JP4186527B2

JP4186527B2 - Discharge lamp lighting device

Info

Publication number: JP4186527B2
Application number: JP2002193936A
Authority: JP
Inventors: 宏光水川
Original assignee: Matsushita Electric Works Ltd
Current assignee: Panasonic Electric Works Co Ltd
Priority date: 2002-07-02
Filing date: 2002-07-02
Publication date: 2008-11-26
Anticipated expiration: 2022-07-02
Also published as: JP2004039408A

Description

【０００１】
【発明の属する技術分野】
本発明は周囲温度特性を改善した放電灯点灯装置に関するものである。
【０００２】
【従来の技術】
従来、特開平８−１８５９９０や特開平１０−１８９２７３に放電灯点灯装置の周囲温度特性の改善方法が開示されている。
特開平８−１８５９９０では、放電灯の温度もしくは周囲温度を検出し、ランプ出力制御回路の出力を一定にするように温度補正を設けている。また、特開平１０−１８９２７３では、ランプ出力制御回路に温度補正素子を設け、放電灯の始動時に発生する始動時共振電圧のみを周囲温度が低いときは増大させ、高いときは低下させるものである。
【０００３】
（従来例１）
特開平８−１８５９９０の放電灯点灯装置を図面を参照して説明する。図１１において、Ｅ１は商用交流電源で、この商用交流電源Ｅ１に、全波整流回路ＤＢが接続されている。この全波整流回路ＤＢの出力端子間には、サージ吸収素子ＴＮＲおよびコンデンサＣ２１が接続されるとともに、インバータ回路２が接続されている。そして、インバータ回路２は、コンデンサＣ２１に対して並列に、コンデンサＣ２２、インダクタＬ１およびダイオードＤ１の谷埋めの平滑を行なう直列回路が接続されている。また、コンデンサＣ２２およびインダクタＬ１の両端子間に、インバータトランスＴｒ１の共振用のインダクタンスを有する１次巻線Ｔｒ１ａおよびスイッチング素子としてのトランジスタＱ２１の直列回路を接続し、１次巻線Ｔｒ１ａに対して並列に共振用のコンデンサＣ２３を接続するとともに、インダクタＬ１およびダイオードＤ１の接続点からトランジスタＱ２１のコレクタにダイオードＤ２を接続する。
【０００４】
さらに、インバータトランスＴｒ１の２次巻線Ｔｒ１ｂには、発振制御回路３の電流トランスＣＴの検知巻線ＣＴ１ａ、コンデンサＣ４および抵抗Ｒ１を介して放電灯ＬａｍｐのフィラメントＦＬａ，ＦＬｂを接続する。さらに、これらフィラメントＦＬａ，ＦＬｂには、始動用のコンデンサＣ５を接続する。そして、この電流トランスＣＴの制御巻線ＣＴ１ｂにはダイオードＤ３が接続され、このダイオードＤ３はトランジスタＱ２１のべースに接続されるとともに、コンデンサＣ６および電界効果トランジスタ（以下、スイッチング素子と呼ぶ）Ｑ１１の直列回路、コンデンサＣ７およびスイッチング素子Ｑ１２の直列回路、ダイオードＤ４およびコンデンサＣ８を介してトランジスタＱ２１のエミッタに接続されている。また、トランジスタＱ２１のベース、エミッタ間には、ダイオードＤ５および抵抗Ｒ２の直列回路が接続されるとともに、始動用の抵抗Ｒ３を介して全波整流回路ＤＢの正極に接続されている。
【０００５】
また、コンデンサＣ５に対して並列に分圧用のコンデンサＣ１０およびコンデンサＣ１１の直列回路が接続され、コンデンサＣ１０には整流用のダイオードＤ６およびダイオードＤ７、抵抗Ｒ４、コンデンサＣ１２およびタイマ回路４が接続されている。このタイマ回路４は、コンデンサＣ１３、ダイオードＤ８および抵抗Ｒ５にて構成され、コンデンサＣ１３および抵抗Ｒ５の接続点には、トランジスタＱ２２のベースが接続され、このトランジスタＱ２２のコレクタおよびダイオードＤ６の間には、コンデンサＣ１４、抵抗Ｒ６および発光ダイオードＬＥＤ１が接続され、トランジスタＱ２２のエミッタおよびダイオードＤ６のカソード間には、ツェナダイオードＺＤ１および発光ダイオードＬＥＤ２の直列回路が接続されている。トランジスタＱ２２のエミッタはコンデンサＣ１０，Ｃ１１の接続点に接続されている。
【０００６】
一方、全波整流回路ＤＢの出力端子には、電圧検出回路５が接続され、この電圧検出回路５は、抵抗Ｒ７およびコンデンサＣ１５が接続され、コンデンサＣ１５にはツェナダイオードＺＤ２および抵抗Ｒ８が接続されている。
【０００７】
また、電圧検出回路５には、ランプ点灯時出力制御回路６が接続されている。このランプ点灯時出力制御回路６は、抵抗Ｒ９およびコンデンサＣ１６の直列回路が接続され、このコンデンサＣ１６には抵抗Ｒ１０、トランジスタＱ３のエミッタ、コレクタ、抵抗Ｒ１１および温度補正手段としての正特性サーミスタＲ１２の直列回路が接続され、抵抗Ｒ１１および温度上昇とともに抵抗値が増加する正特性サーミスタＲ１２の接続点は、スイッチング素子Ｑ１１のゲートに接続されている。さらに、トランジスタＱ３のベースには、抵抗Ｒ１４および出力可変用の可変抵抗Ｒ１５の直列回路が接続されている。また、コンデンサＣ１６に対して並列に、ツェナダイオードＺＤ３、発光ダイオードＬＥＤ１にフォトカップリングされたフォトトランジスタＰＴｒ１および発光ダイオードＬＥＤ２にフォトカップリングされたフォトトランジスタＰＴｒ２が接続されている。
【０００８】
さらに、全波整流回路ＤＢには、ランプ始動時出力制御回路７が接続されている。このランプ始動時出力制御回路７は、コンデンサＣ１６の正極から抵抗Ｒ１６およびコンデンサＣ１７の直列回路が接続され、コンデンサＣ１７と並列に、ツェナダイオードＺＤ４およびトランジスタＱ４のベース、エミッタの直列回路が接続され、このトランジスタＱ４のコレクタは温度上昇とともに抵抗値が増加する正特性サーミスタＲ１７を介して全波整流回路ＤＢの正極側に接続され、トランジスタＱ４のコレクタ、エミッタ間には、抵抗Ｒ１８が接続されている。トランジスタＱ４のコレクタは、スイッチング素子Ｑ１２のゲートに接続されている。
【０００９】
次に、上述の図１１に示す回路の動作について説明する。
まず、電源が投入されると、商用交流電源Ｅ１が全波整流回路ＤＢで全波整流されて、コンデンサＣ２１には脈流が印加される。そして、インバータ回路２は、コンデンサＣ２１から供給された直流電圧をトランジスタＱ２１により高周波でスイッチング制御し、インバータトランスＴｒ１の１次巻線Ｔｒ１ａのインダクタンスとコンデンサＣ２３のキャパシタンスで共振せしめた電圧が２次巻線Ｔｒ１ｂに誘起され、放電灯Ｌａｍｐに供給される。そして、コンデンサＣ５が放電灯ＬａｍｐのフィラメントＦＬａ，ＦＬｂを予熱し、同時にコンデンサＣ５の発生電圧を放電灯Ｌａｍｐに印加し、放電灯Ｌａｍｐを始動、点灯させる。
【００１０】
また、放電灯Ｌａｍｐが始動する際には、タイマ回路４のコンデンサＣ１３には電荷が蓄えられておらず、所定時間経過するまでは、トランジスタＱ２２をオンした状態を保ち、発光ダイオードＬＥＤ１を点灯させる。この発光ダイオードＬＥＤ１が点灯することにより、フォトトランジスタＰＴｒ１はオン状態となるため、コンデンサＣ１６は充電されない。
【００１１】
そして、コンデンサＣ１６が充電されていないため、トランジスタＱ３がオフ状態を保つので、スイッチング素子Ｑ１１のゲートには電圧が印加されず、スイッチング素子Ｑ１１はオフ状態を保ち、コンデンサＣ６は開放状態となり、トランジスタＱ２１のスイッチング動作には寄与しない。一方、コンデンサＣ１７が充電されるまでの間は、ツェナダイオードＺＤ４がオフ状態であるので、トランジスタＱ４もオフ状態を保ち、正特性サーミスタＲ１７および抵抗Ｒ１８の分圧により設定された電圧値で、スイッチング素子Ｑ１２にゲート電圧が印加され、放電灯Ｌａｍｐの点灯時におけるインバータ回路２の出力電圧を決定する。
【００１２】
そして、放電灯Ｌａｍｐの始動時に放電灯Ｌａｍｐあるいは周囲の温度が低い場合には、正特性サーミスタＲ１７の抵抗値が低くなるため、抵抗Ｒ１８の両端電圧が高くなる。したがって、スイッチング素子Ｑ１２のゲート電圧が高くなり、コンデンサＣ７の見掛上の容量が大きくなり、コンデンサＣ７およびコンデンサＣ８の合成容量が大きくなるため、トランジスタＱ２１のベース電流が増加して、インバータ回路２の出力が相対的に増加して、低温時におけるランプ始動時の放電灯Ｌａｍｐに印加される電圧が相対的に増加して、確実に放電灯Ｌａｍｐを始動する。
【００１３】
反対に、放電灯Ｌａｍｐあるいは周囲の温度が高い場合には、正特性サーミスタＲ１７の抵抗値が高くなるため、抵抗Ｒ１８の両端電圧が低くなる。したがって、スイッチング素子Ｑ１２のゲート電圧が低くなり、コンデンサＣ７の見掛上の容量が小さくなり、コンデンサＣ７およびコンデンサＣ８の合成容量が小さくなるため、トランジスタＱ２１のベース電流が減少して、インバータ回路２の出力が相対的に減少して、低温時におけるランプ始動時の放電灯Ｌａｍｐに印加される電圧が相対的に減少して、不必要に高い電圧を印加することなく放電灯Ｌａｍｐを始動する。
【００１４】
すなわち、放電灯Ｌａｍｐあるいは周囲の温度に対応して、温度が低い場合にも確実に放電灯Ｌａｍｐを点灯させるとともに、温度が高い場合には不必要に高い電圧を印加させることなく放電灯Ｌａｍｐを始動させる。
【００１５】
また、放電灯Ｌａｍｐが始動すると、トランジスタＱ２２がオフして発光ダイオードＬＥＤ１が消灯すると、フォトトランジスタＰＴｒ１もオフして、抵抗Ｒ９およびコンデンサＣ１６の時定数により設定した時間後にコンデンサＣ１６が充電される。そして、このコンデンサＣ１６が充電されることにより、トランジスタＱ３がオンし、スイッチング素子Ｑ１１のゲートに、ゲート電圧が印加され、通常時の制御レベルに合わせる。なお、コンデンサＣ１７の充電により、ツェナダイオードＺＤ４がオンし、トランジスタＱ４がオンすることにより、抵抗Ｒ１８に流れる電流がバイパスされてスイッチング素子Ｑ１２のゲート電圧が印加されなくなるので、コンデンサＣ７が開放され、トランジスタＱ２１の発振周波数は、コンデンサＣ６およびコンデンサＣ８の合成容量により決定される。
【００１６】
まず、全波整流回路ＤＢからの出力が上昇し、電圧検出回路５で検出された電圧が上昇した場合には、トランジスタＱ３のベース電流が減少し、スイッチング素子Ｑ１１のゲート電圧を低下させて、トランジスタＱ２１のスイッチングを速くしてインバータ回路２の出力を低下させる。一方、全波整流回路１からの出力が低下し、電圧検出回路５で検出された電圧が低下した場合には、トランジスタＱ３のベース電流が増加し、スイッチング素子Ｑ１１のゲート電圧を増加させて、トランジスタＱ２１のスイッチングを遅くしてインバータ回路２の出力を増加させる。このように、全波整流回路１の出力電圧が増加すると、インバータ回路２の出力を低下させ、反対に、全波整流回路１の出力電圧が低下すると、インバータ回路２の出力を増加させるため、インバータ回路２の出力を常に一定に保つことができる。
【００１７】
そして、放電灯Ｌａｍｐの点灯時に放電灯Ｌａｍｐあるいは周囲の温度が低い場合には、正特性サーミスタＲ１２の抵抗値が低くなるため、正特性サーミスタＲ１２の両端電圧が低くなる。したがって、スイッチング素子Ｑ１１のゲート電圧が低くなり、コンデンサＣ７の見掛上の容量が小さくなり、コンデンサＣ７およびコンデンサＣ８の合成容量が小さくなるため、トランジスタＱ２１のベース電流が減少して、インバータ回路２の出力が相対的に減少して、従来は低温時におけるランプ点灯時の放電灯Ｌａｍｐに印加される電圧は増加したが、相対的に電圧を低下させて、放電灯Ｌａｍｐに印加される電圧をほぼ一定にさせる。反対に、放電灯Ｌａｍｐあるいは周囲の温度が高い場合には、正特性サーミスタＲ１２の抵抗値が高くなるため、正特性サーミスタＲ１２の両端電圧が高くなる。したがって、スイッチング素子Ｑ１１のゲート電圧が高くなり、コンデンサＣ７の見掛上の容量が大きくなり、コンデンサＣ７およびコンデンサＣ８の合成容量が大きくなるため、トランジスタＱ２１のベース電流が増加して、インバータ回路２の出力が相対的に増加して、つまりランプ点灯時の放電灯Ｌａｍｐに印加される電圧を増加させて、放電灯Ｌａｍｐに印加する電圧を一定にさせる。なお、抵抗Ｒ１８に代えて負特性サーミスタを使用しても、抵抗Ｒ１０または抵抗Ｒ１１に代えて負特性サーミスタを使用しても同様の効果を得ることができる。
【００１８】
（従来例２）
また、特開平１０−１８９２７３を図１２を用いて説明すると、商用交流電源Ｅ１と、商用交流電源Ｅ１を全波整流する整流器ＤＢと、整流器ＤＢの出力を平滑する平滑コンデンサＣ３１と、平滑コンデンサＣ３１の両端電圧を交流の高周波電圧に変換して放電灯Ｌａｍｐに供給するインバータ回路と、インバータ回路を構成するスイッチング素子Ｑ３１，Ｑ３２を駆動する駆動回路１と、駆動回路１の入力端子に入力すべき高周波矩形波信号を発生させることにより、前記スイッチング素子Ｑ３１，Ｑ３２の発振を制御する発振制御回路２とから構成される。
【００１９】
前記インバータ回路は、平滑コンデンサＣ３１の両端に接続されたスイッチング素子Ｑ３１，Ｑ３２の直列回路と、スイッチング素子Ｑ３１，Ｑ３２の直列回路の両端に接続されたコンデンサＣ３２，Ｃ３３の直列回路と、スイッチング素子Ｑ３１，Ｑ３２の接続点及びコンデンサＣ３２，Ｃ３３の接続点間に、放電灯Ｌａｍｐを介して接続されたインダクタＬ１と、放電灯Ｌａｍｐの非電源側端子間に並列接続されたコンデンサＣｏとから構成される、所謂ハーフブリッジ式インバータ回路である。なお、インダクタＬ１とコンデンサＣｏとで共振回路を構成している。
【００２０】
駆動回路１は、抵抗Ｒ１１，Ｒ１２を介してハイサイド側のスイッチング素子Ｑ３１を駆動し、抵抗Ｒ２１，Ｒ２２を介してローサイド側のスイッチング素子Ｑ３２を駆動する集積回路ＩＣ２（例えばＩＲ社製ＩＲ２１１１）を含んで構成される。
【００２１】
発振制御回路２は、集積回路ＩＣ１と抵抗Ｒ５１〜Ｒ５４と負特性のサーミスタＴＨ１とコンデンサＣ５１，Ｃ５２とトランジスタＱ５１，Ｑ５２とから構成される。発振制御回路２の発振周波数は、集積回路ＩＣ１のＴｃ端子及びアース間に接続されたコンデンサＣ５１と、集積回路ＩＣ１のＴＲ端子及びアース間に接続された抵抗Ｒ５１，Ｒ５３、負特性のサーミスタＴＨ１の直列回路との時定数で決まる。また、負特性のサーミスタＴＨ１と抵抗Ｒ５３との直列回路の両端にはトランジスタＱ５１が接続され、抵抗Ｒ５３の両端にはスイッチング素子Ｑ５２が接続され、トランジスタＱ５１及びトランジスタＱ５２の制御端は集積回路ＩＣ１に接続されている。
【００２２】
次に、図１３を参照して動作を簡単に説明する。トランジスタＱ５１とトランジスタＱ５２とは、集積回路ＩＣ１のＴＩＭＥＲ端子及びアース間に接続されたコンデンサＣ５２と、集積回路ＩＣ１のＴＩＭＥＲ端子及び外部電源Ｖｃｃ間に接続された抵抗Ｒ５４との時定数で決まるタイマー回路により、図１３（ａ）、（ｂ）に示すように、各々、電源投入から時間ｔｈ，ｔｓ（ｔｈ＜ｔｓ）だけオンする。その結果、集積回路ＩＣ１のｏｕｔ端子から出力される前記インバータ回路の発振周波数は、時間ｔｈだけ周波数ｆｈとなり、次の時間ｔｓ−ｔｈだけ周波数ｆｓ（＜ｆｈ）となり、時間ｔｓ経過後は周波数ｆｏとなる。
【００２３】
周波数と放電灯Ｌａｍｐへ印加される共振電圧との関係を示す特性図を図１５に示す。周波数ｆｈの場合の共振電圧Ｖｈは、周波数ｆｓの場合の共振電圧Ｖｓよりも小さいので、共振電圧Ｖｓと共振電圧Ｖｈとの間に、放電灯Ｌａｍｐの始動電圧を設定しておくと、電源投入から時間ｔｈ経過するまで、放電灯Ｌａは始動はせずに十分に予熱され、その後、電源投入から時間ｔｓ経過するまでに放電灯Ｌａｍｐを始動させることができる。電源投入から時間ｔｓ経過後は、トランジスタＱ５１，Ｑ５２ともオフし、前記インバータ回路の発振周波数はｆｏとなり、放電灯Ｌａｍｐは点灯する。
【００２４】
放電灯Ｌａｍｐの予熱時には、周囲温度に関わらず一定の先行予熱電流を放電灯Ｌａｍｐに供給する。放電灯Ｌａｍｐの始動時には、周囲温度が低い場合、サーミスタＴＨ１の抵抗値が大きくなって、図１４に示すように、前記インバータ回路の発振周波数が周波数ｆｓから周波数ｆｓ”へと低くなり、図１５に示すように、放電灯Ｌａｍｐに印加される共振電圧が電圧Ｖｓから電圧Ｖｓ”へと上昇する。逆に、周囲温度が高い場合、サーミスタＴＨ１の抵抗値が小さくなって、図１４に示すように、前記インバータ回路の発振周波数が周波数ｆｓから周波数ｆｓ’へと高くなり、図１５に示すように、放電灯Ｌａｍｐに印加される共振電圧が電圧Ｖｓから電圧Ｖｓ’へと低下する。
以上のように構成したことにより、放電灯の周囲温度が変化しても、始動性能を確保することができる。
【００２５】
【発明が解決しようとする課題】
しかし、上記従来例の特開平８−１８５９９０においては、以下に示すような問題点が生じる。まず、放電灯Ｌａｍｐの始動電圧は周囲温度に極めて大きな影響を受けるということである。これは放電灯に封入されるガスのペニング効果により常温でもっとも始動電圧は低下し、低温、高温ではペニング効果の低下により始動電圧が高くなるためである。従って、上記従来例の特開平８−１８５９９０では、放電灯への出力を一定にするため、例えば周囲温度が低い場合には放電灯の始動電圧は通常の周囲温度（例えば２５℃）の場合よりも高くなるため、通常の周囲温度での始動電圧に点灯装置の出力を一定にすれば放電灯が始動しにくくなるということが挙げられる。
【００２６】
また、低温時、高温時に始動できるようにあらかじめ始動電圧を大きく設定して一定出力にすることも考えられるが、この設定では周囲温度が通常である場合に放電灯の始動時には過剰の発振電圧が発生し、スイッチング素子などの半導体部品にストレスが印加されやすくなるという問題も生じる。
【００２７】
上記の間題点を解消するための技術が特開平１０−１８９２７３で紹介されている。しかし、放電灯Ｌａｍｐを点灯し続けて一瞬消灯し、再度始動させる場合、放電灯Ｌａｍｐの周囲温度は放電灯の自己発熱により大きくなっており、再始動電圧は上記に述べたように放電灯の特性上、通常の周囲温度での始動電圧よりも若干高くなるために再始動しにくくなる。従って、特開平１０−１８９２７３で紹介されている周囲温度が高い場合には始動電圧が常温時よりも低くなるという技術では、放電灯Ｌａｍｐが再始動しにくくなる。
【００２８】
また、放電灯Ｌａｍｐがアマルガム合金の温度（以下アマルガム温度と呼ぶ）により特性が制御されている場合、周囲温度が低い場合にはアマルガム温度が低下し、光出力が低下する過冷却現象があり、低温時に点灯させる場合には放電灯に流れる電流いわゆる管電流を増加させ、アマルガム温度を上げ光出力の低下を軽減させる必要がある。また、高温時に点灯させる場合、つまりアマルガム温度が高い場合にも光出力が低下する。
【００２９】
従って、同系列の放電灯、例えば片口金コンパクトＦＨＴで最冷点制御とアマルガム制御の２種類があり、かつ最冷点制御のほうがアマルガム制御に比べ管電力が低く、定格光束値が小さい放電灯としても、放電灯を口金上向きに取りつける器具に組み込まれた場合には最冷点制御の放電灯はほぼ最適最冷点になり光出力がほぼ最大になるのに対し、アマルガム制御ではアマルガム温度が高くなりすぎ光出力が低下し、最冷点制御とほぼ光出力が同等になってしまうことが考えられる。
【００３０】
そのため特開平１０−１８９２７３の技術ではインバータの発振周波数が高温で高くなるため、放電灯の管電流が減少する方向となるために上記のようなアマルガム制御の放電灯用にはさらに光出力が低下することが考えられる。
【００３１】
従って、本発明では放電灯の始動時の電圧を低温時、高温時には常温時の始動電圧よりも高くして放電灯が始動しやすいように設定し、なおかつ放電灯点灯装置の点灯時の管電流の周囲温度特性も始動時と同様に低温時と高温時に常温時よりも大きくするように設定することで光出力の低下を軽減することを課題とする。
【００３２】
【発明が解決しようとする課題】
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、直流電源Ｅと、前記直流電源Ｅの電圧を高周波でスイッチングするスイッチング素子Ｑ１，Ｑ２を含むインバータ回路１１と、前記インバータ回路１１の発振出力を印加されるインダクタＴ１とコンデンサＣ１からなる共振回路１２と、前記共振回路１２の共振電圧を印加される放電灯Ｌａｍｐと、前記放電灯Ｌａｍｐの予熱・始動・点灯の各段階の動作状態を呈するように前記インバータ回路１１の発振周波数を切り替える発振周波数制御回路１３とを備え、前記共振回路１２の共振作用によって放電灯Ｌａｍｐを始動点灯させる放電灯点灯装置において、放電灯Ｌａｍｐあるいは前記放電灯点灯装置の周囲温度を検出し、放電灯Ｌａｍｐの始動時に放電灯Ｌａｍｐへ印加される電圧は周囲温度が低温のときに最も高電圧となり、周囲温度が高温のときは常温時の電圧以上となり、放電灯Ｌａｍｐの点灯時に放電灯Ｌａｍｐに流れる電流は周囲温度が低温のときに最も大きく周囲温度が高温のときは常温時の電流以上となるように制御する温度補正手段１４を備えたことを特徴とするものである。
ここで、前記インバータ回路１１の発振周波数は周囲温度が低温のときに最も低い周波数となり、周囲温度が高温のときの発振周波数は常温時の発振周波数以下となるように制御すると良い。このときの共振電圧を図８に示す。
【００３３】
図１の構成では、前記発振周波数制御回路１３は、第１の温度感応素子を含む集積回路ＩＣ１０１と、前記集積回路ＩＣ１０１の第１の入力端子Ｔｃに接続される第２のコンデンサＣ１０１と、前記第２のコンデンサＣ１０１と並列に接続された第２の温度感応素子ＮＴＣ１とを備え、前記第２のコンデンサＣ１０１は、所定電流Ｉにより充電及び放電が繰り返されるとともに、放電灯Ｌａｍｐの予熱時には前記集積回路ＩＣ１０１の第２の入力端子ＴＰＲＥに接続される第１の抵抗Ｒ１０３により前記所定電流値が決定され、放電灯Ｌａｍｐの始動時には前記集積回路ＩＣ１０１の第３の入力端子ＴＳＴＲに接続される第２の抵抗Ｒ１０４により前記所定電流値が決定され、放電灯Ｌａｍｐの点灯時には前記集積回路ＩＣ１０１の第４の入力端子ＴＯＳＣに接続される第３の抵抗Ｒ１０２により前記所定電流値が決定される。
【００３４】
また、図９の構成では、前記発振周波数制御回路１３は、第１の温度感応素子を含む集積回路ＩＣ１０１と、前記集積回路ＩＣ１０１の第１の入力端子Ｔｃに接続される第２のコンデンサＣ１０１とを備え、前記第２のコンデンサＣ１０１は、所定電流Ｉにより充電及び放電が繰り返されるとともに、放電灯Ｌａｍｐの予熱時には前記集積回路ＩＣ１０１の第２の入力端子ＴＰＲＥに接続される第１の抵抗Ｒ１０３により前記所定電流値が決定され、放電灯Ｌａｍｐの始動時には前記集積回路ＩＣ１０１の第３の入力端子ＴＳＴＲに接続される第２の抵抗Ｒ１０４により前記所定電流値が決定され、放電灯Ｌａｍｐの点灯時には前記集積回路ＩＣ１０１の第４の入力端子ＴＯＳＣに接続される第３の抵抗Ｒ１０２により前記所定電流値が決定され、前記第３の抵抗Ｒ１０２と直列に前記第３の温度感応素子Ｒ１０７を接続されている。
【００３５】
【発明の実施の形態】
（実施形態１）
本発明の第１の実施形態を図１に示す。図１の回路は、直流電源Ｅと、その直流電源電圧を高周波電圧に変換するインバータ回路１１と、バラストチョークＴ１、コンデンサＣ１からなる共振回路１２と、共振用のコンデンサＣ１に並列接続される放電灯Ｌａｍｐと、インバータ回路１１を構成するスイッチング素子の発振を制御する発振周波数制御回路１３と、温度補正手段１４、さらに放電灯Ｌａｍｐのフィラメントを予熱する予熱回路１５からなる。
【００３６】
前記インバータ回路１１は直流電源Ｅの両端に接続されたスイッチング素子Ｑ１，Ｑ２の直列回路と、スイッチング素子Ｑ２の両端にコンデンサＣ２とバラストチョークＴ１と放電灯Ｌａｍｐが直列接続され、放電灯Ｌａｍｐに並列接続されたコンデンサＣ１から構成される、ハーフブリッジ式インバータ回路である。バラストチョークＴ１とコンデンサＣ１とで共振回路１２を構成している。また、放電灯Ｌａｍｐのフィラメントを予熱する予熱回路１５が設けられている。発振周波数制御回路１３は、集積回路ＩＣ１０１と抵抗Ｒ１０２〜Ｒ１０５とコンデンサＣ１０１，Ｃ１０３と温度補正手段１４である抵抗Ｒ１０１と負特性サーミスタＮＴＣ１から構成される。
【００３７】
発振周波数制御回路の端子ＯＵＴ１及びＯＵＴ２から出力されるスイッチング素子Ｑ１，Ｑ２を駆動する信号の発振周波数は、集積回路ＩＣ１０１のＴｃ端子及びアース間に接続されたコンデンサＣ１０１とコンデンサＣ１０１と並列に接続される抵抗Ｒ１０１と負特性サーミスタＮＴＣ１の直列回路、及び集積回路ＩＣ１０１のＴＯＳＣ端子とアース間に接続された抵抗Ｒ１０２、ＴＰＲＥ端子とアース間に接続された抵抗Ｒ１０３、ＴＳＴＲ端子とアース間に接続された抵抗Ｒ１０４で決まる。
【００３８】
周波数設定の詳細を述べると、例えば放電灯Ｌａｍｐの予熱時にはＴＰＲＥ端子の集積回路ＩＣ１０１内部のスイッチＳＷ１０１とＴＳＴＲ端子の集積回路ＩＣ１０１内部のスイッチＳＷ１０２がオンし、ＴＯＳＣ端子、ＴＰＲＥ端子、ＴＳＴＲ端子からそれぞれつながれた抵抗に内部から電圧を印加する。コンデンサＣ１０１を充電する電流ＩＣＯＳＣは抵抗Ｒ１０２，Ｒ１０３，Ｒ１０４に流れる電流ＩＲＯＳＣ，ＩＲＰＲＥ，ＩＲＳＴＲの和の比の定電流であり、ＴＯＳＣ端子、ＴＰＲＥ端子、ＴＳＴＲ端子全ての端子に電流が流れるときに最も大きくなる。そのときコンデンサＣ１０１の両端電圧ＶＣＯＳＣは下記のとおりとなる。
【００３９】
まず、温度補正手段の抵抗Ｒ１０１と負特性サーミスタＮＴＣ１がない場合には図２に示すように、基準値Ｖｔｈ＿Ｈまで定電流で充電し、基準値Ｖｔｈ＿Ｈに達すると基準値Ｖｔｈ＿Ｌまで定電流で放電するので三角波となり、その三角波の周期Ｔｃの２倍が発振周波数となる。
すなわち、インバータの発振周波数をｆｃ、集積回路ＩＣ１０１のＴｃ端子から充放電される定電流をＩとすると、図２に示す周期Ｔ＝２×（Ｃ１０１×（Ｖｔｈ＿Ｈ−Ｖｔｈ＿Ｌ））／Ｉと表せるので、インバータの発振周波数ｆｃ＝１／（２×Ｔ）＝Ｉ／（４×Ｃ１０１×（Ｖｔｈ＿Ｈ−Ｖｔｈ＿Ｌ））となる。
【００４０】
従って、放電灯ｌａｍｐの予熱時には最も大きい電流がコンデンサＣ１０１に充放電電流Ｉとして流れるので、発振周波数は最も高く、また、放電灯ｌａｍｐを始動させるときには集積回路ＩＣ１０１内部のスイッチＳＷ１０２のみがオンし、ＴＯＳＣ端子とＴＳＴＲ端子のみに電圧を印加させるので予熱時よりも充放電電流Ｉは小さくなり、発振周波数は予熱時よりも低くなる。さらに、点灯時には集積回路ＩＣ１０１内部のスイッチＳＷ１０１及びＳＷ１０２がオフしているため、ＴＯＳＣ端子につながれた抵抗Ｒ１０２にのみ電圧を印加するので、Ｔｃ端子につながれたコンデンサＣ１０１に流れる充放電電流Ｉは最も小さくなるため、点灯時の発振周波数が最も低くなる。
【００４１】
次に、図３を参照して動作を簡単に説明する。ＴＯＳＣ端子、ＴＰＲＥ端子、ＴＳＴＲ端子が動作するタイミングつまり集積回路ＩＣ１０１内部のスイッチＳＷ１０１，ＳＷ１０２がオン、オフするタイミングは、集積回路ＩＣ１０１の外部電源ＶｃｃとＴＩＭＥＲ端子に接続された抵抗Ｒ１０５とコンデンサＣ１０３の時定数で決まるタイマー回路にて決定される。図３に示すように、集積回路ＩＣ１０１内部の各々のスイッチング素子ＳＷ１０１及びＳＷ１０２は電源投入から時間ｔｈ，ｔｓだけオンする。その結果、集積回路ＩＣ１０１のＯＵＴ１端子、ＯＵＴ２端子から出力される前記発振周波数制御回路の発振周波数は上記の通り、時間ｔｈだけ周波数ｆｈとなり、次の時間ｔｓ−ｔｈだけ周波数ｆｓ（＜ｆｈ）となり、時間ｔｓ経過後は周波数ｆｏとなる。
【００４２】
周波数と放電灯Ｌａｍｐへ印加される共振電圧との関係を示す特性図を図４に示す。周波数ｆｈの場合の共振電圧Ｖｈは、周波数ｆｓの場合の共振電圧Ｖｓよりも小さいので、共振電圧Ｖｓと共振電圧Ｖｈとの間に、放電灯Ｌａｍｐの始動電圧を設定しておくと、電源投入から時間ｔｈ経過するまで放電灯Ｌａｍｐは始動せずに十分に予熱され、その後、電源投入から時間ｔｓ経過するまでに放電灯Ｌａｍｐを始動させることができる。電源投入から時間ｔｓ経過後は、集積回路ＩＣ１０１内部のスイッチＳＷ１０１，ＳＷ１０２ともオフし、前記発振周波数制御回路の発振周波数はｆｏとなる。
【００４３】
次にコンデンサＣ１０１と並列に温度補正手段の抵抗Ｒ１０１と負特性サーミスタＮＴＣ１を接続する場合について述べる。高温時に負特性サーミスタＮＴＣ１の抵抗値が小さくなると、図５に示すように三角波から波形がなまるため、発振周波数がＮＴＣ１が無い場合に比べ低くなる。また、低温時には負特性サーミスタＮＴＣ１の抵抗値が大きくなるためコンデンサＣ１０１の両端波形はほぼ三角波となる。つまり、コンデンサＣ１０１と並列に負特性サーミスタＮＴＣ１を挿入することでコンデンサの両端電圧ＶＣＯＳＣによる周期ＴｎｔｃはコンデンサＣ１０１と並列接続される抵抗値をＲＮＴＣとすると、Ｔｎｔｃ＝−Ｃ１０１×ＲＮＴＣ×[ｌｎ｛（Ｖｔｈ＿Ｈ−ＲＮＴＣ×Ｉ）／（Ｖｔｈ＿Ｌ−ＲＮＴＣ×Ｉ）｝＋ｌｎ｛（Ｖｔｈ＿Ｈ＋ＲＮＴＣ×Ｉ）／（Ｖｔｈ＿Ｌ＋ＲＮＴＣ×Ｉ）｝]と表せるので、インバータの発振周波数ｆｎｔｃはｆｎｔｃ＝１／（２×Ｔ１）となる。
【００４４】
このインバータの発振周波数ｆｎｔｃを、横軸をコンデンサＣ１０１と並列接続される抵抗値ＲＮＴＣで図示すると、図６に示すように抵抗値ＲＮＴＣが小さい場合には発振周波数ｆｎｔｃは低く、抵抗値ＲＮＴＣが大きくなるにつれて発振周波数ｆｎｔｃは高くなる。つまり負特性サーミスタＮＴＣ１を用いることにより低温時には抵抗値がＲｎ２に、高温時には抵抗値がＲｎ１に変化し、各々発振周波数がｆ２からｆ１へ変わるので、図７に示すように周囲温度により放電灯の始動時にかかる共振電圧が低温時のＶ２から高温時のＶ１まで変化する。
また、点灯時も始動時と同様に発振周波数は周囲温度が低温から高温に変化すると低い方向へ変化する。つまり放電灯Ｌａｍｐの管電流は周囲温度が低温から高温に変化すると増加することになる。
【００４５】
さらに、集積回路ＩＣ１０１の発振周波数の周囲温度特性が低温から高温に変化すると周波数が高くなるもの（例えば新電元製ＭＣＺ４００１Ｐなど）を用いることにより負特性サーミスタＮＴＣ１の周囲温度特性と集積回路の周囲温度特性との掛け合わせにより図８に示すように発振周波数の周囲温度特性を達成することができる。つまり、集積回路ＩＣ１０１の周囲温度特性により、抵抗Ｒ１０１と負特性サーミスタＮＴＣ１の合計抵抗値ＲＮＴＣの範囲（図６）を決定する。
【００４６】
従って、放電灯の周囲温度が変化しても適切な始動電圧を放電灯に印加することにより、確実に放電灯が点灯し、なおかつ点灯装置内の部品に過度のストレスを与えることはなくなる。また、点灯時には低温時、高温時とも常温に比べ管電流を増やすように発振周波数が変化するため、周囲温度が変化しても発振周波数が一定である放電灯点灯装置に比べ、より良好な光出力を得ることができる。
【００４７】
さらに、放電灯Ｌａｍｐが低温時に点灯させる場合には、放電灯Ｌａｍｐのアマルガム温度もしくは最冷点温度が低いために光出力の立ち上がりが常温時に比べ遅くなる傾向にあるが、低温時に管電流を増加させるため従来よりも光出力の立ち上がりが良くなるという利点もある。
【００４８】
（実施形態２）
本発明の第２の実施形態を図９を用いて説明する。図９において第１の実施形態と異なる点は、発振周波数制御回路の負特性サーミスタＮＴＣ１と抵抗Ｒ１０１をコンデンサＣ１０１と並列に接続するのではなく、集積回路ＩＣ１０１のＴＯＳＣ端子とアース間に抵抗Ｒ１０２と直列に感温抵抗Ｒ１０７（例えば松下製ＥＲＡシリーズ）を接続したことである。
【００４９】
感温抵抗は周囲温度が高くなると、抵抗値が大きくなるので、ＴＯＳＣ端子に感温抵抗Ｒ１０７を接続すると、低温の場合にはＴＯＳＣ端子とアース間の抵抗値が実質的に小さくなり、Ｔｃ端子から流れる充放電電流Ｉは大きくなる。従って、低温時には発振周波数が高くなり、高温時には発振周波数が低い方向へ動作する。
【００５０】
その他の動作としては、実施形態１と同様、集積回路ＩＣ１０１の発振周波数の周囲温度特性が低温から高温に変化すると周波数が高くなるもの（例えば新電元製ＭＣＺ４００１Ｐなど）を用いることにより、上記感温抵抗Ｒ１０７の周囲温度特性と集積回路の周囲温度特性との掛け合わせにより発振周波数の周囲温度特性を達成することができる。なお、ここでは感温抵抗について述べたが、正特性サーミスタを使用してもよい。
【００５１】
（実施形態３）
本発明の第３の実施形態を図１０を用いて説明する。図１０において第１の実施形態と異なる点は、共振回路のコンデンサＣ１を放電灯Ｌａｍｐの非電源側に並列に接続したことであり、その他は同一構成、同一符号のため説明を省略する。
【００５２】
実施形態１の動作と異なる点は共振回路のコンデンサＣ１を放電灯Ｌａｍｐの非電源側に接続したことにより予熱回路が不用になったことである。すなわち、予熱時には放電灯Ｌａｍｐのフィラメントに流れる電流はインダクタＴ１とコンデンサＣ１の共振電流となる。従って、実施形態１と同様な発振周波数制御回路であれば、予熱時のフィラメントに流れる電流も周囲温度が低い場合と高い場合には常温時よりも多くなる。低温、高温時の予熱時フィラメント電流が多くなることでフィラメントからの電子放出がしやすくなり、低温時の放電灯Ｌａｍｐの始動、高温時の再始動がさらに良くなる。
【００５３】
【発明の効果】
上記のように構成すれば、放電灯の周囲温度が変化しても確実に点灯させることができ、かつ放電灯点灯装置の部品ストレスも緩和できる。また、低温時、高温時に管電流を増加させるように発振周波数が低くなるため、放電灯の光出力の低下を軽減させることが可能となり、低温時の放電灯の光出力の立ち上がりが良好になる。さらに、予熱時の放電灯のフィラメント電流を低温時に増加させることも容易になるためフィラメントの電子放出がされやすくなり放電灯が始動しやすくなる。
【図面の簡単な説明】
【図１】本発明の実施形態１の回路図である。
【図２】本発明の実施形態１の発振回路の動作説明図である。
【図３】本発明の実施形態１の予熱、始動、点灯期間の発振周波数の変化を示す動作説明図である。
【図４】本発明の実施形態１の予熱、始動期間の共振電圧の変化を示す動作説明図である。
【図５】本発明の実施形態１の高温時における発振回路の動作説明図である。
【図６】本発明の実施形態１の周囲温度変化による温度補正手段の抵抗値と発振周波数の関係を示す説明図である。
【図７】本発明の実施形態１の周囲温度変化による発振周波数と共振電圧の関係を示す説明図である。
【図８】本発明の実施形態１の周囲温度と共振電圧の関係を示す説明図である。
【図９】本発明の実施形態２の回路図である。
【図１０】本発明の実施形態３の回路図である。
【図１１】従来例１の回路図である。
【図１２】従来例２の回路図である。
【図１３】従来例２の予熱、始動、点灯期間の発振周波数の変化を示す動作説明図である。
【図１４】従来例２の周囲温度による始動期間の発振周波数の変化を示す動作説明図である。
【図１５】従来例２の周囲温度による始動期間の共振電圧の変化を示す動作説明図である。
【符号の説明】
１１インバータ回路
１２共振回路
１３発振周波数制御回路
１４温度補正手段
１５予熱回路[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a discharge lamp lighting device having improved ambient temperature characteristics.
[0002]
[Prior art]
Conventionally, JP-A-8-185990 and JP-A-10-189273 disclose methods for improving the ambient temperature characteristics of a discharge lamp lighting device.
In JP-A-8-185990, temperature correction is provided so that the temperature of the discharge lamp or the ambient temperature is detected and the output of the lamp output control circuit is kept constant. In JP-A-10-189273, a temperature correction element is provided in the lamp output control circuit, and only the starting resonance voltage generated when starting the discharge lamp is increased when the ambient temperature is low, and is decreased when the ambient temperature is high. .
[0003]
(Conventional example 1)
A discharge lamp lighting device disclosed in JP-A-8-185990 will be described with reference to the drawings. In FIG. 11, E1 is a commercial AC power source, and a full-wave rectifier circuit DB is connected to the commercial AC power source E1. Between the output terminals of the full-wave rectifier circuit DB, a surge absorbing element TNR and a capacitor C21 are connected, and an inverter circuit 2 is connected. Inverter circuit 2 is connected in parallel to capacitor C21 to a series circuit that smoothes the valley filling of capacitor C22, inductor L1, and diode D1. A series circuit of a primary winding Tr1a having a resonance inductance of the inverter transformer Tr1 and a transistor Q21 as a switching element is connected between both terminals of the capacitor C22 and the inductor L1, and the primary winding Tr1a is connected to the primary winding Tr1a. A resonance capacitor C23 is connected in parallel, and a diode D2 is connected from the connection point of the inductor L1 and the diode D1 to the collector of the transistor Q21.
[0004]
Further, the filaments FLa and FLb of the discharge lamp Lamp are connected to the secondary winding Tr1b of the inverter transformer Tr1 through the detection winding CT1a of the current transformer CT of the oscillation control circuit 3, the capacitor C4, and the resistor R1. Further, a starting capacitor C5 is connected to the filaments FLa and FLb. A diode D3 is connected to the control winding CT1b of the current transformer CT. The diode D3 is connected to the base of the transistor Q21, and also includes a capacitor C6 and a field effect transistor (hereinafter referred to as a switching element) Q11. Are connected to the emitter of the transistor Q21 via a series circuit of a capacitor C7 and a switching element Q12, a diode D4 and a capacitor C8. A series circuit of a diode D5 and a resistor R2 is connected between the base and emitter of the transistor Q21, and is connected to the positive electrode of the full-wave rectifier circuit DB via a starting resistor R3.
[0005]
A series circuit of a voltage dividing capacitor C10 and a capacitor C11 is connected in parallel to the capacitor C5. A rectifying diode D6 and a diode D7, a resistor R4, a capacitor C12, and a timer circuit 4 are connected to the capacitor C10. Yes. The timer circuit 4 includes a capacitor C13, a diode D8, and a resistor R5. The base of the transistor Q22 is connected to the connection point between the capacitor C13 and the resistor R5, and the collector of the transistor Q22 and the diode D6 are connected. The capacitor C14, the resistor R6 and the light emitting diode LED1 are connected, and a series circuit of a Zener diode ZD1 and the light emitting diode LED2 is connected between the emitter of the transistor Q22 and the cathode of the diode D6. The emitter of the transistor Q22 is connected to the connection point between the capacitors C10 and C11.
[0006]
On the other hand, the voltage detection circuit 5 is connected to the output terminal of the full-wave rectification circuit DB. The voltage detection circuit 5 is connected to the resistor R7 and the capacitor C15, and the capacitor C15 is connected to the Zener diode ZD2 and the resistor R8. ing.
[0007]
The voltage detection circuit 5 is connected to a lamp lighting output control circuit 6. The lamp lighting output control circuit 6 is connected to a series circuit of a resistor R9 and a capacitor C16. The capacitor C16 has a resistor R10, an emitter and a collector of a transistor Q3, a resistor R11, and a positive temperature coefficient thermistor R12 as temperature correction means. The connection point of the series circuit is connected to the resistor R11 and the positive temperature coefficient thermistor R12 whose resistance value increases as the temperature rises, and is connected to the gate of the switching element Q11. Further, a series circuit of a resistor R14 and a variable resistor R15 for variable output is connected to the base of the transistor Q3. In parallel with the capacitor C16, a Zener diode ZD3, a phototransistor PTr1 photocoupled to the light emitting diode LED1, and a phototransistor PTr2 photocoupled to the light emitting diode LED2 are connected.
[0008]
Further, a lamp start output control circuit 7 is connected to the full-wave rectifier circuit DB. In the lamp start output control circuit 7, a series circuit of a resistor R16 and a capacitor C17 is connected from the positive electrode of the capacitor C16, and a series circuit of a Zener diode ZD4 and a base and emitter of a transistor Q4 is connected in parallel with the capacitor C17. The collector of the transistor Q4 is connected to the positive side of the full-wave rectifier circuit DB via a positive temperature coefficient thermistor R17 whose resistance value increases with increasing temperature, and a resistor R18 is connected between the collector and emitter of the transistor Q4. . The collector of the transistor Q4 is connected to the gate of the switching element Q12.
[0009]
Next, the operation of the circuit shown in FIG. 11 will be described.
First, when the power is turned on, the commercial AC power supply E1 is full-wave rectified by the full-wave rectifier circuit DB, and a pulsating flow is applied to the capacitor C21. The inverter circuit 2 performs switching control of the DC voltage supplied from the capacitor C21 at a high frequency by the transistor Q21, and the voltage resonated by the inductance of the primary winding Tr1a of the inverter transformer Tr1 and the capacitance of the capacitor C23 is the secondary winding. It is induced by the line Tr1b and supplied to the discharge lamp Lamp. Then, the capacitor C5 preheats the filaments FLa and FLb of the discharge lamp Lamp, and simultaneously the voltage generated by the capacitor C5 is applied to the discharge lamp Lamp to start and light the discharge lamp Lamp.
[0010]
Further, when the discharge lamp Lamp is started, no charge is stored in the capacitor C13 of the timer circuit 4, and the transistor Q22 is kept on and the light emitting diode LED1 is turned on until a predetermined time elapses. . Since the light-emitting diode LED1 is turned on, the phototransistor PTr1 is turned on, so that the capacitor C16 is not charged.
[0011]
Since the capacitor C16 is not charged and the transistor Q3 is kept off, no voltage is applied to the gate of the switching element Q11, the switching element Q11 is kept off, and the capacitor C6 is opened. It does not contribute to the switching operation of Q21. On the other hand, until the capacitor C17 is charged, the Zener diode ZD4 is in the OFF state. Therefore, the transistor Q4 also remains in the OFF state, and the switching is performed at the voltage value set by the voltage division of the positive temperature coefficient thermistor R17 and the resistor R18. A gate voltage is applied to the element Q12 to determine the output voltage of the inverter circuit 2 when the discharge lamp Lamp is lit.
[0012]
When the discharge lamp Lamp or the ambient temperature is low at the time of starting the discharge lamp Lamp, the resistance value of the positive temperature coefficient thermistor R17 becomes low, and the voltage across the resistor R18 becomes high. Therefore, the gate voltage of switching element Q12 increases, the apparent capacitance of capacitor C7 increases, and the combined capacitance of capacitor C7 and capacitor C8 increases, so that the base current of transistor Q21 increases and inverter circuit 2 Is relatively increased, the voltage applied to the discharge lamp Lamp at the time of starting the lamp at a low temperature is relatively increased, and the discharge lamp Lamp is reliably started.
[0013]
On the contrary, when the discharge lamp Lamp or the ambient temperature is high, the resistance value of the positive temperature coefficient thermistor R17 is high, and the voltage across the resistor R18 is low. Therefore, the gate voltage of the switching element Q12 is lowered, the apparent capacitance of the capacitor C7 is reduced, and the combined capacitance of the capacitor C7 and the capacitor C8 is reduced. Therefore, the base current of the transistor Q21 is reduced, and the inverter circuit 2 Is relatively decreased, the voltage applied to the discharge lamp Lamp at the time of starting the lamp at a low temperature is relatively decreased, and the discharge lamp Lamp is started without applying an unnecessarily high voltage.
[0014]
That is, according to the discharge lamp Lamp or the ambient temperature, the discharge lamp Lamp is reliably turned on even when the temperature is low, and when the temperature is high, the discharge lamp Lamp is not applied without applying an unnecessarily high voltage. Start.
[0015]
When the discharge lamp Lamp is started, the transistor Q22 is turned off and the light emitting diode LED1 is turned off. The phototransistor PTr1 is also turned off, and the capacitor C16 is charged after a time set by the time constant of the resistor R9 and the capacitor C16. When the capacitor C16 is charged, the transistor Q3 is turned on, and the gate voltage is applied to the gate of the switching element Q11 to match the normal control level. When the capacitor C17 is charged, the Zener diode ZD4 is turned on and the transistor Q4 is turned on, whereby the current flowing through the resistor R18 is bypassed and the gate voltage of the switching element Q12 is not applied, so that the capacitor C7 is opened, The oscillation frequency of transistor Q21 is determined by the combined capacitance of capacitor C6 and capacitor C8.
[0016]
First, when the output from the full-wave rectifier circuit DB rises and the voltage detected by the voltage detection circuit 5 rises, the base current of the transistor Q3 decreases, the gate voltage of the switching element Q11 decreases, The output of the inverter circuit 2 is lowered by speeding up the switching of the transistor Q21. On the other hand, when the output from the full-wave rectifier circuit 1 decreases and the voltage detected by the voltage detection circuit 5 decreases, the base current of the transistor Q3 increases and the gate voltage of the switching element Q11 increases. The switching of the transistor Q21 is delayed to increase the output of the inverter circuit 2. As described above, when the output voltage of the full-wave rectifier circuit 1 increases, the output of the inverter circuit 2 is decreased. Conversely, when the output voltage of the full-wave rectifier circuit 1 decreases, the output of the inverter circuit 2 is increased. The output of the inverter circuit 2 can always be kept constant.
[0017]
When the discharge lamp Lamp or the ambient temperature is low when the discharge lamp Lamp is lit, the resistance value of the positive temperature coefficient thermistor R12 becomes low, and the voltage across the positive temperature coefficient thermistor R12 becomes low. Accordingly, the gate voltage of the switching element Q11 is lowered, the apparent capacitance of the capacitor C7 is reduced, and the combined capacitance of the capacitor C7 and the capacitor C8 is reduced. Therefore, the base current of the transistor Q21 is reduced, and the inverter circuit 2 However, the voltage applied to the discharge lamp Lamp at the time of lighting of the lamp at a low temperature has increased, but the voltage applied to the discharge lamp Lamp is decreased by relatively reducing the voltage. Make it almost constant. On the other hand, when the discharge lamp Lamp or the ambient temperature is high, the resistance value of the positive temperature coefficient thermistor R12 increases, and thus the voltage across the positive temperature coefficient thermistor R12 increases. Therefore, the gate voltage of switching element Q11 increases, the apparent capacitance of capacitor C7 increases, and the combined capacitance of capacitor C7 and capacitor C8 increases, so that the base current of transistor Q21 increases and inverter circuit 2 Is relatively increased, that is, the voltage applied to the discharge lamp Lamp when the lamp is lit is increased to make the voltage applied to the discharge lamp Lamp constant. Even if a negative characteristic thermistor is used instead of the resistor R18 or a negative characteristic thermistor is used instead of the resistor R10 or the resistor R11, the same effect can be obtained.
[0018]
(Conventional example 2)
Further, Japanese Patent Laid-Open No. 10-189273 will be described with reference to FIG. 12. A commercial AC power supply E1, a rectifier DB for full-wave rectification of the commercial AC power supply E1, a smoothing capacitor C31 for smoothing the output of the rectifier DB, and a smoothing capacitor C31. An inverter circuit that converts the voltage between both ends into an AC high-frequency voltage and supplies it to the discharge lamp Lamp, a drive circuit 1 that drives the switching elements Q31 and Q32 constituting the inverter circuit, and an input terminal of the drive circuit 1 The oscillation control circuit 2 controls the oscillation of the switching elements Q31 and Q32 by generating a high-frequency rectangular wave signal.
[0019]
The inverter circuit includes a series circuit of switching elements Q31 and Q32 connected to both ends of a smoothing capacitor C31, a series circuit of capacitors C32 and C33 connected to both ends of a series circuit of switching elements Q31 and Q32, and a switching element Q31. , Q32 and capacitors C32 and C33 between the inductor L1 connected via the discharge lamp Lamp and the capacitor Co connected in parallel between the non-power supply side terminals of the discharge lamp Lamp. This is a so-called half-bridge type inverter circuit. The inductor L1 and the capacitor Co constitute a resonance circuit.
[0020]
The drive circuit 1 drives an integrated circuit IC2 (for example, IR2111 manufactured by IR) that drives the high-side switching element Q31 via resistors R11 and R12 and drives the low-side switching element Q32 via resistors R21 and R22. Consists of including.
[0021]
The oscillation control circuit 2 includes an integrated circuit IC1, resistors R51 to R54, a negative thermistor TH1, capacitors C51 and C52, and transistors Q51 and Q52. The oscillation frequency of the oscillation control circuit 2 includes the capacitor C51 connected between the Tc terminal of the integrated circuit IC1 and the ground, the resistors R51 and R53 connected between the TR terminal of the integrated circuit IC1 and the ground, and the thermistor TH1 having a negative characteristic. Determined by the time constant with the series circuit. A transistor Q51 is connected to both ends of the series circuit of the negative thermistor TH1 and the resistor R53, a switching element Q52 is connected to both ends of the resistor R53, and the control ends of the transistors Q51 and Q52 are connected to the integrated circuit IC1. It is connected.
[0022]
Next, the operation will be briefly described with reference to FIG. The transistor Q51 and the transistor Q52 are a timer circuit determined by a time constant of a capacitor C52 connected between the TIMER terminal of the integrated circuit IC1 and the ground, and a resistor R54 connected between the TIMER terminal of the integrated circuit IC1 and the external power supply Vcc. Accordingly, as shown in FIGS. 13A and 13B, the power is turned on for the time th and ts (th <ts) after the power is turned on. As a result, the oscillation frequency of the inverter circuit output from the out terminal of the integrated circuit IC1 is the frequency fh for the time th, the frequency fs (<fh) for the next time ts-th, and the frequency fo after the time ts has elapsed. It becomes.
[0023]
FIG. 15 is a characteristic diagram showing the relationship between the frequency and the resonance voltage applied to the discharge lamp Lamp. The resonance voltage Vh at the frequency fh is smaller than the resonance voltage Vs at the frequency fs. Therefore, if the starting voltage of the discharge lamp Lamp is set between the resonance voltage Vs and the resonance voltage Vh, the power is turned on. Until the time th elapses, the discharge lamp La is sufficiently preheated without being started, and then the discharge lamp Lamp can be started until the time ts elapses after the power is turned on. After the time ts has elapsed since the power is turned on, both the transistors Q51 and Q52 are turned off, the oscillation frequency of the inverter circuit becomes fo, and the discharge lamp Lamp is lit.
[0024]
During preheating of the discharge lamp Lamp, a constant preceding preheating current is supplied to the discharge lamp Lamp regardless of the ambient temperature. When the discharge lamp Lamp is started, if the ambient temperature is low, the resistance value of the thermistor TH1 increases, and as shown in FIG. 14, the oscillation frequency of the inverter circuit decreases from the frequency fs to the frequency fs ″. As shown, the resonance voltage applied to the discharge lamp Lamp rises from the voltage Vs to the voltage Vs ″. On the other hand, when the ambient temperature is high, the resistance value of the thermistor TH1 decreases, and the oscillation frequency of the inverter circuit increases from the frequency fs to the frequency fs ′ as shown in FIG. 14, and as shown in FIG. The resonance voltage applied to the discharge lamp Lamp decreases from the voltage Vs to the voltage Vs ′.
With the configuration described above, it is possible to ensure starting performance even when the ambient temperature of the discharge lamp changes.
[0025]
[Problems to be solved by the invention]
However, the above-described conventional Japanese Patent Application Laid-Open No. 8-185990 has the following problems. First, the starting voltage of the discharge lamp Lamp is extremely affected by the ambient temperature. This is because the starting voltage decreases most at room temperature due to the Penning effect of the gas sealed in the discharge lamp, and the starting voltage increases due to the decrease in Penning effect at low and high temperatures. Therefore, in Japanese Patent Laid-Open No. 8-185990 of the above conventional example, in order to make the output to the discharge lamp constant, for example, when the ambient temperature is low, the starting voltage of the discharge lamp is higher than the normal ambient temperature (for example, 25 ° C.). Therefore, if the output of the lighting device is made constant at the starting voltage at a normal ambient temperature, it is difficult to start the discharge lamp.
[0026]
In addition, it is conceivable that the starting voltage is set large in advance so that it can be started at a low temperature or a high temperature so that the output is constant.In this setting, when the ambient temperature is normal, an excessive oscillation voltage is generated when starting the discharge lamp. This causes a problem that stress is easily applied to semiconductor components such as switching elements.
[0027]
Japanese Patent Laid-Open No. 10-189273 introduces a technique for solving the above-mentioned problem. However, when the discharge lamp Lamp is continuously turned on and turned off for a moment, and then restarted, the ambient temperature of the discharge lamp Lamp is increased due to the self-heating of the discharge lamp, and the restart voltage is as described above. Due to the characteristics, since it becomes slightly higher than the starting voltage at the normal ambient temperature, it is difficult to restart. Therefore, when the ambient temperature introduced in Japanese Patent Laid-Open No. 10-189273 is high, the discharge lamp Lamp is difficult to restart with the technique in which the starting voltage is lower than that at room temperature.
[0028]
In addition, when the characteristics of the discharge lamp Lamp are controlled by the temperature of the amalgam alloy (hereinafter referred to as the amalgam temperature), when the ambient temperature is low, the amalgam temperature decreases, and there is a supercooling phenomenon in which the light output decreases. In the case of lighting at a low temperature, it is necessary to increase a current flowing through the discharge lamp, a so-called tube current, to raise the amalgam temperature and to reduce the decrease in light output. In addition, when the light is lit at a high temperature, that is, when the amalgam temperature is high, the light output decreases.
[0029]
Therefore, there are two types of discharge lamps of the same series, such as a single-end compact FHT, the coldest spot control and the amalgam control, and the coldest spot control has a lower tube power and a smaller rated luminous flux value than the amalgam control. However, when the discharge lamp is installed in an appliance that mounts the cap upward, the discharge lamp with the coldest spot control is almost the optimal coldest point and the light output is almost maximized, whereas the amalgam control has the amalgam temperature. It is conceivable that the light output is too high and the light output is lowered, so that the light output is almost equivalent to the coldest spot control.
[0030]
Therefore, in the technique disclosed in Japanese Patent Laid-Open No. 10-189273, the oscillation frequency of the inverter increases at a high temperature, so that the tube current of the discharge lamp decreases, so that the light output is further reduced for the amalgam-controlled discharge lamp as described above. It is possible to do.
[0031]
Accordingly, in the present invention, the voltage at the start of the discharge lamp is set at a low temperature and at a high temperature to be higher than the start voltage at the normal temperature so that the discharge lamp can be easily started, and the tube current at the time of lighting of the discharge lamp lighting device is set. It is an object of the present invention to reduce the decrease in light output by setting the ambient temperature characteristics to be larger at the low temperature and the high temperature than at the normal temperature as in the start-up.
[0032]
[Problems to be solved by the invention]
According to the present invention, in order to solve the above problem, as shown in FIG. 1, an inverter circuit 11 including a DC power supply E and switching elements Q1 and Q2 for switching the voltage of the DC power supply E at a high frequency, A resonance circuit 12 including an inductor T1 and a capacitor C1 to which the oscillation output of the inverter circuit 11 is applied, a discharge lamp Lamp to which a resonance voltage of the resonance circuit 12 is applied, and preheating, starting and lighting of the discharge lamp Lamp. In a discharge lamp lighting device comprising an oscillation frequency control circuit 13 for switching an oscillation frequency of the inverter circuit 11 so as to exhibit an operation state of each stage, and starting and lighting the discharge lamp Lamp by a resonance action of the resonance circuit 12, The ambient temperature of the lamp or the discharge lamp lighting device is detected, and the lamp is marked when the discharge lamp Lamp is started. When the ambient temperature is low, the highest voltage is obtained. When the ambient temperature is high, the voltage is equal to or higher than the normal voltage. When the discharge lamp Lamp is turned on, the current flowing through the discharge lamp Lamp is low. The temperature correction means 14 is provided for controlling the current to be equal to or higher than the current at the normal temperature when the ambient temperature is the highest.
Here, the oscillation frequency of the inverter circuit 11 is preferably the lowest frequency when the ambient temperature is low, and is controlled so that the oscillation frequency when the ambient temperature is high is equal to or lower than the oscillation frequency at normal temperature. The resonance voltage at this time is shown in FIG.
[0033]
In the configuration of FIG. 1, the oscillation frequency control circuit 13 includes an integrated circuit IC101 including a first temperature sensitive element, a second capacitor C101 connected to the first input terminal Tc of the integrated circuit IC101, The second capacitor C101 includes a second temperature sensitive element NTC1 connected in parallel with the second capacitor C101. The second capacitor C101 is repeatedly charged and discharged with a predetermined current I, and is integrated when the discharge lamp Lamp is preheated. The predetermined current value is determined by a first resistor R103 connected to the second input terminal TPRE of the circuit IC101, and the second current connected to the third input terminal TSTR of the integrated circuit IC101 when the discharge lamp Lamp is started. The predetermined current value is determined by the resistor R104, and the fourth input of the integrated circuit IC101 is turned on when the discharge lamp Lamp is turned on. The predetermined current value is determined by the third resistor R102 which is connected to the terminal TOSC.
[0034]
In the configuration of FIG. 9, the oscillation frequency control circuit 13 includes an integrated circuit IC101 including a first temperature sensitive element, and a second capacitor C101 connected to the first input terminal Tc of the integrated circuit IC101. The second capacitor C101 is repeatedly charged and discharged by a predetermined current I, and is pre-heated by the first resistor R103 connected to the second input terminal TPRE of the integrated circuit IC101 when the discharge lamp Lamp is preheated. The predetermined current value is determined. When the discharge lamp Lamp is started, the predetermined current value is determined by the second resistor R104 connected to the third input terminal TSTR of the integrated circuit IC101, and when the discharge lamp Lamp is lit, the predetermined current value is determined. The predetermined current value is determined by the third resistor R102 connected to the fourth input terminal TOSC of the integrated circuit IC101. It is, and is connected to the third temperature sensitive element R107 in series with the third resistor R102.
[0035]
DETAILED DESCRIPTION OF THE INVENTION
(Embodiment 1)
A first embodiment of the present invention is shown in FIG. The circuit shown in FIG. 1 includes a DC power supply E, an inverter circuit 11 that converts the DC power supply voltage into a high-frequency voltage, a resonance circuit 12 that includes a ballast choke T1 and a capacitor C1, and a resonant circuit C1 that is connected in parallel to the resonance capacitor C1. It comprises an electric lamp Lamp, an oscillation frequency control circuit 13 for controlling the oscillation of the switching elements constituting the inverter circuit 11, temperature correction means 14, and a preheating circuit 15 for preheating the filament of the discharge lamp Lamp.
[0036]
The inverter circuit 11 has a series circuit of switching elements Q1 and Q2 connected to both ends of a DC power source E, a capacitor C2, a ballast choke T1 and a discharge lamp Lamp connected in series to both ends of the switching element Q2, and is parallel to the discharge lamp Lamp. This is a half-bridge inverter circuit composed of a connected capacitor C1. The ballast choke T1 and the capacitor C1 constitute a resonance circuit 12. Further, a preheating circuit 15 for preheating the filament of the discharge lamp Lamp is provided. The oscillation frequency control circuit 13 includes an integrated circuit IC101, resistors R102 to R105, capacitors C101 and C103, a resistor R101 that is temperature correction means 14, and a negative characteristic thermistor NTC1.
[0037]
The oscillation frequency of the signal for driving the switching elements Q1 and Q2 output from the terminals OUT1 and OUT2 of the oscillation frequency control circuit is connected in parallel with the capacitor C101 and the capacitor C101 connected between the Tc terminal of the integrated circuit IC101 and the ground. The resistor R101 and the negative characteristic thermistor NTC1, and the resistor R102 connected between the TOSC terminal and the ground of the integrated circuit IC101, the resistor R103 connected between the TPRE terminal and the ground, and the TSTR terminal connected between the ground It is determined by the resistor R104.
[0038]
The details of the frequency setting will be described. For example, when the discharge lamp Lamp is preheated, the switch SW101 in the integrated circuit IC101 of the TPRE terminal and the switch SW102 in the integrated circuit IC101 of the TSTR terminal are turned on, respectively from the TOSC terminal, the TPRE terminal, and the TSTR terminal. A voltage is applied to the connected resistor from the inside. The current ICOSC that charges the capacitor C101 is a constant current that is a ratio of the sum of the currents IROSC, IRPRE, and IRSTR flowing through the resistors R102, R103, and R104, and is the most when current flows through all the terminals of the TOSC, TPRE, and TSTR terminals. growing. At that time, the voltage VCOSC across the capacitor C101 is as follows.
[0039]
First, when there is no resistance R101 of the temperature correction means and the negative characteristic thermistor NTC1, as shown in FIG. 2, the battery is charged with a constant current to the reference value Vth_H, and discharged with a constant current to the reference value Vth_L when the reference value Vth_H is reached. Therefore, it becomes a triangular wave, and twice the period Tc of the triangular wave becomes the oscillation frequency.
That is, when the oscillation frequency of the inverter is fc and the constant current charged / discharged from the Tc terminal of the integrated circuit IC101 is I, the period T = 2 × (C101 × (Vth_H−Vth_L)) / I shown in FIG. Inverter oscillation frequency fc = 1 / (2 × T) = I / (4 × C101 × (Vth_H−Vth_L)).
[0040]
Therefore, since the largest current flows through the capacitor C101 as the charging / discharging current I during the preheating of the discharge lamp lamp, the oscillation frequency is the highest, and when starting the discharge lamp lamp, only the switch SW102 inside the integrated circuit IC101 is turned on. Since a voltage is applied only to the TOSC terminal and the TSTR terminal, the charge / discharge current I is smaller than that during preheating, and the oscillation frequency is lower than that during preheating. Further, since the switches SW101 and SW102 in the integrated circuit IC101 are turned off at the time of lighting, voltage is applied only to the resistor R102 connected to the TOSC terminal, so that the charge / discharge current I flowing through the capacitor C101 connected to the Tc terminal is the highest. Therefore, the oscillation frequency at the time of lighting is lowest.
[0041]
Next, the operation will be briefly described with reference to FIG. The timing at which the TOSC terminal, the TPRE terminal, and the TSTR terminal operate, that is, the timing at which the switches SW101 and SW102 in the integrated circuit IC101 are turned on and off is determined by the resistor R105 and the capacitor C103 connected to the external power supply Vcc and the TIMER terminal of the integrated circuit IC101. It is determined by the timer circuit determined by the time constant. As shown in FIG. 3, each of the switching elements SW101 and SW102 in the integrated circuit IC101 is turned on for the time th and ts after the power is turned on. As a result, the oscillation frequency of the oscillation frequency control circuit output from the OUT1 terminal and the OUT2 terminal of the integrated circuit IC101 becomes the frequency fh only for the time th as described above, and becomes the frequency fs (<fh) only for the next time ts-th. After the time ts, the frequency fo is obtained.
[0042]
A characteristic diagram showing the relationship between the frequency and the resonant voltage applied to the discharge lamp Lamp is shown in FIG. The resonance voltage Vh at the frequency fh is smaller than the resonance voltage Vs at the frequency fs. Therefore, if the starting voltage of the discharge lamp Lamp is set between the resonance voltage Vs and the resonance voltage Vh, the power is turned on. Until the time th elapses, the discharge lamp Lamp is sufficiently preheated without being started, and then the discharge lamp Lamp can be started until the time ts elapses after the power is turned on. After the time ts has elapsed since the power was turned on, both the switches SW101 and SW102 in the integrated circuit IC101 are turned off, and the oscillation frequency of the oscillation frequency control circuit becomes fo.
[0043]
Next, the case where the resistor R101 of the temperature correction means and the negative characteristic thermistor NTC1 are connected in parallel with the capacitor C101 will be described. When the resistance value of the negative characteristic thermistor NTC1 becomes small at a high temperature, the waveform becomes distorted from the triangular wave as shown in FIG. 5, so that the oscillation frequency becomes lower than that without the NTC1. Further, since the resistance value of the negative characteristic thermistor NTC1 becomes large at low temperatures, the waveform at both ends of the capacitor C101 becomes a substantially triangular wave. That is, when the negative characteristic thermistor NTC1 is inserted in parallel with the capacitor C101, the period Tntc due to the voltage VCOSC across the capacitor is Tntc = −C101 × RNTC × [ln {( Vth_H−RNTC × I) / (Vth_L−RNTC × I)} + ln {(Vth_H + RNTC × I) / (Vth_L + RNTC × I)}], so that the oscillation frequency fntc of the inverter is fntc = 1 / (2 × T1) Become.
[0044]
When the oscillation frequency fntc of this inverter is illustrated with the resistance value RNTC connected in parallel with the capacitor C101 on the horizontal axis, when the resistance value RNTC is small as shown in FIG. 6, the oscillation frequency fntc is low and the resistance value RNTC is large. As the frequency becomes, the oscillation frequency fntc increases. In other words, by using the negative characteristic thermistor NTC1, the resistance value changes to Rn2 at a low temperature and the resistance value changes to Rn1 at a high temperature, and the oscillation frequency changes from f2 to f1, respectively. Therefore, as shown in FIG. The resonance voltage applied at the time of start-up changes from V2 at low temperature to V1 at high temperature.
Also, at the time of lighting, the oscillation frequency changes in a lower direction when the ambient temperature changes from a low temperature to a high temperature as in the start-up. That is, the tube current of the discharge lamp Lamp increases as the ambient temperature changes from low to high.
[0045]
Further, by using an integrated circuit IC101 whose oscillation frequency ambient temperature characteristic changes from low temperature to high temperature (for example, MCZ4001P manufactured by Shindengen), the ambient temperature characteristic of the negative characteristic thermistor NTC1 and the ambient temperature of the integrated circuit By multiplying with the temperature characteristic, the ambient temperature characteristic of the oscillation frequency can be achieved as shown in FIG. That is, the range (FIG. 6) of the total resistance value RNTC of the resistor R101 and the negative characteristic thermistor NTC1 is determined by the ambient temperature characteristics of the integrated circuit IC101.
[0046]
Therefore, even if the ambient temperature of the discharge lamp changes, by applying an appropriate starting voltage to the discharge lamp, the discharge lamp can be surely turned on, and no excessive stress is applied to the components in the lighting device. In addition, since the oscillation frequency changes so that the tube current is increased at both low and high temperatures when lighting, compared to the normal temperature, better light than a discharge lamp lighting device that has a constant oscillation frequency even when the ambient temperature changes. Output can be obtained.
[0047]
Furthermore, when the discharge lamp Lamp is lit at a low temperature, since the amalgam temperature or the coldest spot temperature of the discharge lamp Lamp is low, the rise of the light output tends to be slower than the normal temperature, but the tube current is increased at a low temperature. Therefore, there is an advantage that the rise of the light output is improved as compared with the conventional case.
[0048]
(Embodiment 2)
A second embodiment of the present invention will be described with reference to FIG. 9 differs from the first embodiment in that the negative characteristic thermistor NTC1 of the oscillation frequency control circuit and the resistor R101 are not connected in parallel with the capacitor C101, but the resistor R102 is connected between the TOSC terminal of the integrated circuit IC101 and the ground. This is that a temperature-sensitive resistor R107 (for example, Matsushita ERA series) is connected in series.
[0049]
Since the resistance value of the temperature-sensitive resistor increases as the ambient temperature increases, when the temperature-sensitive resistor R107 is connected to the TOSC terminal, the resistance value between the TOSC terminal and the ground is substantially decreased at a low temperature, and the Tc terminal. The charging / discharging current I flowing from becomes larger. Therefore, the oscillation frequency is high at low temperatures, and the oscillation frequency is low at high temperatures.
[0050]
As the other operations, as in the first embodiment, the above-mentioned feeling is obtained by using the one whose frequency increases when the ambient temperature characteristic of the oscillation frequency of the integrated circuit IC101 changes from low temperature to high temperature (for example, MCZ4001P manufactured by Shindengen). By multiplying the ambient temperature characteristic of the temperature resistor R107 and the ambient temperature characteristic of the integrated circuit, the ambient temperature characteristic of the oscillation frequency can be achieved. Although the temperature sensitive resistance is described here, a positive temperature coefficient thermistor may be used.
[0051]
(Embodiment 3)
A third embodiment of the present invention will be described with reference to FIG. 10 is different from the first embodiment in that the capacitor C1 of the resonance circuit is connected in parallel to the non-power supply side of the discharge lamp Lamp, and the other components are the same in configuration and reference numerals, and thus the description thereof is omitted.
[0052]
The difference from the operation of the first embodiment is that the preheating circuit becomes unnecessary because the capacitor C1 of the resonance circuit is connected to the non-power supply side of the discharge lamp Lamp. That is, during preheating, the current flowing through the filament of the discharge lamp Lamp becomes the resonance current of the inductor T1 and the capacitor C1. Therefore, if the oscillation frequency control circuit is the same as that of the first embodiment, the current flowing through the filament during preheating also increases when the ambient temperature is low and when the ambient temperature is high. Increasing the filament current during preheating at low temperatures and high temperatures facilitates electron emission from the filament, further improving the start-up of the discharge lamp Lamp at low temperatures and the restart at high temperatures.
[0053]
【The invention's effect】
If comprised as mentioned above, even if the ambient temperature of a discharge lamp changes, it can be made to light reliably, and the part stress of a discharge lamp lighting device can also be relieved. Also, since the oscillation frequency is lowered so that the tube current is increased at low temperatures and high temperatures, it is possible to reduce the decrease in the light output of the discharge lamp, and the rise of the light output of the discharge lamp at low temperatures is good. . Furthermore, since it becomes easy to increase the filament current of the discharge lamp during preheating at low temperatures, electrons are easily emitted from the filament, and the discharge lamp is easily started.
[Brief description of the drawings]
FIG. 1 is a circuit diagram according to a first embodiment of the present invention.
FIG. 2 is an operation explanatory diagram of the oscillation circuit according to the first embodiment of the present invention.
FIG. 3 is an operation explanatory diagram illustrating a change in oscillation frequency during preheating, starting, and lighting period according to the first embodiment of the present invention.
FIG. 4 is an operation explanatory view showing a change in resonance voltage during preheating and starting in the first embodiment of the present invention.
FIG. 5 is an operation explanatory diagram of the oscillation circuit at a high temperature according to the first embodiment of the present invention.
FIG. 6 is an explanatory diagram showing the relationship between the resistance value of the temperature correction means and the oscillation frequency according to the ambient temperature change according to the first embodiment of the present invention.
FIG. 7 is an explanatory diagram showing a relationship between an oscillation frequency and a resonance voltage due to a change in ambient temperature according to the first embodiment of the present invention.
FIG. 8 is an explanatory diagram showing a relationship between an ambient temperature and a resonance voltage according to the first embodiment of the present invention.
FIG. 9 is a circuit diagram of Embodiment 2 of the present invention.
FIG. 10 is a circuit diagram of Embodiment 3 of the present invention.
FIG. 11 is a circuit diagram of Conventional Example 1.
12 is a circuit diagram of Conventional Example 2. FIG.
13 is an operation explanatory diagram showing a change in oscillation frequency during preheating, starting, and lighting period in Conventional Example 2. FIG.
14 is an operation explanatory diagram showing a change in oscillation frequency during the start-up period due to the ambient temperature in Conventional Example 2. FIG.
FIG. 15 is an operation explanatory diagram showing a change in resonance voltage during the start-up period according to the ambient temperature in Conventional Example 2;
[Explanation of symbols]
11 Inverter circuit
12 Resonant circuit
13 Oscillation frequency control circuit
14 Temperature correction means
15 Preheating circuit

Claims

A DC power supply, an inverter circuit including a switching element that switches the voltage of the DC power supply at a high frequency, a resonance circuit including an inductor and a capacitor to which an oscillation output of the inverter circuit is applied, and a resonance voltage of the resonance circuit is applied. A discharge lamp, and oscillation frequency control means for switching the oscillation frequency of the inverter circuit so as to exhibit the operation state of each stage of preheating, starting and lighting of the discharge lamp, and the discharge lamp is controlled by the resonance action of the resonance circuit. In a discharge lamp lighting device for starting and lighting, the discharge lamp or the ambient temperature of the discharge lamp lighting device is detected, and the voltage applied to the discharge lamp at the start of the discharge lamp becomes the highest voltage when the ambient temperature is low, When the temperature is high, the voltage is higher than the voltage at normal temperature, and the current flowing to the discharge lamp when the discharge lamp is lit is the maximum when the ambient temperature is low. Large when the ambient temperature is hot with a temperature compensation means for controlling so that the above current at the normal temperature,
The temperature correction means includes a first temperature sensitive element whose oscillation frequency has a positive characteristic with respect to temperature, and a second temperature sensitive element having an ambient temperature characteristic opposite to the first temperature sensitive element,
The discharge lamp lighting device characterized in that the oscillation frequency control means includes an integrated circuit including the first temperature sensitive element and the second temperature sensitive element connected to an input terminal of the integrated circuit. .

A DC power supply, an inverter circuit including a switching element that switches the voltage of the DC power supply at a high frequency, a resonance circuit including an inductor and a capacitor to which an oscillation output of the inverter circuit is applied, and a resonance voltage of the resonance circuit is applied. A discharge lamp, and oscillation frequency control means for switching the oscillation frequency of the inverter circuit so as to exhibit the operation state of each stage of preheating, starting and lighting of the discharge lamp, and the discharge lamp is controlled by the resonance action of the resonance circuit. In the discharge lamp lighting device that is started and lit, the ambient temperature of the discharge lamp or the discharge lamp lighting device is detected, and the oscillation frequency of the inverter circuit is the lowest when the ambient temperature is low, and when the ambient temperature is high Equipped with temperature correction means to control the oscillation frequency to be below the oscillation frequency at normal temperature ,
The temperature correction means includes a first temperature sensitive element whose oscillation frequency has a positive characteristic with respect to temperature, and a second temperature sensitive element having an ambient temperature characteristic opposite to the first temperature sensitive element,
The discharge lamp lighting device characterized in that the oscillation frequency control means includes an integrated circuit including the first temperature sensitive element and the second temperature sensitive element connected to an input terminal of the integrated circuit. .

The discharge lamp lighting device according to claim 1 , wherein the second temperature sensitive element is a negative characteristic thermistor.

A DC power supply, an inverter circuit including a switching element that switches the voltage of the DC power supply at a high frequency, a resonance circuit including an inductor and a capacitor to which an oscillation output of the inverter circuit is applied, and a resonance voltage of the resonance circuit is applied. A discharge lamp, and oscillation frequency control means for switching the oscillation frequency of the inverter circuit so as to exhibit the operation state of each stage of preheating, starting and lighting of the discharge lamp, and the discharge lamp is controlled by the resonance action of the resonance circuit. In a discharge lamp lighting device for starting and lighting, the discharge lamp or the ambient temperature of the discharge lamp lighting device is detected, and the voltage applied to the discharge lamp at the start of the discharge lamp becomes the highest voltage when the ambient temperature is low, When the temperature is high, the voltage exceeds the normal voltage, and the current flowing to the discharge lamp when the discharge lamp is lit is the maximum when the ambient temperature is low. Large when the ambient temperature is hot with a temperature compensation means for controlling so that the above current at the normal temperature,
The temperature correction means includes a first temperature sensitive element whose oscillation frequency has a positive characteristic with respect to temperature, and a third temperature sensitive element having the same ambient temperature characteristics as the first temperature sensitive element,
The oscillation frequency control means includes an integrated circuit including a first temperature sensitive element and a second capacitor connected to the first input terminal of the integrated circuit, and the second capacitor is driven by a predetermined current. Charging and discharging are repeated, and when the discharge lamp is preheated, the predetermined current value is determined by a first resistor connected to the second input terminal of the integrated circuit, and when the discharge lamp is started, the third current of the integrated circuit is determined. The predetermined current value is determined by a second resistor connected to an input terminal of the integrated circuit, and the predetermined current value is determined by a third resistor connected to the fourth input terminal of the integrated circuit when the discharge lamp is turned on. the discharge lamp lighting device you characterized in that said third temperature sensitive element in said third resistor in series connected.

A DC power supply, an inverter circuit including a switching element that switches the voltage of the DC power supply at a high frequency, a resonance circuit including an inductor and a capacitor to which an oscillation output of the inverter circuit is applied, and a resonance voltage of the resonance circuit is applied. A discharge lamp, and oscillation frequency control means for switching the oscillation frequency of the inverter circuit so as to exhibit the operation state of each stage of preheating, starting and lighting of the discharge lamp, and the discharge lamp is controlled by the resonance action of the resonance circuit. In the discharge lamp lighting device that is started and lit, the ambient temperature of the discharge lamp or the discharge lamp lighting device is detected, and the oscillation frequency of the inverter circuit is the lowest when the ambient temperature is low, and when the ambient temperature is high Equipped with temperature correction means to control the oscillation frequency to be below the oscillation frequency at normal temperature,
The temperature correction means includes a first temperature sensitive element whose oscillation frequency has a positive characteristic with respect to temperature, and a third temperature sensitive element having the same ambient temperature characteristics as the first temperature sensitive element,
The oscillation frequency control means includes an integrated circuit including a first temperature sensitive element and a second capacitor connected to the first input terminal of the integrated circuit, and the second capacitor is driven by a predetermined current. Charging and discharging are repeated, and when the discharge lamp is preheated, the predetermined current value is determined by a first resistor connected to the second input terminal of the integrated circuit, and when the discharge lamp is started, the third current of the integrated circuit is determined. The predetermined current value is determined by a second resistor connected to an input terminal of the integrated circuit, and the predetermined current value is determined by a third resistor connected to the fourth input terminal of the integrated circuit when the discharge lamp is turned on. the discharge lamp lighting device you characterized in that said third temperature sensitive element in said third resistor in series connected.

6. The discharge lamp lighting device according to claim 4 , wherein the third temperature sensitive element is a positive temperature coefficient thermistor or a positive temperature sensitive resistor.