JP4619509B2 - Light emitting device - Google Patents

Light emitting device Download PDF

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JP4619509B2
JP4619509B2 JP2000297546A JP2000297546A JP4619509B2 JP 4619509 B2 JP4619509 B2 JP 4619509B2 JP 2000297546 A JP2000297546 A JP 2000297546A JP 2000297546 A JP2000297546 A JP 2000297546A JP 4619509 B2 JP4619509 B2 JP 4619509B2
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light
phosphor
light emitting
emitting
wavelength
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JP2002105449A (en
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賢二 寺島
伸行 須藤
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Toshiba Corp
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Toshiba Corp
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/42—Wire connectors; Manufacturing methods related thereto
    • H01L2224/47—Structure, shape, material or disposition of the wire connectors after the connecting process
    • H01L2224/48—Structure, shape, material or disposition of the wire connectors after the connecting process of an individual wire connector
    • H01L2224/4805—Shape
    • H01L2224/4809—Loop shape
    • H01L2224/48091—Arched
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/42—Wire connectors; Manufacturing methods related thereto
    • H01L2224/47—Structure, shape, material or disposition of the wire connectors after the connecting process
    • H01L2224/48—Structure, shape, material or disposition of the wire connectors after the connecting process of an individual wire connector
    • H01L2224/481—Disposition
    • H01L2224/48151—Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive
    • H01L2224/48221—Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked
    • H01L2224/48245—Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked the item being metallic
    • H01L2224/48247—Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked the item being metallic connecting the wire to a bond pad of the item
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/42—Wire connectors; Manufacturing methods related thereto
    • H01L2224/47—Structure, shape, material or disposition of the wire connectors after the connecting process
    • H01L2224/48—Structure, shape, material or disposition of the wire connectors after the connecting process of an individual wire connector
    • H01L2224/481—Disposition
    • H01L2224/48151—Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive
    • H01L2224/48221—Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked
    • H01L2224/48245—Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked the item being metallic
    • H01L2224/48257—Connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked the item being metallic connecting the wire to a die pad of the item
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
    • H01L2224/42—Wire connectors; Manufacturing methods related thereto
    • H01L2224/47—Structure, shape, material or disposition of the wire connectors after the connecting process
    • H01L2224/49—Structure, shape, material or disposition of the wire connectors after the connecting process of a plurality of wire connectors
    • H01L2224/491—Disposition
    • H01L2224/49105—Connecting at different heights
    • H01L2224/49107—Connecting at different heights on the semiconductor or solid-state body
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
    • H01L2224/73—Means for bonding being of different types provided for in two or more of groups H01L2224/10, H01L2224/18, H01L2224/26, H01L2224/34, H01L2224/42, H01L2224/50, H01L2224/63, H01L2224/71
    • H01L2224/732—Location after the connecting process
    • H01L2224/73251—Location after the connecting process on different surfaces
    • H01L2224/73265—Layer and wire connectors
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps

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Description

【０００１】
【発明の属する技術分野】
本発明は、発光装置に係り、特に長波長の紫外線による発光効率を向上させた緑色発光蛍光体を用いた発光装置に関する。
【０００２】
【従来の技術】
発光ダイオード（ＬＥＤ）を用いたＬＥＤランプは、携帯機器、ＰＣ周辺機器、ＯＡ機器、各種スイッチ、バックライト用光源、表示板などの各種表示装置に用いられている。ＬＥＤチップは半導体素子であるために、長寿命でかつ信頼性が高く、光源として用いた場合にその交換作業が軽減されることから、種々の用途への応用が試みられている。
【０００３】
ＬＥＤランプを種々の用途に適用する場合、特に1個のＬＥＤランプで白色発光を得ることが重要となる。そこで、ＬＥＤチップの表面に青色、緑色および赤色発光蛍光体を塗布したり、あるいはＬＥＤを構成する樹脂中に各色発光の蛍光体粉末を含有させることによって、1個のＬＥＤランプから白色発光を取り出すことが試みられている。
【０００４】
また、最近では色彩感覚が豊かになり、各種表示装置にも微妙な色合い（色再現性）が要求されるようになってきたことから、1個のＬＥＤランプから白色発光のみならず、任意の中間色の発光を取り出すことが試みられている。このような場合にも、例えばＬＥＤを構成する樹脂中に種々の蛍光体粉末を含有させて構成したＬＥＤランプが用いられる。
【０００５】
上述した白色ないし中間色を発光するＬＥＤランプにおいては、光源として波長370nm前後の長波長紫外線を放射するＬＥＤチップ（例えば発光層としてＧａＮ系化合物半導体層を有するＬＥＤチップ）が用いられている。このため、ＬＥＤランプに用いられる蛍光体には、上記したような長波長の紫外線をよく吸収し、かつ効率よく可視光を発光するものが求められている。
【０００６】
このような特性を満足する蛍光体、すなわち長波長の紫外線で効率よく可視光を発光する蛍光体としては、従来から種々のものが知られている。それらのうち、緑色発光の蛍光体としては2価のマンガン（Ｍｎ）およびユーロピウム（Ｅｕ）付活アルカリ土類アルミン酸塩蛍光体などが知られている。しかし、2価のＭｎによる発光ピークは波長515nm付近にあり、色純度の点からは良好であるものの、視感輝度的には不十分であるため、波長540nm付近に発光ピークを有する緑色発光蛍光体が求められている。
【０００７】
一方、特公昭59-27787号公報や特開昭56-155283号公報には、3価のテルビウム（Ｔｂ）およびセリウム（Ｃｅ）で付活された希土類珪酸塩蛍光体が記載されている。このような希土類珪酸塩蛍光体（（Ｌａ，Ｔｂ，Ｃｅ）2Ｏ3・ｚＳｉＯ2，（Ｇｄ，Ｔｂ，Ｃｅ）2Ｏ3・ｚＳｉＯ2，（Ｙ，Ｔｂ，Ｃｅ）2Ｏ3・ｚＳｉＯ2など）は、波長365nm付近にも励起スペクトルのピークを有することから、広い波長領域の紫外線で実質的に緑色の可視光線を発光することができる。
【０００８】
しかしながら、上記した従来の3価のＴｂおよびＣｅ付活希土類珪酸塩蛍光体は、上述したようなＧａＮ系化合物半導体層を有するＬＥＤチップなどとの組合せが考慮されていないことから、上記ＬＥＤチップと組合せて使用した場合の特性が不十分であるという問題を有している。具体的には、ＬＥＤチップの発光特性に合せて、さらに励起スペクトルを長波長側にシフトさせる必要があり、またその感度を平滑化させることが求められている。
【０００９】
【発明が解決しようとする課題】
上述したように、従来の長波長紫外線を吸収して可視光を発光する緑色発光蛍光体において、2価のＭｎで付活した蛍光体は視感輝度的な特性に問題を有している。一方、緑色発光の希土類珪酸塩蛍光体は、比較的長波長側に発光ピークを有するものの、ＧａＮ系化合物半導体層を有するＬＥＤチップなどと組合せて使用した場合の特性が不十分であることから、紫外線による励起スペクトルをさらに長波長側にシフトさせ、かつその感度を平滑化させることが求められている。これらによって、長波長紫外線による緑色発光蛍光体の発光効率をより一層高めることが強く望まれている。
【００１０】
長波長の紫外線で励起して発光させる発光装置としては、上述したＬＥＤランプが代表例として挙げられるが、これに限られるものではなく、例えば蛍光体を含有させた塗料を所定の形状に塗布し、これにブラックライトなどの蛍光ランプから長波長の紫外線を照射し、蛍光体を含有させた塗料を発光させることにより所定の表示を行う装置が、道路標識のような大型の表示装置として用いられるようになってきている。このような表示装置用の発光装置においても、長波長紫外線による緑色発光蛍光体の発光効率をより一層高めることが望まれている。
【００１１】
本発明はこのような課題に対処するためになされたもので、紫外線領域において励起スペクトルを長波長側にシフトさせ、かつその感度を平滑化させることによって、長波長紫外線による発光効率を高めた緑色発光蛍光体を用いることによって、任意の色温度の白色光や各種の中間色光を効率および精度よく取り出すことを可能にした発光装置を提供することを目的としている。
【００１２】
【課題を解決するための手段】
上記目的を達成するために、本発明者らは緑色発光の希土類珪酸塩蛍光体の組成などについて詳細に調査、実験、検討を重ねた結果、3価のテルビウム（Ｔｂ）およびセリウム（Ｃｅ）で付活された珪酸イットリウム（Ｙ2Ｏ3・nＳｉＯ2：Ｔｂ，Ｃｅ）蛍光体のＹの一部を、それよりイオン半径が大きいＬａ、Ｇｄなどの希土類元素で置換することによって、270〜395nm付近の紫外線領域における励起スペクトル分布に比較的平滑な広がりを持たせることができ、これにより長波長紫外線による発光効率を高めることが可能であることを見出した。
【００１３】
本発明の発光装置は、波長３５０〜３９０ｎｍの長波長紫外線を放射する窒化物系化合物半導体層を有するＬＥＤ発光チップと、このＬＥＤ発光チップからの紫外線により励起されて可視光を発光させる発光部とを具備し、この発光部が、
一般式：（Ｙ １−Ｘ−Ｙ−Ｚ Ｒ Ｘ Ｔｂ Ｙ Ｃｅ Ｚ ） ２ Ｏ ３ ・ｎＳｉＯ ２
（式中、ＲはＬａおよびＧｄから選ばれる少なくとも１種の元素を示し、ｘ、ｙ、ｚおよびｎはそれぞれ５×１０ −４ ≦ｘ≦０．３、０．０５≦ｙ≦０．３、０．００１≦ｚ≦０．１５、０．８≦ｎ≦１．３を満足する数である。）
で表される３価のテルビウムおよびセリウムで付活された希土類珪酸塩蛍光体からなる緑色発光蛍光体を含むことを特徴としている。
【００１５】
本発明の発光装置において、発光部は請求項２に記載したように、上記した本発明の緑色発光蛍光体に加えて、青色発光蛍光体および赤色発光蛍光体を含むことができる。
【００１７】
【発明の実施の形態】
以下、本発明を実施するための形態について説明する。
【００１８】
本発明の緑色発光蛍光体は、
一般式：（Ｙ1-X-y-ZＲxＴｂyＣｅZ）2Ｏ3・nＳｉＯ2 …(1)
（式中、ＲはＬａおよびＧｄから選ばれる少なくとも1種の元素を示し、ｘ、ｙ、ｚおよびｎはそれぞれ5×10-4≦ｘ≦0.3、0.05≦ｙ≦0.3、0.001≦ｚ≦0.15、0.8≦ｎ≦1.3を満足する数である）
で実質的に表される3価のＴｂおよびＣｅで付活された希土類珪酸塩蛍光体からなるものである。
【００１９】
上述した本発明の緑色発光蛍光体は、紫外線励起発光装置の蛍光体などとして好適に用いられるものである。具体的には、波長270〜395nmの紫外線、特に波長350〜390nmの長波長紫外線を照射した際に、このような紫外線を効率よく吸収して、高効率で緑色光を発光する、言い換えると高輝度の緑色光を発光するものである。また、得られる緑色光については、波長543nm近傍に発光ピークを有し、これにより視感輝度的にも良好な特性を得ることができる。
【００２０】
上記した(1)式で表されるＴｂおよびＣｅ付活希土類珪酸塩蛍光体において、3価のＴｂおよびＣｅは、蛍光体母体としての珪酸イットリウム（Ｙ2Ｏ3・nＳｉＯ2）の励起スペクトルを基本的に長波長側に生じさせ、かつ発光効率を高める付活剤である。このように、珪酸イットリウムにＴｂとＣｅを共付活することによって、長波長側での励起による発光効率を高めることができる。すなわち、蛍光体母体中のＣｅ3+により吸収されたエネルギーをＴｂ3+に伝達することによって、Ｔｂ3+に基づく緑色発光の強度を高めることができる。
【００２１】
このような付活剤（共付活剤）のうち、Ｔｂは上記(1)式のｙの値が0.05〜0.3の範囲となるように蛍光体母体としての珪酸イットリウムに含有させる。Ｔｂの含有量を示すｙ値が0.05未満であると、緑色発光の輝度が著しく低下し、一方ｙ値が0.3を超えると濃度消光により輝度低下が生じる。ｙ値は0.13〜0.23の範囲とすることが特に好ましい。
【００２２】
また、Ｃｅは上記(1)式のｚの値が0.001〜0.15の範囲となるように蛍光体母体としての珪酸イットリウムに含有させる。Ｃｅの含有量を示すｚ値が0.001未満であると、Ｃｅ3+によるエネルギーの吸収効率が著しく低下し、一方ｚ値が0.15を超えるとＣｅによる発光が無視できなくなり、発光色度の低下や輝度の低下をもたらす。ｚの値は0.01〜0.05の範囲とすることが特に好ましい。
【００２３】
本発明の緑色発光蛍光体は、上述したような3価のＴｂおよびＣｅで付活した珪酸イットリウム（Ｙ2Ｏ3・nＳｉＯ2）蛍光体の長波長側の励起スペクトル分布をさらに改善したものである。ここで、蛍光体母体としての珪酸イットリウムは、長波長側での基本的な励起スペクトル分布に優れるものであり、本発明はさらにこのような珪酸イットリウム蛍光体の長波長側の励起スペクトル分布を改善したものである。
【００２４】
なお、蛍光体母体としての希土類珪酸塩において、ＳｉＯ2の濃度（ｎ）は0.8〜1.3の範囲とする。ＳｉＯ2の濃度を示すｎの値が0.8未満であると、十分に珪酸塩構造を形成することができず、これにより輝度の低下を招くことになる。一方、ｎの値が1.3を超えると非発光成分が無視できなくなり、これにより輝度が著しく低下する。ＳｉＯ2の濃度を示すｎの値は0.9〜1.1の範囲とすることがさらに好ましい。
【００２５】
本発明の緑色発光蛍光体は、上述したような3価のＴｂおよびＣｅで付活した珪酸イットリウム（Ｙ2Ｏ3・nＳｉＯ2）蛍光体のＹの一部を、ＬａおよびＧｄから選ばれる少なくとも1種の希土類元素（Ｒ元素）で置換したものである。このように、Ｙよりイオン半径が大きいＬａやＧｄ（Ｒ元素）で、蛍光体母体中のＹの一部を置換することによって、Ｃｅを3価のイオン（Ｃｅ3+）として安定に結晶格子中に存在させることができる。
【００２６】
このように、Ｃｅ3+イオンの結晶格子での安定性を高めることによって、結晶場の効果も含めた形で、励起スペクトル分布をさらに長波長側にシフトさせることができると共に、270〜395nm付近の紫外線領域における励起スペクトルに比較的平滑な広がりを持たせることが可能となる。これらによって、波長270〜395nmの紫外線、特に波長350〜390nmの長波長紫外線の吸収効率が高まるため、緑色光の発光効率をより一層向上させることができる。すなわち、上記したような紫外線を照射した際に、高輝度の緑色光を効率よく得ることが可能となる。
【００２７】
上記したような長波長側の励起スペクトル分布の改善効果を得る上で、Ｒ元素は上記(1)式のｘの値が5×10-4〜0.3の範囲となるように蛍光体母体としての珪酸イットリウムに含有させる。Ｒ元素の含有量を示すｘの値が5×10-4未満であると、Ｙの一部を置換したことによる効果を十分に得ることができない。一方、ｘの値が0.3を超えると置換元素による励起スペクトルが支配的になり、上記したような紫外線を照射した際の発光効率、すなわち緑色光の輝度が低下する。ｘの値は0.01〜0.1の範囲とすることが特に好ましい。
【００２８】
上述した本発明の緑色発光蛍光体、すなわち3価のＴｂおよびＣｅで付活された希土類珪酸塩（（Ｙ1-x，Ｒx）2Ｏ3・nＳｉＯ2：Ｔｂ，Ｃｅ）蛍光体は、例えば以下のようにして作製される。
【００２９】
すなわち、まずＹ2Ｏ3、Ｒ2Ｏ3（Ｌａ2Ｏ3、Ｇｄ2Ｏ3など）、Ｔｂ4Ｏ7、ＣｅＯ2、ＳｉＯ2などの各原料粉末を、上記した(1)式の組成となるように所定量秤量し、これらを融剤と共にボールミルなどを用いて十分に混合する。このようにして得られた原料混合物をアルミナるつぼなどに収容して、大気中にて1200〜1400℃の温度で2〜6時間程度焼成する。
【００３０】
ここで、各原料粉末には酸化物に限らず、加熱により容易に酸化物に分解し得る炭酸塩、硝酸塩、蓚酸塩、水酸化物などを用いることができる。また、各原料粉末としての酸化物を反応槽にて酸で溶解し、混合蓚酸塩として沈殿させた後、この沈殿物を焼成して得られる共沈酸化物を出発原料として用いてもよく、この場合には10％前後の輝度の向上を図ることができる。
【００３１】
次に、得られた焼成物を純水（温純水を含む）でよく洗浄して、不要な可溶成分を除去する。洗浄後の焼成物をろ過、乾燥した後、アルミナるつぼなどに収容して、還元性雰囲気中にて1200〜1500℃の温度で2〜6時間程度焼成する。この還元性雰囲気中で焼成した焼成物を微粉砕した後、純水（温純水を含む）でよく洗浄して不要な可溶成分を除去し、さらにろ過、乾燥することによって、目的とする緑色発光蛍光体が得られる。
【００３２】
上述したように、本発明の緑色発光蛍光体は270〜395nm付近の紫外線領域に比較的平滑な広がりを有する励起スペクトルを持つため、このような緑色発光蛍光体に波長270〜395nmの紫外線、特に波長350〜390nmの長波長紫外線を照射することによって、高輝度の緑色光を効率よく得ることができる。さらに、得られる緑色光は波長543nm近傍に発光ピークを有するため、視感輝度的にも良好な特性が得られる。
【００３３】
これらによって、本発明の緑色発光蛍光体を、例えばＬＥＤランプやブラックライトを用いた表示装置などの長波長紫外線励起タイプの発光装置に用いることによって、任意の色温度の白色光や各種の中間色光を効率および精度よく得ることが可能となる。
【００３４】
次に、本発明の発光装置の実施形態について説明する。本発明の発光装置は、上述した本発明の緑色発光蛍光体を少なくとも含む発光装置用蛍光体を有する発光部に、各種の光源から長波長の紫外線などを照射し、これにより発光部から可視光を得るように構成したものである。図１は本発明の発光装置をＬＥＤランプに適用した一実施形態の概略構成を示す断面図である。
【００３５】
同図において、１は例えばＩｎＧａＮ活性層を有する中心波長が370nm付近の紫外ＬＥＤチップであり、この紫外ＬＥＤチップ１はリードフレーム２上に接着剤層３を介して固定されている。紫外ＬＥＤチップ１とリードフレーム２はボンディングワイヤ４により電気的に接続されている。
【００３６】
上記した紫外ＬＥＤチップ１は、ボンディングワイヤ４などと共に樹脂層５により覆われている。ここで、樹脂層５は紫外ＬＥＤチップ１の周囲を覆うプレディップ材６と、このプレディップ材６の周囲を覆うキャスティング材７とを有している。プレディップ材６およびキャスティング材７には透明な樹脂などが用いられる。
【００３７】
図１に示すＬＥＤランプにおいて、プレディップ材６は前述した本発明の緑色発光蛍光体を少なくとも含む発光装置用蛍光体を含有しており、紫外ＬＥＤチップ１から放射された紫外線により励起され、発光装置用蛍光体の種類や混合比率などに応じた可視光を発光させる発光部として機能するものである。なお、発光装置用蛍光体は、プレディップ材６中に含有させて使用することに限られるものではなく、例えば紫外ＬＥＤチップ１の発光面に蛍光体層を形成して用いるなど、種々の形態で使用することができる。
【００３８】
上述した発光装置用蛍光体は、目的とする発光色に応じて、本発明の緑色発光蛍光体に加えて、青色発光蛍光体や赤色発光蛍光体などを混合して用いることができる。ここで、青色および赤色発光成分としての蛍光体は、特に限定されるものではないが、長波長の紫外線による発光効率に優れる蛍光体を使用することが好ましい。
【００３９】
例えば、青色発光蛍光体としては、
一般式：（Ｍ1，Ｅｕ）10（ＰＯ4）6・Ｃｌ2
（式中、Ｍ1はＭｇ、Ｃａ、ＳｒおよびＢａから選ばれる少なくとも1種の元素を示す）
で実質的に表される2価のユーロピウム付活ハロ燐酸塩蛍光体、
一般式：ａ（Ｍ2，Ｅｕ）Ｏ・ｂＡｌ2Ｏ3
（式中、Ｍ2はＭｇ、Ｃａ、Ｓｒ、Ｂａ、Ｚｎ、Ｌｉ、ＲｂおよびＣｓから選ばれる少なくとも1種の元素を示し、ａおよびｂはａ＞0、ｂ＞0、0.2≦ａ／ｂ≦1.5を満足する数である）
で実質的に表される2価のユーロピウム付活アルミン酸塩蛍光体、および
一般式：ａ（Ｍ2，Ｅｕv，Ｍｎw）Ｏ・ｂＡｌ2Ｏ3
（式中、Ｍ2はＭｇ、Ｃａ、Ｓｒ、Ｂａ、Ｚｎ、Ｌｉ、ＲｂおよびＣｓから選ばれる少なくとも1種の元素を示し、ａ、ｂ、ｃおよびｄはａ＞0、ｂ＞0、0.2≦ａ／ｂ≦1.5、0.001≦ｗ／ｖ≦0.2を満足する数である）
で実質的に表される2価のユーロピウムおよびマンガン付活アルミン酸塩蛍光体から選ばれる少なくとも1種を用いることが好ましい。
【００４０】
また、赤色発光蛍光体としては、
一般式：（Ｌａ，Ｅｕ，Ｓｍ）2Ｏ2Ｓ
で実質的に表される3価のユーロピウムおよびサマリウム付活酸硫化ランタン蛍光体を用いることが好ましい。
【００４１】
上記したような青色発光蛍光体および赤色発光蛍光体は、いずれも波長270〜395nmの紫外線、特に波長350〜390nmの長波長紫外線の吸収効率に優れるものであり、従って長波長の紫外線で励起した際に青色光および赤色光を効率よく得ることができる。このような青色および赤色発光蛍光体などを、本発明の緑色発光蛍光体と適宜に組合せて使用することによって、任意の色温度の白色光や紫色、桃色、青緑色などの中間色光を効率よく取り出すことができ、さらには各色の色再現性を大幅に向上させることが可能となる。
【００４２】
緑色、青色、赤色の各色発光成分の混合比率は、目的とする発光色に応じて適宜設定することができる。例えば、白色光を得る際には重量比で、青色発光成分を65％以下、緑色発光成分を5〜65％の範囲、赤色発光成分を15〜95％の範囲とすることが好ましい。このような混合比率によれば、例えば色温度2700K前後から8000K前後の白色光を任意に得ることができ、さらには従来の波長254nmで励起した三波長蛍光体と遜色のない明るさが得られる。
【００４３】
本発明の発光装置は、上述したＬＥＤランプに限られるものではなく、例えば本発明の緑色発光蛍光体を含む発光装置用蛍光体を塗料と共に塗布した発光部と、この発光部に紫外線特に長波長紫外線を照射する光源とを具備する表示装置などにも適用可能である。このような表示装置は標識などに用いられ、その際の光源としてはＢａＳｉ2Ｏ5：Ｐｂ蛍光体（ピーク波長:353nm）やＳｒＢ4Ｏ7：Ｅｕ蛍光体（ピーク波長:370nm）などを用いたブラックライト（蛍光ランプ）が使用される。
【００４４】
【実施例】
次に、本発明の具体的な実施例およびその評価結果について述べる。
【００４５】
実施例１、比較例１
まず、Ｙ2Ｏ3を247.37g、Ｇｄ2Ｏ3を55.16g、Ｔｂ4Ｏ7を91.01g、ＣｅＯ2を10.48g、ＳｉＯ2を95.98g、ＫＦを15.00g正確に秤量し、ボールミルを用いて十分に混合した。この原料混合物をアルミナるつぼに収容して、大気中にて1350℃の温度で3時間焼成した。
【００４６】
次に、得られた焼成物を温純水でよく洗浄（3〜4回）し、さらにろ過、乾燥した後、アルミナるつぼ（蓋付き）に収容して、還元性雰囲気（Ｈ2:4％＋Ｎ2:96％）中にて1400℃の温度で4時間焼成した。この還元性雰囲気中で焼成した焼成物を微粉砕した後、温純水でよく洗浄（3〜4回）し、さらにろ過、乾燥することによって、目的とする緑色発光蛍光体を得た。
【００４７】
このようにして得た緑色発光蛍光体（（Ｙ0.72Ｇｄ0.10Ｔｂ0.16Ｃｅ0.02）2ＳｉＯ5蛍光体）の励起スペクトル分布と発光スペクトル分布を測定した。図２に励起スペクトル分布を、また図３に発光スペクトル分布（380nm励起）を示す。
【００４８】
図３から明らかなように、この実施例の蛍光体は543nm付近に発光ピークを有する緑色発光蛍光体である。そして、図２に示したように、この実施例の緑色発光蛍光体は270〜380nmの紫外線領域に比較的平滑な励起スペクトル分布を有しており、このような紫外線で緑色光を高効率に発光することが分かる。
【００４９】
次に、波長380nmの紫外線で励起した際の輝度を、3（Ｂａ，Ｍｇ）Ｏ・8Ａｌ2Ｏ3：Ｅｕ0.20，Ｍｎ0.40組成の蛍光体（比較例１）を標準試料として測定したところ、実施例１の緑色発光蛍光体は140％と良好な輝度を有していた。このことから、実施例１の緑色発光蛍光体はＬＥＤチップの放射エネルギーを効率よく緑色光に変換し得るものであることが分かる。
【００５０】
なお、図４に比較例１の蛍光体の励起スペクトル分布を、また図５に比較例１の蛍光体の発光スペクトル分布（380nm励起）を示す。さらに、図６に（Ｙ0.63Ｔｂ0.35Ｃｅ0.02）2ＳｉＯ5蛍光体の励起スペクトル分布を示す。図５からは比較例１の蛍光体は発光ピークが515nm付近にあることが分かる。また、図６からは従来の希土類珪酸塩蛍光体は370〜380nm付近の励起スペクトルが低下していることが分かる。
【００５１】
実施例２
まず、Ｙ2Ｏ3を327.30g、Ｌａ2Ｏ3を5.34g、Ｔｂ4Ｏ7を61.23g、ＣｅＯ2を2.82g、ＳｉＯ2を103.32g、Ｈ3ＢＯ3を40.00g、Ｌｉ2Ｂ4Ｏ7を25.00g正確に秤量し、ボールミルを用いて十分に混合した。この原料混合物をアルミナるつぼに収容して、大気中にて1300℃の温度で3時間焼成した。
【００５２】
次に、得られた焼成物を温純水でよく洗浄（3〜4回）し、さらにろ過、乾燥した後、アルミナるつぼ（蓋付き）に収容して、還元性雰囲気（Ｈ2:4％＋Ｎ2:96％）中にて1400℃の温度で4時間焼成した。この還元性雰囲気中で焼成した焼成物を微粉砕した後、温純水でよく洗浄（3〜4回）し、さらにろ過、乾燥することによって、目的とする緑色発光蛍光体を得た。
【００５３】
このようにして得た緑色発光蛍光体（（Ｙ0.885Ｌａ0.01Ｔｂ0.10Ｃｅ0.005）2ＳｉＯ5蛍光体）の輝度を、実施例１と同様の方法（380nm励起）で測定したところ、比較例１の標準試料に対して125％の輝度を有していた。このことから、実施例２の緑色発光蛍光体はＬＥＤチップの放射エネルギーを効率よく緑色光に変換し得るものであることが分かる。
【００５４】
実施例３〜１１、比較例２〜６
表１に組成を示す各蛍光体を、実施例１および実施例２と同様の方法で作製した。これら各蛍光体の輝度を実施例１と同様の方法（380nm励起）で測定した。その結果を表１に示す。なお、比較例２〜６は本発明の範囲外の希土類珪酸塩蛍光体であり、これらについても同様にして輝度を測定した。
【００５５】
【表１】

Figure 0004619509
実施例１２、比較例７
まず、（Ｙ0.72Ｇｄ0.10Ｔｂ0.16Ｃｅ0.02）2ＳｉＯ5組成の緑色発光蛍光体と、（Ｓｒ0.73Ｂａ0.22Ｃａ0.05）10（ＰＯ4）6・Ｃｌ2：Ｅｕ組成の青色発光蛍光体と、Ｌａ2Ｏ2Ｓ：Ｅｕ0.06，Ｓｍ0.002組成の赤色発光蛍光体とを用意した。これら各色の蛍光体を、質量比で緑色発光成分が30.5％、青色発光成分が16.5％、赤色発光成分が53.0％となるように秤量し、これらを十分に混合することによって、色温度が5000K前後の白色発光蛍光体を得た。
【００５６】
このようにして得た蛍光体（混合蛍光体）を波長380nmの紫外線で励起して、白色発光のスペクトル分布を測定した。また、本発明との比較例７として、緑色発光蛍光体に3（Ｂａ，Ｍｇ）Ｏ・8Ａｌ2Ｏ3：Ｅｕ0.20，Ｍｎ0.40組成の蛍光体を用いる以外は、実施例１２と同様にして白色発光蛍光体を作製した。この比較例７の白色発光蛍光体についても、波長380nmの紫外線で励起した際の白色発光のスペクトル分布を測定した。
【００５７】
実施例１２および比較例７によるスペクトル分布からそれぞれの面積を求めて発光輝度を比較した結果、比較例７の白色発光蛍光体を100％とすると、実施例１２の白色発光蛍光体は133％と良好な値を示した。この測定結果から、実施例１２による白色発光蛍光体は、長波長紫外線を励起源とする発光装置用の蛍光体として非常に有用であることが分かる。また実際に、実施例１２の白色発光蛍光体を用いて、図１に示したＬＥＤランプを作製したところ、良好な特性を示すことが確認された。
【００５８】
実施例１３
まず、（Ｙ0.885Ｌａ0.01Ｔｂ0.10Ｃｅ0.005）2ＳｉＯ5組成の緑色発光蛍光体と、実施例１２と同一の青色発光蛍光体および赤色発光蛍光体を用意した。これら各色の蛍光体を、質量比で緑色発光成分が29.0％、青色発光成分が20.0％、赤色発光成分が51.0％となるように秤量し、これらを十分に混合することによって、色温度が6500K前後の白色発光蛍光体を得た。
【００５９】
このようにして得た混合蛍光体の白色発光（380nm励起）の輝度を、実施例１２と同様にして白色発光の輝度を求めたところ、比較例７の輝度に対して実施例１３による白色発光蛍光体の輝度は119％と良好な値を示した。この測定結果から、実施例１３による白色発光蛍光体は、長波長紫外線を励起源とする発光装置用の蛍光体として非常に有用であることが分かる。また実際に、実施例１３の白色発光蛍光体を用いて、図１に示したＬＥＤランプを作製したところ、良好な特性を示すことが確認された。
【００６０】
【発明の効果】
以上説明したように、本発明の緑色発光蛍光体によれば、例えば長波長紫外線を効率よく吸収させることができるため、長波長紫外線の励起により高輝度の緑色光を得ることが可能となる。また、そのような緑色発光蛍光体を用いた発光装置によれば、任意の色温度の白色光や各種の中間色光を効率および精度よく取り出すことができる。
【図面の簡単な説明】
【図１】 本発明の発光装置をＬＥＤランプに適用した一実施形態の概略構成を示す断面図である。
【図２】 本発明の実施例１による緑色発光蛍光体の励起スペクトル分布を示す図である。
【図３】 本発明の実施例１による緑色発光蛍光体を波長380nmの紫外線で励起した際の発光スペクトル分布を示す図である。
【図４】 比較例１による緑色発光蛍光体（アルミン酸塩蛍光体）の励起スペクトル分布を示す図である。
【図５】 比較例１による緑色発光蛍光体を波長380nmの紫外線で励起した際の発光スペクトル分布を示す図である。
【図６】 従来の希土類珪酸塩緑色発光蛍光体の励起スペクトル分布を示す図である。
【符号の説明】
１……紫外ＬＥＤチップ
５……樹脂層
６……プレディップ材
７……キャスティング材[0001]
BACKGROUND OF THE INVENTION
  The present invention, DepartureGreen light-emitting fluorescence, especially related to optical devices, with improved light emission efficiency due to long-wavelength ultraviolet lightBodyIt relates to the light emitting device used.
[0002]
[Prior art]
LED lamps using light-emitting diodes (LEDs) are used in various display devices such as portable devices, PC peripheral devices, OA devices, various switches, backlight light sources, and display plates. Since the LED chip is a semiconductor element, it has a long life and high reliability, and its replacement work is reduced when used as a light source. Therefore, application to various uses has been attempted.
[0003]
When the LED lamp is applied to various uses, it is particularly important to obtain white light emission with one LED lamp. Therefore, white light is extracted from one LED lamp by applying blue, green and red light emitting phosphors on the surface of the LED chip, or by incorporating phosphor powders of each color light emission into the resin constituting the LED. It has been tried.
[0004]
Recently, the color sense has become richer, and various display devices have been required to have subtle shades (color reproducibility). Attempts have been made to extract light emission of a neutral color. Also in such a case, for example, an LED lamp configured by including various phosphor powders in a resin constituting the LED is used.
[0005]
In the above-described LED lamps that emit white or intermediate colors, LED chips that emit long-wavelength ultraviolet rays having a wavelength of around 370 nm (for example, LED chips having a GaN-based compound semiconductor layer as a light-emitting layer) are used as light sources. For this reason, the phosphor used for the LED lamp is required to absorb a long wavelength ultraviolet ray as described above and to emit visible light efficiently.
[0006]
Conventionally, various phosphors satisfying such characteristics, that is, phosphors that efficiently emit visible light with long-wavelength ultraviolet rays are known. Among them, divalent manganese (Mn) and europium (Eu) activated alkaline earth aluminate phosphors are known as green-emitting phosphors. However, although the emission peak due to divalent Mn is near 515 nm in wavelength and good in terms of color purity, it is insufficient in terms of luminous brightness, so green emission fluorescence having an emission peak near 540 nm in wavelength. The body is sought.
[0007]
On the other hand, JP-B-59-27787 and JP-A-56-155283 describe rare earth silicate phosphors activated with trivalent terbium (Tb) and cerium (Ce). Such rare earth silicate phosphors ((La, Tb, Ce)2OThree・ ZSiO2, (Gd, Tb, Ce)2OThree・ ZSiO2, (Y, Tb, Ce)2OThree・ ZSiO2Etc.) have a peak of the excitation spectrum also in the vicinity of a wavelength of 365 nm, and therefore can emit substantially green visible light with ultraviolet rays in a wide wavelength region.
[0008]
However, since the above-described conventional trivalent Tb and Ce-activated rare earth silicate phosphors are not considered in combination with LED chips having a GaN-based compound semiconductor layer as described above, There is a problem that the characteristics when used in combination are insufficient. Specifically, it is necessary to further shift the excitation spectrum to the longer wavelength side in accordance with the light emission characteristics of the LED chip, and it is required to smooth the sensitivity.
[0009]
[Problems to be solved by the invention]
As described above, in the conventional green light-emitting phosphor that absorbs long-wavelength ultraviolet light and emits visible light, the phosphor activated with divalent Mn has a problem in luminous luminance characteristics. On the other hand, the green-emitting rare earth silicate phosphor has an emission peak on a relatively long wavelength side, but has insufficient characteristics when used in combination with an LED chip having a GaN-based compound semiconductor layer, etc. There is a demand for shifting the excitation spectrum of ultraviolet rays to the longer wavelength side and smoothing the sensitivity. Accordingly, it is strongly desired to further increase the light emission efficiency of the green light emitting phosphor by long wavelength ultraviolet rays.
[0010]
As a typical example of the light emitting device that emits light by being excited by ultraviolet light having a long wavelength, the above-mentioned LED lamp is exemplified, but the present invention is not limited to this. For example, a coating material containing phosphor is applied in a predetermined shape. A device that performs predetermined display by irradiating a long-wavelength ultraviolet ray from a fluorescent lamp such as a black light and emitting a paint containing a phosphor is used as a large display device such as a road sign. It has become like this. In such a light emitting device for a display device, it is desired to further increase the light emission efficiency of the green light emitting phosphor by long wavelength ultraviolet rays.
[0011]
  The present invention has been made in order to cope with such problems, and is a green color whose emission efficiency by long-wavelength ultraviolet light is enhanced by shifting the excitation spectrum to the long-wavelength side in the ultraviolet region and smoothing its sensitivity. Luminescent phosphorForTherefore, an object of the present invention is to provide a light emitting device that can efficiently and accurately extract white light of various color temperatures and various intermediate color lights.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, the present inventors have conducted detailed investigations, experiments, and studies on the composition of green-emitting rare earth silicate phosphors. As a result, trivalent terbium (Tb) and cerium (Ce) are used. Activated yttrium silicate (Y2OThree・ NSiO2: Tb, Ce) By replacing a portion of Y of the phosphor with a rare earth element such as La or Gd having an ionic radius larger than that, the excitation spectrum distribution in the ultraviolet region near 270 to 395 nm has a relatively smooth spread. It has been found that it is possible to increase the luminous efficiency by long-wavelength ultraviolet rays.
[0013]
  The light-emitting device of the present invention includes an LED light-emitting chip having a nitride compound semiconductor layer that emits long-wavelength ultraviolet light having a wavelength of 350 to 390 nm, and a light-emitting unit that emits visible light when excited by ultraviolet light from the LED light-emitting chip. And the light emitting part
  General formula: (Y 1-XYZ R X Tb Y Ce Z ) 2 O 3 ・ NSiO 2
(In the formula, R represents at least one element selected from La and Gd, and x, y, z and n are each 5 × 10 5. -4 ≦ x ≦ 0.3, 0.05 ≦ y ≦ 0.3, 0.001 ≦ z ≦ 0.15, 0.8 ≦ n ≦ 1.3. )
  And a green light-emitting phosphor composed of a rare earth silicate phosphor activated with trivalent terbium and cerium.
[0015]
  BookIn the light emitting device of the invention, the light emitting section is claimed.2In addition to the green light emitting phosphor of the present invention described above, a blue light emitting phosphor and a red light emitting phosphor are included.MukoYou can.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, modes for carrying out the present invention will be described.
[0018]
The green-emitting phosphor of the present invention is
General formula: (Y1-XyZRxTbyCeZ)2OThree・ NSiO2  … (1)
(In the formula, R represents at least one element selected from La and Gd, and x, y, z and n are each 5 × 10 5.-Four≦ x ≦ 0.3, 0.05 ≦ y ≦ 0.3, 0.001 ≦ z ≦ 0.15, 0.8 ≦ n ≦ 1.3.
The rare earth silicate phosphor activated by trivalent Tb and Ce substantially represented by
[0019]
The green light-emitting phosphor of the present invention described above is preferably used as a phosphor of an ultraviolet excitation light-emitting device. Specifically, when ultraviolet rays having a wavelength of 270 to 395 nm, particularly long-wavelength ultraviolet rays having a wavelength of 350 to 390 nm are irradiated, such ultraviolet rays are efficiently absorbed and green light is emitted with high efficiency. It emits green light of luminance. In addition, the obtained green light has a light emission peak in the vicinity of a wavelength of 543 nm, and thereby, it is possible to obtain good characteristics in terms of luminous brightness.
[0020]
In the Tb and Ce-activated rare earth silicate phosphor represented by the above formula (1), trivalent Tb and Ce are yttrium silicate (Y2OThree・ NSiO2) Is an activator that basically produces the excitation spectrum on the long wavelength side and increases the luminous efficiency. Thus, by co-activating Tb and Ce with yttrium silicate, the light emission efficiency by excitation on the long wavelength side can be increased. That is, Ce in the phosphor matrix3+Energy absorbed by Tb3+By transmitting to Tb3+Therefore, the intensity of green light emission based on can be increased.
[0021]
Among such activators (co-activators), Tb is contained in yttrium silicate as the phosphor matrix so that the y value in the formula (1) is in the range of 0.05 to 0.3. When the y value indicating the Tb content is less than 0.05, the luminance of green light emission is remarkably lowered. On the other hand, when the y value exceeds 0.3, the luminance is lowered due to concentration quenching. The y value is particularly preferably in the range of 0.13 to 0.23.
[0022]
Further, Ce is contained in yttrium silicate as the phosphor matrix so that the value of z in the formula (1) is in the range of 0.001 to 0.15. When the z value indicating the Ce content is less than 0.001, Ce3+The energy absorption efficiency due to is significantly reduced. On the other hand, if the z value exceeds 0.15, light emission due to Ce cannot be ignored, resulting in a decrease in emission chromaticity and a decrease in luminance. The value of z is particularly preferably in the range of 0.01 to 0.05.
[0023]
The green light-emitting phosphor of the present invention is composed of yttrium silicate (Y) activated with trivalent Tb and Ce as described above.2OThree・ NSiO2) Further improved excitation spectrum distribution on the long wavelength side of the phosphor. Here, yttrium silicate as the phosphor matrix is excellent in basic excitation spectrum distribution on the long wavelength side, and the present invention further improves the excitation spectrum distribution on the long wavelength side of such yttrium silicate phosphor. It is a thing.
[0024]
In the rare earth silicate as the phosphor matrix, SiO2The concentration (n) of is in the range of 0.8 to 1.3. SiO2If the value of n indicating the concentration of is less than 0.8, a silicate structure cannot be formed sufficiently, thereby causing a decrease in luminance. On the other hand, when the value of n exceeds 1.3, the non-light emitting component cannot be ignored, and the luminance is remarkably lowered. SiO2The value of n indicating the concentration of is more preferably in the range of 0.9 to 1.1.
[0025]
The green light-emitting phosphor of the present invention is composed of yttrium silicate (Y) activated with trivalent Tb and Ce as described above.2OThree・ NSiO2) A part of Y of the phosphor is substituted with at least one rare earth element (R element) selected from La and Gd. Thus, by replacing part of Y in the phosphor matrix with La or Gd (R element) having an ionic radius larger than that of Y, Ce is replaced with a trivalent ion (Ce).3+) Can be stably present in the crystal lattice.
[0026]
Thus, Ce3+By enhancing the stability of the ions in the crystal lattice, the excitation spectrum distribution can be further shifted to the longer wavelength side, including the effect of the crystal field, and the excitation spectrum in the ultraviolet region near 270 to 395 nm It becomes possible to have a relatively smooth spread. As a result, the absorption efficiency of ultraviolet rays having a wavelength of 270 to 395 nm, particularly long-wavelength ultraviolet rays having a wavelength of 350 to 390 nm is increased, and thus the emission efficiency of green light can be further improved. That is, it is possible to efficiently obtain high-intensity green light when irradiated with ultraviolet rays as described above.
[0027]
In order to obtain the effect of improving the excitation spectrum distribution on the long wavelength side as described above, the R element has an x value of 5 × 10 5 in the above formula (1).-FourIt is made to contain in the yttrium silicate as a fluorescent substance base so that it may become the range of -0.3. The value of x indicating the content of R element is 5 × 10-FourIf it is less than 1, the effect of substituting a part of Y cannot be sufficiently obtained. On the other hand, when the value of x exceeds 0.3, the excitation spectrum due to the substitution element becomes dominant, and the luminous efficiency when irradiated with ultraviolet rays as described above, that is, the luminance of green light is lowered. The value of x is particularly preferably in the range of 0.01 to 0.1.
[0028]
The green light-emitting phosphor of the present invention described above, that is, a rare earth silicate activated by trivalent Tb and Ce ((Y1-x, Rx)2OThree・ NSiO2: Tb, Ce) The phosphor is produced, for example, as follows.
[0029]
First, Y2OThree, R2OThree(La2OThree, Gd2OThreeEtc.), TbFourO7, CeO2, SiO2Each of the raw material powders is weighed in a predetermined amount so as to have the composition of the above formula (1), and these are sufficiently mixed together with a flux using a ball mill or the like. The raw material mixture thus obtained is accommodated in an alumina crucible or the like and baked in the atmosphere at a temperature of 1200 to 1400 ° C. for about 2 to 6 hours.
[0030]
Here, each raw material powder is not limited to oxides, and carbonates, nitrates, oxalates, hydroxides, and the like that can be easily decomposed into oxides by heating can be used. Moreover, after dissolving the oxide as each raw material powder with an acid in a reaction vessel and precipitating it as a mixed oxalate, a coprecipitated oxide obtained by firing this precipitate may be used as a starting material. In this case, the luminance can be improved by about 10%.
[0031]
Next, the obtained fired product is thoroughly washed with pure water (including warm pure water) to remove unnecessary soluble components. The fired product after washing is filtered and dried, and then stored in an alumina crucible or the like, and fired in a reducing atmosphere at a temperature of 1200 to 1500 ° C. for about 2 to 6 hours. After finely pulverizing the fired product fired in this reducing atmosphere, it is thoroughly washed with pure water (including warm pure water) to remove unnecessary soluble components, and further filtered and dried to produce the desired green light emission. A phosphor is obtained.
[0032]
As described above, since the green light emitting phosphor of the present invention has an excitation spectrum having a relatively smooth spread in the ultraviolet region near 270 to 395 nm, ultraviolet light having a wavelength of 270 to 395 nm, in particular, High-intensity green light can be efficiently obtained by irradiating with long-wavelength ultraviolet light having a wavelength of 350 to 390 nm. Furthermore, since the obtained green light has a light emission peak in the vicinity of a wavelength of 543 nm, good characteristics in terms of luminous brightness can be obtained.
[0033]
As a result, the green light-emitting phosphor of the present invention is used in a long-wavelength ultraviolet excitation type light-emitting device such as a display device using an LED lamp or a black light, thereby allowing white light having an arbitrary color temperature or various kinds of intermediate color light. Can be obtained efficiently and accurately.
[0034]
Next, an embodiment of the light emitting device of the present invention will be described. The light-emitting device of the present invention irradiates a light-emitting unit having a phosphor for a light-emitting device including at least the green light-emitting phosphor of the present invention described above with various light sources, such as long-wavelength ultraviolet rays. It is comprised so that it may obtain. FIG. 1 is a cross-sectional view showing a schematic configuration of an embodiment in which the light emitting device of the present invention is applied to an LED lamp.
[0035]
In the figure, reference numeral 1 denotes, for example, an ultraviolet LED chip having an InGaN active layer and a center wavelength of around 370 nm. The ultraviolet LED chip 1 is fixed on a lead frame 2 via an adhesive layer 3. The ultraviolet LED chip 1 and the lead frame 2 are electrically connected by a bonding wire 4.
[0036]
The ultraviolet LED chip 1 described above is covered with a resin layer 5 together with bonding wires 4 and the like. Here, the resin layer 5 has a pre-dip material 6 covering the periphery of the ultraviolet LED chip 1 and a casting material 7 covering the periphery of the pre-dip material 6. A transparent resin or the like is used for the pre-dip material 6 and the casting material 7.
[0037]
In the LED lamp shown in FIG. 1, the pre-dip material 6 contains a phosphor for a light emitting device including at least the green light emitting phosphor of the present invention described above, and is excited by ultraviolet rays emitted from the ultraviolet LED chip 1 to emit light. It functions as a light emitting unit that emits visible light according to the type and mixing ratio of the phosphor for the device. The phosphor for the light emitting device is not limited to being used in the pre-dip material 6, and various forms such as forming a phosphor layer on the light emitting surface of the ultraviolet LED chip 1 are used. Can be used in
[0038]
The above-described phosphor for a light emitting device can be used by mixing a blue light emitting phosphor, a red light emitting phosphor, or the like in addition to the green light emitting phosphor of the present invention, depending on the target light emission color. Here, the phosphor as the blue and red light-emitting components is not particularly limited, but it is preferable to use a phosphor that is excellent in light emission efficiency due to long-wavelength ultraviolet rays.
[0039]
For example, as a blue light emitting phosphor,
General formula: (M1, Eu)Ten(POFour)6・ Cl2
(Wherein M1 represents at least one element selected from Mg, Ca, Sr and Ba)
A divalent europium-activated halophosphate phosphor substantially represented by
General formula: a (M2, Eu) O.bAl2OThree
(Wherein M2 represents at least one element selected from Mg, Ca, Sr, Ba, Zn, Li, Rb and Cs, and a and b are a> 0, b> 0, 0.2 ≦ a / b ≦ 1.5)
A divalent europium activated aluminate phosphor substantially represented by
General formula: a (M2, Euv, Mnw) O · bAl2OThree
(Wherein, M2 represents at least one element selected from Mg, Ca, Sr, Ba, Zn, Li, Rb and Cs, and a, b, c and d are a> 0, b> 0, 0.2 ≦ a / b ≦ 1.5, 0.001 ≦ w / v ≦ 0.2)
It is preferable to use at least one selected from divalent europium and manganese-activated aluminate phosphors substantially represented by
[0040]
Moreover, as a red light emitting phosphor,
General formula: (La, Eu, Sm)2O2S
It is preferable to use a trivalent europium and samarium activated lanthanum oxysulfide phosphor substantially represented by
[0041]
Both the blue light-emitting phosphor and the red light-emitting phosphor described above are excellent in absorption efficiency of ultraviolet light having a wavelength of 270 to 395 nm, particularly long wavelength ultraviolet light having a wavelength of 350 to 390 nm. In this case, blue light and red light can be obtained efficiently. By using such blue and red light emitting phosphors in combination with the green light emitting phosphor of the present invention as appropriate, white light of any color temperature and intermediate color light such as purple, pink, and blue green can be efficiently obtained. In addition, the color reproducibility of each color can be greatly improved.
[0042]
The mixing ratio of each light emitting component of green, blue, and red can be appropriately set according to the target light emission color. For example, when obtaining white light, it is preferable that the blue light emitting component is 65% or less, the green light emitting component is in the range of 5 to 65%, and the red light emitting component is in the range of 15 to 95% by weight. According to such a mixing ratio, for example, white light having a color temperature of about 2700K to about 8000K can be obtained arbitrarily, and furthermore, brightness comparable to that of a conventional three-wavelength phosphor excited at a wavelength of 254 nm can be obtained. .
[0043]
The light-emitting device of the present invention is not limited to the above-described LED lamp. For example, a light-emitting unit in which a phosphor for a light-emitting device including the green light-emitting phosphor of the present invention is applied together with a paint, and ultraviolet light, particularly a long wavelength, is applied to the light-emitting unit. The present invention can also be applied to a display device including a light source that emits ultraviolet rays. Such a display device is used for signs and the like, and the light source at that time is BaSi.2OFive: Pb phosphor (peak wavelength: 353 nm) or SrBFourO7: Black light (fluorescent lamp) using Eu phosphor (peak wavelength: 370 nm) or the like is used.
[0044]
【Example】
Next, specific examples of the present invention and evaluation results thereof will be described.
[0045]
Example 1 and Comparative Example 1
First, Y2OThree247.37g, Gd2OThree55.16g, TbFourO791.01g, CeO210.48 g, SiO295.98 g and KF 15.00 g were accurately weighed and thoroughly mixed using a ball mill. This raw material mixture was placed in an alumina crucible and calcined in the atmosphere at a temperature of 1350 ° C. for 3 hours.
[0046]
Next, the obtained fired product is thoroughly washed with warm pure water (3 to 4 times), further filtered and dried, then housed in an alumina crucible (with a lid), and reduced atmosphere (H2: 4% + N2: 96%) at 1400 ° C. for 4 hours. The fired product fired in this reducing atmosphere was finely pulverized, then thoroughly washed with warm pure water (3 to 4 times), further filtered and dried to obtain the target green light-emitting phosphor.
[0047]
The green light-emitting phosphor thus obtained ((Y0.72Gd0.10Tb0.16Ce0.02)2SiOFiveThe excitation spectrum distribution and emission spectrum distribution of the phosphor) were measured. FIG. 2 shows an excitation spectrum distribution, and FIG. 3 shows an emission spectrum distribution (380 nm excitation).
[0048]
As is clear from FIG. 3, the phosphor of this example is a green light-emitting phosphor having an emission peak near 543 nm. As shown in FIG. 2, the green light emitting phosphor of this embodiment has a relatively smooth excitation spectrum distribution in the ultraviolet region of 270 to 380 nm. It turns out that it emits light.
[0049]
Next, the luminance when excited by ultraviolet light having a wavelength of 380 nm is 3 (Ba, Mg) O.8Al.2OThree: Eu0.20, Mn0.40When the phosphor having the composition (Comparative Example 1) was measured as a standard sample, the green-emitting phosphor of Example 1 had a good luminance of 140%. From this, it can be seen that the green light-emitting phosphor of Example 1 can efficiently convert the radiant energy of the LED chip into green light.
[0050]
4 shows the excitation spectrum distribution of the phosphor of Comparative Example 1, and FIG. 5 shows the emission spectrum distribution (380 nm excitation) of the phosphor of Comparative Example 1. Further, in FIG.0.63Tb0.35Ce0.02)2SiOFiveThe excitation spectrum distribution of the phosphor is shown. FIG. 5 shows that the phosphor of Comparative Example 1 has an emission peak in the vicinity of 515 nm. Further, FIG. 6 shows that the excitation spectrum in the vicinity of 370 to 380 nm is lowered in the conventional rare earth silicate phosphor.
[0051]
Example 2
First, Y2OThree327.30g, La2OThree5.34g, TbFourO761.23g, CeO22.82g, SiO2103.32g, HThreeBOThree40.00 g Li2BFourO725.00 g was accurately weighed and thoroughly mixed using a ball mill. This raw material mixture was placed in an alumina crucible and baked in the atmosphere at a temperature of 1300 ° C. for 3 hours.
[0052]
Next, the obtained fired product is thoroughly washed with warm pure water (3 to 4 times), further filtered and dried, then housed in an alumina crucible (with a lid), and reduced atmosphere (H2: 4% + N2: 96%) at a temperature of 1400 ° C. for 4 hours. The fired product fired in the reducing atmosphere was finely pulverized, washed thoroughly with warm pure water (3 to 4 times), filtered and dried to obtain the desired green light-emitting phosphor.
[0053]
The green light-emitting phosphor thus obtained ((Y0.885La0.01Tb0.10Ce0.005)2SiOFiveWhen the luminance of the phosphor was measured by the same method as in Example 1 (excitation at 380 nm), it had a luminance of 125% with respect to the standard sample of Comparative Example 1. From this, it can be seen that the green light-emitting phosphor of Example 2 can efficiently convert the radiant energy of the LED chip into green light.
[0054]
Examples 3-11, Comparative Examples 2-6
Each phosphor having the composition shown in Table 1 was produced in the same manner as in Example 1 and Example 2. The luminance of each phosphor was measured by the same method as in Example 1 (excitation at 380 nm). The results are shown in Table 1. Comparative Examples 2 to 6 are rare earth silicate phosphors outside the scope of the present invention, and the luminance was measured in the same manner.
[0055]
[Table 1]
Figure 0004619509
Example 12, Comparative Example 7
First, (Y0.72Gd0.10Tb0.16Ce0.02)2SiOFiveA green light emitting phosphor having a composition; (Sr0.73Ba0.22Ca0.05)Ten(POFour)6・ Cl2: A blue-emitting phosphor having an Eu composition, and La2O2S: Eu0.06, Sm0.002A red light emitting phosphor having a composition was prepared. The phosphors of each color are weighed so that the green light emission component is 30.5%, the blue light emission component is 16.5%, and the red light emission component is 53.0%, and the color temperature is 5000K. Before and after white phosphors were obtained.
[0056]
The phosphor (mixed phosphor) thus obtained was excited with ultraviolet light having a wavelength of 380 nm, and the spectral distribution of white light emission was measured. Further, as Comparative Example 7 with the present invention, 3 (Ba, Mg) O.8Al is used for the green light emitting phosphor.2OThree: Eu0.20, Mn0.40A white light-emitting phosphor was produced in the same manner as in Example 12 except that the phosphor having the composition was used. For the white light-emitting phosphor of Comparative Example 7, the spectral distribution of white light emission when excited by ultraviolet light having a wavelength of 380 nm was measured.
[0057]
As a result of obtaining the respective areas from the spectral distributions of Example 12 and Comparative Example 7 and comparing the emission luminance, the white light-emitting phosphor of Example 12 was 133%, assuming that the white light-emitting phosphor of Comparative Example 7 was 100%. Good value was shown. From this measurement result, it can be seen that the white light-emitting phosphor according to Example 12 is very useful as a phosphor for a light-emitting device using long-wavelength ultraviolet light as an excitation source. Moreover, actually, when the LED lamp shown in FIG. 1 was produced using the white light-emitting phosphor of Example 12, it was confirmed that good characteristics were exhibited.
[0058]
Example 13
First, (Y0.885La0.01Tb0.10Ce0.005)2SiOFiveA green light-emitting phosphor having the composition and the same blue light-emitting phosphor and red light-emitting phosphor as in Example 12 were prepared. The phosphors of each color are weighed so that the mass ratio is 29.0% for the green light-emitting component, 20.0% for the blue light-emitting component, and 51.0% for the red light-emitting component. Before and after white phosphors were obtained.
[0059]
The luminance of white light emission (excitation at 380 nm) of the mixed phosphor thus obtained was determined in the same manner as in Example 12. As a result, white light emission according to Example 13 was obtained with respect to the luminance of Comparative Example 7. The luminance of the phosphor was a good value of 119%. From this measurement result, it can be seen that the white light-emitting phosphor according to Example 13 is very useful as a phosphor for a light-emitting device using long-wavelength ultraviolet light as an excitation source. Moreover, actually, when the LED lamp shown in FIG. 1 was produced using the white light-emitting phosphor of Example 13, it was confirmed that good characteristics were exhibited.
[0060]
【The invention's effect】
As described above, according to the green light-emitting phosphor of the present invention, for example, long-wavelength ultraviolet light can be efficiently absorbed, so that high-intensity green light can be obtained by excitation of long-wavelength ultraviolet light. Further, according to the light emitting device using such a green light emitting phosphor, white light having an arbitrary color temperature and various intermediate color lights can be extracted efficiently and accurately.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a schematic configuration of an embodiment in which a light emitting device of the present invention is applied to an LED lamp.
FIG. 2 is a diagram showing an excitation spectrum distribution of a green light emitting phosphor according to Example 1 of the present invention.
FIG. 3 is a graph showing an emission spectrum distribution when the green light emitting phosphor according to Example 1 of the present invention is excited with ultraviolet light having a wavelength of 380 nm.
4 is a diagram showing an excitation spectrum distribution of a green-emitting phosphor (aluminate phosphor) according to Comparative Example 1. FIG.
5 is a graph showing an emission spectrum distribution when the green light-emitting phosphor according to Comparative Example 1 is excited with ultraviolet light having a wavelength of 380 nm. FIG.
FIG. 6 is a diagram showing an excitation spectrum distribution of a conventional rare earth silicate green light emitting phosphor.
[Explanation of symbols]
1 ... UV LED chip
5 …… Resin layer
6 …… Pre-dip material
7. Casting material

Claims (4)

波長３５０〜３９０ｎｍの長波長紫外線を放射する窒化物系化合物半導体層を有するＬＥＤ発光チップと、前記ＬＥＤ発光チップからの紫外線により励起されて可視光を発光させる発光部とを具備する発光装置において、
前記発光部が
一般式：（Ｙ １−Ｘ−Ｙ−Ｚ Ｒ Ｘ Ｔｂ Ｙ Ｃｅ Ｚ ） ２ Ｏ ３ ・ｎＳｉＯ ２
（式中、ＲはＬａおよびＧｄから選ばれる少なくとも１種の元素を示し、ｘ、ｙ、ｚおよびｎはそれぞれ５×１０ −４ ≦ｘ≦０．３、０．０５≦ｙ≦０．３、０．００１≦ｚ≦０．１５、０．８≦ｎ≦１．３を満足する数である。）
で表される３価のテルビウムおよびセリウムで付活された希土類珪酸塩蛍光体からなる緑色発光蛍光体を含むことを特徴とする発光装置。 In a light emitting device comprising: an LED light emitting chip having a nitride compound semiconductor layer that emits long wavelength ultraviolet light having a wavelength of 350 to 390 nm; and a light emitting unit that emits visible light when excited by ultraviolet light from the LED light emitting chip.
The light emitting part
Formula: (Y 1-X-Y -Z R X Tb Y Ce Z) 2 O 3 · nSiO 2
(In the formula, R represents at least one element selected from La and Gd, and x, y, z and n represent 5 × 10 −4 ≦ x ≦ 0.3 and 0.05 ≦ y ≦ 0.3, respectively. , 0.001 ≦ z ≦ 0.15, 0.8 ≦ n ≦ 1.3.)
A green light emitting phosphor comprising a rare earth silicate phosphor activated with trivalent terbium and cerium represented by the formula: 請求項１記載の発光装置において、
前記発光部は、前記緑色発光蛍光体に加えて、青色発光蛍光体および赤色発光蛍光体を含むことを特徴とする発光装置。The light-emitting device according to claim 1 .
The light emitting unit, in addition to the green-emitting phosphor, the light emitting device comprising a-law contains a blue-emitting phosphor and red-emitting phosphor. 請求項２記載の発光装置において、
前記青色発光蛍光体は、
一般式：（Ｍ１，Ｅｕ）１０（ＰＯ４）６・Ｃｌ２
（式中、Ｍ１はＣａ、ＳｒおよびＢａから選ばれる少なくとも１種の元素を示す）
で表される２価のユーロピウム付活ハロ燐酸塩蛍光体
からなることを特徴とする発光装置。The light-emitting device according to claim 2 .
The blue-emitting phosphor is
General formula: (M1, Eu) 10 (PO 4 ) 6 · Cl 2
(Wherein M1 represents at least one element selected from Ca, Sr and Ba)
In the divalent europium activated halophosphate phosphors Table
The light emitting device characterized in that either Ranaru. 請求項２または３記載の発光装置において、
前記赤色発光蛍光体は、
一般式：（Ｌａ，Ｅｕ，Ｓｍ）２Ｏ２Ｓ
で表される３価のユーロピウムおよびサマリウム付活酸硫化ランタン蛍光体からなることを特徴とする発光装置。The light emitting device according to claim 2 or 3 ,
The red light-emitting phosphor is
General formula: (La, Eu, Sm) 2 O 2 S
In the light emitting device characterized by comprising a trivalent europium and samarium with activated lanthanum oxysulfide phosphors table.
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US7258816B2 (en) 2002-03-22 2007-08-21 Nichia Corporation Nitride phosphor and method for preparation thereof, and light emitting device
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JP4128564B2 (en) * 2004-04-27 2008-07-30 松下電器産業株式会社 Light emitting device
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JP4931372B2 (en) * 2005-06-06 2012-05-16 日亜化学工業株式会社 Light emitting device
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JP2010222389A (en) * 2009-03-19 2010-10-07 Mitsubishi Chemicals Corp Tb-ACTIVATED RARE EARTH SILICATE PHOSPHOR FOR BACKLIGHT, AND COLD-CATHODE FLUORESCENT LAMP AND LIQUID CRYSTAL DISPLAY DEVICE, USING THE PHOSPHOR
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