JP3719009B2

JP3719009B2 - Electrodeless discharge lamp lighting device

Info

Publication number: JP3719009B2
Application number: JP24016498A
Authority: JP
Inventors: 大志城戸
Original assignee: Matsushita Electric Works Ltd
Current assignee: Panasonic Electric Works Co Ltd
Priority date: 1998-08-26
Filing date: 1998-08-26
Publication date: 2005-11-24
Anticipated expiration: 2018-08-26
Also published as: JP2000068087A

Description

【０００１】
【発明の属する技術分野】
本発明は、直流電源回路の直流出力を高周波電源回路に供給し、その高周波電源回路からの高周波出力を無電極放電灯の近傍に配置された誘導コイルに供給し高周波電磁界を誘起して、無電極放電灯を点灯させる無電極放電灯点灯装置に関するものである。
【０００２】
【従来の技術】
従来の無電極放電灯点灯装置（特開平５−２７５１８３号）の回路図を図８に示す。以下、図８の点灯装置の構成について簡単に説明する。直流電源１の両端に第１のフィルタ６ａを介して発振部ａが接続され、この発振部ａの両端に第１のフィルタ６ａとは異なる第２のフィルタ６ｂを介してプリアンプｂが接続され、このプリアンプｂの両端に第２のフィルタ６ｂとは異なる第３のフィルタ６ｃを介してメインアンプｃが接続されている。また、メインアンプｃの出力端には、誘導コイル３及び無電極放電灯４からなる負荷回路が接続されている。このように構成することにより、発振部ａによる直流電源１側に及ぼす干渉は、安定な発振が要求される発振部ａの発振特性に応じたフィルタ特性を有する、専用に設計されたπ型フィルタ６ａにより効果的に防止することができる。また、各回路ブロックａ，ｂ，ｃ間相互の干渉は、各回路ブロックａ，ｂ、各回路ブロックｂ，ｃ又は各回路ブロックａ，ｃの閉回路中に第２のフィルタ６ｂ又は第３のフィルタ６ｃが設けられているので、干渉による障害を防止することができる。この従来例のように、直流電源１とメインアンプｃの間にフィルタ回路を挿入することは、よく知られている。
【０００３】
また、他の従来の無電極放電灯点灯装置（特開平６―１１１９６６号）の回路図を図９に示す。以下、図９の点灯装置の構成について簡単に説明する。過電流保護回路５は、無電極放電灯４が無負荷になると、直流電源１と高周波電源回路２の間に設けられた抵抗Ｒｘに発生する電圧を検出し、プリアンプ７２のトランジスタのべース・エミッタ間を短絡し、高周波電源回路２の回路動作を停止させている。この従来例では、直流電源回路１と高周波電源回路２の間に設けられたフィルタ回路６の構成と過電流保護回路５の検出抵抗Ｒｘの接続関係は、図１０に示す構成になっている。
【０００４】
【発明が解決しようとする課題】
上述の従来例においては、高周波電源回路２から発生するノイズが直流電源回路１に帰還しないようにするために、コンデンサ及びインダクタからなるフィルタ回路６が挿入されている。ところが検出抵抗Ｒｘが、このフィルタ回路６と高周波電源回路２の間に挿入されていると、検出抵抗Ｒｘにはフィルタ回路６で除去されない高周波電源回路２から発生するノイズ成分も印加されることになる。また、検出抵抗Ｒｘの損失を少なくするためには、低抵抗の抵抗を使用する必要があるため、検出抵抗Ｒｘに発生する電圧は非常に小さい。従って、検出抵抗Ｒｘは高周波電源回路２から発生するノイズの影響を受けやすく、このようなノイズの影響を受けると、過電流保護回路５は非常に誤動作しやすくなるという問題がある。
【０００５】
したがって、本発明の目的は、高周波電源回路から発生するノイズを防止するとともに、異常保護回路が誤動作することなく正常に高周波電源回路が動作することができる無電極放電灯点灯装置を提供することである。
【０００６】
【課題を解決するための手段】
本発明によれば、上記の課題を解決するために、図１に示すように、直流電圧を出力する直流電源回路１と、この直流電源回路１の出力端に接続され、高周波電力を出力する、少なくとも１つのスイッチング素子Ｑ１，Ｑ２を含む高周波電源回路２と、この高周波電源回路２の出力端に接続された誘導コイル３と、この誘導コイル３に近接して配置される無電極放電灯４と、前記直流電源回路１の低圧側の一端と誘導コイル３の一端の間に設けられた抵抗ＲＸ１と、その抵抗ＲＸ１により前記高周波電源回路２に流れる過電流を検出し、その検出出力により高周波電源回路２を保護するための異常保護回路５と、前記直流電源回路１の高圧側の一端と前記高周波電源回路２の入力端との間に設けられたインダクタＬ２、及び少なくとも２つのコンデンサＣ４，Ｃ５を有したフィルタ回路６とを備えた無電極放電灯点灯装置において、前記２つのコンデンサＣ４，Ｃ５のそれぞれの一端は前記インダクタＬ２の両端に接続され、それぞれの他端は前記抵抗ＲＸ１の両端に接続することを特徴とするものである。
【０００７】
【発明の実施の形態】
（実施例１）
本発明の第１の実施例を図１に示す。直流電源回路１（図では直流電源）の出力端には、フィルタ回路６を介して、高周波電源回路２（スイッチング素子Ｑ１，Ｑ２及びインダクタＬ１とコンデンサＣ１，Ｃ２からなる、いわゆるＤ級増幅回路）が接続されており、その出力端には誘導コイル３が接続されている。そして、誘導コイル３の近傍には透光性のガラスバルブまたは内面に蛍光体が塗布されたガラスバルブ内に不活性ガス、金属蒸気等の放電ガスを封入した無電極放電灯４が配置されている。
【０００８】
異常保護回路５は、図２に示すように、コンパレータＩＣ１からなり、コンパレータＩＣ１の負入力端は、直流電源回路１の出力端（点Ｅ−Ａ間）と並列に直列接続された抵抗Ｒ１と抵抗Ｒ２の分圧点に接続されている。コンパレータＩＣ１の正入力端は、直流電源回路１と高周波電源回路２の間に設けられた検出抵抗ＲＸ１の高周波電源回路２側（点Ｂ）に接続されている。また検出抵抗ＲＸ１と並列にコンデンサＣ３が接続されている。コンパレータＩＣ１の出力端は、バイアス抵抗Ｒ４を介して、トランジスタＱ３のべース端子と接続されている。さらに、高周波電源回路２のスイッチング素子Ｑ２のゲート・ソース間（点Ｇ−Ａ間）と並列にダイオードＤ２とトランジスタＱ３の直列回路が接続されている。また、コンパレータＩＣ１の出力端は、抵抗Ｒ３とダイオードＤ１を介してコンパレータＩＣ１の正入力端とも接続されている。フィルタ回路６は、インダクタＬ２及びコンデンサＣ４，Ｃ５からなる。
【０００９】
まず、本実施例における正常時の回路動作について説明する。直流電源回路１により直流電圧を高周波電源回路２に供給する。この直流電圧を電源として、高周波電力を誘導コイル３に供給する高周波電源回路２が動作する。なお、高周波電源回路２のスイッチング素子Ｑ１，Ｑ２は交互にＯＮ・ＯＦＦする。そして、この高周波電源回路２により誘導コイル３に数百ｋＨｚから数百ＭＨｚの高周波電流を流すことにより、誘導コイル３に高周波電磁界が発生し、無電極放電灯４が点灯する。
【００１０】
このとき、異常保護回路５のコンパレータＩＣ１の正入力端の電位よりも負入力端の電位の方を高く設定している。よって、コンパレータＩＣ１の出力はＬｏｗレべルであり、異常保護回路５のトランジスタＱ３はＯＦＦであるので、高周波電源回路２も動作し続けて、無電極放電灯４は点灯し続ける。
【００１１】
次に、例えば無電極放電灯１が破損した場合のように、いわゆる無負荷時での回路動作について説明する。無負荷時には、高周波電源回路２に流れる電流が急激に増加するので、検出抵抗ＲＸ１の両端に発生する電圧も上昇し、異常保護回路５のコンパレータＩＣ１の正入力端の電位が負入力端の電位よりも高くなり、コンパレータＩＣ１の出力はＨｉｇｈレべルとなる。コンパレータＩＣ１の出力がＨｉｇｈレべルとなると、抵抗Ｒ３、ダイオードＤ１を介してコンパレータＩＣ１の正入力端にコンパレータＩＣ１の出力が印加されるので、コンパレータＩＣ１の正入力端の電位が負入力端の電位よりも高くなった状態を維持する。
【００１２】
同時に、コンパレータＩＣ１の出力は異常保護回路５のバイアス抵抗Ｒ４を介してトランジスタＱ３のべース端子に電流を流すので、トランジスタＱ３はＯＮ状態となり、ＯＮ状態を維持する。トランジスタＱ３がＯＮ状態となると、高周波電源回路２のスイッチング素子Ｑ２のゲート・ソース間をダイオードＤ２を介して短絡するので、高周波電源回路２の回路動作は停止し、無電極放電灯４は消灯する。そして、無電極放電灯４は消灯し続ける。従って、高周波電源回路２は回路動作を停止維持するので、高周波電源回路２に過大な電圧が印加されたり過大な電流が流れることがない。本実施例では、この異常保護回路５がノイズにより誤動作することがなくなり、高周波電源回路２の回路素子は破壊せず確実に保護される。
【００１３】
（実施例２）
本発明の第２の実施例を図３に示す。図１に示した第１の実施例と同じ回路構成には同じ符号を付し詳細な説明は省略する。第１の実施例と本実施例の異なる点は、フィルタ回路６の回路構成である。フィルタ回路６は、π型のフィルタ回路構成であり、インダクタＬ２とコンデンサＣ４，Ｃ５で構成されている。インダクタＬ２は、直流電源回路１の正極出力端子と高周波電源回路２の正極入力端子の間に設けられ、コンデンサＣ４は、インダクタＬ３の直流電源回路１側の一端と検出抵抗ＲＸ１の高周波電源回路２側の一端の間に接続されている。また、コンデンサＣ５は、インダクタＬ３の高周波電源回路２側の一端と検出抵抗ＲＸ１の直流電源回路１側の一端の間に接続されている。
【００１４】
このように、フィルタ回路６のコンデンサＣ４及びＣ５を検出抵抗ＲＸ１の両端で交差させて接続しても、第１の実施例と同様に、異常保護回路５がノイズにより誤動作することが無くなり、高周波電源回路２の回路素子は破壊せず確実に保護される。異常保護回路５の構成及び動作は図２と同様である。
【００１５】
（実施例３）
本発明の第３の実施例を図４及び図５に示す。なお、第１又は第２の実施例と同じ回路構成については同じ符号を符して詳細な説明は省略する。第１又は第２の実施例と本実施例の異なる点は、直流電源回路１が具体化した点と、フィルタ回路６の回路構成と、高周波電源回路２とドライブ回路７の間に第２のフィルタ回路８を追加した点と、高周波電源回路２と誘導コイル３の間にマッチング回路１１を追加した点と、高周波電源回路２とドライブ回路７の間に検出抵抗ＲＸ２を設けた点である。異常保護回路５の構成及び動作は図２と同様である。
【００１６】
以下、図４及び図５の回路構成について説明する。商用電源ＡＣに、インダクタ及びコンデンサからなる電源フィルタ回路９及びダイオードブリッジからなる整流回路１０を介して直流電源回路１（図ではいわゆる昇圧チョッパ回路）が接続されている。直流電源回路１の出力端には高周波電源回路２（スイッチング素子Ｑ１，Ｑ２及びインダクタＬ１，コンデンサＣ１からなる、いわゆるＤ級増幅回路）が接続されており、誘導コイル３と高周波電源回路２の間のインピーダンスを整合し、無電極放電灯４に効率良く高周波電力を伝達するコンデンサＣ２，Ｃ６，Ｃ７からなるマッチング回路１１を介して誘導コイル３に接続されている。そして、誘導コイル３の近傍には透光性のガラスバルブまたは内面に蛍光体が塗布されたガラスバルブ内に不活性ガス、金属蒸気等の放電ガスを封入した無電極放電灯４が配置されている。また、直流電源回路１の出力端には高周波電源回路２のスイッチング素子Ｑ１，Ｑ２を駆動するためのドライブ回路７が接続されている。そして、高周波電源回路２から誘導コイル３に数百ｋＨｚから数百ＭＨｚの高周波電流を流すことにより、誘導コイル３に高周波電磁界を発生させ、無電極放電灯４に高周波電力を供給し、内部に高周波プラズマ電流を発生させて紫外線もしくは可視光を発生させるようになっている。
【００１７】
直流電源回路１は、インダクタＬ４、スイッチング素子Ｑ４（図ではＭＯＳＦＥＴ）、ダイオードＤ３、コンデンサＣ８、及び、スイッチング素子Ｑ４をＯＮ・ＯＦＦ駆動制御する制御回路からなり、商用電源ＡＣを整流した直流電圧を昇圧した直流電圧に変換している。
【００１８】
ドライブ回路７は、水晶振動子Ｘを用いた発振回路及び増幅回路で構成され、駆動トランスＴ１の１次巻線ｎ１の両端に、高周波の略正弦波電圧を発生させ、高周波電源回路２のスイッチング素子Ｑ１，Ｑ２を駆動する。この回路は、よく知られているので詳細な説明は省略する。
【００１９】
フィルタ回路６は、インダクタＬ５及びコンデンサＣ９〜Ｃ１２で構成され、それぞれのコンデンサの一端は図４に示すＡ点（検出抵抗ＲＸ２の直流電源回路１側の一端）またはＢ点（検出抵抗ＲＸ２の高周波電源回路２側の一端）に接続されている。第２のフィルタ回路８は、インダクタＬ６及びコンデンサＣ１３，Ｃ１４で構成され、コンデンサＣ１３の一端はＡ点に、コンデンサＣ１４はＢ点に接続されている。また、検出抵抗ＲＸ２は、ドライブ回路７と高周波電源回路２の間に設けられている。
【００２０】
次に、本実施例における回路動作について説明する。商用電源ＡＣが投入されると、電源フィルタ回路９及び整流回路１０を介して直流電源回路１（図ではいわゆる昇圧チョッパ回路）が動作し、チョッパ回路の出力電圧は、商用電源ＡＣを整流平滑した電圧（電圧実効値の√２倍）よりも高い直流電圧Ｅとして高周波電源回路２に供給される。この直流電圧Ｅを電源として、高周波電力を誘導コイル３に供給する高周波電源回路２が動作する。ほぼ同時に、ドライブ回路７が動作し、高周波電源回路２のスイッチング素子Ｑ１，Ｑ２を交互にＯＮ・ＯＦＦさせている。そして、この高周波電源回路２によりマッチング回路１１を介して誘導コイル３に高周波電流を流すことにより、誘導コイル３に高周波電磁界が発生し、無電極放電灯４が点灯する。
【００２１】
このとき、異常保護回路５（図２）のコンパレータＩＣ１の正入力端の電位よりも負入力端の電位の方を高く設定している。よって、コンパレータＩＣ１の出力はＬｏｗレべルであり、異常保護回路５のトランジスタＱ３はＯＦＦであるので、高周波電源回路２も動作し続けて、無電極放電灯４は点灯し続ける。
【００２２】
本実施例においては、フィルタ回路６を上記のように構成したので直流電源回路１（いわゆる昇圧チョッパ回路）のスイッチング素子Ｑ４のスイッチング時に発生するノイズが、高周波電源回路２へ影響を与えないという効果がある。また、本実施例においては、ドライブ回路７と高周波電源回路２の間にも第２のフィルタ回路８を設けたので、ドライブ回路７と高周波電源回路２との間の相互干渉による障害を防止できるという効果もある。
【００２３】
（実施例４）
本発明の第４の実施例の要部回路構成を図６に示す。本実施例は、図４に示した第３の実施例において、フィルタ回路６のみを図６に示す構成に置き換えたものである。第３の実施例のフィルタ回路６と本実施例のフィルタ回路６の異なる点は、フィルタ回路を多段構成にした点である。
【００２４】
以下、図６の回路構成について説明する。本実施例におけるフィルタ回路６は、インダクタＬ７及びコンデンサＣ１５，Ｃ１６からなるπ型のフィルタ回路をもう一段追加している。図中の点Ａ，Ｂは図４の点Ａ，Ｂにそれぞれ接続される。特に高周波電源回路２がＤ級増幅回路で構成されている場合においては、スイッチングの電圧波形が略矩形波なので、高周波電源回路２の動作周波数の高調波成分を多く含む。従って、本実施例のように、フィルタ回路６の構成を多段構成にすることにより、高周波電源回路２から発生する高調波成分のノイズは除去され、よりノイズ低減効果がある。なお、本実施例では２段のフィルタ構成であったが、３段、４段などのさらに多段のフィルタ回路構成であっても良いことは言うまでもない。
【００２５】
（実施例５）
本発明の第５の実施例の要部回路構成を図７に示す。本実施例は、図４に示した第３の実施例において、フィルタ回路６のみを図７に示す構成に置き換えたものである。本実施例においては、フィルタ回路６にコンデンサＣ１８とインダクタＬ９の直列回路及びコンデンサＣ１９とインダクタＬ１０の直列回路を有して構成されている。また、直流電源回路１の出力端と並列にコンデンサＣ１７が接続されており、高周波電源回路２の入力端と並列にコンデンサＣ２０が接続されている。そして、フィルタ回路６の入力側端子間には、コモンフィルターＴ２が挿入されている。図中の点Ａ，Ｂは図４の点Ａ，Ｂにそれぞれ接続される。このような構成にすることにより、高周波電源回路２から発生するスイッチングノイズが、より低減される。また、異常保護回路５も誤動作することなく正常に動作できる。
【００２６】
なお、上記各実施例において、高周波電源回路２はＤ級増幅回路に限定されるものではなく、Ｃ級増幅回路やＥ級増幅回路でもよい。また、上記各実施例においては、異常保護回路５は、負荷異常時に一瞬にして高周波電源回路２の回路動作を停止させているが、間欠発振動作などの出力を制限する手段などのように、とにかく高周波電源回路２の回路が保護される手段であれば何でもよいことは言うまでもない。
【００２７】
【発明の効果】
本発明によれば、直流電圧を出力する直流電源回路と、この直流電源回路の出力端に接続され、高周波電力を出力する、少なくとも１つのスイッチング素子を含む高周波電源回路と、この高周波電源回路の出力端に接続された誘導コイルと、この誘導コイルに近接して配置される無電極放電灯と、前記直流電源回路の低圧側の一端と誘導コイルの一端の間に設けられた抵抗と、その抵抗により前記高周波電源回路に流れる過電流を検出し、その検出出力により高周波電源回路を保護するための異常保護回路と、前記直流電源回路の高圧側の一端と前記高周波電源回路の入力端との間に設けられたインダクタ、及び少なくとも２つのコンデンサを有したフィルタ回路とを備えた無電極放電灯点灯装置において、前記２つのコンデンサのそれぞれの一端は前記インダクタの両端に接続され、それぞれの他端は前記抵抗の両端に接続することによって、高周波電源回路から発生するノイズを防止するとともに、異常保護回路が誤動作することなく正常に高周波電源回路が動作することができる無電極放電灯点灯装置を提供できるものである。
【図面の簡単な説明】
【図１】本発明の第１の実施例の回路図である。
【図２】本発明の第１の実施例の異常保護回路の回路図である。
【図３】本発明の第２の実施例の回路図である。
【図４】本発明の第３の実施例の主回路の構成を示す回路図である。
【図５】本発明の第３の実施例の電源回路の構成を示す回路図である。
【図６】本発明の第４の実施例のフィルタ回路の回路図である。
【図７】本発明の第５の実施例のフィルタ回路の回路図である。
【図８】第１の従来例の回路図である。
【図９】第２の従来例の回路図である。
【図１０】第２の従来例の要部回路構成を示す回路図である。
【符号の説明】
１直流電源回路
２高周波電源回路
３誘導コイル
４無電極放電灯
５異常保護回路
６フィルタ回路[0001]
BACKGROUND OF THE INVENTION
The present invention supplies a DC output of a DC power supply circuit to a high frequency power supply circuit, supplies a high frequency output from the high frequency power supply circuit to an induction coil arranged in the vicinity of the electrodeless discharge lamp, induces a high frequency electromagnetic field, The present invention relates to an electrodeless discharge lamp lighting device for lighting an electrodeless discharge lamp.
[0002]
[Prior art]
FIG. 8 shows a circuit diagram of a conventional electrodeless discharge lamp lighting device (Japanese Patent Laid-Open No. 5-275183). Hereinafter, the configuration of the lighting device of FIG. 8 will be briefly described. An oscillating unit a is connected to both ends of the DC power supply 1 via a first filter 6a, and a preamplifier b is connected to both ends of the oscillating unit a via a second filter 6b different from the first filter 6a. A main amplifier c is connected to both ends of the preamplifier b via a third filter 6c different from the second filter 6b. A load circuit including the induction coil 3 and the electrodeless discharge lamp 4 is connected to the output terminal of the main amplifier c. With this configuration, the interference on the DC power supply 1 side by the oscillating unit a has a filter characteristic corresponding to the oscillation characteristic of the oscillating unit a for which stable oscillation is required, and is a π-type filter designed for exclusive use. This can be effectively prevented by 6a. Further, the mutual interference between the circuit blocks a, b, and c is caused by the second filter 6b or the third filter in the closed circuit of each circuit block a, b, each circuit block b, c, or each circuit block a, c. Since the filter 6c is provided, a failure due to interference can be prevented. As in this conventional example, it is well known to insert a filter circuit between the DC power supply 1 and the main amplifier c.
[0003]
FIG. 9 shows a circuit diagram of another conventional electrodeless discharge lamp lighting device (Japanese Patent Laid-Open No. 6-111966). Hereinafter, the configuration of the lighting device of FIG. 9 will be briefly described. The overcurrent protection circuit 5 detects the voltage generated in the resistor Rx provided between the DC power supply 1 and the high frequency power supply circuit 2 when the electrodeless discharge lamp 4 becomes unloaded, and the base of the transistor of the preamplifier 72 is detected. -The emitter is short-circuited, and the circuit operation of the high-frequency power supply circuit 2 is stopped. In this conventional example, the connection relationship between the configuration of the filter circuit 6 provided between the DC power supply circuit 1 and the high frequency power supply circuit 2 and the detection resistor Rx of the overcurrent protection circuit 5 is as shown in FIG.
[0004]
[Problems to be solved by the invention]
In the above-described conventional example, the filter circuit 6 including a capacitor and an inductor is inserted in order to prevent noise generated from the high frequency power supply circuit 2 from being fed back to the DC power supply circuit 1. However, if the detection resistor Rx is inserted between the filter circuit 6 and the high frequency power supply circuit 2, a noise component generated from the high frequency power supply circuit 2 that is not removed by the filter circuit 6 is also applied to the detection resistor Rx. Become. Further, in order to reduce the loss of the detection resistor Rx, it is necessary to use a low-resistance resistor, and therefore the voltage generated in the detection resistor Rx is very small. Therefore, the detection resistor Rx is easily affected by noise generated from the high-frequency power supply circuit 2, and when it is affected by such noise, there is a problem that the overcurrent protection circuit 5 is very likely to malfunction.
[0005]
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an electrodeless discharge lamp lighting device that can prevent noise generated from a high-frequency power supply circuit and that can correctly operate the high-frequency power supply circuit without malfunctioning. is there.
[0006]
[Means for Solving the Problems]
According to the present invention, in order to solve the above-described problem, as shown in FIG. 1, a DC power supply circuit 1 that outputs a DC voltage, and an output terminal of the DC power supply circuit 1 are connected to output high-frequency power. , A high frequency power supply circuit 2 including at least one switching element Q1, Q2, an induction coil 3 connected to the output terminal of the high frequency power supply circuit 2, and an electrodeless discharge lamp 4 disposed in the vicinity of the induction coil 3. When the a resistor RX1 provided between the low pressure side end to one end of the induction coil 3 of the DC power supply circuit 1, detects an overcurrent flowing through said high-frequency power supply circuit 2 by the resistance RX1, high frequency by the detection output An abnormality protection circuit 5 for protecting the power supply circuit 2, an inductor L2 provided between one end on the high voltage side of the DC power supply circuit 1 and an input end of the high frequency power supply circuit 2, and at least two In the electrodeless discharge lamp lighting device that includes a filter circuit 6 having a capacitor C4, C5, one end of each of said two capacitors C4, C5 are connected to both ends of the inductor L2, the other ends are the resistance It is characterized by being connected to both ends of RX1.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
(Example 1)
A first embodiment of the present invention is shown in FIG. The output terminal of the DC power supply circuit 1 (DC power supply in the figure) is connected to a high-frequency power supply circuit 2 (a so-called class D amplifier circuit including switching elements Q1 and Q2, inductor L1 and capacitors C1 and C2) via a filter circuit 6. Is connected, and the induction coil 3 is connected to the output end thereof. In the vicinity of the induction coil 3, an electrodeless discharge lamp 4 in which a discharge gas such as an inert gas or a metal vapor is enclosed is disposed in a translucent glass bulb or a glass bulb having an inner surface coated with a phosphor. Yes.
[0008]
As shown in FIG. 2, the abnormality protection circuit 5 includes a comparator IC1, and the negative input terminal of the comparator IC1 is connected to a resistor R1 connected in series with the output terminal (between points EA) of the DC power supply circuit 1 in parallel. It is connected to the voltage dividing point of the resistor R2. The positive input terminal of the comparator IC 1 is connected to the high-frequency power circuit 2 side (point B) of the detection resistor RX 1 provided between the DC power circuit 1 and the high-frequency power circuit 2. A capacitor C3 is connected in parallel with the detection resistor RX1. The output terminal of the comparator IC1 is connected to the base terminal of the transistor Q3 via the bias resistor R4. Furthermore, a series circuit of a diode D2 and a transistor Q3 is connected in parallel with the gate-source (between the points GA) of the switching element Q2 of the high-frequency power supply circuit 2. The output terminal of the comparator IC1 is also connected to the positive input terminal of the comparator IC1 through the resistor R3 and the diode D1. The filter circuit 6 includes an inductor L2 and capacitors C4 and C5.
[0009]
First, a normal circuit operation in the present embodiment will be described. A direct current voltage is supplied to the high frequency power supply circuit 2 by the direct current power supply circuit 1. A high frequency power supply circuit 2 that supplies high frequency power to the induction coil 3 using this DC voltage as a power supply operates. Note that the switching elements Q1, Q2 of the high-frequency power supply circuit 2 are alternately turned ON / OFF. Then, when a high frequency current of several hundred kHz to several hundred MHz is passed through the induction coil 3 by the high frequency power supply circuit 2, a high frequency electromagnetic field is generated in the induction coil 3, and the electrodeless discharge lamp 4 is turned on.
[0010]
At this time, the potential at the negative input end is set higher than the potential at the positive input end of the comparator IC1 of the abnormality protection circuit 5. Therefore, since the output of the comparator IC1 is at a low level and the transistor Q3 of the abnormality protection circuit 5 is OFF, the high-frequency power supply circuit 2 continues to operate and the electrodeless discharge lamp 4 continues to be lit.
[0011]
Next, a description will be given of the circuit operation at a so-called no load, for example, when the electrodeless discharge lamp 1 is damaged. When there is no load, the current flowing through the high frequency power supply circuit 2 increases rapidly, so that the voltage generated at both ends of the detection resistor RX1 also rises, and the potential at the positive input terminal of the comparator IC1 of the abnormality protection circuit 5 becomes the potential at the negative input terminal. The output of the comparator IC1 becomes a high level. When the output of the comparator IC1 becomes a high level, the output of the comparator IC1 is applied to the positive input terminal of the comparator IC1 via the resistor R3 and the diode D1, so that the potential of the positive input terminal of the comparator IC1 is the negative input terminal. The state where the potential is higher than the potential is maintained.
[0012]
At the same time, the output of the comparator IC1 causes a current to flow to the base terminal of the transistor Q3 via the bias resistor R4 of the abnormality protection circuit 5, so that the transistor Q3 is turned on and is kept on. When the transistor Q3 is turned on, the gate and source of the switching element Q2 of the high frequency power supply circuit 2 are short-circuited via the diode D2, so that the circuit operation of the high frequency power supply circuit 2 is stopped and the electrodeless discharge lamp 4 is turned off. . Then, the electrodeless discharge lamp 4 continues to be turned off. Accordingly, since the high frequency power supply circuit 2 stops and maintains the circuit operation, an excessive voltage is not applied to the high frequency power supply circuit 2 and an excessive current does not flow. In this embodiment, the malfunction protection circuit 5 is prevented from malfunctioning due to noise, and the circuit elements of the high frequency power supply circuit 2 are reliably protected without being destroyed.
[0013]
(Example 2)
A second embodiment of the present invention is shown in FIG. The same circuit configuration as that of the first embodiment shown in FIG. The difference between the first embodiment and this embodiment is the circuit configuration of the filter circuit 6. The filter circuit 6 has a π-type filter circuit configuration and includes an inductor L2 and capacitors C4 and C5. The inductor L2 is provided between the positive output terminal of the DC power supply circuit 1 and the positive input terminal of the high frequency power supply circuit 2, and the capacitor C4 is one end of the inductor L3 on the DC power supply circuit 1 side and the high frequency power supply circuit 2 of the detection resistor RX1. Connected between one end of the side. The capacitor C5 is connected between one end of the inductor L3 on the high frequency power supply circuit 2 side and one end of the detection resistor RX1 on the DC power supply circuit 1 side.
[0014]
As described above, even when the capacitors C4 and C5 of the filter circuit 6 are crossed and connected at both ends of the detection resistor RX1, the abnormality protection circuit 5 does not malfunction due to noise as in the first embodiment, and the high frequency The circuit elements of the power supply circuit 2 are reliably protected without being destroyed. The configuration and operation of the abnormality protection circuit 5 are the same as those in FIG.
[0015]
(Example 3)
A third embodiment of the present invention is shown in FIGS. The same circuit configuration as that of the first or second embodiment is denoted by the same reference numeral, and detailed description thereof is omitted. The difference between the first or second embodiment and the present embodiment is that the DC power supply circuit 1 is embodied, the circuit configuration of the filter circuit 6, and the second configuration between the high-frequency power supply circuit 2 and the drive circuit 7. The filter circuit 8 is added, the matching circuit 11 is added between the high frequency power supply circuit 2 and the induction coil 3, and the detection resistor RX2 is provided between the high frequency power supply circuit 2 and the drive circuit 7. The configuration and operation of the abnormality protection circuit 5 are the same as those in FIG.
[0016]
The circuit configuration of FIGS. 4 and 5 will be described below. A DC power supply circuit 1 (a so-called step-up chopper circuit in the figure) is connected to a commercial power supply AC through a power supply filter circuit 9 made of an inductor and a capacitor and a rectifier circuit 10 made of a diode bridge. A high frequency power supply circuit 2 (a so-called class D amplifier circuit composed of switching elements Q1 and Q2 and an inductor L1 and a capacitor C1) is connected to the output terminal of the DC power supply circuit 1, and between the induction coil 3 and the high frequency power supply circuit 2. Are connected to the induction coil 3 via a matching circuit 11 composed of capacitors C2, C6, C7 that efficiently transmit high-frequency power to the electrodeless discharge lamp 4. In the vicinity of the induction coil 3, an electrodeless discharge lamp 4 in which a discharge gas such as an inert gas or a metal vapor is enclosed is disposed in a translucent glass bulb or a glass bulb having an inner surface coated with a phosphor. Yes. A drive circuit 7 for driving the switching elements Q1 and Q2 of the high frequency power supply circuit 2 is connected to the output terminal of the DC power supply circuit 1. A high frequency current of several hundreds of kHz to several hundreds of MHz is supplied from the high frequency power supply circuit 2 to the induction coil 3 to generate a high frequency electromagnetic field in the induction coil 3 and supply high frequency power to the electrodeless discharge lamp 4. A high frequency plasma current is generated to generate ultraviolet rays or visible light.
[0017]
The DC power supply circuit 1 includes an inductor L4, a switching element Q4 (MOSFET in the figure), a diode D3, a capacitor C8, and a control circuit that controls ON / OFF driving of the switching element Q4. It is converted into a boosted DC voltage.
[0018]
The drive circuit 7 is composed of an oscillation circuit and an amplifier circuit using a crystal resonator X, generates a high-frequency substantially sinusoidal voltage at both ends of the primary winding n1 of the drive transformer T1, and switches the high-frequency power supply circuit 2 Elements Q1 and Q2 are driven. Since this circuit is well known, detailed description thereof will be omitted.
[0019]
The filter circuit 6 includes an inductor L5 and capacitors C9 to C12. One end of each capacitor is a point A (one end of the detection resistor RX2 on the DC power supply circuit 1 side) or a point B (high frequency of the detection resistor RX2) shown in FIG. One end of the power supply circuit 2 side). The second filter circuit 8 includes an inductor L6 and capacitors C13 and C14. One end of the capacitor C13 is connected to the point A, and the capacitor C14 is connected to the point B. The detection resistor RX <b> 2 is provided between the drive circuit 7 and the high frequency power supply circuit 2.
[0020]
Next, the circuit operation in the present embodiment will be described. When the commercial power supply AC is turned on, the DC power supply circuit 1 (the so-called step-up chopper circuit in the figure) operates via the power supply filter circuit 9 and the rectifier circuit 10, and the output voltage of the chopper circuit rectifies and smoothes the commercial power supply AC. It is supplied to the high frequency power supply circuit 2 as a DC voltage E higher than the voltage (√2 times the effective voltage value). The high frequency power supply circuit 2 that supplies high frequency power to the induction coil 3 operates using the DC voltage E as a power source. At substantially the same time, the drive circuit 7 operates, and the switching elements Q1 and Q2 of the high frequency power supply circuit 2 are alternately turned on and off. Then, when a high frequency current is caused to flow through the induction coil 3 via the matching circuit 11 by the high frequency power supply circuit 2, a high frequency electromagnetic field is generated in the induction coil 3, and the electrodeless discharge lamp 4 is turned on.
[0021]
At this time, the potential at the negative input end is set higher than the potential at the positive input end of the comparator IC1 of the abnormality protection circuit 5 (FIG. 2). Therefore, since the output of the comparator IC1 is at a low level and the transistor Q3 of the abnormality protection circuit 5 is OFF, the high-frequency power supply circuit 2 continues to operate and the electrodeless discharge lamp 4 continues to be lit.
[0022]
In the present embodiment, since the filter circuit 6 is configured as described above, the noise generated when switching the switching element Q4 of the DC power supply circuit 1 (so-called boost chopper circuit) does not affect the high frequency power supply circuit 2. There is. In the present embodiment, since the second filter circuit 8 is also provided between the drive circuit 7 and the high frequency power supply circuit 2, it is possible to prevent a failure due to mutual interference between the drive circuit 7 and the high frequency power supply circuit 2. There is also an effect.
[0023]
(Example 4)
FIG. 6 shows the main circuit configuration of the fourth embodiment of the present invention. This embodiment is obtained by replacing only the filter circuit 6 with the configuration shown in FIG. 6 in the third embodiment shown in FIG. The difference between the filter circuit 6 of the third embodiment and the filter circuit 6 of the present embodiment is that the filter circuit has a multistage configuration.
[0024]
Hereinafter, the circuit configuration of FIG. 6 will be described. In the filter circuit 6 in the present embodiment, another π-type filter circuit including an inductor L7 and capacitors C15 and C16 is added. Points A and B in the figure are connected to points A and B in FIG. 4, respectively. In particular, when the high-frequency power supply circuit 2 is composed of a class D amplifier circuit, the switching voltage waveform is a substantially rectangular wave, and therefore includes a large amount of harmonic components of the operating frequency of the high-frequency power supply circuit 2. Therefore, as in this embodiment, by making the configuration of the filter circuit 6 into a multi-stage configuration, the noise of the harmonic component generated from the high frequency power supply circuit 2 is removed, and there is a more noise reduction effect. Although the two-stage filter configuration is used in the present embodiment, it is needless to say that a multi-stage filter circuit configuration such as a three-stage or four-stage filter may be used.
[0025]
(Example 5)
FIG. 7 shows the main circuit configuration of the fifth embodiment of the present invention. This embodiment is obtained by replacing only the filter circuit 6 with the configuration shown in FIG. 7 in the third embodiment shown in FIG. In this embodiment, the filter circuit 6 includes a series circuit of a capacitor C18 and an inductor L9 and a series circuit of a capacitor C19 and an inductor L10. In addition, a capacitor C17 is connected in parallel with the output terminal of the DC power supply circuit 1, and a capacitor C20 is connected in parallel with the input terminal of the high-frequency power supply circuit 2. A common filter T2 is inserted between the input terminals of the filter circuit 6. Points A and B in the figure are connected to points A and B in FIG. 4, respectively. By adopting such a configuration, switching noise generated from the high frequency power supply circuit 2 is further reduced. Also, the abnormality protection circuit 5 can operate normally without malfunctioning.
[0026]
In each of the above embodiments, the high frequency power supply circuit 2 is not limited to the class D amplifier circuit, and may be a class C amplifier circuit or a class E amplifier circuit. Further, in each of the above embodiments, the abnormality protection circuit 5 stops the circuit operation of the high-frequency power supply circuit 2 in an instant when the load is abnormal, but as a means for limiting output such as intermittent oscillation operation, etc. Anyway, it goes without saying that any means can be used as long as the circuit of the high frequency power supply circuit 2 is protected.
[0027]
【The invention's effect】
According to the present invention, a DC power supply circuit that outputs a DC voltage, a high-frequency power supply circuit that is connected to an output terminal of the DC power supply circuit and that outputs high-frequency power, and includes at least one switching element, An induction coil connected to the output end, an electrodeless discharge lamp disposed close to the induction coil, a resistance provided between one end of the low-voltage side of the DC power supply circuit and one end of the induction coil, An overcurrent flowing through the high-frequency power supply circuit is detected by a resistor, an abnormality protection circuit for protecting the high-frequency power supply circuit by the detection output, and a high-voltage end of the DC power supply circuit and an input end of the high-frequency power supply circuit In an electrodeless discharge lamp lighting device comprising an inductor provided therebetween and a filter circuit having at least two capacitors, each of the two capacitors One end is connected to both ends of the inductor, each of the other end by connecting to both ends of said resistor, thereby preventing a noise generated from the high frequency power supply circuit, normally a high-frequency power supply circuit without error protection circuit to malfunction It is possible to provide an electrodeless discharge lamp lighting device that can operate.
[Brief description of the drawings]
FIG. 1 is a circuit diagram of a first embodiment of the present invention.
FIG. 2 is a circuit diagram of an abnormality protection circuit according to the first embodiment of this invention.
FIG. 3 is a circuit diagram of a second embodiment of the present invention.
FIG. 4 is a circuit diagram showing a configuration of a main circuit according to a third embodiment of the present invention.
FIG. 5 is a circuit diagram showing a configuration of a power supply circuit according to a third embodiment of the present invention.
FIG. 6 is a circuit diagram of a filter circuit according to a fourth embodiment of the present invention.
FIG. 7 is a circuit diagram of a filter circuit according to a fifth embodiment of the present invention.
FIG. 8 is a circuit diagram of a first conventional example.
FIG. 9 is a circuit diagram of a second conventional example.
FIG. 10 is a circuit diagram showing a main circuit configuration of a second conventional example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 DC power supply circuit 2 High frequency power supply circuit 3 Induction coil 4 Electrode discharge lamp 5 Abnormal protection circuit 6 Filter circuit

Claims

A DC power supply circuit that outputs a DC voltage;
A high frequency power supply circuit including at least one switching element connected to the output terminal of the DC power supply circuit and outputting high frequency power;
An induction coil connected to the output end of the high-frequency power supply circuit;
An electrodeless discharge lamp disposed close to the induction coil;
A resistor provided between one end of the low-voltage side of the DC power supply circuit and one end of the induction coil;
An abnormality protection circuit for detecting an overcurrent flowing through the high-frequency power supply circuit with this resistor and protecting the high-frequency power supply circuit with the detection output;
In an electrodeless discharge lamp lighting device comprising an inductor provided between one end on the high voltage side of the DC power supply circuit and an input end of the high frequency power supply circuit, and a filter circuit having at least two capacitors,
One end of each of the two capacitors is connected to both ends of the inductor, and the other end of each of the two capacitors is connected to both ends of the resistor .

2. The electrodeless discharge lamp lighting device according to claim 1, wherein the two capacitors are connected to intersect at both ends of the resistor .

3. The electrodeless discharge lamp lighting device according to claim 2, wherein the filter circuit further includes two capacitors, each connected to both ends of the output end of the DC power supply circuit and both ends of the input end of the high-frequency power supply circuit. .

A drive circuit for driving a switching element of the high frequency power supply circuit is provided, and a second filter circuit having the same configuration as the filter circuit is provided between the drive circuit and the high frequency power supply circuit. Item 4. The electrodeless discharge lamp lighting device according to any one of Items 1 to 3.

5. The electrodeless discharge lamp lighting device according to claim 4, wherein the inductance of the inductor of the filter circuit and the second filter circuit is larger than that of the inductor of the filter circuit.

6. The electrodeless discharge lamp lighting device according to claim 4, wherein at least one of the filter circuit and the second filter circuit is a multi-stage filter circuit.

7. The electrodeless discharge lamp lighting device according to claim 6, wherein the inductance of the plurality of inductors in the multi-stage filter circuit is larger than the inductance of the inductor connected to the high frequency power supply circuit.

8. The electrodeless discharge lamp according to claim 4, wherein a wiring length from the DC power supply circuit to the drive circuit is longer than a wiring length from the DC power supply circuit to the high-frequency power supply circuit. Lighting device.

9. The electrodeless discharge lamp lighting device according to claim 1, wherein the resistor is inserted between the drive circuit and the high frequency power supply circuit.

The electrodeless discharge lamp lighting device according to any one of claims 1 to 9 , wherein a common filter is inserted into at least one of an input end and an output end of the filter circuit.

The electrodeless discharge lamp lighting device according to any one of claims 1 to 10 , further comprising a matching circuit that is disposed between the induction coil and the high-frequency power supply circuit and performs impedance matching between them.

A DC power supply circuit that outputs a DC voltage;
A high frequency power supply circuit including at least one switching element connected to the output terminal of the DC power supply circuit and outputting high frequency power;
An induction coil connected to the output end of the high-frequency power supply circuit;
An electrodeless discharge lamp disposed close to the induction coil;
A resistor provided between one end of the low-voltage side of the DC power supply circuit and one end of the induction coil;
An abnormality protection circuit for detecting an overcurrent flowing through the high-frequency power supply circuit with this resistor and protecting the high-frequency power supply circuit with the detection output;
In an electrodeless discharge lamp lighting device comprising an inductor provided between one end on the high voltage side of the DC power supply circuit and an input end of the high frequency power supply circuit, and a filter circuit having at least two capacitors,
One end of each of the two capacitors is connected to both ends of the inductor, the other end of each is connected to both ends of the resistor ,
The filter circuit is composed of multiple stages,
A drive circuit for driving the switching element of the high frequency power supply circuit is provided, and the resistor is inserted between the drive circuit and the high frequency power supply circuit,
The high frequency power supply circuit is an electrodeless discharge lamp lighting device, wherein the Ru D-class amplification circuit der.