviolet wavelength around 370Nm～380nm.

The light emitting device according to any one of claims 4 to 6 , wherein the red light emitting phosphor has a light emission intensity characteristic with emission peaks at wavelengths of 592 nm, 614 nm, and 629 nm.