JP4303989B2 - Fluorescent substance and fluorescent lamp - Google Patents
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- JP4303989B2 JP4303989B2 JP2003079095A JP2003079095A JP4303989B2 JP 4303989 B2 JP4303989 B2 JP 4303989B2 JP 2003079095 A JP2003079095 A JP 2003079095A JP 2003079095 A JP2003079095 A JP 2003079095A JP 4303989 B2 JP4303989 B2 JP 4303989B2
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【０００１】
【発明の属する技術分野】
本発明は、特に水銀封入形の蛍光ランプ等の蛍光膜として使用した際、経時的な輝度低下の少ない蛍光ランプ用蛍光体及びこの蛍光体を使用した光束維持率の改善された蛍光ランプに関する。
【０００２】
【従来の技術】
一般照明用の蛍光ランプとしては、ハロ燐酸塩系蛍光体を蛍光膜とする旧来の白色発光蛍光ランプに加えて、いわゆる三波長域発光形の蛍光ランプが実用化され、高効率性と高演色性とを同時に満足することから三波長域発光形蛍光ランプが、近年、一般照明用の蛍光ランプの主流になってきている。三波長域発光形蛍光ランプは、比較的狭帯域の発光スペクトル分布を有する、青色発光、緑色発光及び赤色発光の３種の蛍光体を任意の割合で混合し、この混合蛍光体からなる蛍光膜（蛍光体層）を蛍光ランプの外囲器であるガラス管の内壁面に形成した構成を有している。これらの蛍光ランプはランプの管内に封入された水銀蒸気の放電によって生じる紫外線で、ランプ管内壁に形成された蛍光膜を励起して発光させる機構を有している。近年、これら蛍光ランプは一般照明用に限らず、ＯＡ機器用光源や液晶ディスプレイのバックライトなどにも利用され、その利用分野が拡大してきている。デイスプレイ素子の色再現に関する基本性能は３原色の色度座標値（色再現範囲）及び白、黒の色度座標値で表される。液晶表示装置（以下ＬＣＤ）にはバックライトと呼ばれる面光源を内蔵したタイプと周囲光を利用するタイプとがある。バックライト内蔵型のカラーＬＣＤでは、液晶によりバックライトからの光の強度を制御し、画素毎に配置されたＲＧＢの３原色のモザイク状カラーフィルターにより、いずれかの波長域の光を選択的に透過させて、併置混色により任意の色を再現している。これらのバックライトにはＲ、Ｇ及びＢの３原色の波長域にそれぞれの発光スペクトル分布を有する蛍光体の混合物を使用した３波長型蛍光ランプが用いられ、またそれを構成する陰極については、細管化が容易であること、長寿命であること、及び低コストであることの理由から冷陰極型が多く用いられている。
【０００３】
従来の三波長域発光形蛍光ランプでは、継続的な点灯中での光束維持率の低下があり、その寿命が必ずしも十分ではないためにその応用分野の拡大を妨げていた。蛍光ランプにおける光束維持率の低下（蛍光体輝度の低下）の原因としては、主に蛍光体表面に蛍光ランプ中の水銀やその化合物等が付着することや、その波長が１８５ｎｍの低波長紫外線による蛍光体表面のダメージ等によるものと考えられている。この様な問題に対し、蛍光ランプ中の水銀や水銀の化合物等による蛍光体の汚染を抑制するための試みとして、蛍光体表面に酸化マグネシウム等のアルカリ土類金属の酸化物を被覆させたり、あるいは水酸化マグネシウムを付着させる（特開平５−２５４７５号公報参照）等の改善策が従来より提案されている。しかし、これらの表面処理が施された蛍光体を用いた蛍光ランプでは、ランプの光束維持率の低下を抑制する効果は、必ずしも十分ではなかった。中でも青色の蛍光体は他の色に比較して経時劣化が大きいため、経時劣化の少ない青色蛍光体が求められていた。
【０００４】
【発明が解決しようとする課題】
本発明は、この様な問題を解決するためになされたもので、色純度がよく、蛍光ランプの蛍光膜として使用した場合、点灯中のランプの輝度低下を効果的に抑制することを可能にした蛍光体、および光束維持率の高い長寿命の蛍光ランプを提供することを目的とする。
【０００５】
【課題を解決するための手段】
本発明者は、上記の目的を達成するために、一般式ａ（Ｍ１−ｘＥｕｘ）Ｏ・６Ａｌ２Ｏ３で表される蛍光体について鋭意検討し、特願２００１−０２４５１３２、２００２−１４３５２４、２００２−１４３５２５、２００３−２９４６０明細書において新たな青色蛍光体を提案しているが、これらの蛍光体の表面処理方法、特に蛍光体表面に付着させる表面処理物質について更なる検討を重ねた結果、蛍光体粒子表面に炭酸塩化合物を付着させることにより、長時間紫外線照射を受けても発光輝度の低下が少なく、この蛍光体を蛍光膜として用いると光束維持率の高い長寿命の蛍光ランプが得られることを見いだし、本発明に至った。
【０００６】
本発明は以下の構成を有する。
（１）一般式、ａ（ＭＩ １−ｘ−ｙＥｕｘＭＩＩ ２ｙ）Ｏ・Ａｌ１２−ｚ−ｋＭＩＩＩ ｚＭＩＶ ｋＯ１８で表されるアルカリ土類アルミン酸塩蛍光体（但し前記式中、ａは０．９≦ａ≦１．８を満たす数であり、ＭＩはＢａ、ＳｒおよびＣａから成る群より選択される少なくとも１種のアルカリ土類金属元素を表し、ｘは０＜ｘ＜１であり、ＭＩＩはＬｉ、Ｔｌから成る群より選択される少なくとも１種で、ｙは０≦ｙ＜１、ｘ＋２ｙ＜１であり、ＭＩＩＩはＢ、Ｌａから成る群より選択される少なくとも１種で、ｚは０≦ｚ＜２であり、ＭＩＶはＳｃ、Ｙ、Ｇｄ、Ｉｎ、Ｇａ、Ｃｅ、Ｔｍ、Ｙｂ、Ｂｉから成る群より選択される少なくとも１種で、ｋは０≦ｋ＜２である）において、該蛍光体の粒子表面に該蛍光体に対して０．００５〜５重量％の炭酸バリウム、炭酸カルシウム、及び希土類金属炭酸塩の中の少なくとも１種が付着していることを特徴とする蛍光ランプ用蛍光体。
【０００７】
（２）前記希土類金属炭酸塩が炭酸ランタン、炭酸ガドリニウムもしくは炭酸イットリウムであることを特徴とする前記（１）に記載の蛍光ランプ用蛍光体。
（３）前記蛍光体のＣｕＫα１特性Ｘ線による粉末回折Ｘ線スペクトルにおいて、該スペクトルの回折角（２θ）が２８°〜３１°の角度領域にわたって幅広い帯状のピークを有することを特徴とする前記（１）又は（２）に記載の蛍光ランプ用蛍光体。
【０００８】
（４）前記蛍光体が水銀蒸気放電ランプ用蛍光体であることを特徴とする（１）〜（３）のいずれかに記載の蛍光ランプ用蛍光体。
（５）ガラス管の内壁面に形成された蛍光膜を具備する蛍光ランプにおいて、前記蛍光膜は前記（１）〜（４）のいずれかに記載の蛍光ランプ用蛍光体を含むことを特徴とする蛍光ランプ。
（６）冷陰極を使用したことを特徴とする前記（５）に記載の蛍光ランプ。
【０００９】
【発明の実施の形態】
以下、本発明を更に詳細に説明する。
蛍光体粒子の表面に炭酸バリウム、炭酸カルシウム、及び希土類金属炭酸塩の中の少なくとも１種の炭酸塩化合物（本願明細書では、以下、これらを総称して単に炭酸塩化合物、又は金属炭酸塩化合物ともいう）が付着した本発明の蛍光体は、所定量の炭酸塩化合物の微粉末とコアとなる蛍光体（コア蛍光体）とを溶媒中で混合して蛍光体スラリーとし、このスラリーを十分に混合した後、脱水、乾燥することにより、製造することができる。この時用いられる溶媒としては水を用いるのが取り扱い性の点で好ましいが、例えば、エタノール等のアルコールやアセトンなどの有機溶剤を使用してもよい。
また、本発明の蛍光体は、蛍光体のスラリー中に所定量の炭酸イオンを含有する溶液と、この炭酸イオンと化学反応して前記炭酸塩化合物を生成し得るだけのバリウム、カルシウム、又は希土類の金属イオンを含有する溶液とを投入するか、または所定量の水に可溶性の炭酸塩の化合物及びバリウム、カルシウム、又は希土類金属の化合物を蛍光体スラリー中に投入するかして、所望の金属炭酸塩化合物を反応生成させ蛍光体表面に沈澱析出、付着させると言った方法でも製造することが出来る。
【００１０】
本発明の蛍光体において、蛍光体表面に最終的に付着させる炭酸塩化合物は、水に対し難溶性もしくは不溶性の化合物であり、炭酸アンモニウム等の非金属の炭酸塩化合物よりも、金属の炭酸塩化合物であることが好ましい。但し、金属炭酸塩化合物の中でもアルカリ金属の炭酸塩は、例えばＨｇを使用した蛍光ランプ用蛍光体として用いた場合、蛍光体表面への水銀付着を加速し光束の劣化を促進するため好ましくない。したがい水銀などに対してより安定であり、水に難溶性もしくは不溶性であり、蛍光体表面に安定に付着させられることから、金属炭酸塩化合物の中でもアルカリ土類金属の炭酸バリウム、炭酸カルシウムや希土類の炭酸塩化合物が、特に好ましいと言える。
【００１１】
本発明の蛍光体において、表面に付着させるアルカリ土類金属や希土類の炭酸塩化合物は、例えばアルカリ土類金属や希土類の酸化物に比べてより疎水性であり、また、結晶水を取り込んだ場合でもより安定化される作用があるため、これらの酸化物を表面に付着させた蛍光体に比べて、これらの炭酸塩化合物を付着させた蛍光体の方が蛍光体全体にとって水分の取り込みが抑制される。従って、これらの炭酸塩化合物を表面に付着させた本発明の蛍光体を用いて蛍光ランプを作製すると、ランプ作製時におけるベーキング工程での残留付着水分の低減化がはかられ、また蛍光ランプ使用時においても、脱ガス化が効果的に抑制され、更に出来上がった蛍光ランプの管内のガス汚染が抑制される。そのためこの様な目的の為に用いられる炭酸塩化合物は、脱炭酸温度が６００℃以上の物が好ましく、８００℃以上の物は更に好ましい。ここで述べる脱炭酸温度とは炭酸塩化合物が脱炭酸し炭酸塩全てが酸化物に変化してしまう温度を意味する。
【００１２】
本発明の蛍光体の表面に付着させる炭酸塩化合物は、単独の化合物であっても、または複数種の炭酸塩化合物の混合物であっても良い。またここで述べている炭酸塩は結晶水を含有している物、アルカリ土類金属、希土類金属及び炭酸根を主成分とする複塩の形を形成している場合も含む。蛍光体表面に付着させる炭酸塩化合物の好ましい付着量は、コア蛍光体に対して０．００５〜５．０重量％、更に好ましくはコア蛍光体に対して０．０１〜３．０重量％の範囲に調整することが好ましい。コア蛍光体表面に付着させる炭酸塩化合物の量が蛍光体に対して０．００５重量％より少ないと、経時的な発光輝度の低下を防ぐ効果が得られず、逆に５重量％を超えると、蛍光体中において非発光成分の比率が高くなるために、蛍光体の発光輝度が低下する。これを蛍光膜として使用した場合もまた、蛍光ランプの全光束が低下してしまうので好ましくない。
【００１３】
なお炭酸塩化合物が表面に付着されるコア蛍光体としては、１）Ｂａ、ＳｒおよびＣａから成る群より選択される少なくとも１種のアルカリ土類元素、２）Ａｌ元素、３）Ｌｉ、Ｔｌから成る群より選択される少なくとも一種の元素、４）ＢおよびＬａから成る群より選択される少なくとも一種の元素、５）Ｓｃ、Ｙ、Ｇｄ、Ｉｎ、Ｇａ、Ｃｅ、Ｔｍ、Ｙｂ、Ｂｉから成る群より選択される元素および６）付活剤であるＥｕ元素の各酸化物、またはこれら１）〜６）の各元素の炭酸塩、硫酸塩、ハロゲン化物等の化合物を、化学量論的にａ（ＭＩ １−ｘ−ｙＥｕｘＭＩＩ ２ｙ）Ｏ・Ａｌ１２−ｚ−ｋＭＩＩＩ ｚＭＩＶ ｋＯ１８（但し前記式中、ａは０．９≦ａ≦１．８を満たす数であり，ＭＩはＢａ、ＳｒおよびＣａから成る群より選択される少なくとも１種のアルカリ土類金属元素を表し、０＜ｘ＜１であり、ＭＩＩはＬｉ、Ｔｌから成る群より選択される少なくとも１種で、０≦ｙ＜１、ｘ＋２ｙ＜１であり、ＭＩＩＩはＢ、Ｌａから成る群より選択される少なくとも１種で０≦ｚ＜２であり、ＭＩＶはＳｃ、Ｙ、Ｇｄ、Ｉｎ、Ｇａ、Ｃｅ、Ｔｍ、Ｙｂ、Ｂｉから成る群より選択される少なくとも１種で０≦ｋ＜２である）となる割合で秤取し、これらの混合物からなる蛍光体原料化合物を十分混合し、アルミナ坩堝等の耐熱容器に充填して焼成し、得られた焼成物に通常の蛍光体製造時に適用される後処理工程と同様に分散、水洗、乾燥、篩分けの諸処理を施すことによって一般式、ａ（ＭＩ １−ｘ−ｙＥｕｘＭＩＩ ２ｙ）Ｏ・Ａｌ１２−ｚ−ｋＭＩＩＩ ｚＭＩＶ ｋＯ１８で表される本発明のアルカリ土類アルミン酸塩蛍光体を製造することができる。なお、本発明において一般式、ａ（ＭＩ１−ｘ−ｙＥｕｘＭＩＩ ２ｙ）Ｏ・Ａｌ１２−ｚ−ｋＭＩＩＩ ｚＭＩＶ ｋＯ１８で表される蛍光体とは、蛍光体中に含有されているＭＩ、Ａｌ、Ｅｕ及びＭＩＩ、ＭＩＩＩ、ＭＩＶの各金属元素の構成比が上記一般式を満足する蛍光体をいう。
【００１４】
本発明のアルカリ土類アルミン酸塩蛍光体は、紫外線励起したときの発光輝度の観点から、特に、ａ（ＭＩ １−ｘ−ｙＥｕｘＭＩＩ ２ｙ）Ｏ・Ａｌ１２−ｚ−ｋＭＩＩＩ ｚＭＩＶ ｋＯ１８なる組成式において、ａ値、ｘ値がそれぞれ１．１≦ａ≦１．５、０．０５≦ｘ≦０．５であることがより好ましい。
また同様な観点から、蛍光体の母体結晶の一部を構成するＭＩ元素がＢａであるか、もしくは５０モル％以下、より好ましくは２０モル％以下のＢａをＳｒおよびＣａの中の少なくとも１つで置換したアルカリ土類金属元素であることが好ましい。また本発明のコア蛍光体としては、特願２００３−２９４６０にある様に、蛍光体中に硫黄元素を含有していると更に好ましい。
なお、この様にして作製された本発明蛍光体は特徴として粉末回折Ｘ線スペクトルにおいて、回折角（２θ°）が２８°〜３１°角度領域にわたって図１に示される様な幅広い帯状のピークを有している。
【００１５】
また、本発明の蛍光ランプはポリエチレンオキサイドなどの水溶性バインダー溶液もしくはニトロセルロースのような有機バインダー溶液に、上述のようにして得られた、炭酸塩化合物が表面に付着した本発明の所望の蛍光体を分散させ、これに結着剤を添加してスラリー化して蛍光体塗布液を調製し、この蛍光体塗布液をガラス管の内壁に塗布し、本発明の蛍光体より構成される蛍光膜以外は、一般に知られている従来の製造方法で水銀蒸気放電ランプ、さらに詳細には熱陰極型ランプや冷陰極ランプが各々製造される。
【００１６】
【作用】
本発明の蛍光体は、蛍光体表面に化学的に安定な特定の炭酸塩化合物が付着していることにより、この蛍光体を蛍光膜として用いた蛍光ランプのランプ点灯中における、水銀やその化合物等による蛍光膜中の蛍光体の汚染に基く光束維持率の低下を、効果的に抑制することができる。その理由としては、蛍光ランプ点灯中にランプ内に放射されている波長１８５ｎｍの紫外線、２００ｎｍ以下の短波長紫外線等による蛍光体表面のダメージを特定の炭酸塩化合物表面付着物であるアルカリ土類金属や希土類の炭酸塩化合物等により、効果的に抑制していると考えられる。
また詳細な調査によると、本発明の炭酸塩化合物が付着した蛍光体は、水銀を用いた蛍光ランプにおいて、水銀付着を低減させる効果を有していることが分かった。
【００１７】
【実施例】
以下、実施例により本発明を説明する。
〔実施例１〕
ＢａＣＯ３ ：１．１５７４ モル
Ｅｕ２Ｏ３ ：０．０６４３ モル
Ａｌ２Ｏ３ ：６．０ モル
ＡｌＦ３ ：０．０１ モル
上記各蛍光体原料を十分混合した後、アルミナ坩堝に充填し黒鉛を入れ、蓋をして水蒸気を含んだ窒素中で最高温度１６００℃で昇降温時間を含め２４時間かけて焼成した。この蛍光体のＣｕＫα１特性Ｘ線による粉末回折Ｘ線スペクトルを測定したところ、図１に示すように回折角（２θ）が２８°〜３１°の角度領域にかけて幅広い帯状のピークが観測された。該幅広い帯状のピークを有しており、半値幅が１．１０°であった。
【００１８】
得られた蛍光体（コア蛍光体）１００ｇと重炭酸アンモニウム３．５ｇを純水３００ｍｌ中に投入して充分に撹拌してコア蛍光体スラリーを調製した。次に、このコア蛍光体スラリー中に１．２ｍｏｌ／ｌの硝酸イットリウム水溶液を４．７ｍｌ添加し、その蛍光体スラリー中において炭酸イットリウムの沈殿を生成させ、さらにこの蛍光体スラリーを十分に攪拌してから濾過した後、水洗と脱水を行って乾燥し、最後に篩を行って、組成式が１．２８６（Ｂａ０．９Ｅｕ０．１）Ｏ・６Ａｌ２Ｏ３であって、蛍光体に対して１重量％の炭酸イットリウムが表面に付着した実施例１のアルカリ土類アルミン酸塩蛍光体を製造した。
【００１９】
次に、コア蛍光体として実施例１の蛍光体を用いた以外は常法に従って４０Ｗの直管形蛍光ランプを製造した。すなわち、上記実施例１の蛍光体をニトロセルロース−酢酸ブチルの混合溶剤によく分散させて蛍光体塗布スラリーを調製し、このスラリーを蛍光ランプのガラスバルブの内壁面に塗布し、これを乾燥させた後、およそ５５０℃でベーキングし、ガラスバルブの両端に熱陰極型電極を取り付けた。その後更にガラスバルブの中を真空排気し、アルゴンガスと水銀を注入することにより、実施例１の蛍光体を用いた蛍光ランプを製造した。
【００２０】
〔比較例１〕
これとは別に、比較のために、実施例１の蛍光体の代わりに、表面に炭酸イットリウムが付着される前の未処理コア蛍光体を用いた以外は実施例１と同様にして比較例１の蛍光ランプを製造した。
【００２１】
〔実施例２〕
実施例１の蛍光体の製造時において、コア蛍光体スラリー中に１．２ｍｏｌ／ｌの硝酸イットリウム水溶液を４．７ｍｌ添加する代わりに、１．２ｍｏｌ／ｌの硝酸ランタン水溶液を３．７ｍｌ添加した以外は実施例１の蛍光体と同様にして蛍光体に対して１重量％の炭酸ランタンが表面に付着した実施例２のアルカリ土類アルミン酸塩蛍光体を製造した。
次に、蛍光体として、表面に炭酸イットリウムを付着させた実施例１の蛍光体に代えて表面に炭酸ランタンを付着させた実施例２の蛍光体を用いた以外は実施例１の蛍光ランプと同様にして実施例２の蛍光ランプを作製した。
【００２２】
〔実施例３〕
実施例１の蛍光体の製造時において、コア蛍光体スラリー中に１．２ｍｏｌ／ｌの硝酸イットリウム水溶液を４．７ｍｌ添加する代わりに、１．２ｍｏｌ／ｌの硝酸ガドリニウム水溶液を３．３ｍｌ添加した以外は実施例１の蛍光体と同様にして蛍光体に対して１重量％の炭酸ガドリニウムが表面に付着した実施例３のアルカリ土類アルミン酸塩蛍光体を製造した。
次に、蛍光体として、表面に炭酸イットリウムを付着させた実施例１の蛍光体に代えて表面に炭酸ガドリニウムを付着させた実施例３の蛍光体を用いた以外は実施例１の蛍光ランプと同様にして実施例３の蛍光ランプを作製した。
【００２３】
〔実施例４〕
実施例１の蛍光体の製造時において、コア蛍光体スラリー中に１．２ｍｏｌ／ｌの硝酸イットリウム水溶液を４．７ｍｌ添加する代わりに、１．２ｍｏｌ／ｌの酢酸バリウム水溶液を４．３ｍｌ添加した以外は実施例１の蛍光体と同様にして蛍光体に対して１重量％の炭酸バリウムが表面に付着した実施例４のアルカリ土類アルミン酸塩蛍光体を製造した。
次に、蛍光体として、表面に炭酸イットリウムを付着させた実施例１の蛍光体に代えて表面に炭酸バリウムを付着させた実施例４の蛍光体を用いた以外は実施例１の蛍光ランプと同様にして実施例４の蛍光ランプを作製した。
【００２４】
〔実施例５〕
実施例１の蛍光体の製造時において、コア蛍光体スラリー中に１．２ｍｏｌ／ｌの硝酸イットリウム水溶液を４．７ｍｌ添加する代わりに、１．２ｍｏｌ／ｌの硝酸カルシウム水溶液を８．３ｍｌ添加した以外は実施例１の蛍光体と同様にして蛍光体に対して１重量％の炭酸カルシウムが表面に付着した実施例５のアルカリ土類アルミン酸塩蛍光体を製造した。
次に、蛍光体として、表面に炭酸イットリウムを付着させた実施例１の蛍光体に代えて表面に炭酸カルシウムを付着させた実施例５の蛍光体を用いた以外は実施例１の蛍光ランプと同様にして実施例５の蛍光ランプを作製した。
【００２６】
〔実施例７〕
コア蛍光体としてＹ２Ｏ３：Ｅｕ蛍光体及びＬａＰＯ４：Ｃｅ，Ｔｂ蛍光体を用い、実施例１の蛍光体と同様にしてこれらのコア蛍光体の表面にそれぞれ１重量％の炭酸イットリウムを付着させた赤色発光成分であるＹ２Ｏ３：Ｅｕ蛍光体と緑色発光成分蛍光体であるＬａＰＯ４：Ｃｅ，Ｔｂ蛍光体を製造した。
次に、青色発光成分である実施例１の蛍光体と、上述のようにして得た表面にそれぞれ炭酸イットリウムを付着させた赤色発光成分であるＹ２Ｏ３：Ｅｕ蛍光体と緑色発光成分蛍光体であるＬａＰＯ４：Ｃｅ，Ｔｂ蛍光体とを、発光色がＥＸ−Ｄ色を呈するような混合比で混合して実施例７の混合蛍光体を得た。
次いで、蛍光体として用いた以外は実施例１の蛍光ランプと同様にして実施例７の蛍光ランプを作製した。
【００２７】
〔実施例８〕
実施例１の蛍光体の製造時において、コア蛍光体として原料の配合組成を下記のごとく変更した以外は実施例１のコア蛍光体合成と同様の工程にて組成式が、１．２８６（Ｂａ０．９Ｅｕ０．１）Ｏ・Ａｌ１１．８８Ｇａ０．１２Ｏ１８である蛍光体を製造した。
ＢａＣＯ３ ：１．１５７４ モル
Ｅｕ２Ｏ３ ：０．０６４３ モル
Ａｌ２Ｏ３ ：５．９４ モル
Ｇａ２Ｏ３ ：０．０６ モル
ＡｌＦ３ ：０．０１ モル
次に、このコア蛍光体に実施例１と同様の工程にて蛍光体に対して１重量％の炭酸イットリウムが表面に付着した実施例８の蛍光体を製造した。
次に、蛍光体として、実施例８の蛍光体を用いた以外は実施例１の蛍光ランプと同様にして実施例８の蛍光ランプを作製した。
【００２８】
〔比較例２〕
これとは別に、比較のために、実施例８の蛍光体の代わりに、表面に炭酸イットリウムが付着される前の未処理コア蛍光体を用いた以外は実施例１と同様にして比較例２の蛍光ランプを製造した。
【００２９】
〔実施例９〕
実施例１の蛍光体の製造時において、コア蛍光体として原料の配合組成を下記のごとく変更した以外は実施例１のコア蛍光体合成と同様の工程にて組成式が１．２８６（Ｂａ０．９Ｅｕ０．１）Ｏ・Ａｌ１１．８８Ｔｍ０．１２Ｏ１８である蛍光体を製造した。
ＢａＣＯ３ ：１．１５７４ モル
Ｅｕ２Ｏ３ ：０．０６４３ モル
Ａｌ２Ｏ３ ：５．９４ モル
Ｔｍ２Ｏ３ ：０．０６ モル
ＡｌＦ３ ：０．０１ モル
次に、このコア蛍光体に実施例１と同様の工程にて蛍光体に対して１重量％の炭酸イットリウムが表面に付着した実施例９の蛍光体を製造した。
次に、蛍光体として、実施例９の蛍光体を用いた以外は実施例１の蛍光ランプと同様にして実施例９の蛍光ランプを作製した。
【００３０】
〔比較例３〕
実施例７の蛍光ランプとの比較のため、実施例７の混合蛍光体を製造するためにコア蛍光体として用いた、いずれもその表面に炭酸イットリウムが付着される前の未処理赤色発光成分Ｙ２Ｏ３：Ｅｕ蛍光体、緑色発光成分ＬａＰＯ４：Ｃｅ，Ｔｂ蛍光体及び青色発光成分比較例１蛍光体を実施例７と同様に同じＥＸ−Ｄ色を呈するような混合比で混合して、比較例３の混合蛍光体を製造し、またさらに実施例７の蛍光ランプと同様にして比較例３の蛍光ランプを製造した。
上述の実施例１〜９並びに比較例１〜３の各蛍光ランプについて、一定時間連続して点灯し、その際の各ランプの光束維持率を測定した。またその結果を蛍光体の表面の付着処理の有無及び付着物質の種類との関係を対比して表１に示す。
【００３１】
なお、それぞれのランプについて、点灯した直後の全光束（Ｌｍ０）と５００時間連続点灯後の全光束（Ｌｍ５００）をそれぞれ測定し、点灯した直後の全光束（Ｌｍ０）に対する５００時間連続点灯後の全光束（Ｌｍ５００）の比（Ｌｍ５００／Ｌｍ０）の相対百分率を求め、この値を各ランプの光束維持率と定義して各蛍光ランプの経時劣化の程度を判断する評価の目安とした。
【００３２】
【表１】
〔実施例１０〕
実施例７の混合蛍光体を用いバインダーを添加しスラリーとしバックライト用冷陰極蛍光ランプガラス内壁に塗布した。電極を設置し、Ｎｅ／Ａｒと適量の水銀を封入して蛍光ランプを作成した。
【００３４】
〔比較例４〕
比較例３の混合蛍光体を用いて、実施例１０と同様の方法で比較例４の冷陰極型蛍光ランプを作成した。
実施例１０と比較例４の各蛍光ランプについて、１０００時間点灯し、その際の各ランプの輝度維持率を測定した結果を表２に示す。
なお、それぞれのランプについて、点灯した直後の中心輝度と１０００時間連続点灯後の中心輝度をそれぞれ測定し、点灯した直後の中心輝度に対する１０００時間連続点灯後の中心輝度の比の相対百分率を求め、この値を各ランプの輝度維持率と定義して各冷陰極型蛍光ランプの経時劣化の程度を判断する評価の目安とした。
【００３５】
【表２】
表１の結果から明らかなように、本発明の蛍光体を蛍光膜として用いた蛍光ランプ（実施例１〜６、８、９）と比較例１〜２の蛍光ランプとの比較においても、また一方混合蛍光体を蛍光膜として用いた蛍光ランプ（実施例７の蛍光ランプと比較例３の蛍光ランプとの比較）においても特定の炭酸塩化合物を表面に付着させた本発明の蛍光体を蛍光膜として用いることにより、光束維持率を改善することができ、連続点灯による経時的な明るさの低下が少なくなり、蛍光ランプの長寿命化が達成できる。
また表２の結果からも明らかなように、冷陰極型ランプにおいても炭酸塩化合物を表面に付着させた本発明の蛍光体を蛍光膜として用いた蛍光ランプでは、光束維持率を改善することができ、連続点灯による経時的な明るさの低下が少なく、蛍光ランプの長寿命化が達成できる。
【００３７】
【発明の効果】
本発明の蛍光体は上述のような構成としたので、長時間の紫外線照射においても発光輝度の低下を少なくすることができ、更に本発明の蛍光体からなる蛍光膜を具備した蛍光ランプにおいては、光束維持率が向上し、長寿命で高品質の特性を有することが可能となる。
【図面の簡単な説明】
【図１】 本発明の蛍光体の粉末回折Ｘ線スペクトルを例示するものである。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fluorescent lamp phosphor that is less susceptible to a decrease in luminance over time, particularly when used as a fluorescent film such as a mercury-enclosed fluorescent lamp, and to a fluorescent lamp with improved luminous flux maintenance factor using this phosphor.
[0002]
[Prior art]
As a fluorescent lamp for general lighting, in addition to the conventional white light emitting fluorescent lamp using a halophosphate phosphor as a fluorescent film, a so-called three-wavelength fluorescent lamp has been put into practical use, and has high efficiency and high color rendering. In recent years, the three-wavelength fluorescent lamp has become the mainstream fluorescent lamp for general illumination. A three-wavelength light emitting fluorescent lamp has a relatively narrow emission spectrum distribution, and is mixed with three kinds of phosphors of blue light emission, green light emission, and red light emission at an arbitrary ratio, and a phosphor film comprising this mixed phosphor (Phosphor layer) is formed on the inner wall surface of a glass tube which is an envelope of a fluorescent lamp. These fluorescent lamps have a mechanism that excites a fluorescent film formed on the inner wall of the lamp tube to emit light by ultraviolet rays generated by the discharge of mercury vapor sealed in the lamp tube. In recent years, these fluorescent lamps are used not only for general illumination but also for light sources for office automation equipment, backlights for liquid crystal displays, and the like, and their fields of use are expanding. The basic performance of the display element regarding color reproduction is represented by chromaticity coordinate values (color reproduction range) of three primary colors and chromaticity coordinate values of white and black. There are two types of liquid crystal display devices (hereinafter referred to as LCDs) that have a built-in surface light source called a backlight and a type that uses ambient light. In a color LCD with a built-in backlight, the intensity of light from the backlight is controlled by liquid crystal, and light in one of the wavelength ranges is selectively selected by a mosaic color filter of three primary colors of RGB arranged for each pixel. Through transmission, any color is reproduced by side-by-side color mixing. For these backlights, three-wavelength fluorescent lamps using a mixture of phosphors having respective emission spectrum distributions in the wavelength regions of the three primary colors of R, G and B are used. The cold cathode type is often used because it is easy to make a thin tube, has a long life, and is low in cost.
[0003]
The conventional three-wavelength-range fluorescent lamp has a decrease in the luminous flux maintenance factor during continuous lighting, and its life is not always sufficient, which hinders the expansion of its application field. The cause of the decrease in the luminous flux maintenance factor (decrease in phosphor brightness) in the fluorescent lamp is mainly due to the mercury or its compounds in the fluorescent lamp adhering to the phosphor surface or the low wavelength ultraviolet light having a wavelength of 185 nm. This is thought to be due to damage on the phosphor surface. For such problems, as an attempt to suppress the contamination of the phosphor by mercury or mercury compounds in the fluorescent lamp, the phosphor surface is coated with an oxide of an alkaline earth metal such as magnesium oxide, Or improvement measures, such as making magnesium hydroxide adhere (refer JP, 5-25475, A) are proposed conventionally. However, in the fluorescent lamp using the phosphor subjected to these surface treatments, the effect of suppressing the decrease in the luminous flux maintenance factor of the lamp is not always sufficient. In particular, blue phosphors have a greater deterioration with time than other colors, and therefore, there has been a demand for blue phosphors with less deterioration with time.
[0004]
[Problems to be solved by the invention]
The present invention has been made to solve such problems, and has good color purity. When used as a fluorescent film of a fluorescent lamp, it is possible to effectively suppress a decrease in brightness of the lamp during lighting. It is an object of the present invention to provide a long-life fluorescent lamp having a high luminous flux maintenance factor.
[0005]
[Means for Solving the Problems]
In order to achieve the above-mentioned object, the present inventor diligently studied the phosphor represented by the general formula a (M 1-x Eu x ) O.6Al 2 O 3 and applied for Japanese Patent Application Nos. 2001-0245132 and 2002. 143524, 2002-143525, and 2003-29460 have proposed new blue phosphors, and further studies have been made on surface treatment methods of these phosphors, particularly surface treatment substances to be attached to the phosphor surface. As a result, by attaching a carbonate compound to the surface of the phosphor particles, there is little decrease in light emission luminance even when exposed to ultraviolet rays for a long time, and when this phosphor is used as a phosphor film, a long-life fluorescent lamp with a high luminous flux maintenance factor Was obtained, and the present invention was achieved.
[0006]
The present invention has the following configuration.
(1) Alkaline earth aluminate phosphor represented by the general formula: a (M I 1-xy Eu x M II 2y ) O.Al 12-zk M III z M IV k O 18 In the above formula, a is a number satisfying 0.9 ≦ a ≦ 1.8, M I represents at least one alkaline earth metal element selected from the group consisting of Ba, Sr and Ca, and x Is 0 <x <1, M II is at least one selected from the group consisting of Li and Tl, y is 0 ≦ y <1, x + 2y <1, and M III is a group consisting of B and La Z is 0 ≦ z <2, and M IV is at least one selected from the group consisting of Sc, Y, Gd, In, Ga, Ce, Tm, Yb, Bi. , K is 0 ≦ k <2, the particle surface of the phosphor is .005～5 wt% barium carbonate, calcium carbonate, and the fluorescent lamp phosphor, wherein at least one is attached in the rare earth metal carbonate.
[0007]
(2) The fluorescent lamp phosphor according to (1), wherein the rare earth metal carbonate is lanthanum carbonate, gadolinium carbonate, or yttrium carbonate.
(3) In the powder diffraction X-ray spectrum by CuKα1 characteristic X-ray of the phosphor, the diffraction angle (2θ) of the spectrum has a wide band-like peak over an angle region of 28 ° to 31 ° ( The fluorescent substance for fluorescent lamps according to 1) or (2).
[0008]
(4) The phosphor for a fluorescent lamp according to any one of (1) to (3), wherein the phosphor is a phosphor for a mercury vapor discharge lamp.
(5) A fluorescent lamp having a fluorescent film formed on an inner wall surface of a glass tube, wherein the fluorescent film includes the fluorescent lamp phosphor according to any one of (1) to (4). Fluorescent lamp.
(6) The fluorescent lamp as described in (5) above, wherein a cold cathode is used.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in more detail.
At least one carbonate compound of barium carbonate, calcium carbonate, and rare earth metal carbonate on the surface of the phosphor particles (in the present specification, these are collectively referred to as a carbonate compound or a metal carbonate compound hereinafter) phosphor also referred) is the invention of contact with the phosphor comprising a fine powder and core of a predetermined amount of the carbonate compound (core phosphor) and a phosphor slurry is mixed in a solvent, sufficient slurry After being mixed, it can be produced by dehydration and drying. As the solvent used at this time, water is preferably used from the viewpoint of handleability, but for example, an alcohol such as ethanol or an organic solvent such as acetone may be used.
In addition, the phosphor of the present invention includes a solution containing a predetermined amount of carbonate ions in a phosphor slurry, and barium, calcium, or rare earth that can chemically react with the carbonate ions to form the carbonate compound. if to put the solution containing the metal ion, or a predetermined amount of the compound and barium soluble carbonate in water and either charged calcium or a rare earth metal compound to the phosphor slurry, the desired metal It can also be produced by a method in which a carbonate compound is produced by reaction, and is precipitated and deposited on the phosphor surface.
[0010]
In the phosphor of the present invention, the carbonate compound finally attached to the phosphor surface is a compound that is hardly soluble or insoluble in water, and is a metal carbonate rather than a non-metal carbonate compound such as ammonium carbonate. A compound is preferred. However, among the metal carbonate compounds, alkali metal carbonates are not preferable, for example, when used as a phosphor for a fluorescent lamp using Hg, because acceleration of mercury adhesion to the phosphor surface and acceleration of the luminous flux are promoted. Therefore, it is more stable to mercury, etc., is hardly soluble or insoluble in water, and can be stably attached to the phosphor surface. Among metal carbonate compounds, alkaline earth metal barium carbonate, calcium carbonate and rare earth The carbonate compound is particularly preferred.
[0011]
In the phosphor of the present invention, the alkaline earth metal or rare earth carbonate compound adhered to the surface is more hydrophobic than, for example, an alkaline earth metal or rare earth oxide, and when crystal water is taken in However, since it has a more stabilized action, phosphors with these carbonate compounds attached have less moisture uptake for the whole phosphor than phosphors with these oxides attached to the surface. Is done. Therefore, when a fluorescent lamp is produced using the phosphor of the present invention having these carbonate compounds adhered to the surface, the residual adhering moisture in the baking process during the production of the lamp can be reduced, and the fluorescent lamp can be used. Even at times, degasification is effectively suppressed, and further gas contamination in the tube of the completed fluorescent lamp is suppressed. Therefore, the carbonate compound used for such a purpose is preferably one having a decarboxylation temperature of 600 ° C. or higher, more preferably 800 ° C. or higher. The decarboxylation temperature described here means a temperature at which the carbonate compound is decarboxylated and all of the carbonate is converted into an oxide.
[0012]
The carbonate compound attached to the surface of the phosphor of the present invention may be a single compound or a mixture of a plurality of carbonate compounds. In addition, the carbonate described here includes a case of forming a double salt mainly composed of water containing crystal water, an alkaline earth metal, a rare earth metal and a carbonate radical. The preferable adhesion amount of the carbonate compound to be adhered to the phosphor surface is 0.005 to 5.0% by weight, more preferably 0.01 to 3.0% by weight with respect to the core phosphor. It is preferable to adjust to the range. If the amount of the carbonate compound attached to the surface of the core phosphor is less than 0.005% by weight with respect to the phosphor, the effect of preventing the decrease in light emission luminance over time cannot be obtained. Since the ratio of the non-light emitting component in the phosphor is increased, the light emission luminance of the phosphor is lowered. Also when this is used as a fluorescent film, the total luminous flux of the fluorescent lamp decreases, which is not preferable.
[0013]
The core phosphor to which the carbonate compound is attached is 1) at least one alkaline earth element selected from the group consisting of Ba, Sr and Ca, 2) Al element, 3) Li and Tl. At least one element selected from the group consisting of 4) at least one element selected from the group consisting of B and La, 5) a group consisting of Sc, Y, Gd, In, Ga, Ce, Tm, Yb, Bi Stoichiometrically selected elements selected from 6) each oxide of Eu element which is an activator, or carbonates, sulfates, halides, etc. of these elements 1) to 6) (M I 1-x-y Eu x M II 2y) in O · Al 12-z-k M III z M IV k O 18 ( where the equation, the number a is satisfying 0.9 ≦ a ≦ 1.8 And M I is a group consisting of Ba, Sr and Ca Represents at least one alkaline earth metal element selected from the group consisting of 0 <x <1, M II is at least one selected from the group consisting of Li and Tl, and 0 ≦ y <1, x + 2y < 1 and M III is at least one selected from the group consisting of B and La, and 0 ≦ z <2, and M IV is from Sc, Y, Gd, In, Ga, Ce, Tm, Yb, and Bi. At least one selected from the group consisting of 0 ≦ k <2), sufficiently mixing the phosphor raw material compounds made of these mixtures, and filling the heat-resistant container such as an alumina crucible The general formula, a (M I 1-x- ) is obtained by subjecting the fired product to various treatments such as dispersion, water washing, drying, and sieving in the same manner as in the post-treatment step applied during normal phosphor production. y Eu x M II 2y) O · Al 12-z-k M I It is possible to produce an alkaline earth aluminate phosphor of the present invention represented by I z M IV k O 18. In the present invention, the phosphor represented by the general formula, a (M I1 -xy Eu x MII 2y ) O.Al 12-zk M III z M IV k O 18 Refers to a phosphor in which the constituent ratios of M I , Al, Eu, and M II , M III , and M IV metal elements contained in the above satisfy the above general formula.
[0014]
The alkaline earth aluminate phosphor of the present invention is particularly suitable for a (M I 1-xy Eu x M II 2y ) O.Al 12-zk M from the viewpoint of emission luminance when excited with ultraviolet light. in III z M IV k O 18 having a composition formula, a value, it is more preferable x value is 1.1 ≦ a ≦ 1.5,0.05 ≦ x ≦ 0.5 , respectively.
From the same viewpoint, the MI element constituting a part of the host crystal of the phosphor is Ba, or 50 mol% or less, more preferably 20 mol% or less of Ba is added to at least one of Sr and Ca. An alkaline earth metal element substituted with is preferable. Further, as the core phosphor of the present invention, as described in Japanese Patent Application No. 2003-29460, it is more preferable that the phosphor contains a sulfur element.
The phosphor of the present invention thus produced has a wide band-like peak as shown in FIG. 1 in the powder diffraction X-ray spectrum over the region where the diffraction angle (2θ °) is 28 ° to 31 °. Have.
[0015]
In addition, the fluorescent lamp of the present invention has the desired fluorescent light of the present invention obtained by adhering a carbonate compound to the surface of a water-soluble binder solution such as polyethylene oxide or an organic binder solution such as nitrocellulose. The phosphor is dispersed by adding a binder to form a slurry to prepare a phosphor coating solution, and this phosphor coating solution is applied to the inner wall of the glass tube, and the phosphor film composed of the phosphor of the present invention Except for the above, mercury vapor discharge lamps, and more specifically, hot cathode lamps and cold cathode lamps, respectively, are manufactured by generally known conventional manufacturing methods.
[0016]
[Action]
Since the phosphor of the present invention has a specific chemically stable carbonate compound adhering to the phosphor surface, mercury and its compounds during the lamp operation of a fluorescent lamp using the phosphor as a phosphor film. It is possible to effectively suppress a decrease in luminous flux maintenance factor due to contamination of the phosphor in the phosphor film due to the above. The reason for this is that alkaline earth metal, which is a surface adhering to a specific carbonate compound, is caused by damage to the phosphor surface caused by ultraviolet rays having a wavelength of 185 nm, short-wavelength ultraviolet rays having a wavelength of 200 nm or less, etc. emitted into the lamp while the fluorescent lamp is lit. And rare earth carbonate compounds and the like.
Further, according to a detailed investigation, it has been found that the phosphor to which the carbonate compound of the present invention is attached has an effect of reducing mercury adhesion in a fluorescent lamp using mercury.
[0017]
【Example】
Hereinafter, the present invention will be described by way of examples.
[Example 1]
BaCO 3 : 1.1574 mol Eu 2 O 3 : 0.0643 mol Al 2 O 3 : 6.0 mol AlF 3 : 0.01 mol After sufficiently mixing the above phosphor raw materials, the alumina crucible was filled with graphite. Then, the mixture was covered and baked in nitrogen containing water vapor at a maximum temperature of 1600 ° C. for 24 hours including the temperature rise and fall time. When a powder diffraction X-ray spectrum by CuKα1 characteristic X-ray of this phosphor was measured, as shown in FIG. 1, a wide band-like peak was observed over an angle region where the diffraction angle (2θ) was 28 ° to 31 °. The broad band-like peak was found, and the full width at half maximum was 1.10 °.
[0018]
100 g of the obtained phosphor (core phosphor) and 3.5 g of ammonium bicarbonate were put into 300 ml of pure water and sufficiently stirred to prepare a core phosphor slurry. Next, 4.7 ml of a 1.2 mol / l aqueous yttrium nitrate solution is added to the core phosphor slurry to form a precipitate of yttrium carbonate in the phosphor slurry, and the phosphor slurry is sufficiently stirred. And filtered, washed with water and dehydrated, dried and finally sieved, the composition formula is 1.286 (Ba 0.9 Eu 0.1 ) O.6Al 2 O 3 and the phosphor The alkaline earth aluminate phosphor of Example 1 having 1% by weight of yttrium carbonate adhered to the surface was produced.
[0019]
Next, a 40 W straight tube fluorescent lamp was manufactured according to a conventional method except that the phosphor of Example 1 was used as the core phosphor. That is, the phosphor of Example 1 was well dispersed in a mixed solvent of nitrocellulose and butyl acetate to prepare a phosphor-coated slurry, and this slurry was applied to the inner wall surface of a glass bulb of a fluorescent lamp and dried. After that, baking was performed at approximately 550 ° C., and hot cathode electrodes were attached to both ends of the glass bulb. Thereafter, the inside of the glass bulb was further evacuated, and argon gas and mercury were injected to produce a fluorescent lamp using the phosphor of Example 1.
[0020]
[Comparative Example 1]
Separately from this, for comparison, Comparative Example 1 was carried out in the same manner as in Example 1 except that an untreated core phosphor before yttrium carbonate was attached to the surface was used instead of the phosphor of Example 1. A fluorescent lamp was manufactured.
[0021]
[Example 2]
In the production of the phosphor of Example 1, 3.7 ml of 1.2 mol / l lanthanum nitrate aqueous solution was added to the core phosphor slurry instead of adding 4.7 ml of 1.2 mol / l yttrium nitrate aqueous solution. The alkaline earth aluminate phosphor of Example 2 was manufactured in the same manner as the phosphor of Example 1 except that 1% by weight of lanthanum carbonate adhered to the phosphor surface.
Next, the phosphor of Example 1 except that the phosphor of Example 2 with lanthanum carbonate attached to the surface was used instead of the phosphor of Example 1 with yttrium carbonate attached to the surface as the phosphor. Similarly, the fluorescent lamp of Example 2 was produced.
[0022]
Example 3
In the production of the phosphor of Example 1, 3.3 ml of 1.2 mol / l gadolinium nitrate aqueous solution was added to the core phosphor slurry instead of adding 4.7 ml of 1.2 mol / l yttrium nitrate aqueous solution. Except that, the alkaline earth aluminate phosphor of Example 3 in which 1% by weight of gadolinium carbonate was adhered to the surface in the same manner as the phosphor of Example 1 was produced.
Next, as the phosphor, the phosphor of Example 1 except that the phosphor of Example 3 having gadolinium carbonate adhered to the surface was used instead of the phosphor of Example 1 having yttrium carbonate adhered to the surface. Similarly, the fluorescent lamp of Example 3 was produced.
[0023]
Example 4
In the production of the phosphor of Example 1, instead of adding 4.7 ml of 1.2 mol / l yttrium nitrate aqueous solution to the core phosphor slurry, 4.3 ml of 1.2 mol / l barium acetate aqueous solution was added. Except that, the alkaline earth aluminate phosphor of Example 4 in which 1% by weight of barium carbonate was adhered to the surface in the same manner as the phosphor of Example 1 was produced.
Next, the phosphor of Example 1 except that the phosphor of Example 4 with barium carbonate attached to the surface was used instead of the phosphor of Example 1 with yttrium carbonate attached to the surface as the phosphor. Similarly, the fluorescent lamp of Example 4 was produced.
[0024]
Example 5
In the manufacture of the phosphor of Example 1, 8.3 ml of 1.2 mol / l calcium nitrate aqueous solution was added to the core phosphor slurry instead of adding 4.7 ml of 1.2 mol / l yttrium nitrate aqueous solution. The alkaline earth aluminate phosphor of Example 5 was manufactured in the same manner as the phosphor of Example 1 except that 1% by weight of calcium carbonate adhered to the surface of the phosphor.
Next, the phosphor of Example 1 except that the phosphor of Example 5 with calcium carbonate attached to the surface was used instead of the phosphor of Example 1 with yttrium carbonate attached to the surface as the phosphor. Similarly, the fluorescent lamp of Example 5 was produced.
[0026]
Example 7
Using Y 2 O 3 : Eu phosphor and LaPO 4 : Ce, Tb phosphor as the core phosphor, 1 wt% yttrium carbonate was added to the surface of each of the core phosphors in the same manner as the phosphor of Example 1. A Y 2 O 3 : Eu phosphor, which is a red light emitting component, and a LaPO 4 : Ce, Tb phosphor, which is a green light emitting component phosphor, were manufactured.
Next, the phosphor of Example 1 which is a blue light emitting component, and the Y 2 O 3 : Eu phosphor which is a red light emitting component in which yttrium carbonate is adhered to the surface obtained as described above, and the green light emitting component fluorescence. The LaPO 4 : Ce, Tb phosphor, which is the body, was mixed at a mixing ratio such that the emission color exhibited the EX-D color to obtain a mixed phosphor of Example 7.
Next, a fluorescent lamp of Example 7 was produced in the same manner as the fluorescent lamp of Example 1 except that it was used as a phosphor.
[0027]
Example 8
At the time of manufacturing the phosphor of Example 1, the composition formula is 1.286 (Ba) in the same process as the core phosphor synthesis of Example 1 except that the composition of the raw material as the core phosphor is changed as follows. A phosphor of 0.9 Eu 0.1 ) O.Al 11.88 Ga 0.12 O 18 was produced.
BaCO 3 : 1.1574 mol Eu 2 O 3 : 0.0643 mol Al 2 O 3 : 5.94 mol Ga 2 O 3 : 0.06 mol AlF 3 : 0.01 mol In the same process as in Example 1, the phosphor of Example 8 having 1% by weight of yttrium carbonate attached to the surface of the phosphor was produced.
Next, a fluorescent lamp of Example 8 was produced in the same manner as the fluorescent lamp of Example 1 except that the phosphor of Example 8 was used as the fluorescent substance.
[0028]
[Comparative Example 2]
Separately from this, for comparison, Comparative Example 2 was performed in the same manner as in Example 1 except that an untreated core phosphor before yttrium carbonate was attached to the surface was used instead of the phosphor of Example 8. A fluorescent lamp was manufactured.
[0029]
Example 9
In the production of the phosphor of Example 1, the composition formula is 1.286 (Ba 0) in the same process as the synthesis of the core phosphor of Example 1 except that the composition of the raw material as the core phosphor is changed as follows. .9 Eu 0.1 ) O · Al 11.88 Tm 0.12 O 18 phosphor was produced.
BaCO 3 : 1.1574 mol Eu 2 O 3 : 0.0643 mol Al 2 O 3 : 5.94 mol Tm 2 O 3 : 0.06 mol AlF 3 : 0.01 mol In the same process as in Example 1, the phosphor of Example 9 having 1% by weight of yttrium carbonate attached to the surface of the phosphor was produced.
Next, a fluorescent lamp of Example 9 was produced in the same manner as the fluorescent lamp of Example 1 except that the phosphor of Example 9 was used as the fluorescent substance.
[0030]
[Comparative Example 3]
For comparison with the fluorescent lamp of Example 7, it was used as a core phosphor to produce the mixed phosphor of Example 7, both of which were treated with an untreated red light-emitting component Y before yttrium carbonate was attached to its surface. 2 O 3 : Eu phosphor, green light emitting component LaPO 4 : Ce, Tb phosphor and blue light emitting component Comparative Example 1 In the same manner as in Example 7, the phosphors were mixed at a mixing ratio so as to exhibit the same EX-D color. A mixed phosphor of Comparative Example 3 was manufactured, and a fluorescent lamp of Comparative Example 3 was manufactured in the same manner as the fluorescent lamp of Example 7.
About each fluorescent lamp of the above-mentioned Examples 1-9 and Comparative Examples 1-3, it lighted continuously for a fixed time, and the luminous flux maintenance factor of each lamp in that case was measured. The results are shown in Table 1 by comparing the relationship between the presence / absence of the adhesion treatment on the surface of the phosphor and the kind of the adhesion substance.
[0031]
For each lamp, the total luminous flux (Lm0) immediately after lighting and the total luminous flux (Lm500) after 500 hours of continuous lighting are measured, and the total luminous flux after continuous lighting for 500 hours with respect to the total luminous flux (Lm0) immediately after lighting is measured. The relative percentage of the luminous flux (Lm500) ratio (Lm500 / Lm0) was determined, and this value was defined as the luminous flux maintenance factor of each lamp, which was used as a guideline for evaluating the degree of deterioration with time of each fluorescent lamp.
[0032]
[Table 1]
Example 10
Using the mixed phosphor of Example 7, a binder was added to form a slurry, which was applied to the inner wall of a cold cathode fluorescent lamp glass for backlight. An electrode was installed, and Ne / Ar and an appropriate amount of mercury were enclosed to produce a fluorescent lamp.
[0034]
[Comparative Example 4]
Using the mixed phosphor of Comparative Example 3, a cold cathode fluorescent lamp of Comparative Example 4 was produced in the same manner as in Example 10.
Table 2 shows the results of measuring the luminance maintenance rate of each of the fluorescent lamps of Example 10 and Comparative Example 4 for 1000 hours and lighting.
For each lamp, the central luminance immediately after lighting and the central luminance after 1000 hours of continuous lighting are measured, and the relative percentage of the ratio of the central luminance after 1000 hours of continuous lighting to the central luminance immediately after lighting is determined, This value was defined as the luminance maintenance rate of each lamp, and was used as a guideline for evaluating the degree of deterioration with time of each cold cathode fluorescent lamp.
[0035]
[Table 2]
As is apparent from the results in Table 1, in comparison between the fluorescent lamps (Examples 1 to 6, 8, and 9) using the phosphor of the present invention as a fluorescent film and the fluorescent lamps of Comparative Examples 1 and 2, On the other hand, in the fluorescent lamp using the mixed fluorescent material as the fluorescent film (comparison between the fluorescent lamp of Example 7 and the fluorescent lamp of Comparative Example 3), the fluorescent material of the present invention having a specific carbonate compound attached to the surface is fluorescent. By using it as a film, the luminous flux maintenance factor can be improved, the decrease in brightness over time due to continuous lighting is reduced, and the life of the fluorescent lamp can be extended.
As is apparent from the results in Table 2, even in the cold cathode type lamp, the fluorescent lamp using the phosphor of the present invention having the carbonate compound attached to the surface as the fluorescent film can improve the luminous flux maintenance factor. The decrease in brightness over time due to continuous lighting is small, and the life of the fluorescent lamp can be extended.
[0037]
【The invention's effect】
Since the phosphor of the present invention has the above-described configuration, it is possible to reduce the decrease in light emission luminance even when irradiated for a long time, and in the fluorescent lamp equipped with the phosphor film made of the phosphor of the present invention. The luminous flux maintenance factor is improved, and it is possible to have a long life and high quality characteristics.
[Brief description of the drawings]
FIG. 1 illustrates a powder diffraction X-ray spectrum of the phosphor of the present invention.
Claims (6)
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| US7652416B2 (en) | 2005-03-30 | 2010-01-26 | Daegoo Electronic Materials Co., Ltd. | Lamp having good maintenance behavior of brightness and color coordinations |
| TW201011092A (en) * | 2008-07-24 | 2010-03-16 | Mitsubishi Chem Corp | Aluminate phosphor and preparation method thereof, and fluorescent lamp and liquid crystal display device using the aluminate phosphor |
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