JP2004331934A

JP2004331934A - Phosphor and light emitting device using it

Info

Publication number: JP2004331934A
Application number: JP2003168473A
Authority: JP
Inventors: Hideo Suzuki; 秀雄鈴木; Hisao Suzuki; 尚生鈴木
Original assignee: Kasei Optonix Ltd
Current assignee: Mitsubishi Chemical Corp
Priority date: 2003-05-09
Filing date: 2003-05-09
Publication date: 2004-11-25
Anticipated expiration: 2023-05-09
Also published as: JP4233929B2

Abstract

【課題】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及びこれを用いた白色発光及び多色発光する蛍光体を提供すること、また更に、近紫外線を放出するＬＥＤ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高輝度の赤色及び白色発光のＬＥＤ発光素子も併せて提供することを目的とする。
【解決手段】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、Ｓｉ、Ｇｅ、Ｇａ、Ｔｉ、Ｔａの少なくとも一元素を含有することを、特徴とする紫外線励起用赤色発光蛍光体と該赤色発光蛍光体を用いた白色及び多色発光の蛍光体及びこれら蛍光体と近紫外線発光ＬＥＤチップを組み合わせて構成される発光素子。
【選択図】図１A red phosphor having a higher luminance than conventional phosphors emitting red light when excited by near-ultraviolet light of 360 to 410 nm, having a high powder reflectivity and a small body color, and a phosphor emitting white and multicolor light using the same. And a high-brightness red and white light-emitting LED light-emitting element composed of an LED chip that emits near-ultraviolet light and a phosphor that receives and emits light emitted from the LED chip. With the goal.
A general formula _{_{_{(La 1-x, Eu x}}} ) phosphor represented by 2 _{O 2} S (where, 0.02 ≦ x ≦ 0.50) in, Si, Ge, Ga, Ti , and Ta A red light emitting phosphor for ultraviolet excitation characterized by containing at least one element, a white and multicolor light emitting phosphor using the red light emitting phosphor, and a combination of these phosphors and a near ultraviolet light emitting LED chip Light emitting element.
[Selection diagram] Fig. 1

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、Ｇｅ、Ｇａ、Ｔｉ、Ｔａ、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、Ｇｅ、Ｇａ、Ｔｉ、Ｔａ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が、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，Ｅｕｘ）_２Ｏ_２Ｓで表される蛍光体（但し、０．０２≦ｘ≦０．５０）において、Ｓｉ、Ｇｅ、Ｇａ、Ｔｉ、Ｔａの少なくとも一元素を含有することを、特徴とする紫外線励起用赤色発光蛍光体。
（２）前記Ｓｉ、Ｇｅ、Ｇａ、Ｔｉ、Ｔａの含有量が、前記蛍光体重量に対し、１０ｐｐｍ〜２０００ｐｐｍ含有することを特徴とする（１）に記載の紫外線励起用赤色発光蛍光体。
（３）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（１）に記載の紫外線励起用赤色発光蛍光体。
（４）前記赤色発光蛍光体において、波長４５０ｎｍ、５４５ｎｍ、６２４ｎｍにおける粉末粉体反射率が８４％、９４％、９７％以上であることを特徴とする（１）に記載の紫外線励起用赤色発光蛍光体。
【００１４】
（５）前記赤色発光蛍光体と、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で構成されることを特徴とする白色発光及び多色発光蛍光体。
（６）前記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の蛍光体を含有し、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の蛍光体を含有することを特徴とする前記（５）に記載の白色発光及び多色発光蛍光体。
（７）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が前記（１）〜（６）に記載の蛍光体を備え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、Ｇｅ、Ｇａ、Ｔｉ及びＴａ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。Ｇａの場合は、酸化ガリウム（Ｇａ_２Ｏ_３）、硫化ガリウム（Ｇａ_２Ｓ）またはガリウムなどのガリウムを含む化合物。Ｔｉの場合は酸化チタン（ＴｉＯ_２）、チタン酸アルコキシドやチタン等、チタンを含む化合物。Ｔａの場合は酸化タンタル（Ｔａ_２Ｏ_５）、Ｎａ_３ＴａＯ_４、Ｋ_３ＴａＯ_４等のタンタル酸塩やタンタル等、タンタルを含む化合物。
【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なお不純物の添加量については、１０〜２０００ｐｐｍで輝度への向上効果を示し、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）、実施例３（Ｇａ添加）、実施例４（Ｔｉ添加）、実施例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】

但し、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を示す。
【００２５】
〔実施例２〜５〕
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含有する実施例３，Ｔｉを２５０ｐｐｍ含有する実施例４，Ｔｉを５１０ｐｐｍ含有する実施例５の本発明の蛍光体を得た。評価については、実施例１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】

但し、ＢＡＭ：ＥｕはＢａＭｇＡｌ_１０Ｏ_１７：Ｅｕ、ＢＡＭ：Ｍｎ，ＥｕはＢａＭｇＡｌ_１０Ｏ_１７：Ｅｕ、ＣＣＢ：ＥｕはＣａ_２Ｂ_５Ｏ_９Ｃｌ：Ｅｕを示す。
【００２９】
〔実施例６〜１０〕
実施例１〜５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６〜１０の白色発光の蛍光体を得た。
実施例１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１〜５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１１〕
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１１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６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１２〕
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１２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１３〕
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１４〕
実施例６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１３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１３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１３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]
TECHNICAL FIELD 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 light having a wavelength shorter than 410 nm, a red light-emitting phosphor, and a white light-emitting and multicolor light-emitting phosphor using the phosphor. The present invention relates to a light-emitting element used for illumination that emits light, for a backlight of a liquid crystal display, a portable information terminal, or the like, for an indicator light source, and for a display.
[0002]
[Prior art]
A fluorescent lamp is known as one of typical uses of the phosphor, and has been used for a long time as a lighting or a display. As is well known, a fluorescent lamp utilizes a fluorescent film formed of a phosphor formed on an inner wall of a glass tube, which is excited by ultraviolet rays generated by electric discharge in a glass tube filled with mercury vapor to emit light. Used as a light source.
[0003]
By the way, in recent years, a light emitting diode (LED) or a semiconductor laser (LD) has been used as a light source for excitation, which does not use mercury and consumes less power, from the viewpoint of environmental problems and power saving. In addition, a method has been developed in which light is emitted from an LED or LD to excite a phosphor to emit light, and 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 light by absorbing a blue visible light emitted from an LED chip and a part of the blue light emitted from the LED chip. There is disclosed a light emitting diode which emits white light as a whole by additive mixing with yellow light emitted from a light emitting device.
[0004]
However, in the conventional light source of the type in which an excitation light source such as an LED and a phosphor are combined and disclosed in Japanese Patent No. 2,927,279, the emission wavelength of the excitation light source such as an LED is limited. Because the types of phosphors that can emit light by the excitation light source used are extremely limited, the emission color finally obtained is limited to white light or multicolored colors cannot be produced. was there. Also, with respect to white, a preferable color was not reproduced for the color under illumination, and color rendering was also a problem.
[0005]
In recent years, in order to solve such a problem, U.S. Pat. S. P. 6294800, U.S.A. S. P. No. 6,255,670 and the like, a method of mixing three components, green, blue and red, is introduced. The phosphor used here is 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 a red light-emitting phosphor. , Y ₂ O ₂ S: Eu or Y ₂ O ₃ : Eu, Bi, and the like.
[0006]
The method of mixing the three components has considerably improved the reproduction of the projected color under the illumination of the light source as compared with the two-color component method. However, when the color tone of each phosphor used as a component itself is not preferable, the color projected under the illumination of the light source has poor reproducibility and the desired color cannot be obtained, and in the case of the conventional technique as described above, In particular, since the color tone of the red phosphor deviates from the desired red color, a satisfactory white light source cannot be obtained.
[0007]
As a measure for resolving such a problem, (La, Eu, Sm) ₂ O ₂ S is converted to red fluorescent light in an LED light-emitting element in which an LED chip emitting near-ultraviolet light of about 370 nm and a phosphor are combined in JP-A-11-246857. It has been reported to be used as a body and has shown efficacy. The (La, Eu, Sm) ₂ O ₂ S red phosphor has efficient absorption of near ultraviolet light at around 370 nm, has a relatively good emission color with a peak wavelength of around 625 nm, and also has a comparative brightness. The target is good.
However, in light of market demands, the luminance is still insufficient and further higher luminance is desired. On the other hand, at present, phosphors and light emitting elements that emit white light or multicolor light are still insufficient in terms of luminance and color rendering.
[0008]
[Problems to be solved by the invention]
LED light-emitting elements are expected to be used as lighting sources instead of fluorescent lamps, as light sources for liquid crystal and mobile phone backlights, and improvements in color reproducibility, color rendering, luminance and luminous efficiency are always desired.
(La, Eu) ₂ O ₂ S and the (La, Eu, Sm) ₂ O ₂ S phosphor for LED disclosed in JP-A-11-246857 are typical red phosphors commonly used in displays and the like. Is higher than that of (Y, Eu) ₂ O ₂ S under excitation of near-ultraviolet light near 382 nm, and is considered to be a relatively good phosphor. Improvement in brightness is desired.
[0009]
On the other hand, for the white phosphor and the multicolor phosphor, the (La, Eu) ₂ O ₂ S or (La, Eu, Sm) ₂ O ₂ S phosphor is used as a red component to emit blue light, green light, and yellow light. When the white phosphor is obtained by mixing with the body, the body color of the red phosphor is yellow, and the powder reflectance is low in the blue and green wavelength regions as shown in FIG. Light such as 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 has a higher luminance than a conventional phosphor that emits red light by excitation of near-ultraviolet light of 360 to 410 nm, a powder reflectivity, and a red phosphor having a small body color. An object of the present invention is to provide a mixed phosphor containing a phosphor and containing at least one different phosphor, which emits white light and multicolor light when excited by near ultraviolet light.
Further, red light emission and white light emission composed of an LED chip (light-emitting diode chip) that emits near-ultraviolet light having a wavelength in the range of 360 to 410 nm and a phosphor that emits light by receiving light emitted from the LED chip. It is another object of the present invention to provide a multicolor LED light emitting element.
[0011]
[Means for Solving the Problems]
The present inventors have produced red phosphors having various compositions to achieve the above object, and studied the effects of the types of the composition components and the production method on the emission luminance and the body color of the phosphors. A high-brightness white-light-emitting phosphor obtained by mixing a phosphor and a blue phosphor and a green phosphor having other light emission was examined.
As a result, by adding a predetermined amount of Si, Ge, Ga, Ti, and Ta to the europium-activated lanthanum oxysulfide phosphor, the luminous efficiency is high upon irradiation with near-ultraviolet light near 382 nm, and the body color is white and blue. It was possible to obtain a phosphor having a high powder reflectance in the green visible region.
[0012]
Further, as a result of studying a high-luminance white light-emitting phosphor obtained by mixing a red phosphor, a blue phosphor, and a green phosphor of the present invention, a europium-activated acid containing Si, Ge, Ga, Ti, and Ta of the present invention was obtained. Lanthanum sulfide red light emitting phosphor, 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 fluorescent light. The present inventor has found that a white light-emitting phosphor obtained by combining and mixing bodies has high luminance.
[0013]
The present invention has the following configuration.
(1) In the phosphor represented by the general formula (La _1-x , Eux) ₂ O ₂ S (where 0.02 ≦ x ≦ 0.50), at least one of Si, Ge, Ga, Ti, and Ta is used. A red-light emitting phosphor for exciting ultraviolet light, characterized by containing an element.
(2) The red-light-emitting phosphor for ultraviolet excitation according to (1), wherein the content of the Si, Ge, Ga, Ti, and Ta is from 10 ppm to 2000 ppm based on the weight of the phosphor.
(3) The red light emitting phosphor for ultraviolet excitation according to (1), wherein the wavelength of the ultraviolet light is near ultraviolet of 360 to 410 nm.
(4) The red light emission for ultraviolet excitation according to (1), wherein the red light-emitting phosphor has a powder reflectance of 84%, 94%, or 97% or more at wavelengths of 450 nm, 545 nm, and 624 nm. Phosphor.
[0014]
(5) A white light-emitting and multicolor light-emitting phosphor comprising a mixture of the red light-emitting phosphor, a green light-emitting phosphor and / or a blue light-emitting component phosphor.
(6) As the green light emitting phosphor, ZnS: Cu, Al, ZnS: Au, Al, ZnS: Au, Cu, Al, BaMgAl ₁₀ O ₁₇ : Eu, Mn, and BaMgAl ₁₀ O ₁₇ : Mn It contains one phosphor, and as a blue light-emitting 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 and multicolor-emitting phosphor according to the above (5), which contains at least one phosphor of Eu and ZnS: Ag, Al.
(7) The 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 the phosphor that emits light by receiving light emitted from the LED chip (1) to (6). A light-emitting device comprising the phosphor according to item 1.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in more detail.
The phosphor of the present invention is manufactured as follows. Formula _{_{_{(La 1-x, Eu x}}} ) 2 O 2 S ( where, 0.02 ≦ x ≦ 0.50) has the configuration of a matrix composition, Si as an impurity additive element, Ge, Ga, Ti and Ta 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 weight of the base material.
As a method of adding impurities, a method of directly adding a predetermined amount of impurities in solid or powder form to La ₂ O ₃ or Eu ₂ O ₃ weighed in a predetermined amount and mixing them, an aqueous solution containing impurities once or an alcohol There is a method of preparing a liquid, adding a predetermined amount to the rare earth material, mixing a paste, drying, and sieving to obtain a rare earth main material containing a predetermined amount of a target impurity. The following can be used as impurities. In the case of Si, a silicon compound such as a silicate such as sodium silicate or potassium silicate, an organic silicate such as ethyl silicate, or a compound containing silicon such as silicon. In the case of Ge, a compound containing germanium such as germanium oxide (GeO ₂ ), germanium sulfide (GeS ₂ ), and a germanate such as Na ₂ GeO ₄ or Na ₂ Ge ₂ O ₅ or germanium. In the case of Ga, a compound containing gallium such as gallium oxide (Ga ₂ O ₃ ), gallium sulfide (Ga ₂ S), or gallium. In the case of Ti, a compound containing titanium such as titanium oxide (TiO ₂ ), alkoxide titanate and titanium. In the case of Ta, a compound containing tantalum, such as a tantalum salt such as tantalum oxide (Ta ₂ O ₅ ), Na ₃ TaO ₄ , and K ₃ TaO _4, and tantalum.
[0016]
Next, with respect to the main raw material containing the target impurity thus obtained in a predetermined amount, the amount of S as the auxiliary raw material is more than the theoretical value in consideration of the loss in the firing step, etc. In addition, Na ₂ CO ₃ , LiPO _4, etc. 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 once, washed with water to dissolve and remove unnecessary substances such as alkali polysulfide generated during firing, washed with a dilute mineral acid aqueous solution, and then washed with water, and then washed. After performing a dispersion treatment by a ball mill or the like as necessary, a classification treatment such as removal of unnecessary large particles is performed by a wet classification method such as a water sieve, and then the phosphor of the present invention is obtained by drying and sieving. Can be Further, if necessary, an inorganic or organic surface treatment may be applied to improve durability.
[0017]
With respect to the addition amount of impurities, which is a main element of the present invention, an improvement effect on luminance is exhibited at 10 to 2000 ppm, a remarkable effect is not exhibited at 10 ppm or less, and no effect is exhibited at 2000 ppm or more, or conversely, the luminance is increased. Causes a decline. In addition, the relationship between the added amount and the amount actually incorporated and contained in the phosphor crystal is shown in Example 1 (Si added), Example 2 (Ge added), Example 3 (Ga added), and Example 4 in Table 1. As shown in the addition amounts and contents of (Ti addition) and Example 5 (Ta addition), the degree of incorporation differs depending on the element, so it is necessary to add a larger amount in advance than the target set amount if necessary. There is.
[0018]
FIG. 1 shows the powder reflection spectrum of the Si-doped phosphor of the present invention (denoted as La ₂ O ₂ S: Eu + Si), and shows the untreated untreated phosphor (denoted as La ₂ O ₂ S: Eu). On the other hand, it has a feature that the powder reflectance at wavelengths of 450 nm, 545 nm and 624 nm, which are the entire visible region, is increased. Although it is influenced by the type of the element to be added and the amount of the addition, at each wavelength point, values of 84%, 94%, 97% or more are shown as shown in Table 1, and the reflectance is high and the body color is whiter. It means that it has become.
When the phosphor of the present invention (La, Eu) ₂ O ₂ S having such a high reflectivity is used as a red component and mixed with phosphors of blue light emission, green light emission and yellow light emission to obtain a white light emitting phosphor. The red phosphor has a yellow body color, has a low powder reflectance in the blue and green wavelength regions (450 nm, 545 nm), and partially emits light such as blue light, green light or yellow light to the red phosphor crystal. The conventional problem of absorption and loss can be reduced and improved. Therefore, the brightness of the white light-emitting phosphor or the multi-color light-emitting fluorescent light is increased and improved as a whole. Further, as the blue light-emitting phosphor which is a component of the white light-emitting phosphor or the multicolor light-emitting phosphor used here, 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 and Al, and the green light emitting phosphor is ZnS: Cu, Al, ZnS: Au, Al, ZnS: Au, Cu , Al, BaMgAl ₁₀ O ₁₇ : Eu, Mn, and BaMgAl ₁₀ O ₁₇ : Mn.
[0019]
Further, in order to more effectively use the red light-emitting phosphor of the present invention with improved powder reflectivity, it is desirable that the reflectance of the combined phosphor is similarly high, and the green light-emitting phosphor has a body color of yellow. BaMgAl ₁₀ O ₁₇ : Eu, Mn, which is green and has a relatively high reflectance with a whiter body color than ZnS: Cu, Al, ZnS: Au, Al, ZnS: Au, Cu, Al with a relatively low reflectance. .
On the other hand, the light-emitting device of the present invention using the above-described phosphor of the present invention receives an LED chip (light-emitting diode chip) emitting near-ultraviolet light having a wavelength having a peak in the range of 360 to 410 nm and light emitted from the LED chip. It is a red, white, and multicolor LED light-emitting element composed of a phosphor that emits light, and has a schematic structure as shown in FIG. 2 and is specifically manufactured as follows. First, a light-emitting element that emits light in the wavelength range of near-ultraviolet light to short-wavelength visible light is used as emission light for excitation, which is one of the components. The light emitting element as the excitation light source is relatively easily available, has high luminous efficiency, and can emit a phosphor with higher luminance. A light emitting diode (LED) or a semiconductor laser (LD) made of a nitride-based compound semiconductor such as (Ga _1-x In _x ) N (where x is 0 ≦ x ≦ 0.5), preferably 360 to 480 nm. Can be used.
[0020]
The light emitting element of the present invention has such a positional relationship that the phosphor can receive and absorb light from the excitation light source, and is arranged so as to face the excitation light source.
As shown in FIG. 2, a semiconductor light emitting element chip 3 is electrically adhered to the stem 1 while the other electrode of the semiconductor light emitting element chip 3 and one of the leads 2 are connected to a lead wire 5. Are electrically connected to each other.
A dome-shaped transparent resin-coated lid 5 is fixed to the stem 1. Then, on the inner surface of the transparent resin-coated lid 5, a binder in which a phosphor is dispersed is applied to form a phosphor layer 6. The transparent resin-coated lid 5 is made of a material that is transparent to light, such as a resin such as epoxy resin, acrylic resin, silicon resin, or polystyrene, or glass, and serves as a cap for hermetically sealing the semiconductor light emitting element chip 3. Also 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 applied to the surface of the phosphor layer 6 formed on the inner wall surface of the transparent resin covering lid 5 via the space layer, and the fluorescent light is emitted. The body layer 6 absorbs the light emitted from the semiconductor light-emitting element chip 3 and is excited to emit light having a light emission wavelength different from that of the semiconductor light-emitting element chip 3 and specific to the phosphor shown as a component of the present invention.
[0021]
In the phosphor layer which is one component of the light emitting device of the present invention having such a configuration, a white light emitting phosphor or a 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 having no problem in color reproducibility and color rendering can be obtained. By realizing such a light emitting element, not only a white light source but also a multicolor light source can be used for lighting, for a backlight of a liquid crystal display, a portable information terminal, etc., for an indicator light source and a display. It is possible to provide something that has no problem with sex.
[0022]
【Example】
Next, the present invention will be described with reference to examples, but the present invention is not limited to the embodiments exemplified 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, and 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 a paste liquid. After drying, pulverizing and mixing, 20 g of Na ₂ CO ₃ and 15 g of S were added and mixed to obtain a mixture.
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. Then, dilute hydrochloric acid was added to the phosphor slurry solution, washed with a slurry having a pH of 1.5 or less, washed with water, and thereafter subjected to ordinary dispersion treatment, drying, and sieving. A phosphor with an amount of 220 ppm was obtained.
[0023]
By this way the phosphor obtained by the X-ray diffraction analysis and ICP analysis, it was confirmed that the phosphor of the Si containing _{_{220ppm (La 1-x, Eu}} x) 2 O 2 S becomes present invention. The luminance was measured by irradiating near-ultraviolet light of 382 nm obtained by dispersing the Xe lamp light, and the light emission from the phosphor was measured by a luminance meter. It was confirmed that it was improved by 14%. Further, the powder reflectance as a feature of the phosphor of the present invention was measured using SHIMAZU UV-3100PC. As shown in Table 1, the powder reflectance at each of the wavelengths 450 nm, 545 nm and 624 nm was as follows. 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]

However, LOS: Eu is _{_{_{(La 1-x, Eu x}}} ) the _{2 O} 2 S LOS: shows the Eu + Si contains impurities _{_{Si (La 1-x, Eu}} x) 2 O 2 S.
[0025]
[Examples 2 to 5]
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 in which Ge ₂ O ₃ was dissolved in nitric acid to adjust the Ge concentration to 5 mg / ml was used. Example 1 was repeated except that 4 ml was added, 21.3 ml of a solution in which Ga was dissolved 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. In the same manner as in Example 1, the phosphor of the present invention of Example 2, containing 20 ppm of Ge, Example 3 containing 20 ppm of Ga, Example 4 containing 250 ppm of Ti, and Example 5 containing 510 ppm of Ti were obtained. The evaluation was performed in the same manner as in Example 1. It was confirmed that the addition of Ge, Ga, Ti, and Ta had the same effect as that of Si, although there was a slight level difference as shown in Table 1. We were able to.
[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 obtain a mixture. Filling and the subsequent firing step of formulations in the same manner as in Example _{1, (La 1-x,} Eu x) of the prior specification does not include a specific impurity 2 _O 3 _S to prepare a phosphor luminescent material of Comparative Example 1 Got.
[0027]
[Comparative Example 2]
An existing pigment-free Y ₂ O ₂ S: Eu phosphor prepared to compare the level of the phosphor of the example with a typical red phosphor generally used in a color television or the like is used. It was confirmed that the luminance of the Y ₂ O ₂ S: Eu phosphor was about half the luminance of the phosphor of the present invention.
[0028]
[Table 2]

However, BAM: Eu represents BaMgAl ₁₀ O ₁₇ : Eu, BAM: Mn, Eu represents BaMgAl ₁₀ O ₁₇ : Eu, and CCB: Eu represents Ca ₂ B ₅ O ₉ Cl: Eu.
[0029]
[Examples 6 to 10]
Containing a predetermined element described in Example _{_{1~5 (La 1-x, Eu}} x) for each of the 2 _{O 2} S red phosphor, ZnS: Cu, Al green-emitting phosphor and _BaMgAl 10 _O 17: Eu Blue light-emitting phosphors were mixed in appropriate amounts so that the chromaticity values became x = 0.31, y = 0.33, and white-light-emitting phosphors of Examples 6 to 10 were obtained.
The evaluation was performed in the same manner as in Example 1. However, as with the phosphors of Examples 1 to 5, the improvement effect was reflected in the white light-emitting phosphor, and the luminance was the same as that of the conventional phosphor as shown in Table 2. It was confirmed that the phosphor of Comparative Example 3 was improved by 2 to 8%.
[0030]
[Example 11]
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 The phosphor was mixed in an appropriate amount so that the chromaticity values became x = 0.31 and y = 0.33 to obtain a white light-emitting phosphor of Example 11. As shown in Table 2, it was confirmed that, even when the phosphors in the combination were changed, the effect of improving the luminance was obtained as in Example 6.
[0031]
[Example 12]
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 bodies were mixed in an appropriate amount so that the chromaticity value was x = 0.31 and y = 0.33, to obtain a white light-emitting phosphor of Example 12. As described above, it was confirmed that the same effect was obtained as shown in Table 2 even when the combination of phosphors was changed.
[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 .31, y = 0.33, and the mixture was mixed in an appropriate amount to prepare a white light-emitting phosphor of Comparative Example 3.
[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 .31, y = 0.33 to obtain a white light-emitting phosphor of Comparative Example 4.
[0034]
[Example 13]
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 Co., Ltd., NT8014) and 1 g of an acid anhydride-based curing agent to prepare a phosphor coating solution. Separately from this, the wafer part of the light emitting diode element that emits near-ultraviolet light with a main peak wavelength of 400 nm as a light source for excitation is held horizontally, and the phosphor coating liquid prepared above is dropped from a thin nozzle onto the light emitting part. After forming a dome-shaped phosphor coating film, and then half-turning the phosphor coating surface in reverse to make the phosphor coating surface horizontal and using a surface tension, the phosphor is naturally dried at room temperature in the dome-shaped coating film. After further drying at about 150 ° C. for 3 hours, a light emitting device having the phosphor of the present invention applied on the surface thereof was produced.
When a current is applied to the electrodes of the light-emitting element thus obtained, the light-emitting element that emits red light and has a light emission chromaticity point represented by the CIE color system of x = 0.65 and y = 0.34. was gotten. The luminance of the obtained light emitting device was 15% brighter than that of Comparative Example 5 described below.
[0035]
[Example 14]
Containing Si as described in Example _{_{6 (La 1-x, Eu}} x) and 2 _{O 2} S red phosphor, ZnS: Cu, Al green-emitting phosphor and _BaMgAl 10 _O 17: the Eu blue phosphor A phosphor coating solution was prepared by mixing 10 g of the white light-emitting phosphor composed of the mixture, 1 g of an epoxy resin (NT8014, manufactured by Nitto Denko Corporation), and 1 g of an acid anhydride-based curing agent. Thereafter, in the same manner as in Example 13, a light-emitting element emitting white light was manufactured.
When a current is applied to the electrodes of the light-emitting element obtained in this way, the light-emitting element that emits white light has an emission chromaticity point represented by the CIE color system of x = 0.34 and y = 0.38. was gotten. The luminance of the obtained light emitting device was 10% brighter than that of Comparative Example 6 described 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 Thus, a phosphor coating solution was prepared. Thereafter, in the same manner as in Example 13, a red light emitting element of Comparative Example 5 was produced.
[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 13, a white light emitting element of Comparative Example 6 was produced.
[0038]
In the above embodiment, the composition of the red light-emitting phosphor is described as (La, Eu) ₂ O ₂ S, but the specification of the present invention for improving the luminance by adding a specific impurity is based on the above composition. For example, a phosphor (La, Eu, Sm) ₂ O ₂ S in which Eu is partially substituted with Sm, and trace amounts of rare earth elements Tb, Pr, etc., aiming at a sensitizing effect for improving luminance, are used. The same applies to the added phosphor.
[0039]
【The invention's effect】
According to the present invention, a high-luminance red phosphor and a white-light-emitting phosphor or a multicolor-light-emitting phosphor can be obtained by adopting the above-described structure. You can get something not. By realizing such a light emitting element, not only a white light source but also a multicolor light source for lighting, backlight for liquid crystal displays, portable information terminals, etc., not only for white light sources, but also for high brightness, color reproducibility and color rendering Can be provided with no problem.
[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 9 is a graph illustrating a comparison.
FIG. 2 is a schematic sectional view showing one embodiment of the 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-coated lid 6 Phosphor layer

Claims

In the general formula _{_{_{(La 1-x, Eu x}}} ) phosphor represented by 2 _{O 2} S (where, 0.02 ≦ x ≦ 0.50), Si, Ge, Ga, Ti, at least one element of Ta A red light-emitting phosphor for exciting ultraviolet light, characterized in that it contains.

The red light emitting phosphor for ultraviolet excitation according to claim 1, wherein the content of the Si, Ge, Ga, Ti, and Ta is from 10 ppm to 2000 ppm based on the weight of the phosphor.

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.

The red light emitting phosphor for ultraviolet excitation according to claim 1, wherein the red light emitting phosphor has a powder reflectance of 84%, 94%, 97% or more at wavelengths of 450 nm, 545 nm, and 624 nm.

A white light-emitting and multicolor light-emitting phosphor comprising a mixture of the red light-emitting phosphor, a green light-emitting phosphor and / or a blue light-emitting component phosphor.

Examples of the green light-emitting phosphor include at least one of ZnS: Cu, Al, ZnS: Au, Al, ZnS: Au, Cu, Al, BaMgAl ₁₀ O ₁₇ : Eu, Mn, and BaMgAl ₁₀ O ₁₇ : Mn. And a blue light-emitting phosphor containing 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 6. The white light-emitting and multicolor light-emitting phosphor according to claim 5, wherein the phosphor contains at least one of Ag and Al.

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 by receiving light emitted from the LED chip includes the phosphor according to claim 1. A light-emitting element comprising: