JP2004253747A - Light emitting device and lighting device using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light emitting device combining a first luminous body (excitation source) generating light of 350 to 415 nm with a second luminous body (phosphor) with high emission intensity. <P>SOLUTION: This light emitting device fulfills the following conditions (A) and/or (B) in a device combining a first luminous body (excitation source) generating the light of 350 to 415 nm with a second luminous body (phosphor). (A) The quantum absorption efficiency α<SB>q</SB>of the phosphor is 0.8 or more. (B) The product α<SB>q</SB>×η<SB>i</SB>of the quantum absorption efficiency α<SB>q</SB>of the phosphor and the internal quantum efficiency η<SB>i</SB>is 0.55 or more. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

ここで、積分区間は実質的にＩ_ｒｅｆ（λ）が有意な値を持つ区間のみで行ったもので良い。図１６にＩ_ｒｅｆ（λ）の一例を示すが、この場合は、３８０ｎｍから４２０ｎｍの範囲で取れば十分である。前者のＮ_ａｂｓは（式２）で求められる量に比例する。
【００１３】
【数２】

ここで、Ｉ（λ）は，α_ｑを求めようとしている対象サンプルを取り付けたときの、反射スペクトルである。（式２）の積分範囲は（式１）で定めた積分範囲と同じにする。このように積分範囲を限定することで、（式２）の第二項は，対象サンプルが励起光を反射することによって生じたフォトン数に対応したもの、すなわち、対象サンプルから生ずる全フォトンのうち励起光によるフォトルミネッセンスで生じたフォトンを除いたものに対応したものになる。実際のスペクトル測定値は、一般にはλに関するある有限のバンド幅で区切ったデジタルデータとして得られるため、（式１）および（式２）の積分は、そのバンド幅に基づいた和分によって求まる。以上より、α_ｑ＝Ｎ_ａｂｓ／Ｎ＝（式２）／（式１）と求まる。
【００１４】
次に、内部量子効率η_ｉを求める方法を説明する。η_ｉは、フォトルミネッセンスによって生じたフォトンの数Ｎ_ＰＬをサンプルが吸収したフォトンの数Ｎ_ａｂｓで割った値である。
ここで、Ｎ_ＰＬは、（式３）で求められる量に比例する。
【００１５】
【数３】
∫λ・Ｉ（λ）ｄλ ―――（式３）
この時、積分区間は、サンプルからフォトルミネッセンスによって生じたフォトンが持つ波長域に限定する。サンプルから反射されたフォトンの寄与をＩ（λ）から除くためである。具体的に（式３）の積分の下限は、（式１）の積分の上端を取り、フォトルミネッセンス由来のスペクトルを含むのに好適な範囲を上端とする。図１７がＩ（λ）の例であるが、この場合、４２０ｎｍから５２０ｎｍを（式３）における積分範囲に取れば良い。以上により、η_ｉ＝（式３）／（式２）と求まる。なお、デジタルデータとなったスペクトルから積分を行うことに関しては、α_ｑを求めた場合と同様である。
【００１６】
一般に量子吸収効率α_ｑを高めること自体は、サンプル内に取り込まれる励起光源のフォトン数を上昇させることにつながるので発光輝度が高まる期待はある。しかし実際には、例えば発光中心であるＥｕ等の濃度を上昇させることなどでα_ｑの上昇を試みると、フォトンが最終的なフォトルミネッセンスの過程に到達する前に、そのエネルギーをサンプル結晶内のフォノンの励起に変えてしまう確率が高まり、十分な発光強度を得ることができなかった。しかしながら、励起光源の波長を特に３５０−４１５ｎｍに選び、かつ発光装置の第２の発光体として量子吸収効率α_ｑの高い蛍光体を用いると、前記非フォトルミネッセンス過程が抑制され、高発光強度の発光装置が実現されることが見出された。またここで、α_ｑが高いことに加え、α_ｑ・η_ｉの値が高い蛍光体を用いた第２の発光体と、３５０−４１５ｎｍの波長を持つ第１の発光体を組み合わせることで、さらに好ましい特性をもった発光装置が得られることも見出された。
【００１７】
上記（Ａ）及び／または、（Ｂ）の条件を満たす限り、蛍光体を構成する材料は、特に限定されないが、結晶相を有することが好ましく、下記一般式［１］の化学組成を有する結晶相を有するもの（以下、一般式［１］の結晶相と略すことがある）から選ぶのがより好ましい。なお、該蛍光体には、性能を損なわない範囲で他の成分、例えば、光散乱物質等を含んでいてもよいため、蛍光体中に含まれる前記結晶相の割合は、１０ｗｔ％以上、好ましくは５０ｗｔ％以上、より好ましくは８０ｗｔ％以上である。
【００１８】
【化４】
Ｅｕ_ａＳｒ_ｂＭ_{５−ａ−ｂ}（ＰＯ_４）_ｃＸ_ｄ・・・・・・［１］
但し、ＭはＥｕ及びＳｒ以外の金属元素を表す。また、ＸはＰＯ_４以外の一価のアニオン基を表す。ｃ及びｄは、２．７≦ｃ≦３．３、０．９≦ｄ≦１．１を満足する数である。ａはａ＞０、ｂはｂ≧０、ａ＋ｂ≦５となる数であるが、ａ≧０．１又はｂ≧３という条件を満足する。
【００１９】
第２の発光体が、上記一般式［１］の蛍光体を含有する本発明の発光装置自体新規で、従来の発光装置より優れた発光強度を有する。但し、上記（Ａ）及び／または（Ｂ）の条件を満たす蛍光体を含有する第２の発光体は、これに含有される蛍光体として、上記一般式［１］の蛍光体の中でも好ましいものを選択することで得ることが出来る傾向にある。以下、一般式［１］の蛍光体について説明する。式［１］中の元素ＭはＥｕとＳｒ以外の金属元素を表す。元素Ｍについては、発光強度等の面から、Ｂａ、Ｍｇ、Ｃａ、Ｚｎ、およびＭｎの合計の元素Ｍに占める割合を７０ｍｏｌ％以上とすることが好ましく、中でもＢａ、Ｍｇ、およびＣａの合計の元素Ｍに占める割合を７０ｍｏｌ％以上とすることが好ましく、Ｂａ、Ｍｇ、およびＣａの合計の元素Ｍに占める割合を９０ｍｏｌ％以上とすることが更に好ましく、元素ＭのすべてをＢａ、Ｍｇ、Ｃａ、Ｚｎ、およびＭｎからなる群から選ばれる少なくとも一種の元素とするのがさらに好ましく、元素ＭのすべてをＢａ、Ｍｇ、およびＣａからなる群から選ばれる少なくとも一種の元素とするのが最も好ましい。
【００２０】
元素Ｍ中の金属元素として上記以外の金属元素を結晶中に含有させる場合、その金属元素に特に制約はないが、Ｓｒやこれら５種金属元素と同じ価数、即ち２価の金属元素を含有させると、結晶構造を保持しやすいので、望ましい。２価の金属元素及び発光中心Ｅｕ^２＋の焼成時の固体内拡散による複合酸化物の結晶化を助ける意味で、１価、３価、４価、５価、又は６価等の金属元素を少量導入しても良い。一つの例を挙げると、Ｓｒ_５（ＰＯ_４）_３Ｃｌ：Ｅｕ蛍光体中のＳｒ^２＋の一部を等モルのＬｉ^＋とＧａ^３＋で電荷補償効果を保持しながら置換することができる。増感剤となりうる金属元素を少量置換してもよい。
【００２１】
なお、金属元素Ｍを含有させない、即ちａ＋ｂの値を５とすることもできる。前記一般式［１］中のＸはＰＯ_４以外の一価の基である。Ｘについては、発光強度等の面から、Ｘのうちの５０ｍｏｌ％以上をハロゲン原子とすることが好ましく、７０ｍｏｌ％以上、特に９０ｍｏｌ％以上とすることがより好ましい。ハロゲン原子としてはＣｌ、Ｆ、Ｂｒ等を挙げることができるが、好ましくはＣｌである。Ｘとして、その５０ｍｏｌ％以上をハロゲン原子とした場合、残余のアニオン基として水酸基等を含んでいてもよい。最も好ましい態様においては、アニオン基Ｘのうちの５０ｍｏｌ％以上、特に７０ｍｏｌ％以上、さらには９０ｍｏｌ％以上をＣｌとする。この場合、残余の基としては、他のハロゲン原子やＯＨ基を挙げることができる。
【００２２】
前記一般式［１］中のＳｒのモル比ｂについては、ｂ≧０、好ましくはｂ＞０であり、具体的には０≦ｂ＜５、好ましくは０＜ｂ＜５とし、通常は０．０１以上、好ましくは０．１以上、さらに好ましくは０．２以上とするが、発光強度等の面から、３以上、特に４以上とするのが最も好ましい。一般にＳｒ，Ｂａ，Ｃａ）_５（ＰＯ_４）_３Ｃｌ：Ｅｕ^２＋を基本的な組成とする結晶相はＳｒのモル比として広範な値をとりうるが、本発明においては、上記のようなｂ＜５を上限とする比較的大きめの数値を採用することによって顕著に高い発光強度を得ることができる。一方、Ｓｒのモル比が小さい場合、即ちｂの値を小さめの数値、特に０とすることにより、原料コストを低減させることが出来るため好ましく、特にＣａを５０ｍｏｌ％以上とすることが好ましく、この場合においても比較的高い発光強度を得ることができる。
【００２３】
前記一般式［１］中のＥｕのモル比ａについては、０＜ａ＜５とし、通常は０．０００１以上、好ましくは０．００１以上、さらに好ましくは０．００５以上とするが、発光強度等の面から、通常ａ≧０．１、好ましくはａ≧０．２、より好ましくはａ＞０．２、さらに好ましくはａ≧０．３とし、特に、ａ≧０．４、さらにはａ≧０．４５とするのが最も好ましい。発光中心イオンＥｕ^２＋のモル比ａが小さすぎると、発光強度が小さくなる傾向があるが、あまりにａの値が大きいと、濃度消光と呼ばれる現象により、やはり発光強度が減少する傾向があるので通常はａ≦４．８、好ましくはａ≦３、より好ましくはａ≦２．５、特に好ましくはａ≦２、最も好ましくはａ≦１．５とする。前記一般式［１］中、ａ＞０．２、更にはａ≧０．３のものを用いると、条件（Ａ）及び／または（Ｂ）を満たす蛍光体を有する第２の発光体よりなる発光装置を得る上で、特に好ましい。
【００２４】
本発明においては、ａ≧０．１及びｂ≧３のどちらか一方を満足すれば、十分な発光強度を得ることができる。従って、ａ及びｂのどちらか一方が上記式を満足すれば、必ずしも他方は上記式を満足する必要はないので、この点についてａ及びｂの値の好ましい組み合わせを列挙すれば、（１）ａ≧０．１且つｂ≧０．０１、（２）ａ≧０．１且つｂ≧０．１、（３）ａ≧０．１且つｂ≧０．２、（４）ａ≧０．２且つｂ≧０．０１、（５）ａ≧０．２且つｂ≧０．１、（６）０．０００１≦ａ、且つｂ≧３、（７）０．００１≦ａ、且つｂ≧３、（８）０．００５≦ａ、且つｂ≧３、（９）０．０００１≦ａ、且つｂ≧４、（１０）０．００１≦ａ、且つｂ≧４、（１１）０．００５≦ａ、且つｂ≧４等を挙げることができる。ただし、発光強度をさらに大きくできる点で、本発明においては、ａ≧０．１及びｂ≧３の両者を満足させるのが特に好ましく、この点についてａ及びｂの値の好ましい組み合わせを列挙すれば、（１）ａ≧０．１且つｂ≧３、（２）ａ≧０．１且つｂ≧４、（３）ａ≧０．２且つｂ≧３、（４）ａ≧０．２且つｂ≧４等を挙げることができる。特に、ａ＞０．２及びｂ≧３の両者を満足させることにより、より発光強度を大きくすることができ、この点についてａ及びｂの値のさらに好ましい組み合わせを列挙すれば、（１）ａ＞０．２且つｂ≧３、（２）ａ＞０．２且つｂ≧４、（３）ａ≧０．３且つｂ≧３、（４）ａ≧０．３且つｂ≧４、（５）ａ≧０．４且つｂ≧３、（６）ａ≧０．４且つｂ≧４、（７）ａ≧０．４５且つｂ≧３、（８）ａ≧０．４５且つｂ≧４等を挙げることができる。
【００２５】
前記一般式［１］において、ｃおよびｄは、２．７≦ｃ≦３．３、０．９≦ｄ≦１．１を満足するが、ｃについては、好ましくは２．８≦ｃ≦３．２、さらに好ましくは２．９≦ｃ≦３．１であり、ｄについては、好ましくは０．９３ｄ≦１．０７、さらに好ましくは０．９５≦ｄ≦１．０５とする。
前記一般式［１］の基本結晶Ｅｕ_ａＳｒ_ｂＭ_{５−ａ−ｂ}（ＰＯ_４）_ｃＸ_ｄにおいては、格子欠損が多少生じていても本目的の蛍光性能に大きな影響がないので、上記ａ，ｂ，ｃ，ｄの不等式の範囲で使用することができる。
【００２６】
一般にＡ_５（ＰＯ_４）_３Ｃｌ（Ａはアルカリ土類金属）の結晶は、六方晶構造をとり、その空間群はＰ６_３／ｍである。
本発明における結晶構造は、通常上記に示したＡ_５（ＰＯ_４）_３Ｃｌ構造である。図１に代表的なＳｒ_５（ＰＯ_４）_３ＣｌのＸ線回折パターンを示す（粉末Ｘ線回折データベースより）。Ｓｒ_５（ＰＯ_４）_３ＣｌのＳｒサイトには、Ｂａ、Ｍｇ、Ｃａ、Ｚｎ、Ｍｎ等の２価金属を広い組成範囲で置換させることができる。また、少量であれば、ＮａやＬａ等の価数の異なる金属も置換させうる。そのＣｌサイトには、Ｆ、Ｂｒ、ＯＨ等のアニオン種を置換させることができ、その構造が保たれる。本発明においては、これら置換体のうち、通常カチオン種としてＳｒを用いた置換体を母体とし、更にカチオンサイトにＥｕ^２＋を付活剤として置換させた結晶相に対応する。
【００２７】
本発明で使用する蛍光体は、第１の発光体からの３５０−４１５ｎｍの光によって励起され、可視光を発生する。上記蛍光体は、３５０−４１５ｎｍの光の励起によって非常に強い発光強度の可視光を発生する。
本発明で使用する蛍光体は、前記一般式［１］に示されるようなＭ源、Ｘ源、ＰＯ_４源の化合物、Ｓｒ源の化合物、及び、発光中心イオン（Ｅｕ）の元素源化合物を、ハンマーミル、ロールミル、ボールミル、ジェットミル等の乾式粉砕機を用いて粉砕した後、リボンブレンダー、Ｖ型ブレンダー、ヘンシェルミキサー等の混合機により混合するか、或いは、混合した後、乾式粉砕機を用いて粉砕する乾式法、又は、水等の媒体中にこれらの化合物を加え、媒体攪拌式粉砕機等の湿式粉砕機を用いて粉砕及び混合するか、或いは、これらの化合物を乾式粉砕機により粉砕した後、水等の媒体中に加え混合することにより調製されたスラリーを、噴霧乾燥等により乾燥させる湿式法により、調製した粉砕混合物を、加熱処理して焼成することにより製造することができる。
【００２８】
これらの粉砕混合法の中で、特に、発光中心イオンの元素源化合物においては、少量の化合物を全体に均一に混合、分散させる必要があることから液体媒体を用いるのが好ましく、又、他の元素源化合物において全体に均一な混合が得られる面からも、後者湿式法が好ましく、又、加熱処理法としては、アルミナや石英製の坩堝やトレイ等の耐熱容器中で、通常７００〜１５００℃、好ましくは９００〜１３００℃の温度で、大気、酸素、一酸化炭素、二酸化炭素、窒素、水素、アルゴン等の気体の単独或いは混合雰囲気下、１０分〜２４時間、加熱することによりなされる。尚、加熱処理後、必要に応じて、洗浄、乾燥、分級処理等がなされる。
【００２９】
尚、前記加熱雰囲気としては、発光中心イオンの元素が発光に寄与するイオン状態（価数）を得るために必要な雰囲気が選択される。本発明における２価のＥｕ等の場合には、一酸化炭素、窒素、水素、アルゴン等の中性若しくは還元雰囲気下が好ましいが、大気、酸素等の酸化雰囲気下も条件さえ選べば可能である。又、ここで、Ｍ源、Ｘ源、Ｓｒ源、およびＥｕ源の化合物としては、Ｍ、Ｘ、Ｓｒ、およびＥｕの各酸化物、水酸化物、炭酸塩、硝酸塩、硫酸塩、蓚酸塩、カルボン酸塩、ハロゲン化物等が挙げられ、ＰＯ_４源の化合物としては、元素Ｍ、ＮＨ_４等のリン酸水素塩、リン酸塩、メタリン酸塩、ピロリン酸塩、Ｐ_２Ｏ_５、ＰＸ_３、ＰＸ_５、Ｍ_２ＰＯ_４Ｘ、リン酸、メタリン酸、ピロリン酸等が挙げられ、Ｘ源の化合物としては、ＭＸ、ＮＨ_４Ｘ、ＨＸ、Ｍ_２ＰＯ_４Ｘ等が挙げられ、これらの中から、化学組成、反応性、及び、焼成時におけるＮＯ_ｘ 、ＳＯ_ｘ等の非発生性等を考慮して選択される。
【００３０】
Ｓｒに対して好ましいとするＳｒ源化合物を具体的に例示すれば、ＳｒＯ、Ｓｒ（ＯＨ）_２・８Ｈ_２Ｏ 、ＳｒＣＯ_３ 、Ｓｒ（ＮＯ_３ ）_２ 、Ｓｒ（ＯＣＯ）_２ ・Ｈ_２ Ｏ、Ｓｒ（ＯＣＯＣＨ_３ ）_２ ・０．５Ｈ_２ Ｏ、ＳｒＣｌ_２ 等が挙げられる。金属元素群Ｍ中のＢａ、Ｍｇ、Ｃａ、Ｚｎ、またはＭｎの合成原料用化合物を具体的に例示すれば、Ｂａ源化合物としては、ＢａＯ、Ｂａ（ＯＨ）_２・８Ｈ_２Ｏ、ＢａＣＯ_３ 、Ｂａ（ＮＯ_３ ）_２、ＢａＳＯ_４、Ｂａ（ＯＣＯ）_２ ・２Ｈ_２ Ｏ、Ｂａ（ＯＣＯＣＨ_３ ）_２、ＢａＣｌ_２ 等が、又、Ｍｇ源化合物としては、ＭｇＯ、Ｍｇ（ＯＨ）_２ 、ＭｇＣＯ_３ 、Ｍｇ（ＯＨ）_２ ・３ＭｇＣＯ_３ ・３Ｈ_２ Ｏ、Ｍｇ（ＮＯ_３ ）_２ ・６Ｈ_２ Ｏ、Ｍｇ（ＯＣＯ）_２ ・２Ｈ_２ Ｏ、Ｍｇ（ＯＣＯＣＨ_３ ）_２ ・４Ｈ_２ Ｏ、ＭｇＣｌ_２ 等が、又、Ｃａ源化合物としては、ＣａＯ、Ｃａ（ＯＨ）_２ 、ＣａＣＯ_３ 、Ｃａ（ＮＯ_３ ）_２ ・４Ｈ_２ Ｏ、Ｃａ（ＯＣＯ）_２ ・Ｈ_２ Ｏ、Ｃａ（ＯＣＯＣＨ_３ ）_２ ・Ｈ_２ Ｏ、ＣａＣｌ_２ 等が、又、Ｚｎ源化合物としては、ＺｎＯ、Ｚｎ（ＯＨ）_２ 、ＺｎＣＯ_３ 、Ｚｎ（ＮＯ_３ ）_２ ・６Ｈ_２Ｏ、Ｚｎ（ＯＣＯ）_２ 、Ｚｎ（ＯＣＯＣＨ_３）_２ 、ＺｎＣｌ_２ 等が、又、Ｍｎ源化合物としては、ＭｎＯ_２、Ｍｎ_２Ｏ_３、Ｍｎ_３Ｏ_４、ＭｎＯＯＨ、ＭｎＣＯ_３、Ｍｎ（ＮＯ_３）_２、Ｍｎ（ＯＣＯＣＨ_３）_２・２Ｈ_２Ｏ、Ｍｎ（ＯＣＯＣＨ_３）_３・ｎＨ_２Ｏ、ＭｎＣｌ_２・４Ｈ_２Ｏ等がそれぞれ挙げられる。
【００３１】
更に、発光中心イオンの元素として好ましいとする前記Ｅｕについて、その元素源化合物を具体的に例示すれば、Ｅｕ_２ Ｏ_３ 、Ｅｕ（ＯＣＯＣＨ_３）_３ ・４Ｈ_２Ｏ、ＥｕＣｌ_３ ・６Ｈ_２Ｏ、Ｅｕ_２（ＯＣＯ）_３・６Ｈ_２Ｏ等が挙げられる。
本発明において、前記蛍光体に光を照射する第１の発光体は、波長３５０−４１５ｎｍの光を発生する。好ましくは波長３５０−４１５ｎｍの範囲にピーク波長を有する光を発生する発光体を使用する。第１の発光体の具体例としては、発光ダイオード（ＬＥＤ）またはレーザーダイオード（ＬＤ）等を挙げることができる。消費電力が良く少ない点でより好ましくはレーザーダイオードである。その中で、ＧａＮ系化合物半導体を使用した、ＧａＮ系ＬＥＤやＬＤが好ましい。なぜなら、ＧａＮ系ＬＥＤやＬＤは、この領域の光を発するＳｉＣ系ＬＥＤ等に比し、発光出力や外部量子効率が格段に大きく、前記蛍光体と組み合わせることによって、非常に低電力で非常に明るい発光が得られるからである。例えば、２０ｍＡの電流負荷に対し、通常ＧａＮ系はＳｉＣ系の１００倍以上の発光強度を有する。ＧａＮ系ＬＥＤやＬＤにおいては、Ａｌ_ＸＧａ_ＹＮ発光層、ＧａＮ発光層、またはＩｎ_ＸＧａ_ＹＮ発光層を有しているものが好ましい。ＧａＮ系ＬＥＤにおいては、それらの中でＩｎ_ＸＧａ_ＹＮ発光層を有するものが発光強度が非常に強いので、特に好ましく、ＧａＮ系ＬＤにおいては、Ｉｎ_ＸＧａ_ＹＮ層とＧａＮ層の多重量子井戸構造のものが発光強度が非常に強いので、特に好ましい。なお、上記においてＸ＋Ｙの値は通常０．８〜１．２の範囲の値である。ＧａＮ系ＬＥＤにおいて、これら発光層にＺｎやＳｉをドープしたものやドーパント無しのものが発光特性を調節する上で好ましいものである。ＧａＮ系ＬＥＤはこれら発光層、ｐ層、ｎ層、電極、および基板を基本構成要素としたものであり、発光層をｎ型とｐ型のＡｌ_ＸＧａ_ＹＮ層、ＧａＮ層、またはＩｎ_ＸＧａ_ＹＮ層などでサンドイッチにしたヘテロ構造を有しているものが発光効率が高く、好ましく、さらにヘテロ構造を量子井戸構造にしたものが発光効率がさらに高く、より好ましい。
【００３２】
本発明においては、面発光型の発光体、特に面発光型ＧａＮ系レーザーダイオードを第１の発光体として使用することは、発光装置全体の発光効率を高めることになるので、特に好ましい。面発光型の発光体とは、膜の面方向に強い発光を有する発光体であり、面発光型ＧａＮ系レーザーダイオードにおいては、発光層等の結晶成長を制御し、かつ、反射層等をうまく工夫することにより、発光層の縁方向よりも面方向の発光を強くすることができる。面発光型のものを使用することによって、発光層の縁から発光するタイプに比べ、単位発光量あたりの発光断面積が大きくとれる結果、第２の発光体を構成する蛍光体にその光を照射する場合、同じ光量で照射面積を非常に大きくすることができ、照射効率を良くすることができるので、蛍光体からより強い発光を得ることができる。
【００３３】
第１の発光体として面発光型のものを使用する場合、第２の発光体を膜状とするのが好ましい。その結果、面発光型の発光体からの光は断面積が十分大きいので、第２の発光体をその断面の方向に膜状とすると、第１の発光体からの蛍光体への照射断面積が蛍光体単位量あたり大きくなるので、蛍光体からの発光の強度をより大きくすることができる。
【００３４】
また、第１の発光体として面発光型のものを使用し、第２の発光体として膜状のものを用いる場合、第１の発光体の発光面に、直接膜状の第２の発光体を接触させるた形状とするのが好ましい。ここでいう接触とは、第１の発光体と第２の発光体とが空気や気体を介さないでぴたりと接している状態をつくることを言う。その結果、第１の発光体からの光が第２の発光体の膜面で反射されて外にしみ出るという光量損失を避けることができるので、装置全体の発光効率を良くすることができる。
【００３５】
本発明の発光装置の一例における第１の発光体と第２の発光体との位置関係を示す模式的斜視図を図２に示す。図２中の１は、前記蛍光体を有する膜状の第２の発光体、２は第１の発光体としての面発光型ＧａＮ系ＬＤ、３は基板を表す。相互に接触した状態をつくるために、ＬＤ２と第２の発光体１とそれぞれ別個にをつくっておいてそれらの面同士を接着剤やその他の手段によって接触させても良いし、ＬＤ２の発光面上に第２の発光体をを製膜（成型）させても良い。これらの結果、ＬＤ２と第２の発光体１とを接触した状態とすることができる。
【００３６】
第１の発光体からの光や第２の発光体からの光は通常四方八方に向いているが、第２の発光体として用いられる蛍光体の粉を樹脂中に分散させると、光が樹脂の外に出る時にその一部が反射されるので、ある程度光の向きを揃えられる。従って、効率の良い向きに光をある程度誘導できるので、第２の発光体として、前記蛍光体の粉を樹脂中へ分散したものを使用するのが好ましい。蛍光体の粉としては、通常、平均粒径が０．５〜１５μｍ程度のものが用いられる。第１の発光体の光を有効に使用できるので、平均粒径は０．８〜５μｍが好ましく、０．８〜２μｍがより好ましい。また、蛍光体を樹脂中に分散させると、第１の発光体からの光の第２の発光体への全照射面積が大きくなるので、第２の発光体からの発光強度を大きくすることができるという利点も有する。この場合に使用できる樹脂としては、エポキシ樹脂、ポリビニル系樹脂、ポリエチレン系樹脂、ポリプロピレン系樹脂、ポリエステル系樹脂等各種のものが挙げられるが、蛍光体粉の分散性が良い点で好ましくはエポキシ樹脂である。蛍光体の粉を樹脂中に分散させる場合、蛍光体の粉と樹脂の全体に対するその粉の重量比は、通常１０〜９５％、好ましくは２０〜９０％、さらに好ましくは３０〜８０％である。蛍光体が多すぎると粉の凝集により発光効率が低下することがあり、少なすぎると今度は樹脂による光の吸収や散乱のため発光効率が低下することがある。
【００３７】
本発明の発光装置は、第１の発光体からの光、第２の発光体からの光を混合して発光装置からの取り出し光を白色にすることができる。この時、第２の発光体として本発明の蛍光体の他に、その他の蛍光体、例えば、青色、緑色、赤色の蛍光体を必要に応じて組み合わせることにより白色とすることができる。また、必要に応じてカラーフィルター等を用いても良い。取り出し光を白色光にすることで、発光装置によって照射される物体の演色性が高くなる。これは特に本発光装置を照明用途に応用する際において重要である。
【００３８】
本発明の発光装置は、波長変換材料としての前記蛍光体と、３５０−４１５ｎｍの光を発生する発光素子とから構成されてなり、前記蛍光体が発光素子の発する３５０−４１５ｎｍの光を吸収して、使用環境によらず演色性が良く、かつ、高強度の可視光を発生させることのできる発光装置であり、バックライト光源、信号機などの発光源、又、カラー液晶ディスプレイ等の画像表示装置や面発光等の照明装置等の光源に適している。
【００３９】
本発明の発光装置を図面に基づいて説明すると、図３は、第１の発光体（３５０−４１５ｎｍ発光体）と第２の発光体とを有する発光装置の一実施例を示す模式的断面図であり、４は発光装置、５はマウントリード、６はインナーリード、７は第１の発光体（３５０−４１５ｎｍの発光体）、８は第２の発光体としての蛍光体含有樹脂部、９は導電性ワイヤー、１０はモールド部材である。
【００４０】
本発明の一例である発光装置は、図３に示されるように、一般的な砲弾型の形態をなし、マウントリード５の上部カップ内には、ＧａＮ系発光ダイオード等からなる第１の発光体（３５０−４１５ｎｍ発光体）７が、その上に、蛍光体をエポキシ樹脂やアクリル樹脂等のバインダーに混合、分散させ、カップ内に流し込むことにより第２の発光体として形成された蛍光体含有樹脂部８で被覆されることにより固定されている。一方、第１の発光体７とマウントリード５、及び第１の発光体７とインナーリード６は、それぞれ導電性ワイヤー９で導通されており、これら全体がエポキシ樹脂等によるモールド部材１０で被覆、保護されてなる。
【００４１】
又、この発光素子１を組み込んだ面発光照明装置９８は、図９に示されるように、内面を白色の平滑面等の光不透過性とした方形の保持ケース９１０の底面に、多数の発光装置９１を、その外側に発光素子９１の駆動のための電源及び回路等（図示せず。）を設けて配置し、保持ケース９１０の蓋部に相当する箇所に、乳白色としたアクリル板等の拡散板９９を発光の均一化のために固定してなる。
【００４２】
そして、面発光照明装置９８を駆動して、発光素子９１の第１の発光体に電圧を印加することにより３５０−４１５ｎｍの光を発光させ、その発光の一部を、第２の発光体としての蛍光体含有樹脂部における前記蛍光体が吸収し、可視光を発光し、一方、蛍光体に吸収されなかった青色光等との混色により演色性の高い発光が得られ、この光が拡散板９９を透過して、図面上方に出射され、保持ケース９１０の拡散板９９面内において均一な明るさの照明光が得られることとなる。
【００４３】
【実施例】
以下、本発明を実施例によりさらに具体的に説明するが、本発明はその要旨を越えない限り以下の実施例に限定されるものではない。なお、以下の実施例、比較例における相対発光強度は、比較例１における発光強度を１００とし、その相対値で表した。
【００４４】
実施例１
ＳｒＨＰＯ_４；０．１０５５モル、ＳｒＣＯ_３；０．０３５２モル、ＳｒＣｌ_２；０．０１７６モル、およびＥｕ_２Ｏ_３；０．００８８モルを純水と共に、アルミナ製容器及びビーズの湿式ボールミル中で粉砕、混合し、乾燥後、ナイロンメッシュを通過させた後、得られた粉砕混合物をアルミナ製坩堝中で、４％の水素を含む窒素ガス流下、１２００℃で２時間、加熱することにより焼成し、引き続いて、水洗浄、乾燥、及び分級処理を行うことにより蛍光体Ｓｒ_４．５Ｅｕ_０．５（ＰＯ_４）_３Ｃｌを製造した。図４に、この蛍光体のＸ線回折パターンを示す。図４のピークパターンは図１のＳｒ_５（ＰＯ_４）_３Ｃｌのそれと結晶構造的に一致していることがわかる。図５に、ＧａＮ系発光ダイオードの紫外光領域の主波長である４００ｎｍでこの蛍光体を励起したときの発光スペクトルを示した。表−１に、ＧａＮ系発光ダイオードの紫外光領域の主波長である４００ｎｍでこの蛍光体を励起したときの発光ピークの波長、相対発光強度、蛍光体の量子吸収効率α_ｑ、蛍光体の量子吸収効率α_ｑと内部量子効率η_ｉの積α_ｑ・η_ｉを示した。
【００４５】
実施例２
仕込み原料を、ＳｒＨＰＯ_４；０．１０５５モル、ＳｒＣＯ_３；０．０１７６モル、ＳｒＣｌ_２；０．０１７６モル、およびＥｕ_２Ｏ_３；０．０１７６モルと変えた以外は、実施例１と同様にして蛍光体Ｓｒ_４Ｅｕ_１（ＰＯ_４）_３Ｃｌを製造した。図６に、この蛍光体のＸ線回折パターンを示す。図６のピークパターンは図１のＳｒ_５（ＰＯ_４）_３Ｃｌのそれと結晶構造的に一致していることがわかる。ＧａＮ系発光ダイオードの紫外光領域の主波長である４００ｎｍでこの蛍光体を励起し、発光スペクトルを測定した。表−１にその発光ピークの波長、相対発光強度、蛍光体の量子吸収効率α_ｑ、蛍光体の量子吸収効率α_ｑと内部量子効率η_ｉの積α_ｑ・η_ｉを示した。
【００４６】
実施例３
仕込み原料を、ＳｒＨＰＯ_４；０．１０５５モル、ＳｒＣｌ_２；０．０１７６モル、およびＥｕ_２Ｏ_３；０．０２６４モルと変えた以外は、実施例１と同様にして蛍光体Ｓｒ_３．５Ｅｕ_１．５（ＰＯ_４）_３Ｃｌを製造した。図７に、この蛍光体のＸ線回折パターンを示す。図７のピークパターンは図１のＳｒ_５（ＰＯ_４）_３Ｃｌのそれと結晶構造的に一致していることがわかる。ＧａＮ系発光ダイオードの紫外光領域の主波長である４００ｎｍでこの蛍光体を励起し、発光スペクトルを測定した。表−１にその発光ピークの波長、相対発光強度、蛍光体の量子吸収効率α_ｑ、蛍光体の量子吸収効率α_ｑと内部量子効率η_ｉの積α_ｑ・η_ｉを示した。
【００４７】
実施例４
仕込み原料を、ＳｒＨＰＯ_４；０．０８７９モル、ＳｒＣｌ_２；０．０１７６モル、Ｅｕ_２Ｏ_３；０．０３５２、および（ＮＨ_４）_２ＨＰＯ_４；０．０１７６モルと変えた以外は、実施例１と同様にして蛍光体Ｓｒ_３Ｅｕ_２（ＰＯ_４）_３Ｃｌを製造した。図８に、この蛍光体のＸ線回折パターンを示す。図８のピークパターンは図１のＳｒ_５（ＰＯ_４）_３Ｃｌのそれと結晶構造的に一致していることがわかる。ＧａＮ系発光ダイオードの紫外光領域の主波長である４００ｎｍでこの蛍光体を励起し、発光スペクトルを測定した。表−１にその発光ピークの波長と相対発光強度を示した。
【００４８】
実施例５
仕込み原料を、ＳｒＨＰＯ_４；０．１０５５モル、ＳｒＣＯ_３；０．０４８４モル、ＳｒＣｌ_２；０．０１７６モル、ＣａＣＯ_３；０．００１７６モル、塩基性炭酸マグネシウム（Ｍｇのモル数０．０００８８モル）、およびＥｕ_２Ｏ_３；０．０００８８モルと変えた以外は、実施例１と同様にして蛍光体Ｓｒ_{４．８７５}Ｃａ_０．０５Ｍｇ_{０．０２５}Ｅｕ_０．０５（ＰＯ_４）_３Ｃｌを製造した。図１０に、この蛍光体のＸ線回折パターンを示す。図１０のピークパターンは図１のＳｒ_５（ＰＯ_４）_３Ｃｌのそれと結晶構造的に一致していることがわかる。ＧａＮ系発光ダイオードの紫外光領域の主波長である４００ｎｍでこの蛍光体を励起し、発光スペクトルを測定した。表−１にその発光ピークの波長と相対発光強度、蛍光体の量子吸収効率α_ｑ、蛍光体の量子吸収効率α_ｑと内部量子効率η_ｉの積α_ｑ・η_ｉを示した。
【００４９】
実施例６
仕込み原料を、ＳｒＨＰＯ_４；０．１０５５モル、ＳｒＣＯ_３；０．０３９６モル、ＢａＣＯ_３；０．００８７９モル、塩基性炭酸マグネシウム（Ｍｇのモル数０．００２６４モル）、ＢａＣｌ_２；０．０１７６モル、およびＥｕ_２Ｏ_３；０．０００８８モルと変えた以外は、実施例１と同様にして蛍光体Ｓｒ_{４．１２５}Ｂａ_０．７５Ｍｇ_{０．０７５}Ｅｕ_０．０５（ＰＯ_４）_３Ｃｌを製造した。図１１に、この蛍光体のＸ線回折パターンを示す。図１１のピークパターンは図１のＳｒ_５（ＰＯ_４）_３Ｃｌのそれと結晶構造的に一致していることがわかる。ＧａＮ系発光ダイオードの紫外光領域の主波長である４００ｎｍでこの蛍光体を励起し、発光スペクトルを測定した。表−１にその発光ピークの波長と相対発光強度を示した。
【００５０】
実施例７
仕込み原料を、ＳｒＨＰＯ_４；０．０５２７モル、ＳｒＣｌ_２；０．０１７６モル、Ｅｕ_２Ｏ_３；０．０５２７、および（ＮＨ_４）_２ＨＰＯ_４；０．０５２７モルと変えた以外は、実施例１と同様にして蛍光体Ｓｒ_２Ｅｕ_３（ＰＯ_４）_３Ｃｌを製造した。図１２に、この蛍光体のＸ線回折パターンを示す。図１２のピークパターンは図１のＳｒ_５（ＰＯ_４）_３Ｃｌのそれと結晶構造的に一致していることがわかる。ＧａＮ系発光ダイオードの紫外光領域の主波長である４００ｎｍでこの蛍光体を励起し、発光スペクトルを測定した。表−１にその発光ピークの波長、相対発光強度、蛍光体の量子吸収効率α_ｑ、蛍光体の量子吸収効率α_ｑと内部量子効率η_ｉの積α_ｑ・η_ｉを示した。
【００５１】
実施例８
仕込み原料を、ＳｒＣｌ_２；０．０１７６モル、Ｅｕ_２Ｏ_３；０．０７９１、および（ＮＨ_４）_２ＨＰＯ_４；０．１０５５モルと変えた以外は、実施例１と同様にして蛍光体Ｓｒ_０．５Ｅｕ_４．５（ＰＯ_４）_３Ｃｌを製造した。図１３に、この蛍光体のＸ線回折パターンを示す。図１３のピークパターンは図１のＳｒ_５（ＰＯ_４）_３Ｃｌのそれと結晶構造的に一致していることがわかる。ＧａＮ系発光ダイオードの紫外光領域の主波長である４００ｎｍでこの蛍光体を励起し、発光スペクトルを測定した。表−１にその発光ピークの波長と相対発光強度を示した。
【００５２】
実施例９
仕込み原料を、ＳｒＨＰＯ_４；０．１０５５モル、ＳｒＣＯ_３；０．０３０２モル、ＣａＣＯ_３；０．０１９９モル、塩基性炭酸マグネシウム（Ｍｇのモル数０．０００８８モル）、ＢａＣｌ_２；０．０１７６モル、およびＥｕ_２Ｏ_３；０．０００８８モルと変えた以外は、実施例１と同様にして蛍光体Ｓｒ_３．８６Ｂａ_０．５Ｃａ_{０．５６５}Ｍｇ_{０．０２５}Ｅｕ_０．０５（ＰＯ_４）_３Ｃｌを製造した。図１４に、この蛍光体のＸ線回折パターンを示す。図１４のピークパターンは図１のＳｒ_５（ＰＯ_４）_３Ｃｌのそれと結晶構造的に一致していることがわかる。ＧａＮ系発光ダイオードの紫外光領域の主波長である４００ｎｍでこの蛍光体を励起し、発光スペクトルを測定した。表−１にその発光ピークの波長と相対発光強度を示した。
【００５３】
実施例１０
仕込み原料を、ＳｒＨＰＯ_４；０．１０５５モル、ＳｒＣＯ_３；０．０１２１モル、ＢａＣＯ_３；０．０２０４モル、ＣａＣＯ_３；０．０１７６モル、塩基性炭酸マグネシウム（Ｍｇのモル数０．０００８８モル）、ＢａＣｌ_２；０．０１７６モル、およびＥｕ_２Ｏ_３；０．０００８８モルと変えた以外は、実施例１と同様にして蛍光体Ｓｒ_{３．３４５}Ｂａ_１．０８Ｃａ_０．５Ｍｇ_{０．０２５}Ｅｕ_０．０５（ＰＯ_４）_３Ｃｌを製造した。図１５に、この蛍光体のＸ線回折パターンを示す。図１５のピークパターンは図１のＳｒ_５（ＰＯ_４）_３Ｃｌのそれと結晶構造的に一致していることがわかる。ＧａＮ系発光ダイオードの紫外光領域の主波長である４００ｎｍでこの蛍光体を励起し、発光スペクトルを測定した。表−１にその発光ピークの波長と相対発光強度を示した。
【００５４】
実施例１１
塩化カルシウム２水和物；０．０１３８２モル、塩化ユーロピウム６水和物；０．０００２８モルを秤取り２０ｍｌの水に溶解させた。この水溶液に８５％リン酸をリン酸として０．００８４６モル添加し、混合溶液を磁性皿に移し全溶液量を３０〜４０ｍｌにした。この溶液を、攪拌下、加熱、乾燥させた。乾燥後の固体を回収し、メノウ乳鉢で粉砕した。この粉砕品の一部をアルミナ製坩堝に移し、４％の水素を含む窒素ガス流下、１０００℃で２時間焼成し、蛍光体Ｃａ_４．９Ｅｕ_０．１（ＰＯ_４）_３Ｃｌを製造した。
【００５５】
表−１にＧａＮ系発光ダイオードの紫外光領域の主波長である４００ｎｍでこの蛍光体を励起したときの発光ピークの波長と相対発光強度を示す。
実施例１２
塩化カルシウム２水和物；０．０１３２５モル、塩化ユーロピウム６水和物；０．０００５５モルを秤取り２０ｍｌの水に溶解させた。この水溶液に８５％リン酸をリン酸として０．００８２８モル添加し、混合溶液を磁性皿に移し全溶液量を３０〜４０ｍｌにした。この溶液を、攪拌下、加熱、乾燥させた。以下、実施例１１と同様にして蛍光体Ｃａ_４．８Ｅｕ_０．２（ＰＯ_４）_３Ｃｌを製造した。
【００５６】
表−１にＧａＮ系発光ダイオードの紫外光領域の主波長である４００ｎｍでこの蛍光体を励起したときの発光ピークの波長と相対発光強度を示す。
実施例１３
塩化カルシウム２水和物；０．０１２２モル、塩化ユーロピウム６水和物；０．００１０６モルを秤取り２０ｍｌの水に溶解させた。この水溶液に８５％リン酸をリン酸として０．００７９６モル添加し、混合溶液を磁性皿に移し全溶液量を３０〜４０ｍｌにした。更に３５％塩酸水溶液５０マイクロリットルを滴下し、攪拌下、加熱、乾燥させた。以下、実施例１１と同様にして蛍光体Ｃａ_４．６Ｅｕ_０．４（ＰＯ_４）_３Ｃｌを製造した。
【００５７】
表−１にＧａＮ系発光ダイオードの紫外光領域の主波長である４００ｎｍでこの蛍光体を励起したときの発光ピークの波長と相対発光強度を示す。
実施例１４
塩化カルシウム２水和物；０．０１１７モル、塩化ユーロピウム６水和物；０．００１３モルを秤取り２０ｍｌの水に溶解させた。この水溶液に８５％リン酸をリン酸として０．００７８モル添加し、混合溶液を磁性皿に移し全溶液量を３０〜４０ｍｌにした。更に３５％塩酸水溶液５０マイクロリットルを滴下し、攪拌下、加熱、乾燥させた。以下、実施例１１と同様にして蛍光体Ｃａ_４．５Ｅｕ_０．５（ＰＯ_４）_３Ｃｌを製造した。
【００５８】
表−１にＧａＮ系発光ダイオードの紫外光領域の主波長である４００ｎｍでこの蛍光体を励起したときの発光ピークの波長と相対発光強度を示す。
実施例１５
塩化カルシウム２水和物；０．０１０５４モル、硝酸ユーロピウム６水和物；０．００１８６モルを秤取り２０ｍｌの水に溶解させた。この水溶液に８５％リン酸をリン酸として０．００７４４モル添加し、混合溶液を磁性皿に移し全溶液量を３０〜４０ｍｌにした。更に３５％塩酸水溶液１００マイクロリットルを滴下し、攪拌下、加熱、乾燥させた。以下、実施例１１と同様にして蛍光体Ｃａ_４．２５Ｅｕ_０．７５（ＰＯ_４）_３Ｃｌを製造した。この蛍光体のＸ線回折パターンは、Ｃａ_５（ＰＯ_４）_３Ｃｌのそれと結晶構造的に一致していることがわかった。
【００５９】
表−１にＧａＮ系発光ダイオードの紫外光領域の主波長である４００ｎｍでこの蛍光体を励起したときの発光ピークの波長と相対発光強度を示す。
実施例１６
塩化カルシウム２水和物；０．００９４８モル、硝酸ユーロピウム６水和物；０．００２３７モルを秤取り２０ｍｌの水に溶解させた。この水溶液に８５％リン酸をリン酸として０．００７１１モル添加し、混合溶液を磁性皿に移し全溶液量を３０〜４０ｍｌにした。更に３５％塩酸水溶液１５０マイクロリットルを滴下し、攪拌下、加熱、乾燥させた。以下、実施例１１と同様にして蛍光体Ｃａ_４Ｅｕ_１（ＰＯ_４）_３Ｃｌを製造した。
【００６０】
表−１にＧａＮ系発光ダイオードの紫外光領域の主波長である４００ｎｍでこの蛍光体を励起したときの発光ピークの波長と相対発光強度を示す。
比較例１
ＢａＣＯ_３ ；０．０１０３モル、塩基性炭酸マグネシウム（Ｍｇのモル数０．０１０３モル）、及びγ−Ａｌ_２Ｏ_３；０．０５７０モル、並びに発光中心イオンの元素源化合物としてＥｕ_２Ｏ_３；０．０００５７モルを純水と共に、アルミナ製容器及びビーズの湿式ボールミル中で粉砕、混合し、乾燥後、ナイロンメッシュを通過させた後、得られた粉砕混合物をアルミナ製坩堝中で、４％の水素を含む窒素ガス流下、１５００℃で２時間、加熱することにより焼成し、引き続いて、水洗浄、乾燥、及び分級処理を行うことにより青色発光の蛍光体Ｂａ_０．９Ｅｕ_０．１ＭｇＡｌ_１０Ｏ_１７を製造した。図５に、ＧａＮ系発光ダイオードの紫外光領域の主波長である４００ｎｍでこの蛍光体を励起したときの発光スペクトルを示し、実施例１と比較例１の青色発光蛍光体の性能を比較した。表−１にその発光ピークの波長と相対発光強度を示した。４００ｎｍ励起による実施例１の蛍光体の発光強度が比較例１の蛍光体のそれの５．１倍もあることがわかる。
【００６１】
比較例２
仕込み原料を、ＳｒＨＰＯ_４；０．０８９７モル、ＢａＣＯ_３；０．０３２５モル、ＣａＣＯ_３；０．０１７６モル、塩基性炭酸マグネシウム（Ｍｇのモル数０．０００８８モル）、ＢａＣｌ_２；０．０１７６モル、ＢａＨＰＯ_４；０．０１５８モル、およびＥｕ_２Ｏ_３；０．０００８８モルと変えた以外は、実施例１と同様にして蛍光体Ｓｒ_２．５５Ｂａ_{１．８７５}Ｃａ_０．５Ｍｇ_{０．０２５}Ｅｕ_０．０５（ＰＯ_４）_３Ｃｌを製造した。表１に、ＧａＮ系発光ダイオードの紫外光領域の主波長である４００ｎｍでこの蛍光体を励起したときの発光ピークの波長と相対強度を示した。図５に、ＧａＮ系発光ダイオードの紫外光領域の主波長である４００ｎｍでこの蛍光体を励起したときの発光スペクトルを示し、実施例１と比較例２の青色発光蛍光体の性能を比較した。表−１にその発光ピークの波長と相対発光強度を示した。４００ｎｍ励起による実施例１の蛍光体の発光強度が比較例２の蛍光体のそれの５．１倍もあることがわかる。
【００６２】
【表１】

【００６３】
【発明の効果】
本発明によれば、発光強度の高い発光装置を提供することができる。
【図面の簡単な説明】
【図１】Ｓｒ_５（ＰＯ_４）_８ＣｌのＸ線回折パターン（Ｘ線源Ｃｕ Ｋαに換算したもの）
【図２】面発光型ＧａＮ系ダイオードに膜状蛍光体を接触させた発光装置の一例を示す模式的斜視図。
【図３】本発明の発光装置の一実施例を示す模式的断面図である。
【図４】本発明の実施例１の蛍光体のＸ線回折パターン（Ｘ線源：Ｃｕ Ｋα）
【図５】発光波長４００ｎｍのＧａＮ系発光ダイオードにより照射を受けた本発明の実施例１、比較例１、および比較例２のそれぞれの蛍光体の発光スペクトルを重ね合わせたスペクトル。
【図６】本発明の実施例２の蛍光体のＸ線回折パターン（Ｘ線源：Ｃｕ Ｋα）
【図７】本発明の実施例３の蛍光体のＸ線回折パターン（Ｘ線源：Ｃｕ Ｋα）
【図８】本発明の実施例４の蛍光体のＸ線回折パターン（Ｘ線源：Ｃｕ Ｋα）
【図９】本発明の面発光照明装置の一例を示す模式的断面図。
【図１０】本発明の実施例５の蛍光体のＸ線回折パターン（Ｘ線源：Ｃｕ Ｋα）
【図１１】本発明の実施例６の蛍光体のＸ線回折パターン（Ｘ線源：Ｃｕ Ｋα）
【図１２】本発明の実施例７の蛍光体のＸ線回折パターン（Ｘ線源：Ｃｕ Ｋα）
【図１３】本発明の実施例８の蛍光体のＸ線回折パターン（Ｘ線源：Ｃｕ Ｋα）
【図１４】本発明の実施例９の蛍光体のＸ線回折パターン（Ｘ線源：Ｃｕ Ｋα）
【図１５】本発明の実施例１０の蛍光体のＸ線回折パターン（Ｘ線源：Ｃｕ Ｋα）
【図１６】分光光度計に反射板を取り付けて測定した際のスペクトルＩ_ｒｅｆ（λ）
【図１７】分光光度計に量子吸収効率α_ｑ，内部量子効率η_ｉを測定しようとするサンプルを取り付けて測定したした際のスペクトルＩ（λ）
【符号の説明】
１；第２の発光体
２；面発光型ＧａＮ系ＬＥＤ
３；基板
４；発光装置
５；マウントリード
６；インナーリード
７；第１の発光体（３５０〜４１５ｎｍの発光体）
８；本発明中の蛍光体を含有させた樹脂部
９；導電性ワイヤー
１０；モールド部材[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a light-emitting device, and more specifically, a first light-emitting body that emits light in the visible light region from ultraviolet light by a power source, and absorbs light in the visible light region from the ultraviolet light to emit long-wavelength visible light. By combining with a second luminous body as a wavelength conversion material having a luminescent substance containing a luminous center ion-containing phosphor as a base compound to emit, it has good color rendering properties and generates high-intensity luminescence regardless of the use environment. To a light emitting device that can be used.
[0002]
[Prior art]
In order to generate white and other various colors uniformly and with good color rendering properties by a mixture of blue, red, and green, a light emitting device has been proposed in which light emitted from an LED or LD is color-converted by a phosphor. For example, in Japanese Patent Publication No. 49-1221, a laser beam emitting a radiation beam having a wavelength of 300 to 530 nm is used as a phosphor (Y _3-xy Ce _x Gd _y M _5-z Ga _z O ₁₂ (Y represents Y, Lu, or La, and M represents Al, Al-In, or Al-Sc.)) And emits light to form a display. Further, in recent years, a white light emitting light emitting device configured by combining a gallium nitride (GaN) -based LED or LD with high luminous efficiency, which has attracted attention as a blue light emitting semiconductor light emitting element, and a phosphor as a wavelength conversion material. However, it has been proposed as a light-emitting source of an image display device or a lighting device by taking advantage of its features of low power consumption and long life. Actually, Japanese Patent Application Laid-Open No. Hei 10-242513 discloses a light emitting device characterized by using the nitride semiconductor LED or LD chip and using an yttrium / aluminum / garnet system as a phosphor. . In U.S. Patent No. 6,294,800, Ca is used as a substance capable of generating white light emission upon irradiation with light in a 330 to 420 nm region represented by light from an LED. ₈ Mg (SiO ₄ ) ₄ Cl ₂ : Eu ²⁺ , Mn ²⁺ There is disclosed a substance obtained by combining a green phosphor, a red phosphor and a blue phosphor, including (Sr, Ba, Ca) as the blue phosphor. ₅ (PO ₄ ) ₃ Cl: Eu ²⁺ Is given.
[0003]
However, so far, a light emitting device in which an yttrium / aluminum / garnet-based fluorescent material as disclosed in Japanese Patent Application Laid-Open No. 10-242513 is combined as a second light emitting material with respect to a first light emitting material such as an LED. The light emission intensity of the device is not sufficient, and further improvement is required for a light source such as a display, a backlight light source, and a traffic light. Further, it is described as a material for converting LED light into blue-visible light as shown in US Pat. No. 6,294,800 (Sr, Ba, Ca). ₅ (PO ₄ ) ₃ Cl: Eu ²⁺ The same is true for, and a higher emission intensity is required.
[0004]
[Patent Document 1]
JP-B-49-1221
[Patent Document 2]
JP-A-10-242513
[Patent Document 3]
US Patent No. 6,294,800
[0005]
[Problems to be solved by the invention]
The present invention has been made in view of the above-mentioned prior art, and has been made to develop a light-emitting device having an extremely high emission intensity. Therefore, the present invention is easy to manufacture, and at the same time, is a double light-emitting device having an extremely high emission intensity. It is an object to provide a light emitting device.
[0006]
[Means for Solving the Problems]
As a result of intensive studies to solve the above-described problems, the present inventors have found that a first luminous body that emits light of 350 to 415 nm and a second luminous body that generates visible light by irradiating light from the first luminous body. (A) quantum absorption efficiency α as the second luminous body. _q Is 0.8 or more, and / or (B) α which is the product of quantum absorption efficiency and internal quantum efficiency _q ・ Η _i It is found that when a phosphor that satisfies the condition of 0.55 or more is used, the phosphor is irradiated with light near 350 to 415 nm and emits visible light with high intensity, thereby achieving the above object. The invention has been reached. In addition, the use of a phosphor containing a crystal phase having the chemical composition represented by the general formula [1] as the second luminous body achieves the above object, and a preferable specific example is (Sr, Ba, Ca) ₅ (PO ₄ ) ₃ Cl: Eu ²⁺ The inventors have found that the above object can be achieved by using a composition having a higher ratio of Sr and / or using a composition having a higher ratio of Eu in a crystal phase having a basic composition of .
[0007]
Embedded image
Eu _a Sr _b M _5-ab (PO ₄ ) _c X _d ... [1]
(In the above general formula [1], M represents a metal element other than Eu and Sr, and X represents PO ₄ Represents a monovalent anion group other than c and d are numbers satisfying 2.7 ≦ c ≦ 3.3 and 0.9 ≦ d ≦ 1.1. a is a number satisfying a> 0 and b is a number satisfying b ≧ 0 and a + b ≦ 5, and satisfies the condition of a ≧ 0.1 or b ≧ 3. )
Here, 5-ab, d, c, a, and b are respectively the molar ratio of the element corresponding to the element M, the molar ratio of the anion group X, and PO ₄ The molar ratio of groups, the molar ratio of Eu atoms, and the molar ratio of Sr atoms are shown. For example, Eu _0.5 Sr _3.5 Ba _0.8 Mn _0.195 Sm _0.005 (PO ₄ ) ₃ Cl _0.95 F _0.05 In the case of the following composition, M represents Ba, Mn, and Sm, and X represents Cl and F. _0.5 Sr _3.5 M _1.0 (PO ₄ ) ₃ X _1.0 Therefore, it falls within the category of the above-mentioned formula [1].
[0008]
Generally A ₅ (PO ₄ ) ₃ Eu is added to the A site in the crystal of Cl (A is an alkaline earth metal). ²⁺ It is known that such a divalent metal element can be used as a phosphor for a lamp by utilizing the fact that the substituted product is excited by short ultraviolet rays having a Hg resonance line of 254 nm to emit light. . According to the present invention, the emission intensity due to the excitation light near 400 nm having a different wavelength from the above is A ₅ (PO ₄ ) ₃ It greatly differs depending on the type of the alkaline earth metal A of Cl, and when a substance containing a large amount of Sr as the alkaline earth metal A is used, a large emission intensity can be obtained by the excitation of light around 400 nm specifically. Is based on the knowledge that the higher the content of Eu as an activator, the higher the specific intensity.
[0009]
Therefore, the present invention provides a light-emitting device including a first light-emitting body that emits light of 350 to 415 nm, and a second light-emitting body that emits visible light by irradiation of light from the first light-emitting body. The phosphor contained in the second luminous body is (1) quantum absorption efficiency α _q Is 0.8 or more, and / or α which is the product of quantum absorption efficiency and internal quantum efficiency _q ・ Η _i Satisfies the condition of 0.55 or more, or (2) contains a phosphor having a crystal phase having a chemical composition represented by the general formula [1].
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
The present invention is a light-emitting device in which a first light-emitting body that emits light of 350 to 415 nm and a second light-emitting body including a fluorescent material are combined, and the phosphor included in the second light-emitting body is (A) ) Quantum absorption efficiency α _q Is 0.8 or more, more preferably 0.9 or more, still more preferably 0.95 or more, and / or (B) α which is the product of the quantum absorption efficiency and the internal quantum efficiency. _q ・ Η _i Is 0.55 or more, preferably 0.6 or more, and more preferably 0.65 or more. In effect, α _q The upper limit of the value that can be taken is 1, η _i Is 0.99. When the phosphor satisfies the condition (A), of the photons emitted from the first luminous body, the number of those that can cause elementary excitation in the phosphor increases, and as a result, the unit time from the phosphor becomes longer. It is possible to increase the number of photons emitted per light, that is, to obtain a light-emitting device having high emission intensity. Here, elementary excitation refers to energy excitation due to a change in the spin state of Eu (generally referred to as emission center excitation), and energy excitation due to a change in the average number of electrons having an existence probability near each ion. (Generally referred to as CT excitation) and energy excitation (generally referred to as band excitation) due to inter-band transition of electrons. Further, when the phosphor satisfies the condition (B), the proportion of the elementary excitations caused by the photons emitted from the first luminous body that traces the process of further causing the formation of photons thereafter increases. As a result, the number of photons emitted per unit time from the phosphor can be increased, that is, a light-emitting device having high emission intensity can be obtained. When the phosphor satisfies the condition of (B), α _q And η _i Is 0.55 ≦ α, respectively. _q ≦ 1, 0.55 ≦ η _i ≤ 0.99.
[0011]
Below, the quantum absorption efficiency α _q , Internal quantum efficiency η _i A method for obtaining the following will be described. First, a powdery phosphor sample to be measured is packed into a cell having a sufficiently smooth surface so that the measurement accuracy is maintained, and the phosphor sample is attached to a spectrophotometer provided with an integrating sphere or the like. As the spectrophotometer, for example, there is MCPD2000 manufactured by Otsuka Electronics Co., Ltd. The reason for using the integrating sphere or the like is to allow all photons reflected by the sample and photons emitted by the photoluminescence from the sample to be counted, that is, to eliminate photons that are not counted and fly out of the measurement system. A light source for exciting the phosphor is attached to the spectrophotometer. This light source is, for example, a Xe lamp, and is adjusted using a filter or the like so that the light emission peak wavelength becomes 400 nm. The sample to be measured is irradiated with light from the light emission source adjusted to have a wavelength peak of 400 nm, and the emission spectrum is measured. In actuality, the measured spectrum includes not only photons emitted from the sample by photoluminescence with light from the excitation light source (hereinafter simply referred to as excitation light) but also the amount of excitation light reflected by the sample. The contribution of photons overlaps. Absorption efficiency α _q Is the number N of photons of the excitation light absorbed by the sample. _abs Is divided by the total number of photons N of the excitation light. First, the latter total number N of photons of the excitation light is obtained as follows. That is, a spectroscopic material such as a Spectralon (having a reflectivity of 98% with respect to 400 nm excitation light) made of a material having a reflectance R of almost 100% with respect to the excitation light is used as the measurement target. Attached to photometer, reflection spectrum I _ref Measure (λ). Here, this reflection spectrum I _ref The numerical value obtained from (λ) by (Equation 1) is proportional to N.
[0012]
(Equation 1)

Here, the integration interval is substantially I _ref It may be performed only in a section where (λ) has a significant value. FIG. _ref An example of (λ) is shown. In this case, it is sufficient to set the wavelength in the range of 380 nm to 420 nm. The former N _abs Is proportional to the quantity determined by (Equation 2).
[0013]
(Equation 2)

Here, I (λ) is α _q 4 is a reflection spectrum when the target sample for which the determination is required is attached. The integration range of (Equation 2) is the same as the integration range defined by (Equation 1). By limiting the integration range in this way, the second term of (Equation 2) corresponds to the number of photons generated by the target sample reflecting the excitation light, that is, of all the photons generated from the target sample. This corresponds to one excluding photons generated by photoluminescence by the excitation light. Since the actual spectrum measurement is generally obtained as digital data separated by a certain finite bandwidth with respect to λ, the integrals of (Equation 1) and (Equation 2) are obtained by summation based on the bandwidth. From the above, α _q = N _abs / N = (formula 2) / (formula 1).
[0014]
Next, the internal quantum efficiency η _i A method for obtaining the following will be described. η _i Is the number of photons generated by photoluminescence N _PL Of photons absorbed by the sample N _abs Divided by.
Where N _PL Is proportional to the quantity obtained by (Equation 3).
[0015]
[Equation 3]
∫λ · I (λ) dλ --- (Equation 3)
At this time, the integration interval is limited to the wavelength range of the photons generated by the photoluminescence from the sample. This is to remove the contribution of photons reflected from the sample from I (λ). Specifically, the lower limit of the integration of (Equation 3) takes the upper end of the integration of (Equation 1) and sets the upper end to a range suitable for including the spectrum derived from photoluminescence. FIG. 17 shows an example of I (λ). In this case, 420 nm to 520 nm may be set in the integration range in (Equation 3). From the above, η _i = (Equation 3) / (Equation 2). It should be noted that regarding integration from a spectrum that has become digital data, α _q Is the same as in the case where.
[0016]
In general, quantum absorption efficiency α _q Increasing the emission intensity itself leads to an increase in the number of photons of the excitation light source taken into the sample, so that there is an expectation that emission luminance will increase. However, in practice, α is increased by, for example, increasing the concentration of Eu or the like that is the emission center. _q Increase the probability that photons will convert their energy to the excitation of phonons in the sample crystal before reaching the final photoluminescence process, resulting in insufficient emission intensity . However, the wavelength of the excitation light source is particularly selected to be 350 to 415 nm, and the quantum absorption efficiency α is used as the second light emitter of the light emitting device. _q It has been found that the use of a phosphor having a high light emission suppresses the non-photoluminescence process, thereby realizing a light emitting device with high emission intensity. Where α _q Is high, and α _q ・ Η _i It has also been found that a light emitting device having more preferable characteristics can be obtained by combining the second luminous body using a phosphor having a high value of with the first luminous body having a wavelength of 350 to 415 nm. .
[0017]
As long as the conditions (A) and / or (B) are satisfied, the material constituting the phosphor is not particularly limited, but preferably has a crystal phase, and has a chemical composition represented by the following general formula [1]. It is more preferable to select from those having a phase (hereinafter, may be abbreviated as the crystal phase of the general formula [1]). The phosphor may contain other components, for example, a light-scattering substance, as long as the performance is not impaired. Therefore, the ratio of the crystal phase contained in the phosphor is preferably 10% by weight or more. Is at least 50 wt%, more preferably at least 80 wt%.
[0018]
Embedded image
Eu _a Sr _b M _5-ab (PO ₄ ) _c X _d ... [1]
Here, M represents a metal element other than Eu and Sr. X is PO ₄ Represents a monovalent anion group other than c and d are numbers satisfying 2.7 ≦ c ≦ 3.3 and 0.9 ≦ d ≦ 1.1. a is a number satisfying a> 0 and b is a number satisfying b ≧ 0 and a + b ≦ 5, and satisfies the condition of a ≧ 0.1 or b ≧ 3.
[0019]
The second luminous body is a novel luminous device of the present invention containing the phosphor of the general formula [1] itself, and has a luminous intensity superior to that of the conventional luminous device. However, the second luminous body containing the phosphor satisfying the above conditions (A) and / or (B) is preferable as the phosphor contained therein, among the phosphors of the above general formula [1]. Tends to be obtained by selecting. Hereinafter, the phosphor of the general formula [1] will be described. The element M in the formula [1] represents a metal element other than Eu and Sr. As for the element M, the proportion of the total of Ba, Mg, Ca, Zn, and Mn in the element M is preferably 70 mol% or more from the viewpoint of emission intensity and the like. It is preferable that the proportion of the element M is 70 mol% or more, and it is more preferable that the total proportion of Ba, Mg, and Ca to the element M is 90 mol% or more. , Zn, and Mn, and more preferably at least one element selected from the group consisting of Ba, Mg, and Ca.
[0020]
When a metal element other than the above is contained in the crystal as a metal element in the element M, the metal element is not particularly limited, but contains Sr or the same valence as these five metal elements, that is, contains a divalent metal element. This is desirable because the crystal structure is easily maintained. Divalent metal element and emission center Eu ²⁺ A small amount of a metal element such as monovalent, trivalent, tetravalent, pentavalent, or hexavalent may be introduced in order to assist crystallization of the composite oxide due to diffusion into the solid during baking. To give one example, Sr ₅ (PO ₄ ) ₃ Cl: Sr in Eu phosphor ²⁺ Is partially equimolar Li ⁺ And Ga ³⁺ Can be substituted while maintaining the charge compensation effect. A small amount of a metal element that can serve as a sensitizer may be substituted.
[0021]
The metal element M may not be contained, that is, the value of a + b may be set to 5. X in the general formula [1] is PO ₄ Is a monovalent group other than As for X, from the viewpoint of emission intensity and the like, it is preferable that 50 mol% or more of X is a halogen atom, more preferably 70 mol% or more, particularly preferably 90 mol% or more. Examples of the halogen atom include Cl, F, and Br, but Cl is preferred. When 50 mol% or more of X is a halogen atom, X may contain a hydroxyl group or the like as a residual anion group. In the most preferred embodiment, Cl accounts for 50 mol% or more, particularly 70 mol% or more, and more preferably 90 mol% or more of the anionic group X. In this case, the remaining groups include other halogen atoms and OH groups.
[0022]
The molar ratio b of Sr in the general formula [1] is b ≧ 0, preferably b> 0, specifically, 0 ≦ b <5, preferably 0 <b <5, and usually 0 0.01 or more, preferably 0.1 or more, more preferably 0.2 or more, and most preferably 3 or more, particularly 4 or more from the viewpoint of emission intensity and the like. Generally Sr, Ba, Ca) ₅ (PO ₄ ) ₃ Cl: Eu ²⁺ Although the crystal phase having a basic composition of can take a wide range of values as the molar ratio of Sr, in the present invention, it is remarkable by adopting a relatively large numerical value having an upper limit of b <5 as described above. A high emission intensity can be obtained. On the other hand, when the molar ratio of Sr is small, that is, by setting the value of b to a smaller value, especially 0, the cost of the raw material can be reduced, and it is particularly preferable to set Ca to 50 mol% or more. Even in this case, a relatively high emission intensity can be obtained.
[0023]
The molar ratio a of Eu in the general formula [1] is 0 <a <5, usually 0.0001 or more, preferably 0.001 or more, and more preferably 0.005 or more. From the viewpoint of, for example, a ≧ 0.1, preferably a ≧ 0.2, more preferably a> 0.2, further preferably a ≧ 0.3, particularly a ≧ 0.4, and furthermore a It is most preferred that ≧ 0.45. Emission center ion Eu ²⁺ If the molar ratio a is too small, the emission intensity tends to decrease. If the value of a is too large, the emission intensity also tends to decrease due to a phenomenon called concentration quenching. 8, preferably a ≦ 3, more preferably a ≦ 2.5, particularly preferably a ≦ 2, and most preferably a ≦ 1.5. In the general formula [1], if a> 0.2 and a ≧ 0.3 are used, the second light-emitting body having the phosphor satisfying the condition (A) and / or (B) is used. It is particularly preferable for obtaining a light emitting device.
[0024]
In the present invention, if one of a ≧ 0.1 and b ≧ 3 is satisfied, a sufficient emission intensity can be obtained. Therefore, if either one of a and b satisfies the above equation, the other does not necessarily have to satisfy the above equation. In this regard, a preferred combination of the values of a and b is listed as (1) a ≧ 0.1 and b ≧ 0.01, (2) a ≧ 0.1 and b ≧ 0.1, (3) a ≧ 0.1 and b ≧ 0.2, (4) a ≧ 0.2 and b ≧ 0.01, (5) a ≧ 0.2 and b ≧ 0.1, (6) 0.0001 ≦ a and b ≧ 3, (7) 0.001 ≦ a and b ≧ 3, ( 8) 0.005 ≦ a and b ≧ 3, (9) 0.0001 ≦ a and b ≧ 4, (10) 0.001 ≦ a, and b ≧ 4, (11) 0.005 ≦ a, And b ≧ 4. However, in the present invention, it is particularly preferable that both a ≧ 0.1 and b ≧ 3 are satisfied from the viewpoint that the emission intensity can be further increased. In this regard, preferred combinations of the values of a and b are listed. (1) a ≧ 0.1 and b ≧ 3, (2) a ≧ 0.1 and b ≧ 4, (3) a ≧ 0.2 and b ≧ 3, (4) a ≧ 0.2 and b ≧ 4. In particular, by satisfying both a> 0.2 and b ≧ 3, the emission intensity can be further increased. In this regard, more preferable combinations of the values of a and b are listed as (1) a > 0.2 and b ≧ 3, (2) a> 0.2 and b ≧ 4, (3) a ≧ 0.3 and b ≧ 3, (4) a ≧ 0.3 and b ≧ 4, (5 A) 0.4 and b≥3, (6) a≥0.4 and b≥4, (7) a≥0.45 and b≥3, (8) a≥0.45 and b≥4, etc. Can be mentioned.
[0025]
In the general formula [1], c and d satisfy 2.7 ≦ c ≦ 3.3 and 0.9 ≦ d ≦ 1.1, and for c, preferably 2.8 ≦ c ≦ 3. .2, more preferably 2.9 ≦ c ≦ 3.1, and d is preferably 0.93d ≦ 1.07, more preferably 0.95 ≦ d ≦ 1.05.
The basic crystal Eu of the general formula [1] _a Sr _b M _5-ab (PO ₄ ) _c X _d In the case of, even if some lattice deficiency occurs, the fluorescent performance of the present invention is not largely affected, so that it can be used in the range of the above inequalities a, b, c, and d.
[0026]
Generally A ₅ (PO ₄ ) ₃ The crystal of Cl (A is an alkaline earth metal) has a hexagonal structure, and its space group is P6 ₃ / M.
In the present invention, the crystal structure is usually represented by A ₅ (PO ₄ ) ₃ Cl structure. FIG. 1 shows a typical Sr ₅ (PO ₄ ) ₃ 2 shows the X-ray diffraction pattern of Cl (from powder X-ray diffraction database). Sr ₅ (PO ₄ ) ₃ Divalent metals such as Ba, Mg, Ca, Zn, and Mn can be substituted in the Sr site of Cl in a wide composition range. If the amount is small, metals having different valences such as Na and La can be substituted. The Cl site can be substituted with an anionic species such as F, Br, OH, etc., and its structure is maintained. In the present invention, of these substituents, a substituent which usually uses Sr as a cation species is used as a base, and further, Eu is added to a cation site. ²⁺ Corresponds to a crystal phase substituted as an activator.
[0027]
The phosphor used in the present invention is excited by light of 350-415 nm from the first light emitter to generate visible light. The phosphor emits visible light having a very strong light emission intensity by exciting light of 350 to 415 nm.
The phosphor used in the present invention includes an M source, an X source, and a PO source represented by the general formula [1]. ₄ The source compound, the Sr source compound, and the emission center ion (Eu) element source compound are pulverized using a dry pulverizer such as a hammer mill, a roll mill, a ball mill, and a jet mill, and then a ribbon blender or a V-type blender. Mixing with a mixer such as a Henschel mixer, or, after mixing, a dry method of pulverizing using a dry pulverizer, or adding these compounds in a medium such as water, and a medium stirring type pulverizer or the like. A wet type in which the slurry prepared by pulverizing and mixing using a wet pulverizer, or after pulverizing these compounds with a dry pulverizer and then adding the mixture to a medium such as water, is dried by spray drying or the like. According to the method, the pulverized mixture prepared can be produced by heating and baking.
[0028]
Among these pulverization and mixing methods, in particular, in the element source compound of the luminescent center ion, it is preferable to use a liquid medium because a small amount of the compound needs to be uniformly mixed and dispersed throughout the element. The latter wet method is preferable also from the viewpoint of obtaining uniform mixing in the element source compound as a whole, and the heat treatment method is usually 700 to 1500 ° C. in a heat-resistant container such as a crucible or tray made of alumina or quartz. Preferably, the heating is carried out at a temperature of 900 to 1300 ° C. for 10 minutes to 24 hours in an atmosphere of a gas such as air, oxygen, carbon monoxide, carbon dioxide, nitrogen, hydrogen, argon or the like alone or in a mixed atmosphere. After the heat treatment, washing, drying, classification, and the like are performed as necessary.
[0029]
As the heating atmosphere, an atmosphere necessary for obtaining an ion state (valence) in which the element of the emission center ion contributes to light emission is selected. In the case of divalent Eu or the like in the present invention, a neutral or reducing atmosphere such as carbon monoxide, nitrogen, hydrogen, or argon is preferable, but an oxidizing atmosphere such as air or oxygen can be used as long as conditions are selected. . Here, the compounds of M source, X source, Sr source and Eu source include oxides, hydroxides, carbonates, nitrates, sulfates, oxalates of each of M, X, Sr and Eu. Carboxylic acid salts, halides and the like; ₄ Source compounds include the elements M, NH ₄ Such as hydrogen phosphate, phosphate, metaphosphate, pyrophosphate, P ₂ O ₅ , PX ₃ , PX ₅ , M ₂ PO ₄ X, phosphoric acid, metaphosphoric acid, pyrophosphoric acid and the like. Examples of the compound of X source include MX, NH ₄ X, HX, M ₂ PO ₄ X and the like, and among these, the chemical composition, reactivity, and NO during firing _x , SO _x Is selected in consideration of non-occurrence of the above.
[0030]
Specific examples of Sr source compounds that are preferable for Sr include SrO and Sr (OH). ₂ ・ 8H ₂ O, SrCO ₃ , Sr (NO ₃ ) ₂ , Sr (OCO) ₂ ・ H ₂ O, Sr (OCOCH ₃ ) ₂ ・ 0.5H ₂ O, SrCl ₂ And the like. If the compound for synthesis raw material of Ba, Mg, Ca, Zn, or Mn in the metal element group M is specifically illustrated, BaO, Ba (OH) ₂ ・ 8H ₂ O, BaCO ₃ , Ba (NO ₃ ) ₂ , BaSO ₄ , Ba (OCO) ₂ ・ 2H ₂ O, Ba (OCOCH ₃ ) ₂ , BaCl ₂ And the Mg source compound is MgO, Mg (OH) ₂ , MgCO ₃ , Mg (OH) ₂ ・ 3MgCO ₃ ・ 3H ₂ O, Mg (NO ₃ ) ₂ ・ 6H ₂ O, Mg (OCO) ₂ ・ 2H ₂ O, Mg (OCOCH ₃ ) ₂ ・ 4H ₂ O, MgCl ₂ And the Ca source compounds include CaO, Ca (OH) ₂ , CaCO ₃ , Ca (NO ₃ ) ₂ ・ 4H ₂ O, Ca (OCO) ₂ ・ H ₂ O, Ca (OCOCH ₃ ) ₂ ・ H ₂ O, CaCl ₂ And Zn source compounds include ZnO, Zn (OH) ₂ , ZnCO ₃ , Zn (NO ₃ ) ₂ ・ 6H ₂ O, Zn (OCO) ₂ , Zn (OCOCH ₃ ) ₂ , ZnCl ₂ And the Mn source compound is MnO ₂ , Mn ₂ O ₃ , Mn ₃ O ₄ , MnOOH, MnCO ₃ , Mn (NO ₃ ) ₂ , Mn (OCOCH ₃ ) ₂ ・ 2H ₂ O, Mn (OCOCH ₃ ) ₃ ・ NH ₂ O, MnCl ₂ ・ 4H ₂ O etc. are each mentioned.
[0031]
Further, with regard to Eu, which is preferable as an element of the luminescence center ion, if the element source compound is specifically exemplified, ₂ O ₃ , Eu (OCOCH ₃ ) ₃ ・ 4H ₂ O, EuCl ₃ ・ 6H ₂ O, Eu ₂ (OCO) ₃ ・ 6H ₂ O and the like.
In the present invention, the first luminous body that irradiates the phosphor with light generates light having a wavelength of 350 to 415 nm. Preferably, a luminous body that generates light having a peak wavelength in the range of 350 to 415 nm is used. Specific examples of the first light emitter include a light emitting diode (LED) and a laser diode (LD). A laser diode is more preferable in terms of good power consumption and low power consumption. Among them, a GaN-based LED or LD using a GaN-based compound semiconductor is preferable. This is because GaN-based LEDs and LDs have much higher luminous output and external quantum efficiency than SiC-based LEDs that emit light in this region, and are extremely low power and very bright when combined with the phosphor. This is because light emission can be obtained. For example, for a current load of 20 mA, a GaN-based material usually has an emission intensity 100 times or more that of a SiC-based material. In GaN-based LEDs and LDs, Al _X Ga _Y N light emitting layer, GaN light emitting layer, or In _X Ga _Y Those having an N light emitting layer are preferred. In GaN-based LEDs, among them, In _X Ga _Y Those having an N light emitting layer are particularly preferable because the light emission intensity is very high. _X Ga _Y A multi-quantum well structure having an N layer and a GaN layer is particularly preferable because the light emission intensity is very high. In the above description, the value of X + Y is usually in the range of 0.8 to 1.2. In the GaN-based LED, those in which these light emitting layers are doped with Zn or Si or those without a dopant are preferable in terms of adjusting the light emitting characteristics. The GaN-based LED has these light-emitting layers, p-layers, n-layers, electrodes, and a substrate as basic components, and the light-emitting layers are n-type and p-type Al. _X Ga _Y N layer, GaN layer, or In _X Ga _Y Those having a hetero structure sandwiched by N layers or the like have high luminous efficiency and are preferable, and those having a hetero structure with a quantum well structure are further preferable because they have higher luminous efficiency.
[0032]
In the present invention, it is particularly preferable to use a surface-emitting type luminous body, particularly a surface-emitting type GaN-based laser diode, as the first luminous body, since this increases the luminous efficiency of the entire light-emitting device. A surface-emitting type illuminant is an illuminant that emits strong light in the plane direction of the film. In a surface-emitting GaN-based laser diode, crystal growth of a light-emitting layer and the like is controlled, and a reflection layer and the like are well controlled. By devising, light emission in the surface direction can be made stronger than in the edge direction of the light emitting layer. By using a surface-emitting type, the emission cross-sectional area per unit emission amount can be increased as compared with the type emitting light from the edge of the emission layer, so that the phosphor constituting the second light-emitting body is irradiated with the light. In this case, the irradiation area can be made very large with the same light quantity, and the irradiation efficiency can be improved, so that stronger light emission can be obtained from the phosphor.
[0033]
When a surface-emitting type is used as the first illuminant, it is preferable that the second illuminant is in the form of a film. As a result, the light from the surface-emitting type illuminant has a sufficiently large cross-sectional area. Therefore, when the second illuminant is formed into a film in the direction of the cross-section, the irradiation cross-sectional area of the first illuminant to the phosphor is reduced. Is increased per phosphor unit amount, so that the intensity of light emission from the phosphor can be further increased.
[0034]
When a surface-emitting type is used as the first illuminant and a film-like illuminant is used as the second illuminant, a film-like second illuminant is directly provided on the light-emitting surface of the first illuminant. It is preferable to make the shape contact. Here, the term “contact” refers to a state in which the first luminous body and the second luminous body are in contact with each other without air or gas. As a result, it is possible to avoid a light amount loss that the light from the first luminous body is reflected on the film surface of the second luminous body and leaks out, so that the luminous efficiency of the entire device can be improved.
[0035]
FIG. 2 is a schematic perspective view showing the positional relationship between the first light emitter and the second light emitter in an example of the light emitting device of the present invention. In FIG. 2, 1 is a film-shaped second light-emitting body having the phosphor, 2 is a surface-emitting GaN-based LD as a first light-emitting body, and 3 is a substrate. In order to form a state of mutual contact, the LD 2 and the second luminous body 1 may be separately formed, and their surfaces may be brought into contact with each other by an adhesive or other means. A second luminous body may be formed (molded) on top. As a result, the LD 2 and the second luminous body 1 can be brought into contact with each other.
[0036]
The light from the first luminous body and the light from the second luminous body usually face in all directions, but when the powder of the phosphor used as the second luminous body is dispersed in the resin, the light is dispersed in the resin. Part of the light is reflected when it goes out of the room, so that the direction of light can be aligned to some extent. Accordingly, since light can be guided to an efficient direction to some extent, it is preferable to use the second luminous body in which powder of the phosphor is dispersed in a resin. As the phosphor powder, one having an average particle size of about 0.5 to 15 μm is usually used. The average particle size is preferably 0.8 to 5 μm, and more preferably 0.8 to 2 μm, because the light of the first luminous body can be used effectively. Further, when the phosphor is dispersed in the resin, the total irradiation area of the light from the first luminous body to the second luminous body increases, so that the luminous intensity from the second luminous body can be increased. It also has the advantage of being able to. Examples of resins that can be used in this case include epoxy resins, polyvinyl resins, polyethylene resins, polypropylene resins, polyester resins, and various other resins. However, epoxy resins are preferred because of their good dispersibility of phosphor powder. It is. When the phosphor powder is dispersed in the resin, the weight ratio of the phosphor powder to the whole resin is usually 10 to 95%, preferably 20 to 90%, and more preferably 30 to 80%. . If the amount of the phosphor is too large, the luminous efficiency may decrease due to aggregation of the powder, and if the amount is too small, the luminous efficiency may decrease due to light absorption or scattering by the resin.
[0037]
The light-emitting device of the present invention can mix light from the first light-emitting body and light from the second light-emitting body to make the light extracted from the light-emitting device white. At this time, in addition to the phosphor of the present invention, other phosphors, for example, blue, green, and red phosphors can be combined as necessary as the second luminous body to make the second luminous body white. Further, a color filter or the like may be used as needed. By setting the extracted light to white light, the color rendering of the object irradiated by the light emitting device is improved. This is particularly important when the present light emitting device is applied to lighting applications.
[0038]
The light emitting device of the present invention comprises the phosphor as a wavelength conversion material and a light emitting element that emits light of 350 to 415 nm, and the phosphor absorbs light of 350 to 415 nm emitted from the light emitting element. It is a light emitting device that has good color rendering properties and can generate high-intensity visible light regardless of the use environment, and is a light source such as a backlight light source and a traffic light, and an image display device such as a color liquid crystal display. It is suitable for a light source such as a lighting device such as a light emitting device or a surface light emitting device.
[0039]
The light emitting device of the present invention will be described with reference to the drawings. FIG. 3 is a schematic cross-sectional view showing one embodiment of a light emitting device having a first light emitter (350-415 nm light emitter) and a second light emitter. 4 is a light emitting device, 5 is a mount lead, 6 is an inner lead, 7 is a first luminous body (350-415 nm luminous body), 8 is a phosphor-containing resin part as a second luminous body, 9 Is a conductive wire, and 10 is a mold member.
[0040]
As shown in FIG. 3, the light emitting device as an example of the present invention has a general shell shape, and a first light emitting body made of a GaN-based light emitting diode or the like is provided in an upper cup of the mount lead 5. (350-415 nm luminous body) 7 is a phosphor-containing resin formed as a second luminous body by mixing and dispersing the phosphor in a binder such as an epoxy resin or an acrylic resin and pouring the mixture into a cup. It is fixed by being covered with the part 8. On the other hand, the first luminous body 7 and the mount lead 5 and the first luminous body 7 and the inner lead 6 are each electrically connected by a conductive wire 9, and are entirely covered with a mold member 10 made of epoxy resin or the like. Be protected.
[0041]
Further, as shown in FIG. 9, the surface-emitting lighting device 98 incorporating the light-emitting element 1 has a large number of light-emitting elements formed on the bottom surface of a rectangular holding case 910 whose inner surface is made of light-impermeable material such as a white smooth surface. The device 91 is provided with a power supply and a circuit (not shown) for driving the light emitting element 91 provided outside thereof, and a device such as an acrylic plate made of milky white is provided at a position corresponding to the lid of the holding case 910. The diffusion plate 99 is fixed for uniform light emission.
[0042]
Then, by driving the surface-emitting lighting device 98 and applying a voltage to the first light-emitting body of the light-emitting element 91, light of 350 to 415 nm is emitted, and a part of the light emission is used as a second light-emitting body. The phosphor in the phosphor-containing resin portion absorbs and emits visible light, and on the other hand, high color rendering light emission is obtained by mixing with blue light and the like not absorbed by the phosphor. Thus, illumination light having a uniform brightness can be obtained in the plane of the diffusion plate 99 of the holding case 910 after being transmitted through the light 99 and emitted upward in the drawing.
[0043]
【Example】
Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples as long as the gist of the present invention is not exceeded. The relative light emission intensity in the following Examples and Comparative Examples was expressed as a relative value, with the light emission intensity in Comparative Example 1 being 100.
[0044]
Example 1
SrHPO ₄ 0.1055 mol, SrCO ₃ ; 0.0352 mol, SrCl ₂ 0.0176 mol, and Eu ₂ O ₃ 0.0088 mol together with pure water in an alumina container and beads in a wet ball mill, and mixed, dried, passed through a nylon mesh, and the obtained ground mixture was placed in an alumina crucible at 4%. Baking by heating at 1200 ° C. for 2 hours in a flow of nitrogen gas containing hydrogen, followed by washing with water, drying and classification to obtain phosphor Sr _4.5 Eu _0.5 (PO ₄ ) ₃ Cl was produced. FIG. 4 shows an X-ray diffraction pattern of this phosphor. The peak pattern of FIG. ₅ (PO ₄ ) ₃ It can be seen that the crystal structure matches that of Cl. FIG. 5 shows an emission spectrum when the phosphor is excited at 400 nm, which is the main wavelength in the ultraviolet region of the GaN-based light emitting diode. Table 1 shows the wavelength of the emission peak, the relative emission intensity, and the quantum absorption efficiency α of the phosphor when the phosphor was excited at 400 nm, which is the main wavelength in the ultraviolet region of the GaN-based light emitting diode. _q , The quantum absorption efficiency α of the phosphor _q And internal quantum efficiency η _i Product of α _q ・ Η _i showed that.
[0045]
Example 2
SrHPO ₄ 0.1055 mol, SrCO ₃ ; 0.0176 mol, SrCl ₂ 0.0176 mol, and Eu ₂ O ₃ Phosphor Sr in the same manner as in Example 1 except that it was changed to 0.0176 mol; ₄ Eu ₁ (PO ₄ ) ₃ Cl was produced. FIG. 6 shows an X-ray diffraction pattern of this phosphor. The peak pattern of FIG. ₅ (PO ₄ ) ₃ It can be seen that the crystal structure matches that of Cl. This phosphor was excited at 400 nm, which is the main wavelength in the ultraviolet region of the GaN-based light emitting diode, and the emission spectrum was measured. Table 1 shows the wavelength of the emission peak, the relative emission intensity, and the quantum absorption efficiency α of the phosphor. _q , The quantum absorption efficiency α of the phosphor _q And internal quantum efficiency η _i Product of α _q ・ Η _i showed that.
[0046]
Example 3
SrHPO ₄ 0.1055 mol, SrCl ₂ 0.0176 mol, and Eu ₂ O ₃ Phosphor Sr in the same manner as in Example 1 except that it was changed to 0.0264 mol; _3.5 Eu _1.5 (PO ₄ ) ₃ Cl was produced. FIG. 7 shows an X-ray diffraction pattern of this phosphor. The peak pattern of FIG. ₅ (PO ₄ ) ₃ It can be seen that the crystal structure matches that of Cl. This phosphor was excited at 400 nm, which is the main wavelength in the ultraviolet region of the GaN-based light emitting diode, and the emission spectrum was measured. Table 1 shows the wavelength of the emission peak, the relative emission intensity, and the quantum absorption efficiency α of the phosphor. _q , The quantum absorption efficiency α of the phosphor _q And internal quantum efficiency η _i Product of α _q ・ Η _i showed that.
[0047]
Example 4
SrHPO ₄ 0.0879 mol, SrCl ₂ 0.0176 mol, Eu ₂ O ₃ 0.0352, and (NH ₄ ) ₂ HPO ₄ Phosphor Sr in the same manner as in Example 1 except that it was changed to 0.0176 mol; ₃ Eu ₂ (PO ₄ ) ₃ Cl was produced. FIG. 8 shows an X-ray diffraction pattern of this phosphor. The peak pattern of FIG. ₅ (PO ₄ ) ₃ It can be seen that the crystal structure matches that of Cl. This phosphor was excited at 400 nm, which is the main wavelength in the ultraviolet region of the GaN-based light emitting diode, and the emission spectrum was measured. Table 1 shows the wavelength of the emission peak and the relative emission intensity.
[0048]
Example 5
SrHPO ₄ 0.1055 mol, SrCO ₃ 0.0484 mol, SrCl ₂ 0.0176 mol, CaCO ₃ 0.00176 mol, basic magnesium carbonate (0.0088 mol of Mg) and Eu ₂ O ₃ The phosphor Sr in the same manner as in Example 1 except that the amount was changed to 0.00088 mol; _4.875 Ca _0.05 Mg _0.025 Eu _0.05 (PO ₄ ) ₃ Cl was produced. FIG. 10 shows an X-ray diffraction pattern of this phosphor. The peak pattern of FIG. ₅ (PO ₄ ) ₃ It can be seen that the crystal structure matches that of Cl. This phosphor was excited at 400 nm, which is the main wavelength in the ultraviolet region of the GaN-based light emitting diode, and the emission spectrum was measured. Table 1 shows the wavelength of the emission peak, the relative emission intensity, and the quantum absorption efficiency α of the phosphor. _q , The quantum absorption efficiency α of the phosphor _q And internal quantum efficiency η _i Product of α _q ・ Η _i showed that.
[0049]
Example 6
SrHPO ₄ 0.1055 mol, SrCO ₃ 0.0396 mol, BaCO ₃ 0.00879 mol, basic magnesium carbonate (0.00264 mol of Mg), BaCl ₂ 0.0176 mol, and Eu ₂ O ₃ The phosphor Sr in the same manner as in Example 1 except that the amount was changed to 0.00088 mol; _4.125 Ba _0.75 Mg _0.075 Eu _0.05 (PO ₄ ) ₃ Cl was produced. FIG. 11 shows an X-ray diffraction pattern of this phosphor. The peak pattern of FIG. ₅ (PO ₄ ) ₃ It can be seen that the crystal structure matches that of Cl. This phosphor was excited at 400 nm, which is the main wavelength in the ultraviolet region of the GaN-based light emitting diode, and the emission spectrum was measured. Table 1 shows the wavelength of the emission peak and the relative emission intensity.
[0050]
Example 7
SrHPO ₄ ; 0.0527 mol, SrCl ₂ 0.0176 mol, Eu ₂ O ₃ 0.0527, and (NH ₄ ) ₂ HPO ₄ The phosphor Sr in the same manner as in Example 1 except that the phosphor Sr was changed to 0.0527 mol; ₂ Eu ₃ (PO ₄ ) ₃ Cl was produced. FIG. 12 shows an X-ray diffraction pattern of this phosphor. The peak pattern of FIG. ₅ (PO ₄ ) ₃ It can be seen that the crystal structure matches that of Cl. This phosphor was excited at 400 nm, which is the main wavelength in the ultraviolet region of the GaN-based light emitting diode, and the emission spectrum was measured. Table 1 shows the wavelength of the emission peak, the relative emission intensity, and the quantum absorption efficiency α of the phosphor. _q , The quantum absorption efficiency α of the phosphor _q And internal quantum efficiency η _i Product of α _q ・ Η _i showed that.
[0051]
Example 8
Charged raw material is SrCl ₂ 0.0176 mol, Eu ₂ O ₃ 0.0791, and (NH ₄ ) ₂ HPO ₄ Phosphor Sr in the same manner as in Example 1 except that it was changed to 0.1055 mol. _0.5 Eu _4.5 (PO ₄ ) ₃ Cl was produced. FIG. 13 shows an X-ray diffraction pattern of this phosphor. The peak pattern of FIG. ₅ (PO ₄ ) ₃ It can be seen that the crystal structure matches that of Cl. This phosphor was excited at 400 nm, which is the main wavelength in the ultraviolet region of the GaN-based light emitting diode, and the emission spectrum was measured. Table 1 shows the wavelength of the emission peak and the relative emission intensity.
[0052]
Example 9
SrHPO ₄ 0.1055 mol, SrCO ₃ 0.0302 mol, CaCO ₃ 0.0199 mol, basic magnesium carbonate (0.0088 mol of Mg), BaCl ₂ 0.0176 mol, and Eu ₂ O ₃ The phosphor Sr in the same manner as in Example 1 except that the amount was changed to 0.00088 mol; _3.86 Ba _0.5 Ca _0.565 Mg _0.025 Eu _0.05 (PO ₄ ) ₃ Cl was produced. FIG. 14 shows an X-ray diffraction pattern of this phosphor. The peak pattern of FIG. ₅ (PO ₄ ) ₃ It can be seen that the crystal structure matches that of Cl. This phosphor was excited at 400 nm, which is the main wavelength in the ultraviolet region of the GaN-based light emitting diode, and the emission spectrum was measured. Table 1 shows the wavelength of the emission peak and the relative emission intensity.
[0053]
Example 10
SrHPO ₄ 0.1055 mol, SrCO ₃ ; 0.0121 mol, BaCO ₃ 0.0204 mol, CaCO ₃ 0.0176 mol, basic magnesium carbonate (0.0088 mol of Mg), BaCl ₂ 0.0176 mol, and Eu ₂ O ₃ The phosphor Sr in the same manner as in Example 1 except that the amount was changed to 0.00088 mol; _3.345 Ba _1.08 Ca _0.5 Mg _0.025 Eu _0.05 (PO ₄ ) ₃ Cl was produced. FIG. 15 shows an X-ray diffraction pattern of this phosphor. The peak pattern of FIG. ₅ (PO ₄ ) ₃ It can be seen that the crystal structure matches that of Cl. This phosphor was excited at 400 nm, which is the main wavelength in the ultraviolet region of the GaN-based light emitting diode, and the emission spectrum was measured. Table 1 shows the wavelength of the emission peak and the relative emission intensity.
[0054]
Example 11
Calcium chloride dihydrate; 0.01382 mol, europium chloride hexahydrate; 0.00028 mol were weighed and dissolved in 20 ml of water. To this aqueous solution, 0.00846 mol of 85% phosphoric acid as phosphoric acid was added, and the mixed solution was transferred to a magnetic dish to make the total solution volume 30 to 40 ml. This solution was heated and dried with stirring. The solid after drying was collected and ground in an agate mortar. A part of the pulverized product was transferred to an alumina crucible and baked at 1000 ° C. for 2 hours under a nitrogen gas flow containing 4% hydrogen to obtain phosphor Ca. _4.9 Eu _0.1 (PO ₄ ) ₃ Cl was produced.
[0055]
Table 1 shows the wavelength of the emission peak and the relative emission intensity when this phosphor is excited at 400 nm, which is the main wavelength in the ultraviolet region of the GaN-based light emitting diode.
Example 12
Calcium chloride dihydrate; 0.01325 mol, europium chloride hexahydrate; 0.00055 mol were weighed and dissolved in 20 ml of water. To this aqueous solution, 0.00828 mol of 85% phosphoric acid as phosphoric acid was added, and the mixed solution was transferred to a magnetic dish to make the total solution volume 30 to 40 ml. This solution was heated and dried with stirring. Hereinafter, the phosphor Ca was prepared in the same manner as in Example 11. _4.8 Eu _0.2 (PO ₄ ) ₃ Cl was produced.
[0056]
Table 1 shows the wavelength of the emission peak and the relative emission intensity when this phosphor is excited at 400 nm, which is the main wavelength in the ultraviolet region of the GaN-based light emitting diode.
Example 13
Calcium chloride dihydrate; 0.0122 mol, europium chloride hexahydrate; 0.00106 mol were weighed and dissolved in 20 ml of water. To this aqueous solution, 0.00796 mol of 85% phosphoric acid as phosphoric acid was added, and the mixed solution was transferred to a magnetic dish to make the total solution volume 30 to 40 ml. Further, 50 microliters of a 35% hydrochloric acid aqueous solution was added dropwise, and the mixture was heated and dried under stirring. Hereinafter, the phosphor Ca was prepared in the same manner as in Example 11. _4.6 Eu _0.4 (PO ₄ ) ₃ Cl was produced.
[0057]
Table 1 shows the wavelength of the emission peak and the relative emission intensity when this phosphor is excited at 400 nm, which is the main wavelength in the ultraviolet region of the GaN-based light emitting diode.
Example 14
Calcium chloride dihydrate; 0.0117 mol, europium chloride hexahydrate; 0.0013 mol were weighed and dissolved in 20 ml of water. To this aqueous solution, 0.0078 mol of 85% phosphoric acid as phosphoric acid was added, and the mixed solution was transferred to a magnetic dish to make the total solution volume 30 to 40 ml. Further, 50 microliters of a 35% hydrochloric acid aqueous solution was added dropwise, and the mixture was heated and dried under stirring. Hereinafter, the phosphor Ca was prepared in the same manner as in Example 11. _4.5 Eu _0.5 (PO ₄ ) ₃ Cl was produced.
[0058]
Table 1 shows the wavelength of the emission peak and the relative emission intensity when this phosphor is excited at 400 nm, which is the main wavelength in the ultraviolet region of the GaN-based light emitting diode.
Example 15
0.01054 mol of calcium chloride dihydrate; 0.00186 mol of europium nitrate hexahydrate were weighed and dissolved in 20 ml of water. To this aqueous solution, 0.00744 mol of 85% phosphoric acid as phosphoric acid was added, and the mixed solution was transferred to a magnetic dish to make the total solution volume 30 to 40 ml. Further, 100 microliters of a 35% hydrochloric acid aqueous solution was added dropwise, and the mixture was heated and dried under stirring. Hereinafter, the phosphor Ca was prepared in the same manner as in Example 11. _4.25 Eu _0.75 (PO ₄ ) ₃ Cl was produced. The X-ray diffraction pattern of this phosphor was Ca ₅ (PO ₄ ) ₃ It was found that the crystal structure was consistent with that of Cl.
[0059]
Table 1 shows the wavelength of the emission peak and the relative emission intensity when this phosphor is excited at 400 nm, which is the main wavelength in the ultraviolet region of the GaN-based light emitting diode.
Example 16
0.00948 mol of calcium chloride dihydrate; 0.00237 mol of europium nitrate hexahydrate was weighed and dissolved in 20 ml of water. To this aqueous solution, 0.00711 mol of 85% phosphoric acid as phosphoric acid was added, and the mixed solution was transferred to a magnetic dish to make the total solution volume 30 to 40 ml. Further, 150 microliters of a 35% hydrochloric acid aqueous solution was added dropwise, and the mixture was heated and dried under stirring. Hereinafter, the phosphor Ca was prepared in the same manner as in Example 11. ₄ Eu ₁ (PO ₄ ) ₃ Cl was produced.
[0060]
Table 1 shows the wavelength of the emission peak and the relative emission intensity when this phosphor is excited at 400 nm, which is the main wavelength in the ultraviolet region of the GaN-based light emitting diode.
Comparative Example 1
BaCO ₃ 0.0103 mol, basic magnesium carbonate (mol number of Mg of 0.0103 mol), and γ-Al ₂ O ₃ 0.0570 mol, and Eu as an element source compound of the emission center ion ₂ O ₃ 0.00057 mol was mixed with pure water in an alumina container and beads in a wet ball mill, mixed and dried, passed through a nylon mesh, and the obtained ground mixture was added to an alumina crucible at 4%. Baking by heating at 1500 ° C. for 2 hours in a flow of nitrogen gas containing hydrogen, followed by washing with water, drying, and classification to obtain a blue-emitting phosphor Ba. _0.9 Eu _0.1 MgAl ₁₀ O ₁₇ Was manufactured. FIG. 5 shows an emission spectrum when this phosphor was excited at 400 nm, which is the main wavelength in the ultraviolet region of the GaN-based light-emitting diode, and the performance of the blue light-emitting phosphor of Example 1 and Comparative Example 1 was compared. Table 1 shows the wavelength of the emission peak and the relative emission intensity. It can be seen that the emission intensity of the phosphor of Example 1 when excited by 400 nm is 5.1 times that of the phosphor of Comparative Example 1.
[0061]
Comparative Example 2
SrHPO ₄ 0.0897 mol, BaCO ₃ 0.0325 mol, CaCO ₃ 0.0176 mol, basic magnesium carbonate (0.0088 mol of Mg), BaCl ₂ ; 0.0176 mol, BaHPO ₄ 0.0158 mol, and Eu ₂ O ₃ The phosphor Sr in the same manner as in Example 1 except that the amount was changed to 0.00088 mol; _2.55 Ba _1.875 Ca _0.5 Mg _0.025 Eu _0.05 (PO ₄ ) ₃ Cl was produced. Table 1 shows the wavelength and relative intensity of the emission peak when this phosphor was excited at 400 nm, which is the main wavelength in the ultraviolet light region of the GaN-based light emitting diode. FIG. 5 shows an emission spectrum when this phosphor was excited at 400 nm, which is the main wavelength in the ultraviolet region of the GaN-based light emitting diode, and the performances of the blue light emitting phosphors of Example 1 and Comparative Example 2 were compared. Table 1 shows the wavelength of the emission peak and the relative emission intensity. It can be seen that the emission intensity of the phosphor of Example 1 when excited by 400 nm is 5.1 times that of the phosphor of Comparative Example 2.
[0062]
[Table 1]

[0063]
【The invention's effect】
According to the present invention, a light emitting device with high light emission intensity can be provided.
[Brief description of the drawings]
FIG. 1 Sr ₅ (PO ₄ ) ₈ X-ray diffraction pattern of Cl (converted to X-ray source Cu Kα)
FIG. 2 is a schematic perspective view showing an example of a light emitting device in which a film phosphor is brought into contact with a surface-emitting GaN-based diode.
FIG. 3 is a schematic sectional view showing one embodiment of the light emitting device of the present invention.
FIG. 4 is an X-ray diffraction pattern (X-ray source: Cu Kα) of the phosphor of Example 1 of the present invention.
FIG. 5 is a spectrum obtained by superimposing the emission spectra of the respective phosphors of Example 1, Comparative Example 1, and Comparative Example 2 of the present invention irradiated with a GaN-based light emitting diode having an emission wavelength of 400 nm.
FIG. 6 is an X-ray diffraction pattern (X-ray source: Cu Kα) of the phosphor of Example 2 of the present invention.
FIG. 7 is an X-ray diffraction pattern (X-ray source: Cu Kα) of the phosphor of Example 3 of the present invention.
FIG. 8 is an X-ray diffraction pattern (X-ray source: Cu Kα) of the phosphor of Example 4 of the present invention.
FIG. 9 is a schematic cross-sectional view showing an example of the surface emitting lighting device of the present invention.
FIG. 10 is an X-ray diffraction pattern (X-ray source: Cu Kα) of the phosphor of Example 5 of the present invention.
FIG. 11 is an X-ray diffraction pattern (X-ray source: Cu Kα) of the phosphor of Example 6 of the present invention.
FIG. 12 is an X-ray diffraction pattern (X-ray source: Cu Kα) of the phosphor of Example 7 of the present invention.
FIG. 13 is an X-ray diffraction pattern (X-ray source: Cu Kα) of the phosphor of Example 8 of the present invention.
FIG. 14 is an X-ray diffraction pattern (X-ray source: Cu Kα) of the phosphor of Example 9 of the present invention.
FIG. 15 is an X-ray diffraction pattern (X-ray source: Cu Kα) of the phosphor of Example 10 of the present invention.
FIG. 16 shows a spectrum I obtained by measuring a spectrophotometer with a reflector attached. _ref (Λ)
FIG. 17: Quantum absorption efficiency α in the spectrophotometer _q , Internal quantum efficiency η _i Spectrum (I (λ)) when a sample to be measured was attached and measured.
[Explanation of symbols]
1; second luminous body
2: Surface-emitting GaN-based LED
3: substrate
4: Light emitting device
5; Mount lead
6; inner lead
7; first light emitter (light emitter of 350 to 415 nm)
8; Resin portion containing phosphor of the present invention
9; conductive wire
10; Mold member

Claims (21)

In a light-emitting device including a first light-emitting body that emits light of 350 to 415 nm and a second light-emitting body that emits visible light by irradiation with light from the first light-emitting body, the second light-emitting body is A light emitting device comprising a phosphor satisfying the following conditions (A) and / or (B):
(A) quantum absorption efficiency alpha _q is 0.8 or more (B) a product α _q · η _i of a quantum absorption efficiency alpha _q and internal quantum efficiency eta _i is 0.55 or more 2. The light emitting device according to claim 1, wherein the phosphor contains a crystal phase having a chemical composition represented by the general formula [1].
Embedded image
_{Eu a Sr b M 5-a} -b (PO 4) c X d ······ [1]
(In the general formula [1], M represents a metal element other than Eu and Sr. X represents a monovalent anion group other than PO _4. C and d are 2.7 ≦ c ≦ 3. 3, a number that satisfies 0.9 ≦ d ≦ 1.1, where a is a> 0 and b is a number that satisfies b ≧ 0 and a + b ≦ 5, but is a ≧ 0.1 or b ≧ 3. Satisfies the conditions.) In a light-emitting device including a first light-emitting body that emits light of 350 to 415 nm and a second light-emitting body that emits visible light by irradiation of light from the first light-emitting body, the second light-emitting body Comprises a phosphor having a crystal phase having a chemical composition represented by the general formula [1].
Embedded image
_{Eu a Sr b M 5-a} -b (PO 4) c X d ······ [1]
(In the general formula [1], M represents a metal element other than Eu and Sr. X represents a monovalent anion group other than PO _4. C and d are 2.7 ≦ c ≦ 3. 3, a number that satisfies 0.9 ≦ d ≦ 1.1, where a is a> 0 and b is a number that satisfies b ≧ 0 and a + b ≦ 5, but is a ≧ 0.1 or b ≧ 3. Satisfies the conditions.) The light emitting device according to claim 3, wherein b is greater than 0. The light emitting device according to any one of claims 1 to 4, wherein the first light emitting body is a laser diode or a light emitting diode. The light emitting device according to claim 5, wherein the first light emitter is a laser diode. 3. The device according to claim 2, wherein a and b satisfy 0.1 ≦ a <5 and 0.01 ≦ b <5, or satisfy 0.0001 ≦ a <5 and 3 ≦ b <5. 7. The light emitting device according to any one of items 6 to 6. The light emitting device according to any one of claims 2 to 7, wherein 70 mol% or more of the element M is at least one element selected from the group consisting of Ba, Mg, Ca, Zn, and Mn. . 9. The light emitting device according to claim 2, wherein 50 mol% or more of X is Cl. The light emitting device according to claim 2, wherein a and b satisfy a ≧ 0.1 and b ≧ 3. The light emitting device according to claim 2, wherein a satisfies a> 0.2. The light emitting device according to claim 11, wherein a satisfies 0.2 <a ≦ 3. The light emitting device according to any one of claims 2 to 12, wherein the element M is at least one selected from the group consisting of Ba, Mg, Ca, Zn, and Mn, and X is Cl. The light emitting device according to any one of claims 2 to 13, wherein the element M is at least one selected from the group consisting of Ba, Mg, and Ca, and X is Cl. The light emitting device according to claim 1, wherein the first light emitter uses a GaN-based compound semiconductor. The light emitting device according to any one of claims 1 to 15, wherein the first light emitter is a surface emitting GaN-based laser diode. The light emitting device according to any one of claims 1 to 16, wherein the second luminous body has a film shape. 18. The light emitting device according to claim 17, wherein the light emitting surface of the first light emitting body is brought into direct contact with the film surface of the second light emitting body. 19. The light-emitting device according to claim 1, wherein the second light-emitting body is formed by dispersing phosphor powder in a resin. 20. The light extracted from the light emitting device is light obtained by mixing light from the first light emitter and light from the second light emitter, and the extracted light is white. The light emitting device according to any one of the above. A lighting device comprising the light-emitting device according to claim 1.

Images