JP4233929B2

JP4233929B2 - Phosphor and light emitting device using the same

Info

Publication number: JP4233929B2
Application number: JP2003168473A
Authority: JP
Inventors: 秀雄鈴木; 尚生鈴木
Original assignee: 化成オプトニクス株式会社
Priority date: 2003-05-09
Filing date: 2003-05-09
Publication date: 2009-03-04
Anticipated expiration: 2023-05-09
Also published as: JP2004331934A

Description

【０００１】
【発明の属する技術分野】
本発明は、４１０ｎｍより短波長の近紫外線を発する発光ダイオード（ＬＥＤ）の様な励起光源と、赤色発光蛍光体及びこの蛍光体を用いた白色発光及び多色発光蛍光体との組み合わせにより、種々の発光を呈する照明用、液晶ディスプレイや携帯情報端末等のバックライト用、インジケータ光源用及びディスプレイ用として用いられる発光素子に関する。
【０００２】
【従来の技術】
蛍光体の代表的な用途の１つとして蛍光ランプが知られており、古くから照明やディスプレーとして実用されている。周知のように蛍光ランプはガラス管の内壁に形成された蛍光体からなる蛍光膜が、水銀蒸気を封入したガラス管内において、放電で発生する紫外線より励起され発光することを利用し、照明用等の光源として用いられている。
【０００３】
ところで、近年、環境問題や省電力の観点から水銀を使用しない、より消費電力の少ない照明用の光源として、発光ダイオード（ＬＥＤ）や半導体レーザー（ＬＤ）を励起用光源として用い、これと蛍光体とを組合せて、ＬＥＤやＬＤからの発光を用い蛍光体を励起して発光させ、その時出る光を光源として用いる方法が開発されている。例えば、特許第２，９２７，２７９号公報には、ＬＥＤチップが発する青色系の可視光と、このＬＥＤチップの青色系発光の一部を吸収して発光するＣｅ付活希土類アルミン酸塩蛍光体からの黄色系の発光との加色混合によって全体として白色系の発光を呈する発光ダイオードが開示されている。
【０００４】
しかしながら、特許第２，９２７，２７９号に開示されている従来のＬＥＤ等の励起用光源と蛍光体とを組み合わせたタイプの光源では、ＬＥＤ等の励起用光源の発光波長が限定されることや、用いられる励起用光源により発光し得る蛍光体の種類が極めて限られている等のため、最終的に得られる発光色が白色系に限定されるとかマルチカラー的な色が出せない等の制約があった。また白色についても照明下の色は好ましい色が再現されず、演色性も問題であった。
【０００５】
近年、この様な問題を解決するため、２色加色での白色合成の欠点を補う方法として、Ｕ．Ｓ．Ｐ．６２９４８００、Ｕ．Ｓ．Ｐ．６２５５６７０等で３成分、緑、青、赤での混合による方法が紹介されている。ここで使用されている蛍光体は緑発光蛍光体としてはＣａ_８Ｍｇ（ＳｉＯ_４）_４Ｃｌ：Ｅｕ，Ｍｎ、青発光蛍光体としてはＢａＭｇＡｌ_１０Ｏ_１７：Ｅｕ等が、また赤色蛍光体としては、Ｙ_２Ｏ_２Ｓ：ＥｕまたはＹ_２Ｏ_３：Ｅｕ，Ｂｉ等があげられている。
【０００６】
この３成分の混合による方法は、２色成分法に比べればその光源照明下での映り出される色の再現はかなり改善されて来ている。しかしながら成分として用いられている個々の蛍光体自身の色調が好ましくない場合、その光源の照明下で映り出される色は再現性が乏しく望む色が出せず、前記の様な従来の技術の場合は、特に赤色の蛍光体の色調が望ましい赤色から離れているため、満足な白色光源を得ることができない。
【０００７】
この様な問題の改善策として、特開平１１−２４６８５７で３７０ｎｍ前後の近紫外線を発するＬＥＤチップと蛍光体とを組み合わせたＬＥＤ発光素子において、（Ｌａ，Ｅｕ，Ｓｍ）_２Ｏ_２Ｓを赤色蛍光体として使用することが報告され、効果があることが示されている。（Ｌａ，Ｅｕ，Ｓｍ）_２Ｏ_２Ｓ赤色蛍光体は３７０ｎｍ前後の近紫外線に対し、効率的な吸収を有し、ピーク波長が６２５ｎｍ付近の比較的良好な発光色を持ち、輝度についても比較的良好である。
しかしながら、市場要望と照らし合せると、輝度の面でなお不十分であり更なる高輝度が望まれている。また一方白色発光や多色発光の蛍光体及び発光素子についても、輝度及び演色性の面で依然不十分であるのが現状である。
【０００８】
【発明が解決しようとする課題】
ＬＥＤ発光素子は、蛍光ランプに代わる照明、液晶や携帯電話バックライト用光源として期待されており、色再現性、演色性、及び輝度や発光効率などの特性の向上が常に望まれている。
（Ｌａ，Ｅｕ）_２Ｏ_２Ｓや特開平１１−２４６８５７で開示されているＬＥＤ用（Ｌａ，Ｅｕ，Ｓｍ）_２Ｏ_２Ｓ蛍光体は、ディスプレイ等で汎用されている代表的な赤色蛍光体である（Ｙ，Ｅｕ）_２Ｏ_２Ｓよりも、３８２ｎｍ近辺の近紫外線の励起下ではより高い輝度を示し、比較的良好な蛍光体と考えられるが、しかし実用においては不十分であり一層の輝度向上が望まれている。
【０００９】
一方白色蛍光体及び多色蛍光体については、（Ｌａ，Ｅｕ）_２Ｏ_２Ｓ又は（Ｌａ，Ｅｕ，Ｓｍ）_２Ｏ_２Ｓ蛍光体を赤色成分として用い青色発光や緑色発光及び黄色発光の蛍光体と混合し白色発光蛍光体を得た場合、この赤色蛍光体の体色が黄色を呈し、青色及び緑色の波長領域で図１に示される様に粉末反射率が低くなっているため、青色光や緑色光あるいは黄色光等の光は一部赤色蛍光体の結晶に吸収されロスしてしまう。結果白色蛍光体としてのトータル輝度は低下して、十分な輝度が得られない問題があった。
【００１０】
本発明はかかる事情を鑑みてなされたもので、３６０〜４１０ｎｍの近紫外線の励起で従来の赤色発光の蛍光体より高輝度で、粉末反射率が高く体色の少ない赤色蛍光体と、この赤色蛍光体を含有しこれとは異なる蛍光体を一種以上含有する混合蛍光体で、同近紫外線の励起により白色発光及び多色発光する蛍光体を提供することを目的とする。
また更に、３６０〜４１０ｎｍの範囲にピークがある波長の近紫外線を放出するＬＥＤチップ〔発光ダイオードチップ〕とＬＥＤチップからの放射光を受けて発光する蛍光体から構成される赤色発光及び白色発光及び多色発光のＬＥＤ発光素子も併せて提供することを目的とする。
【００１１】
【課題を解決するための手段】
本発明者らは、上記目的達成のため、種々の組成から成る赤色蛍光体を作製し、この組成成分の種類及び製造法が蛍光体の発光輝度と体色に及ぼす影響について検討すると共に、赤色蛍光体とそれ以外の発光を有する青色蛍光体と緑色蛍光体の混合による高輝度な白色発光蛍光体を検討した。
その結果、ユーロピウム付活酸硫化ランタン蛍光体に所定量のＳｉ及びＧｅの中の少なくとも１種を添加することにより、３８２ｎｍ近辺の近紫外線の照射で発光効率が高く、体色が白く青色及び緑色の可視域での粉末反射率が高い蛍光体を得ることが出来た。
【００１２】
また、本発明の赤色蛍光体と青色蛍光体と緑色蛍光体の混合による高輝度な白色発光蛍光体を検討した結果、本発明のＳｉ及びＧｅの中の少なくとも１種を含有するユーロピウム付活酸硫化ランタン赤色発光蛍光体と特に緑色発光のＺｎＳ：Ａｕ，Ｃｕ，Ａｌ又はＢａＭｇＡｌ_１０Ｏ_１７：Ｅｕ，Ｍｎ、と青色発光のＢａＭｇＡｌ_１０Ｏ_１７：Ｅｕ，Ｍｎ又はＣａ_２Ｂ_５Ｏ_９Ｃｌ：Ｅｕ蛍光体を組み合わせ混合した白色発光蛍光体は、高輝度であることを見いだし本発明に至った。
【００１３】
本発明は下記の構成から成る。
（１）一般式（Ｌａ_１−ｘ，Ｅｕ_ｘ）_２Ｏ_２Ｓで表される蛍光体（但し、０．０２≦ｘ≦０．５０）において、該蛍光体重量に対し１０ｐｐｍ〜２０００ｐｐｍのＳｉ及び／又はＧｅを含有することを特徴とする紫外線励起用赤色発光蛍光体。
（２）前記紫外線の波長が３６０〜４１０ｎｍの近紫外であることを特徴とする前記（１）に記載の紫外線励起用赤色発光蛍光体。
（３）前記紫外線励起用赤色発光蛍光体において、波長４５０ｎｍ、５４５ｎｍ、及び６２４ｎｍにおける粉末反射率がそれぞれ８４％以上、９４％以上、及び９７％以上であることを特徴とする前記（１）に記載の紫外線励起用赤色発光蛍光体。
【００１４】
（４）前記（１）〜（３）のいずれかに記載の紫外線励起用赤色発光蛍光体と、緑色発光蛍光体及び／または青色発光成分蛍光体との混合蛍光体からなることを特徴とする白色発光蛍光体又は多色発光蛍光体。
（５）前記緑色発光蛍光体として、ＺｎＳ：Ｃｕ，Ａｌ、ＺｎＳ：Ａｕ，Ａｌ、ＺｎＳ：Ａｕ，Ｃｕ，Ａｌ、ＢａＭｇＡｌ_１０Ｏ_１７：Ｅｕ，Ｍｎ及びＢａＭｇＡｌ_１０Ｏ_１７：Ｍｎの中の少なくとも一つの蛍光体を含有し、青色発光蛍光体として、ＢａＭｇＡｌ_１０Ｏ_１７：Ｅｕ又は（Ｓｒ，Ｃａ，Ｂａ，Ｍｇ）_１０（ＰＯ_４）_６Ｃｌ_２：Ｅｕ、Ｃａ_２Ｂ_５Ｏ_９Ｃｌ：Ｅｕ及びＺｎＳ：Ａｇ，Ａｌの中の少なくとも一つの蛍光体を含有することを特徴とする前記（４）に記載の白色発光蛍光体又は多色発光蛍光体。
（６）３６０〜４１０ｎｍの波長領域に発光ピークを有する近紫外線を放出するＬＥＤチップ〔発光ダイオードチップ〕と、前記ＬＥＤチップからの放射光を受けて発光する蛍光体とを備える発光素子であって、前記蛍光体が前記（１）〜（３）のいずれかに記載の紫外線励起用赤色発光蛍光体、又は前記（４）、（５）のいずれかに記載の白色発光蛍光体及び多色発光蛍光体からなることを特徴とする発光素子。
【００１５】
【発明の実施の形態】
以下、本発明を更に詳細に説明する。
本発明の蛍光体は次の様にして製造される。一般式（Ｌａ_１−ｘ，Ｅｕ_ｘ）_２Ｏ_２Ｓ（但し、０．０２≦ｘ≦０．５０）の母体組成の構成を有し、不純物添加元素としてＳｉ及びＧｅの中の少なくとも１種の濃度が母体重量に対し１０〜２０００ｐｐｍとなる様、まず目的不純物が所定量添加された希土類原料（Ｌａ_２Ｏ_３、Ｅｕ_２Ｏ_３）を作製する。
不純物の添加法としては、所定量秤量されたＬａ_２Ｏ_３、Ｅｕ_２Ｏ_３に対し所定量の不純物を固形、粉体の形で直接投入し混合する方法と、一旦不純物を含む水溶液又はアルコール液を作製し、それを希土類原料に所定量添加、ペースト混合、乾燥、篩いを施して、目的の不純物が所定量含有した希土類主原料を得る方法とがある。
不純物としては、次のものを使用することができる。Ｓｉの場合は珪酸ナトリウム、珪酸カリウム等の珪酸塩、エチルシリケートなどの有機珪酸塩等珪素化合物または珪素等、珪素を含む化合物。Ｇｅの場合は酸化ゲルマニウム（ＧｅＯ_２）、硫化ゲルマニウム（ＧｅＳ_２）及びＮａ_２ＧｅＯ_４やＮａ_２Ｇｅ_２Ｏ_５などのゲルマニウム酸塩またはゲルマニウム等、ゲルマニウムを含む化合物が使用される。
【００１６】
次いで、このようにして得られた目的の不純物を所定量含有した主原料に対し、副原料であるＳを一般式で表せる量に対し、焼成工程時のロス分等考慮し理論値より過剰量加える、更に焼成雰囲気保持剤、結晶成長剤としてＮａ_２ＣＯ_３、ＬｉＰＯ_４などを加えて混合する。上記の様にして得られた原料混合体を蓋付きのアルミナ坩堝等の焼成容器に詰め、１０００〜１３００℃で２〜６時間焼成する。
焼成を終えた焼成物は、一旦水に漬けた後、水洗を行って焼成時発生した多硫化アルカリ等の不要物を溶解除去し、うすい鉱酸水溶液で洗浄した後水洗を加え、其の後必要に応じボールミル等による分散処理を施した後、水篩等の湿式分級法で不要な大粒子を除くなどの分級処理を加えた後、乾燥、篩いを行うことにより本発明の蛍光体が得られる。更に必要性に応じ耐久性の改善のために無機物又は有機物の表面処理を施してもよい。
【００１７】
なお本発明の主要素である不純物の添加量については、１０〜２０００ｐｐｍで輝度の向上効果を示し、１０ｐｐｍ以下では顕著な効果が現れず、また２０００ｐｐｍ以上では効果がないか又は逆に輝度低下を招く。また添加量と実際に蛍光体結晶に取り込まれ含有される量との関係は表１の実施例１（Ｓｉ添加）、実施例２（Ｇｅ添加）、参考例３（Ｇａ添加）、参考例４（Ｔｉ添加）、参考例５（Ｔａ添加）の添加量と含有量に示される様に、その元素により取り込まれる程度が異なるため、必要に応じ目的の含有設定量よりも予め多めに添加する必要がある。
【００１８】
図１はＳｉ添加の本発明蛍光体（Ｌａ_２Ｏ_２Ｓ：Ｅｕ＋Ｓｉと表示）の粉末反射スペクトルを示しているが、未添加の未処理蛍光体（Ｌａ_２Ｏ_２Ｓ：Ｅｕと表示）に対し可視全域である波長４５０ｎｍ、５４５ｎｍ、６２４ｎｍにおける粉末反射率が高くなる特徴を有している。添加される元素の種類及び添加の量にも影響されるが、表１の様にその各波長ポイントにおいて、８４％、９４％、９７％以上の値を示し反射率が高く体色がより白くなっていることを意味している。この様な反射率の高い本発明蛍光体（Ｌａ，Ｅｕ）_２Ｏ_２Ｓを赤色成分として用いて、青色発光や緑色発光及び黄色発光の蛍光体と混合し白色発光蛍光体を得た場合は、赤色蛍光体の体色が黄色を呈し、青色及び緑色の波長領域（４５０ｎｍ、５４５ｎｍ）で粉末反射率が低く、青色光や緑色光あるいは黄色光等の光が一部赤色蛍光体の結晶に吸収されロスしてしまうと言う従来の問題は軽減、改善することができる。そのため白色発光蛍光体または多色発光蛍光の輝度はトータル的には高くなり改善される。またここで用いられる白色発光蛍光体または多色発光蛍光体の構成成分である青色発光蛍光体としては、ＢａＭｇＡｌ_１０Ｏ_１７：Ｅｕ又は（Ｓｒ，Ｃａ，Ｂａ，Ｍｇ）_１０（ＰＯ_４）_６Ｃｌ_２：Ｅｕ、Ｃａ_２Ｂ_５Ｏ_９Ｃｌ：Ｅｕ及びＺｎＳ：Ａｇ，Ａｌの中の少なくとも一つ、緑色発光蛍光体としては、ＺｎＳ：Ｃｕ，Ａｌ、ＺｎＳ：Ａｕ，Ａｌ、ＺｎＳ：Ａｕ，Ｃｕ，Ａｌ、ＢａＭｇＡｌ_１０Ｏ_１７：Ｅｕ，Ｍｎ及びＢａＭｇＡｌ_１０Ｏ_１７：Ｍｎの中の少なくとも一つを用いることができる。
【００１９】
また粉末反射率の改善された本発明の赤色発光蛍光体をより効果的に用いるためには、組合せの蛍光体の反射率が同様に高いことが望ましく、緑色発光蛍光体としては体色が黄緑で比較的反射率の低いＺｎＳ：Ｃｕ，Ａｌ、ＺｎＳ：Ａｕ，Ａｌ、ＺｎＳ：Ａｕ，Ｃｕ，Ａｌよりも体色が白く反射率の高いＢａＭｇＡｌ_１０Ｏ_１７：Ｅｕ，Ｍｎがより好適と言える。
一方前記の本発明蛍光体を用いた、本発明の発光素子は３６０〜４１０ｎｍの範囲にピークがある波長の近紫外線を放出するＬＥＤチップ〔発光ダイオードチップ〕とＬＥＤチップからの放射光を受けて発光する蛍光体から構成される赤色発光及び白色発光及び多色発光のＬＥＤ発光素子で、図２の様な概略構造を有し具体的には下記の様に作製される。まず構成要素の一つである励起用発光としては、近紫外〜短波長可視光の波長域に発光する発光素子が用いられる。この励起用光源である発光素子としては、比較的入手し易く、しかも発光効率が高くて、蛍光体をより高輝度に発光させ得る点で、その発光ピークの波長λが３００〜５００ｎｍで、より好ましくは３６０〜４８０ｎｍである（Ｇａ_１−ｘＩｎ_ｘ）Ｎ（但し、ｘは０≦ｘ≦０．５）等の窒化物系化合物半導体からなる発光ダイオード（ＬＥＤ）や半導体レーザー（ＬＤ）を使用することができる。
【００２０】
本発明の発光素子は、前記の蛍光体が励起用光源からの光を受光して吸収し得るような位置関係にあり、励起光源に対峙するような配置で構成されている。
図２に示されている様に、ステム１上には半導体発光素子チップ３が電気的に接着されており、一方、半導体発光素子チップ３の他方の電極とリード２の１つとがリード線５により電気的に接続されている。
このステム１にはドーム状の透明樹脂被覆蓋体５が固着される。そして、この透明樹脂被覆蓋体５の内面には、蛍光体を分散させた結合剤が塗布され蛍光体層６が形成されている。透明樹脂被覆蓋体５は、エポキシ樹脂、アクリル樹脂、シリコン樹脂、ポリスチレンなどの樹脂やガラス等の光に対して透明な材料で構成され、半導体発光素子チップ３の気密封止用キャップの役割を兼ねてステム１に整固着されている。リード線２に通電することによって半導体発光素子チップ３が発光し、この発光光が空間層を介して透明樹脂被覆蓋体５の内壁面に形成されている蛍光体層６面に照射され、蛍光体層６がこの半導体発光素子チップ３からの発光を吸収して励起され、半導体発光素子チップ３とは異なる発光波長で本発明の構成要素として示された蛍光体に固有の発光を呈する。
【００２１】
このような構成を有する本発明の発光素子の一構成要素である蛍光体層において、本発明の赤色蛍光体または発光色の異なる複数の蛍光体と混合された白色発光蛍光体または多色発光蛍光体を用いることにより、高輝度で色再現性、演色性にも問題ない発光素子を得ることができる。この様な発光素子の実現により、照明用、液晶ディスプレイや携帯情報端末等のバックライト用、インジケータ光源用及びディスプレイ用として白色光源に限らず多色光源としても、高輝度で色再現性、演色性にも問題ないものを提供することが可能となる。
【００２２】
【実施例】
次に実施例により本発明を説明するが、本発明は以下の実施例に例示した実施の態様に限定されるものではない。
〔実施例１〕
蛍光体出発原料として、Ｌａ_２Ｏ_３粉末を４６．８ｇと、Ｅｕ_２Ｏ_３を３．２３ｇ混合し、次いで珪酸カリウム（ＳｉＯ_２含有量２０％）を希釈しＳｉ濃度を５ｍｇ／ｍｌに調整した珪酸カリウム溶液を２．３ｍｌ添加し、混合物全体がペースト液状になるまで水を添加し混合する。これを乾燥して粉砕・混合した後、Ｎａ_２ＣＯ_３を２０ｇとＳを１５ｇ投入し、混合して調合物とした。
次に、得られた混合物をアルミナルツボに充填し、蓋をして最高温度１２００℃にて３時間焼成した。得られた焼成物を純水にて十分洗浄し多硫化アルカリなどの不純物を取り除いた。ついで、蛍光体スラリー液中に希釈塩酸を加え、ＰＨ＝１．５以下のスラリーで洗浄したのち水洗を行い、以降は通常の分散処理、乾燥、篩いを行うことにより、実施例１のＳｉ添加量２２０ｐｐｍの蛍光体が得られた。
【００２３】
このようにして得られた蛍光体はＸ線回折分析並びにＩＣＰ分析により、Ｓｉを２２０ｐｐｍ含有する（Ｌａ_１−ｘ，Ｅｕ_ｘ）_２Ｏ_２Ｓなる本発明の蛍光体であることを確認した。また輝度については、Ｘｅランプ光を分光して得た３８２ｎｍの近紫外線を照射し、蛍光体からの発光を輝度計にて測定し、表１に示されている様に従来の比較蛍光体１に対し１４％向上していることが確認した。更に本発明蛍光体の特徴である粉末反射率については、ＳＨＩＭＡＺＵＵＶ−３１００ＰＣを用い測定した結果、表１に示されている様に、波長４５０ｎｍ、５４５ｎｍ、６２４ｎｍの各点での粉末反射率は未処理の比較蛍光体のそれに比較し高い値を示している。詳細には、図１の粉末反射スペクトルでその差を明確に確認できた。
【００２４】
【表１】

表１において、ＬＯＳ：Ｅｕは（Ｌａ_１−ｘ，Ｅｕ_ｘ）_２Ｏ_２Ｓを、ＬＯＳ：Ｅｕ＋Ｓｉは不純物Ｓｉを含む（Ｌａ_１−ｘ，Ｅｕ_ｘ）_２Ｏ_２Ｓをそれぞれ示す。
【００２５】
〔実施例２、参考例１〜３〕
実施例１でＳｉ濃度を５ｍｇ／ｍｌに調整した珪酸カリウム溶液を２．３ｍｌ添加することに替え、それぞれＧｅ_２Ｏ_３を硝酸に溶解してＧｅ濃度を５ｍｇ／ｍｌに調整した溶液を４．４ｍｌ添加すること、Ｇａを硝酸に溶解してＧａ濃度を１ｍｇ／ｍｌに調整した溶液を２１．３ｍｌ添加すること、Ｔｉ濃度１ｍｇ／ｍｌの硫酸水溶液を１４．６ｍｌ添加すること以外は実施例１と同様にしてＧｅを２０ｐｐｍ含有する実施例２、Ｇａを２０ｐｐｍ含有する参考例１、Ｔｉを２５０ｐｐｍ含有する参考例２、Ｔａを５１０ｐｐｍ含有する参考例３の本発明の蛍光体を得た。評価については、実施例１と同様の方法で行い、Ｇｅ、Ｇａ、Ｔｉ、Ｔａ添加についても表１に示されている様に多少のレベル差はあるものの、Ｓｉと同様の効果があることを確認することができた。
【００２６】
〔比較例１〕
出発原料として、Ｌａ_２Ｏ_３粉末を４６．８ｇとＥｕ_２Ｏ_３を３．２３ｇ混合し、次いでＮａ_２ＣＯ_３を２０ｇとＳを１５ｇ投入し混合して調合物とした。調合物の充填及び焼成以降の工程は実施例１と同様にて、特定不純物を含まない従来仕様の（Ｌａ_１−ｘ，Ｅｕ_ｘ）_２Ｏ_３Ｓ蛍光体を作製し比較例１の蛍光体を得た。
【００２７】
〔比較例２〕
実施例の蛍光体をカラーテレビなどで一般的に用いられている代表的赤色蛍光体とレベル比較する為に準備した既存の顔料を付着していないＹ_２Ｏ_２Ｓ：Ｅｕ蛍光体である。Ｙ_２Ｏ_２Ｓ：Ｅｕ蛍光体は本発明蛍光体に対し輝度が約半分のレベルであることが確認できた。
【００２８】
【表２】

表２において、ＢＡＭ：ＥｕはＢａＭｇＡｌ_１０Ｏ_１７：Ｅｕ、ＢＡＭ：Ｍｎ，ＥｕはＢａＭｇＡｌ_１０Ｏ_１７：Ｅｕ、ＣＣＢ：ＥｕはＣａ_２Ｂ_５Ｏ_９Ｃｌ：Ｅｕをそれぞれ示す。
【００２９】
〔実施例３〜６、参考例４〜６〕
実施例１、２に記載の所定の元素を含有する（Ｌａ_１−ｘ，Ｅｕ_ｘ）_２Ｏ_２Ｓ赤色蛍光体の各々について、ＺｎＳ：Ｃｕ，Ａｌ緑色発光蛍光体及びＢａＭｇＡｌ_１０Ｏ_１７：Ｅｕ青色発光蛍光体とを色度値がｘ＝０．３１，ｙ＝０．３３となるように適当量混合し、実施例３〜、及び参考例４〜６の白色発光の蛍光体を得た。
実施例１と同様の方法で評価を行ったが、白色発光蛍光体においても実施例１、２の蛍光体同様、改善効果が反映されており、輝度は表２に示されている様に従来の比較例３の蛍光体に対し、２〜８％向上していることが確認できた。
【００３０】
〔実施例５〕
実施例１に記載のＳｉを含有する（Ｌａ_１−ｘ，Ｅｕ_ｘ）_２Ｏ_２Ｓ赤色蛍光体とＢａＭｇＡｌ_１０Ｏ_１７：Ｅｕ，Ｍｎ緑色蛍光体及びＢａＭｇＡｌ_１０Ｏ_１７：Ｅｕ青色蛍光体とを色度値がｘ＝０．３１，ｙ＝０．３３となるように適当量混合し、実施例５の白色発光の蛍光体を得た。組合せの蛍光体を変えても、表２に示されている様に実施例３と同様に輝度向上の効果があることが確認できた。
【００３１】
〔実施例６〕
実施例１に記載のＳｉを含有する（Ｌａ_１−ｘ，Ｅｕ_ｘ）_２Ｏ_２Ｓ赤色蛍光体とＢａＭｇＡｌ_１０Ｏ_１７：Ｅｕ，Ｍｎ緑色蛍光体及びＣａ_２Ｂ_５Ｏ_９Ｃｌ：Ｅｕ青色蛍光体を色度値とをｘ＝０．３１，ｙ＝０．３３となるように適当量混合し実施例６の白色発光の蛍光体を得た。前記同様、組合せの蛍光体を変えても、表２に示されている様に同様の効果があることが確認できた。
【００３２】
〔比較例３〕
比較例１に記載の（Ｌａ_１−ｘ，Ｅｕ_ｘ）_２Ｏ_２Ｓ赤色蛍光体とＺｎＳ：Ｃｕ，Ａｌ緑色蛍光体及びＢａＭｇＡｌ_１０Ｏ_１７：Ｅｕ青色蛍光体とを色度値がｘ＝０．３１，ｙ＝０．３３となるように適当量混合し、比較例３の白色発光の蛍光体を作製した。
【００３３】
〔比較例４〕
比較例２に記載の（Ｙ_１−ｘ，Ｅｕ_ｘ）_２Ｏ_２Ｓ赤色蛍光体とＺｎＳ：Ｃｕ，Ａｌ緑色蛍光体及びＢａＭｇＡｌ_１０Ｏ_１７：Ｅｕ青色蛍光体とを色度値がｘ＝０．３１，ｙ＝０．３３となるように適当量混合し、比較例４の白色発光蛍光体を作製した。
【００３４】
〔実施例７〕
本発明蛍光体を用いた、本発明の発光素子については、実施例１に記載のＳｉを含有する（Ｌａ_１−ｘ，Ｅｕ_ｘ）_２Ｏ_２Ｓ赤色蛍光体１０ｇとエポキシ樹脂（日東電工社製、ＮＴ８０１４）１ｇと酸無水物系硬化剤１ｇを混合して蛍光体塗布液を調製した。これとは別に、励起用光源として主ピーク波長４００ｎｍの近紫外発光を示す発光ダイオード素子のウエハー部分を水平に保持し、先に調製した蛍光体塗布液をその発光部上に細いノズルから滴下してドーム状の蛍光体塗布膜を作り、次いでこれをそのまま半回転して蛍光体塗布面を逆水平にして表面張力を利用しドーム状の塗膜内で蛍光体を室温で自然乾燥させた後、およそ１５０℃で３時間更に乾燥して表面に本発明の蛍光体が塗布された発光素子を作製した。
このようにして得られた発光素子の電極に通電したところ、ＣＩＥ表色系で表される発光色度点がｘ＝０．６５、ｙ＝０．３４である、赤色の発光を示す発光素子が得られた。得られた発光素子の輝度は下記の比較例５に対し１５％明るかった。
【００３５】
〔実施例８〕実施例３に記載のＳｉを含有する（Ｌａ_１−ｘ，Ｅｕ_ｘ）_２Ｏ_２Ｓ赤色蛍光体と、ＺｎＳ：Ｃｕ，Ａｌ緑色発光蛍光体及びＢａＭｇＡｌ_１０Ｏ_１７：Ｅｕ青色発光蛍光体との混合で構成された白色発光蛍光体１０ｇとエポキシ樹脂（日東電工社製、ＮＴ８０１４）１ｇと酸無水物系硬化剤１ｇを混合して蛍光体塗布液を調製した。以降実施例７と同様にして白色発光の発光素子を作製した。
このようにして得られた発光素子の電極に通電したところ、ＣＩＥ表色系で表される発光色度点がｘ＝０．３４、ｙ＝０．３８である、白色の発光を示す発光素子が得られた。得られた発光素子の輝度は、下記の比較例６に対し１０％明るかった。
【００３６】
〔比較例５〕
比較例１に記載のＳｉを含有しない（Ｌａ_１−ｘ，Ｅｕ_ｘ）_２Ｏ_２Ｓ赤色蛍光体１０ｇとエポキシ樹脂（日東電工社製、ＮＴ８０１４）１ｇと酸無水物系硬化剤１ｇを混合して蛍光体塗布液を調製した。以降実施例７と同様にして，比較例５の赤色発光の発光素子を作製した。
【００３７】
〔比較例６〕
比較例３に記載のＳｉを含有しない（Ｌａ_１−ｘ，Ｅｕ_ｘ）_２Ｏ_２Ｓ赤色蛍光体を用いた白色発光蛍光体１０ｇとエポキシ樹脂（日東電工社製、ＮＴ８０１４）１ｇと酸無水物系硬化剤１ｇを混合して蛍光体塗布液を調製した。以降実施例７と同様にして比較例６の白色発光の発光素子を作製した。
【００３８】
なお、上記実施例では、赤色発光蛍光体の組成として、（Ｌａ，Ｅｕ）_２Ｏ_２Ｓを基本として例記したが、本発明の特定不純物添加で輝度向上を図る仕様は、上記組成を基本としてモディファイされた公知技術、例えばＥｕの一部をＳｍ置換した蛍光体（Ｌａ，Ｅｕ，Ｓｍ）_２Ｏ_２Ｓ、及び輝度向上のため増感効果を狙って微量の希土類元素Ｔｂ，Ｐｒ等を添加した蛍光体にも同様に適用できる。
【００３９】
【発明の効果】
本発明は、上記の様な構成とすることにより、高輝度の赤色蛍光体及び白色発光蛍光体または多色発光蛍光体を得ることができ、発光素子においても高輝度で色再現性にも問題ないものを得ることができる。この様な発光素子の実現により、照明用、液晶ディスプレイや携帯情報端末等のバックライト用、インジケータ光源用及びディスプレイ用として白色光源に限らず多色光源として、高輝度で色再現性、演色性にも問題ないものを提供することができる。
【００４０】
【図面の簡単な説明】
【図１】Ｓｉを含有する本発明の（Ｌａ_１−ｘ，Ｅｕ_ｘ）_２Ｏ_２Ｓ蛍光体とＳｉを含有しない従来の（Ｌａ_１−ｘ，Ｅｕ_ｘ）_２Ｏ_２Ｓの反射スペクトルの比較を例示するグラフである。
【図２】本発明の発光素子の一実施例を示す概略断面図である。
【符号の説明】
１ステム
２リード線
３半導体発光素子チップ（ＬＥＤチップ）
４金線
５透明樹脂被覆蓋体
６蛍光体層[0001]
BACKGROUND OF THE INVENTION
The present invention provides various combinations of an excitation light source such as a light emitting diode (LED) that emits near ultraviolet rays having a wavelength shorter than 410 nm, a red light emitting phosphor, and white light emission and multicolor light emission phosphors using this phosphor. The present invention relates to a light-emitting element used for lighting that emits light, for backlights such as liquid crystal displays and portable information terminals, indicator light sources, and displays.
[0002]
[Prior art]
A fluorescent lamp is known as one of the typical uses of a phosphor, and has been practically used as an illumination or a display for a long time. As is well known, a fluorescent lamp uses a fluorescent film made of a phosphor formed on the inner wall of a glass tube to emit light by being excited by ultraviolet rays generated by discharge in a glass tube filled with mercury vapor. It is used as a light source.
[0003]
By the way, in recent years, light emitting diodes (LEDs) and semiconductor lasers (LDs) have been used as excitation light sources as a light source for lighting that consumes less power and does not use mercury from the viewpoint of environmental problems and power saving. In combination with the above, a method has been developed in which light emitted from an LED or LD is used to excite a phosphor to emit light, and the light emitted at that time is used as a light source. For example, Japanese Patent No. 2,927,279 discloses a Ce-activated rare earth aluminate phosphor that emits blue visible light emitted from an LED chip and absorbs part of the blue light emitted from the LED chip. Discloses a light emitting diode that exhibits white light emission as a whole by additive color mixing with yellow light emission.
[0004]
However, in the type of light source that combines the excitation light source such as LED and the phosphor disclosed in Patent No. 2,927,279, the emission wavelength of the excitation light source such as LED is limited. Restrictions such as the fact that the type of phosphor that can be emitted by the excitation light source used is extremely limited, so that the final emission color is limited to white or multicolored colors cannot be produced. was there. In addition, with regard to white, a preferred color is not reproduced under illumination, and color rendering is also a problem.
[0005]
In order to solve such problems in recent years, U.S. Pat. S. P. 6294800, U.S. Pat. S. P. 6255670 et al. Introduces a method of mixing three components, green, blue and red. The phosphors used here are Ca ₈ Mg (SiO ₄ ) ₄ Cl: Eu, Mn as a green light emitting phosphor, BaMgAl ₁₀ O ₁₇ : Eu as a blue light emitting phosphor, and as a red phosphor. Y ₂ O ₂ S: Eu or Y ₂ O ₃ : Eu, Bi or the like.
[0006]
Compared with the two-color component method, the method of mixing these three components has considerably improved the reproduction of the colors reflected under the illumination of the light source. However, when the color tone of each phosphor used as a component is not preferable, the color projected under the illumination of the light source is poorly reproducible and the desired color cannot be produced. In particular, since the color tone of the red phosphor is far from the desired red color, a satisfactory white light source cannot be obtained.
[0007]
As a measure for solving such a problem, in Japanese Patent Application Laid-Open No. 11-246857, (La, Eu, Sm) ₂ O ₂ S is used as a red fluorescent light in an LED light emitting device in which an LED chip that emits near ultraviolet light of around 370 nm and a phosphor are combined. It has been reported for use as a body and has been shown to be effective. The (La, Eu, Sm) ₂ O ₂ S red phosphor has efficient absorption for near ultraviolet rays around 370 nm, has a relatively good emission color with a peak wavelength of around 625 nm, and also compares luminance. Good.
However, in light of market demand, the luminance is still insufficient, and further high luminance is desired. On the other hand, white phosphors and multicolor phosphors and light emitting elements are still insufficient in terms of luminance and color rendering.
[0008]
[Problems to be solved by the invention]
LED light-emitting elements are expected as light sources for fluorescent lamps, light sources for liquid crystals and mobile phone backlights, and improvements in characteristics such as color reproducibility, color rendering properties, luminance, and luminous efficiency are always desired.
(La, Eu) ₂ O ₂ S and (La, Eu, Sm) ₂ O ₂ S phosphors for LEDs disclosed in JP-A-11-246857 are typical red phosphors widely used in displays and the like. Is higher than that of (Y, Eu) ₂ O ₂ S, which is near 382 nm, and is considered to be a relatively good phosphor, but is insufficient in practical use. Improvement in brightness is desired.
[0009]
On the other hand, for white phosphors and multicolor phosphors, (La, Eu) ₂ O ₂ S or (La, Eu, Sm) ₂ O ₂ S phosphors are used as red components to emit blue, green, and yellow light emission. When a white light-emitting phosphor is obtained by mixing with a body, the body color of the red phosphor is yellow, and the powder reflectance is low as shown in FIG. 1 in the blue and green wavelength regions. Light, green light, or yellow light is partially absorbed by the red phosphor crystal and lost. As a result, there was a problem that the total luminance as a white phosphor was lowered and sufficient luminance could not be obtained.
[0010]
The present invention has been made in view of such circumstances, and a red phosphor having a higher luminance than a conventional red light-emitting phosphor by excitation of near ultraviolet rays of 360 to 410 nm, a high powder reflectance, and a low body color, and the red color. An object of the present invention is to provide a phosphor that contains a phosphor and contains at least one phosphor that is different from the phosphor, and emits white light and multicolor light by excitation of near-ultraviolet rays.
Still further, a red light emission and a white light emission composed of an LED chip (light emitting diode chip) that emits near ultraviolet light having a wavelength having a peak in the range of 360 to 410 nm and a phosphor that emits light by receiving light emitted from the LED chip. An object of the present invention is to provide a multicolor LED light emitting device.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, the present inventors prepared red phosphors having various compositions, examined the effects of the types and production methods of the composition components on the emission luminance and body color of the phosphors, and High-intensity white light-emitting phosphors were studied by mixing phosphors and other blue and green phosphors that emit light.
As a result, by adding at least one of a predetermined amount of Si and Ge to the europium activated lanthanum oxysulfide phosphor, the emission efficiency is high when irradiated with near ultraviolet rays around 382 nm, and the body color is white and blue and green. A phosphor having a high powder reflectance in the visible region was obtained.
[0012]
Further, as a result of studying a high-luminance white light emitting phosphor by mixing the red phosphor, the blue phosphor and the green phosphor of the present invention, the europium activated acid containing at least one of Si and Ge of the present invention Lanthanum sulfide red light-emitting phosphor, and particularly green light-emitting ZnS: Au, Cu, Al or BaMgAl ₁₀ O ₁₇ : Eu, Mn, and blue light-emitting BaMgAl ₁₀ O ₁₇ : Eu, Mn or Ca ₂ B ₅ O ₉ Cl: Eu The present inventors have found that a white light-emitting phosphor obtained by combining and mixing phosphors has high luminance, and has reached the present invention.
[0013]
The present invention has the following configuration.
(1) In the phosphor represented by the general formula (La _1-x , Eu _x ) ₂ O ₂ S (where 0.02 ≦ x ≦ 0.50), 10 ppm to 2000 ppm of Si with respect to the weight of the phosphor and / or ultraviolet excitation for red-emitting phosphor to feature in that it contains a G e.
( 2 ) The ultraviolet light-exciting red light-emitting phosphor as described in (1) above, wherein the wavelength of the ultraviolet light is near-ultraviolet of 360 to 410 nm.
(3) In the ultraviolet excited red-emitting phosphor, wavelength 450 nm, 545 nm, and powder reflectance respectively 84% or more at 624 nm, 94% or more, and said, characterized in that less than 97% (1) The red light-emitting phosphor for ultraviolet excitation as described.
[0014]
(4) the (1) to an ultraviolet excitation red light-emitting phosphor according to any one of (3), and wherein Rukoto such a phosphor mixture of a green-emitting phosphor and / or blue-emitting component phosphor White light emitting phosphor or multicolor light emitting phosphor.
(5) and the green-emitting phosphor, ZnS: Cu, Al, ZnS : Au, Al, ZnS: Au, Cu, Al, BaMgAl 10 O 17: Eu, Mn and _BaMgAl 10 _O 17: At least in the Mn containing one phosphor, and a blue phosphor, _BaMgAl 10 _O 17: Eu or _{_{_{(Sr, Ca, Ba, Mg}}} ) 10 (PO 4) 6 Cl 2: Eu, Ca 2 B 5 O 9 Cl: The white light emitting phosphor or the multicolor light emitting phosphor as described in ( 4 ) above, which contains at least one phosphor of Eu and ZnS: Ag, Al.
( 6 ) A light emitting device comprising: an LED chip [light emitting diode chip] that emits near ultraviolet rays having a light emission peak in a wavelength region of 360 to 410 nm; and a phosphor that emits light upon receiving radiation from the LED chip. The phosphor is a red light emitting phosphor for ultraviolet excitation according to any one of (1) to (3) , or a white light emitting phosphor and multicolor light emission according to any one of (4) and (5). emitting device characterized Rukoto a phosphor.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in more detail.
The phosphor of the present invention is manufactured as follows. At least one of Si and Ge as an impurity-added element having a matrix composition of the general formula (La _1-x , Eu _x ) ₂ O ₂ S (where 0.02 ≦ x ≦ 0.50) First, a rare earth material (La ₂ O ₃ , Eu ₂ O ₃ ) to which a predetermined amount of a target impurity is added is prepared so that the concentration of is 10 to 2000 ppm with respect to the base weight.
As a method for adding impurities, a predetermined amount of impurities are directly added in solid and powder form to La ₂ O ₃ and Eu ₂ O ₃ weighed in a predetermined amount, and mixed with an aqueous solution or alcohol once containing impurities. There is a method in which a liquid is prepared, and a predetermined amount is added to the rare earth material, paste mixing, drying, and sieving are performed to obtain a rare earth main material containing a predetermined amount of target impurities.
As impurities, the following can be used. In the case of Si, silicon compounds such as silicates such as sodium silicate and potassium silicate, organic silicates such as ethyl silicate, or compounds containing silicon such as silicon. In the case of Ge, germanium-containing compounds such as germanium oxide (GeO ₂ ), germanium sulfide (GeS ₂ ), and germanate or germanium such as Na ₂ GeO ₄ and Na ₂ Ge ₂ O ₅ are used .
[0016]
Next, with respect to the main raw material containing a predetermined amount of the target impurity thus obtained, the amount of S, which is a secondary raw material, can be expressed by a general formula, and the excess amount from the theoretical value in consideration of the loss during the firing process. Furthermore, Na ₂ CO ₃ , LiPO _{4 and the} like are added and mixed as a firing atmosphere holding agent and a crystal growth agent. The raw material mixture obtained as described above is packed in a firing container such as an alumina crucible with a lid and fired at 1000 to 1300 ° C. for 2 to 6 hours.
The fired product after firing is immersed in water, washed with water to dissolve and remove unnecessary substances such as alkali polysulfide generated during firing, washed with a light aqueous mineral acid solution, and then washed with water. If necessary, after applying a dispersion treatment with a ball mill, etc., after applying a classification treatment such as removing a large unnecessary particle by a wet classification method such as a water sieve, the phosphor of the present invention is obtained by drying and sieving. It is done. Further, an inorganic or organic surface treatment may be applied to improve durability according to need.
[0017]
Note that although the main elements der Ru not neat amount of the present invention exhibits the effect of improving bright degree 10～2000Ppm, does not appear significant effect at 10ppm or less, also ineffective or reversed in 2000ppm or higher Lowers brightness. The relationship between the amount added and the amount actually incorporated and contained in the phosphor crystal is shown in Example 1 (Si addition), Example 2 (Ge addition), Reference Example 3 (Ga addition) and Reference Example 4 in Table 1. (Ti addition), as shown in the addition amount and content of Reference Example 5 (Ta addition), the degree of incorporation differs depending on the element, so it is necessary to add more in advance than the target content setting amount if necessary There is.
[0018]
Figure 1 is the invention phosphors Si added: while indicating powder reflection spectra of _{_{(La 2 O 2 S Eu +}} Si and the display), the untreated phosphor not added: the _(La ₂ O ₂ S Eu and display) On the other hand, it has the characteristic that the powder reflectance becomes high at wavelengths of 450 nm, 545 nm, and 624 nm, which are the entire visible region. Although it is affected by the kind of element to be added and the amount of addition, as shown in Table 1, at each wavelength point, the values are 84%, 94%, 97% or more, and the reflectance is high and the body color is whiter It means that When the phosphor of the present invention (La, Eu) ₂ O ₂ S having such a high reflectance is used as a red component and mixed with blue, green, and yellow light emitting phosphors, a white light emitting phosphor is obtained. The red phosphor body color is yellow, the powder reflectance is low in the blue and green wavelength regions (450 nm, 545 nm), and some of the light such as blue light, green light or yellow light is in the crystal of the red phosphor The conventional problem of absorption and loss can be reduced and improved. Therefore, the brightness of the white light-emitting phosphor or multicolor light-emitting fluorescence is totally increased and improved. As the blue-emitting phosphor which is a component of the white light emitting phosphor or multicolor light emitting phosphor used herein, _BaMgAl 10 _O 17: Eu or _{(Sr, Ca, Ba, Mg} ) 10 (PO 4) 6 Cl ₂ : Eu, Ca ₂ B ₅ O ₉ Cl: Eu and at least one of ZnS: Ag, Al, green light emitting phosphors include ZnS: Cu, Al, ZnS: Au, Al, ZnS: Au, Cu , Al, BaMgAl ₁₀ O ₁₇ : Eu, Mn and BaMgAl ₁₀ O ₁₇ : Mn can be used.
[0019]
In addition, in order to use the red light emitting phosphor of the present invention with improved powder reflectance more effectively, it is desirable that the combined phosphor has a high reflectance as well, and the green light emitting phosphor has a yellow body color. ZnS: Cu, Al, ZnS: Au, Al, which has a relatively low reflectance, is more suitable than BaMgAl ₁₀ O ₁₇ : Eu, Mn, which has a white body color and a higher reflectance than ZnS: Au, Cu, Al. .
On the other hand, the light emitting device of the present invention using the phosphor of the present invention receives an LED chip (light emitting diode chip) that emits near ultraviolet light having a wavelength having a peak in the range of 360 to 410 nm and radiated light from the LED chip. A red light emitting element, a white light emitting element, and a multicolor emitting LED element composed of a phosphor that emits light. The LED light emitting element has a schematic structure as shown in FIG. 2, and is specifically manufactured as follows. First, as the light emission for excitation, which is one of the constituent elements, a light-emitting element that emits light in the near ultraviolet to short wavelength visible light wavelength range is used. As the light emitting element that is the light source for excitation, the wavelength λ of the light emission peak is 300 to 500 nm because it is relatively easily available, has high luminous efficiency, and can emit phosphor with higher luminance. Preferably, a light emitting diode (LED) or a semiconductor laser (LD) made of a nitride compound semiconductor such as (Ga _1-x In _x ) N (where x is 0 ≦ x ≦ 0.5) is 360 to 480 nm. Can be used.
[0020]
The light-emitting element of the present invention has a positional relationship such that the phosphor can receive and absorb light from the excitation light source, and is configured to face the excitation light source.
As shown in FIG. 2, the semiconductor light emitting element chip 3 is electrically bonded on the stem 1, while the other electrode of the semiconductor light emitting element chip 3 and one of the leads 2 are connected to the lead wire 5. Are electrically connected.
A dome-shaped transparent resin-coated lid 5 is fixed to the stem 1. A phosphor layer 6 is formed on the inner surface of the transparent resin-coated lid 5 by applying a binder in which the phosphor is dispersed. The transparent resin-coated lid 5 is made of a material transparent to light such as resin such as epoxy resin, acrylic resin, silicon resin, polystyrene, or glass, and serves as a hermetic sealing cap for the semiconductor light emitting element chip 3. In addition, it is fixedly fixed to the stem 1. When the lead wire 2 is energized, the semiconductor light emitting element chip 3 emits light, and this emitted light is irradiated to the surface of the phosphor layer 6 formed on the inner wall surface of the transparent resin-coated lid body 5 through the space layer. The body layer 6 is excited by absorbing light emitted from the semiconductor light-emitting element chip 3 and emits light specific to the phosphor shown as a component of the present invention at a light emission wavelength different from that of the semiconductor light-emitting element chip 3.
[0021]
In the phosphor layer which is one component of the light emitting device of the present invention having such a configuration, the white light emitting phosphor or the multicolor light emitting phosphor mixed with the red phosphor of the present invention or a plurality of phosphors having different emission colors. By using the body, a light-emitting element having high luminance and no problem in color reproducibility and color rendering can be obtained. By realizing such a light emitting element, high brightness, color reproducibility and color rendering can be used not only for white light sources but also for multi-color light sources for lighting, backlights for liquid crystal displays and portable information terminals, indicator light sources and displays. It is possible to provide a product that is not problematic in terms of sex.
[0022]
【Example】
EXAMPLES Next, the present invention will be described with reference to examples, but the present invention is not limited to the embodiments illustrated in the following examples.
[Example 1]
As a phosphor starting material, 46.8 g of La ₂ O ₃ powder and 3.23 g of Eu ₂ O ₃ were mixed, then potassium silicate (SiO ₂ content 20%) was diluted to adjust the Si concentration to 5 mg / ml. 2.3 ml of the potassium silicate solution is added, and water is added and mixed until the whole mixture becomes paste liquid. After drying, pulverizing and mixing, 20 g of Na ₂ CO ₃ and 15 g of S were added and mixed to prepare a preparation.
Next, the obtained mixture was filled in an alumina crucible, covered, and fired at a maximum temperature of 1200 ° C. for 3 hours. The obtained fired product was sufficiently washed with pure water to remove impurities such as alkali polysulfide. Next, dilute hydrochloric acid is added to the phosphor slurry, and after washing with a slurry having a pH of 1.5 or less, washing with water is performed. Thereafter, normal dispersion treatment, drying, and sieving are performed, thereby adding Si in Example 1. An amount of 220 ppm of phosphor was obtained.
[0023]
The phosphor thus obtained was confirmed by X-ray diffraction analysis and ICP analysis to be the phosphor of the present invention containing (La _1-x , Eu _x ) ₂ O ₂ S containing 220 ppm of Si. As for the luminance, the near-ultraviolet ray of 382 nm obtained by spectrally separating the Xe lamp light was irradiated, and the light emission from the phosphor was measured with a luminance meter. As shown in Table 1, the conventional comparative phosphor 1 It was confirmed that the improvement was 14%. Furthermore, as for the powder reflectance that is a feature of the phosphor of the present invention, as a result of measurement using SHIMAZU UV-3100PC, as shown in Table 1, the powder reflectance at each of the wavelengths of 450 nm, 545 nm, and 624 nm is The value is higher than that of the untreated comparative phosphor. Specifically, the difference was clearly confirmed in the powder reflection spectrum of FIG.
[0024]
[Table 1]

In Table 1, LOS: Eu is _{_{_{(La 1-x, Eu x}}} ) the _{2 O 2 S, LOS: Eu} + Si represents impure _{_{Si (La 1-x, Eu}} x) the 2 _{O 2} S, respectively.
[0025]
[Example 2 and Reference Examples 1 to 3 ]
Instead of adding 2.3 ml of the potassium silicate solution whose Si concentration was adjusted to 5 mg / ml in Example 1, each solution was prepared by dissolving Ge ₂ O ₃ in nitric acid and adjusting the Ge concentration to 5 mg / ml. Example 1 except that 4 ml was added, 21.3 ml of a solution prepared by dissolving Ga in nitric acid to adjust the Ga concentration to 1 mg / ml, and 14.6 ml of a sulfuric acid aqueous solution having a Ti concentration of 1 mg / ml were added. The phosphor of the present invention was obtained in the same manner as in Example 2, containing 20 ppm of Ge, Reference Example 1 containing 20 ppm of Ga, Reference Example 2 containing 250 ppm of Ti, and Reference Example 3 containing 510 ppm of Ta . The evaluation performed in the same manner as in Example 1, Ge, Ga, Ti, although slight level difference as shown in Table 1 also Ta added is, that the effect is as Si I was able to confirm.
[0026]
[Comparative Example 1]
As a starting material, 46.8 g of La ₂ O ₃ powder and 3.23 g of Eu ₂ O ₃ were mixed, and then 20 g of Na ₂ CO ₃ and 15 g of S were added and mixed to prepare a formulation. The steps after filling and baking of the preparation are the same as in Example 1, and a (La _1-x , Eu _x ) ₂ O ₃ S phosphor having no specific impurities is produced to produce the phosphor of Comparative Example 1. Got.
[0027]
[Comparative Example 2]
The phosphor of the example is a Y ₂ O ₂ S: Eu phosphor not attached with an existing pigment prepared for level comparison with a typical red phosphor generally used in a color television or the like. It was confirmed that the Y ₂ O ₂ S: Eu phosphor had a luminance level about half that of the phosphor of the present invention.
[0028]
[Table 2]

In Table 2, BAM: Eu is _{_{BaMgAl 10 O 17: Eu, BAM}} : Mn, Eu is _{_{BaMgAl 10 O 17: Eu, CCB}} : Eu is _Ca 2 _B 5 _O 9 Cl: shows Eu, respectively.
[0029]
[Examples 3 to 6, Reference Examples 4 to 6 ]
For each of Examples 1, 2 containing a predetermined element according to _{_{_{(La 1-x, Eu x}}} ) 2 O 2 S red phosphor, ZnS: Cu, Al green-emitting phosphor and _BaMgAl 10 _O 17: Eu blue-emitting phosphor and the chromaticity values x = 0.31 was mixed an appropriate amount such that y = 0.33, example 3, and to obtain a phosphor of white light emission of reference examples 4-6 .
Although evaluated in the same manner as in Example 1, also the same phosphor of Example 1, 2 in the white light emitting phosphor, improvement has been reflected, the luminance is conventional as shown in Table 2 It was confirmed that the phosphor of Comparative Example 3 was improved by 2 to 8%.
[0030]
[Example 5 ]
Containing Si as described in Example _{_{1 (La 1-x, Eu}} x) 2 O 2 S red phosphor and _BaMgAl 10 _O 17: Eu, Mn green phosphor and _BaMgAl 10 _O 17: Eu and a blue phosphor Appropriate amounts were mixed so that the chromaticity values were x = 0.31 and y = 0.33 to obtain a white light-emitting phosphor of Example 5 . Even if the phosphors of the combination were changed, as shown in Table 2, it was confirmed that there was an effect of improving the luminance as in Example 3 .
[0031]
[Example 6 ]
Containing Si as described in Example _{_{1 (La 1-x, Eu}} x) 2 O 2 S red phosphor and _BaMgAl 10 _O 17: Eu, Mn green phosphor and _{_{_{Ca 2 B 5 O 9 Cl:}}} Eu blue phosphor The body was mixed with appropriate amounts so that the chromaticity values were x = 0.31 and y = 0.33 to obtain a white light-emitting phosphor of Example 6 . As described above, it was confirmed that even when the phosphors in the combination were changed, the same effect was obtained as shown in Table 2.
[0032]
[Comparative Example 3]
Comparative Example according to _{_{1 (La 1-x, Eu}} x) 2 O 2 S red phosphor and ZnS: Cu, Al green phosphor and _BaMgAl 10 _O 17: Eu blue phosphor and the chromaticity values are x = 0 An appropriate amount was mixed so that .31, y = 0.33, and a white light emitting phosphor of Comparative Example 3 was produced.
[0033]
[Comparative Example 4]
Comparative Example according to _{_{2 (Y 1-x, Eu}} x) 2 O 2 S red phosphor and ZnS: Cu, Al green phosphor and _BaMgAl 10 _O 17: Eu blue phosphor and the chromaticity values are x = 0 An appropriate amount was mixed so that .31, y = 0.33, and a white light emitting phosphor of Comparative Example 4 was produced.
[0034]
[Example 7 ]
The present invention phosphor used for the light-emitting device of the present invention contains Si as described in Example _{_{1 (La 1-x, Eu}} x) 2 O 2 S red phosphor 10g and an epoxy resin (Nitto Denko Corporation Manufactured by NT8014) and 1 g of an acid anhydride curing agent were mixed to prepare a phosphor coating solution. Separately, a wafer portion of a light emitting diode element that exhibits near-ultraviolet light emission with a main peak wavelength of 400 nm as an excitation light source is held horizontally, and the phosphor coating solution prepared earlier is dropped from a thin nozzle onto the light emitting portion. After making a dome-shaped phosphor coating film, and then rotating it halfway as it is, the phosphor coating surface is reversed horizontally and surface tension is used to naturally dry the phosphor at room temperature in the dome-shaped coating film. Then, it was further dried at about 150 ° C. for 3 hours to produce a light emitting device having the surface coated with the phosphor of the present invention.
When the electrode of the light-emitting element thus obtained was energized, the light-emitting element exhibiting red light emission in which the light emission chromaticity point represented by the CIE color system was x = 0.65 and y = 0.34 was gotten. The luminance of the obtained light emitting element was 15% brighter than that of Comparative Example 5 below.
[0035]
Example 8 containing Si as described in Example _{_{3 (La 1-x, Eu}} x) and 2 _{O 2} S red phosphor, ZnS: Cu, Al green-emitting phosphor and _BaMgAl 10 _O 17: Eu blue A phosphor coating solution was prepared by mixing 10 g of a white light-emitting phosphor composed of a mixture with a light-emitting phosphor, 1 g of an epoxy resin (manufactured by Nitto Denko Corporation, NT8014) and 1 g of an acid anhydride curing agent. Thereafter, a white light emitting element was produced in the same manner as in Example 7 .
When the electrode of the light-emitting element thus obtained was energized, the light-emitting element exhibiting white light emission with emission chromaticity points represented by the CIE color system of x = 0.34 and y = 0.38 was gotten. The luminance of the obtained light-emitting element was 10% brighter than that of Comparative Example 6 below.
[0036]
[Comparative Example 5]
Comparative Example 1 containing no Si according _{_{_{(La 1-x, Eu x}}} ) 2 O 2 S red phosphor 10g and an epoxy resin (manufactured by Nitto Denko Corporation, NT8014) were mixed 1g and an acid anhydride curing agent 1g A phosphor coating solution was prepared. Thereafter, a red light emitting element of Comparative Example 5 was produced in the same manner as in Example 7 .
[0037]
[Comparative Example 6]
Comparative Example 3 containing no Si according _{_{_{(La 1-x, Eu x}}} ) 2 O 2 S red phosphor white light emitting phosphor 10g and epoxy resin used (manufactured by Nitto Denko Corporation, NT8014) 1g acid anhydride A phosphor coating solution was prepared by mixing 1 g of a system curing agent. Thereafter, in the same manner as in Example 7 , a white light emitting element of Comparative Example 6 was produced.
[0038]
In the above-described embodiments, (La, Eu) ₂ O ₂ S is basically used as the composition of the red light-emitting phosphor. However, the specification for improving the luminance by adding the specific impurity of the present invention is based on the above composition. For example, a phosphor (La, Eu, Sm) ₂ O ₂ S in which a part of Eu is modified with Sm, and a small amount of rare earth elements Tb, Pr, etc. aiming at a sensitization effect for improving luminance are modified. The same applies to the added phosphor.
[0039]
【The invention's effect】
In the present invention, a high-intensity red phosphor and a white light-emitting phosphor or a multicolor light-emitting phosphor can be obtained by using the above-described configuration. You can get something not. By realizing such a light emitting element, it is not limited to a white light source for illumination, backlights for liquid crystal displays, personal digital assistants, etc. You can provide something that doesn't matter.
[0040]
[Brief description of the drawings]
[1] of the present invention containing a _{_{Si (La 1-x, Eu}} x) prior containing no 2 _{O 2} S phosphor and _{_{Si (La 1-x, Eu}} x) of the reflection spectrum of the 2 _{O 2} S It is a graph which illustrates a comparison.
FIG. 2 is a schematic cross-sectional view showing an embodiment of a light emitting device of the present invention.
[Explanation of symbols]
1 Stem 2 Lead Wire 3 Semiconductor Light Emitting Element Chip (LED Chip)
4 Gold wire 5 Transparent resin cover 6 Phosphor layer

Claims

In the phosphor represented by the general formula (La _1-x , Eu _x ) ₂ O ₂ S (where 0.02 ≦ x ≦ 0.50), 10 ppm to 2000 ppm of Si and / or ultraviolet excitation for red-emitting phosphor to feature in that it contains a G e.

The red light-emitting phosphor for ultraviolet excitation according to claim 1, wherein the wavelength of the ultraviolet light is near-ultraviolet of 360 to 410 nm.

2. The ultraviolet excitation according to claim 1, wherein in the red phosphor for ultraviolet excitation, powder reflectances at wavelengths of 450 nm, 545 nm, and 624 nm are 84% or more , 94% or more , and 97% or more, respectively. Red light emitting phosphor.

White light-emitting phosphor, wherein the ultraviolet excitation red-emitting phosphor according the Rukoto such a phosphor mixture of a green-emitting phosphor and / or blue-emitting component phosphor in any one of claims 1 to 3 Body or multicolor phosphor.

And said green-emitting phosphor, ZnS: Cu, Al, ZnS : Au, Al, ZnS: Au, Cu, Al, BaMgAl 10 O 17: Eu, Mn and _BaMgAl 10 _O 17: at least one fluorescent in Mn containing body, as the blue phosphor, _BaMgAl 10 _O 17: Eu or _{_{_{_{(Sr, Ca, Ba, Mg}}}} ) 10 (PO 4) 6 Cl 2: Eu, Ca 2 B 5 O 9 Cl: Eu and ZnS The white light-emitting phosphor or the multicolor light-emitting phosphor according to claim 4 , wherein the phosphor contains at least one phosphor of Ag and Al.

A light emitting device comprising an LED chip (light emitting diode chip) that emits near-ultraviolet light having an emission peak in a wavelength region of 360 to 410 nm, and a phosphor that emits light upon receiving light emitted from the LED chip , ultraviolet excitation for red-emitting phosphor according to any one of the body according to claim 1 to 3, or a Rukoto a white light emitting phosphor or multicolor light emitting phosphor according to any one of claims 4 and 5 A light emitting device characterized.