JP2004193310A

JP2004193310A - Transformer

Info

Publication number: JP2004193310A
Application number: JP2002359061A
Authority: JP
Inventors: Tomohiro Sugimura; 智宏杉村; Katsumi Matsumura; 勝己松村; Yoshihiro Kuniya; 佳弘国谷; Sadao Morimoto; 貞雄森元
Original assignee: Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Holdings Corp
Priority date: 2002-12-11
Filing date: 2002-12-11
Publication date: 2004-07-08

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transformer with which the design is flexible for a discharge-lamp lighting system by suppressing the leakage inductance. <P>SOLUTION: The transformer is constituted so that collars 35 are formed at the upper-lower ends of winding shafts 34 while planes 36 are formed on the side faces of the collars 35 in two split magnetic cores 31, an input winding 37 is wound on the outer periphery of the winding shaft 34 for one split magnetic core 31 while an output winding 38 is wound on the winding shaft 34 for the other split magnetic core 31, the planes 36 of the two split magnetic cores 31 are abutted to form a closed magnetic circuit and the sectional area C of the winding shaft 34 for the split magnetic core 31, on which the output winding 38 is wound, is made larger than that A of the winding shaft 34 for the split magnetic core 31, on which the input winding 37 is wound. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、放電灯点灯装置等に用いるトランスに関するものである。
【０００２】
【従来の技術】
以下、従来のトランスについて図面を参照しながら説明する。
【０００３】
図８は従来のトランスの断面図、図９は同トランスの斜視図である。
【０００４】
図８、図９において、従来のトランスは、巻軸１の中央に貫通孔２を有するとともに上下端に鍔３を設けた二つのコイルボビン４と、巻軸１の外周に巻回した巻線５と、コイルボビン４の貫通孔２に挿通するとともに二つの分割磁心６を突合せて閉磁路を構成した閉磁路磁心７と、二つのコイルボビン４の端部に植設するとともに巻線５と接続した端子８を備えていた。
【０００５】
そして、閉磁路磁心７は、一つの中脚９と二つの磁脚１０を連接脚１１で連接した断面Ｅ字形状の分割磁心６と平板状の分割磁心６とを突合せて形成しており、このとき、一方のコイルボビン４の貫通孔２に一方の磁脚１０を挿通しており、他方のコイルボビン４の貫通孔２に他方の磁脚１０を挿通してトランスを構成していた。
【０００６】
次に、上記従来のトランスを放電灯点灯装置に用いた使用例について説明する。
【０００７】
図１０は従来のトランスを用いた放電灯点灯装置のブロック図である。
【０００８】
同図において、従来のトランスを用いた放電灯点灯装置は、放電灯１２の点灯を開始する第一の周波数２４と放電灯１２の点灯を維持する第二の周波数２５とを切替えて正電位の高周波パルスを出力する発振部１３と、発振部１３の出力を入力するとともに発振部１３の出力に応じて直流電圧＋Ｂを変換して正電位のパルスと負電位のパルスを交互に出力する駆動部１４と、入力巻線１５と出力巻線１６とを有し駆動部１４の出力を高電圧に昇圧して出力する昇圧トランス１７と、昇圧トランス１７の出力巻線１６の両端に容量素子１８を接続した共振容量１９と、共振容量１９と並列に接続して昇圧トランス１７の出力巻線１６の両端と接続した放電灯１２と、放電灯１２に流れる電流を検出して発振部１３に第一の周波数２４と第二の周波数２５を切替える制御信号を出力する制御部２０とを有していた。
【０００９】
上記従来のトランスは放電灯点灯装置において昇圧トランス１７として用いられ、一方のコイルボビン４に絶縁被膜付電線を十数ターン程度巻回した入力巻線１５が施され、他方のコイルボビン４に入力巻線１５より細い絶縁被膜付電線を千数百ターン程度施して用いており、駆動部１４からの出力を入力巻線１５に入力し、入力巻線１５と出力巻線１６との巻数比倍の高電圧を出力したいわゆる他励方式の昇圧トランス１７として用いられていた。
【００１０】
そして、従来のトランスを放電灯点灯装置の昇圧トランスに用いたときの、入力巻線１５側から見たときのインピーダンス周波数特性は図１１の曲線２１に示すように、第一の共振点２２と第二の共振点２３を有していた。
【００１１】
この第一の共振点２２は昇圧トランス１７の出力巻線１６と共振容量１９の並列共振による共振点であり、第二の共振点２３はトランスの出力巻線１６の漏れインダクタンスと共振容量１９の直列共振によるもので、第一の共振点２２から第二の共振点２３にかけてインピーダンスが小さくなっている。
【００１２】
次に、放電灯点灯装置の動作について、図１２の従来のトランスを用いた放電灯点灯装置の要部波形図を用いて説明する。
【００１３】
図１２（ａ）は発振部の第一の周波数の出力波形図、同図（ｂ）は発振部の第一の周波数における駆動部の出力波形図、同図（ｃ）は発振部の第一周波数における昇圧トランスの出力波形図である。
【００１４】
同図において、放電灯１２の点灯開始時、図１２（ａ）に示すように発振部１３が第一の周波数２４の正電位のパルスを出力する。
【００１５】
この第一の周波数２４は、放電灯１２の点灯開始時に駆動部１４側から昇圧トランス１７により大きな電力を供給するために、駆動部１４側のインピーダンスに対して昇圧トランス１７側のインピーダンスが小さくなるように、図１１に示した曲線２１の第二の共振点２３に近づけた周波数に予め設定したものである。
【００１６】
そして、図１２（ｂ）に示すように、駆動部１４において、発振部１３の出力に応じて直流電圧＋Ｂを変換して正電位と負電位の交互のパルス波形を出力する。
【００１７】
この駆動部１４の出力を入力した昇圧トランス１７の出力波形は、図１２（ｃ）に示すように、昇圧トランス１７の巻線分布容量によってパルス波形から概正弦波形に歪んだ交流の高電圧で出力され、放電灯１２に高電圧が印加されて放電灯１２が点灯する。
【００１８】
次に、放電灯１２が点灯開始した後の、放電灯点灯装置の動作について、図１２（ｄ）の発振部の第二の周波数の出力波形図、同図（ｅ）の発振部の第二の周波数における駆動部の出力波形図、同図（ｆ）の発振部の第二周波数における昇圧トランスの出力波形図を用いて説明する。
【００１９】
放電灯１２が点灯すると制御部２０が放電灯に流れた電流を検出して発振部１３に制御信号を出力し、発振部１３は制御部２０からの制御信号に応じて図１２（ｄ）に示すように発振周波数を第一の周波数２４から第二の周波数２５に切替えて出力する。
【００２０】
この第二の周波数２５は、放電灯１２が点灯すると、放電灯１２が負性特性であるので点灯開始時の大きな電力は必要なくなり、昇圧トランス１７のインピーダンスを大きくして駆動部１４側から昇圧トランス１７側への電力の供給を少なくするために、図１１の曲線２１の第一の共振点２２に近づけた周波数に予め設定したものである。
【００２１】
そして、放電灯１２の点灯開始時と同様に、図１２（ｅ）に示すように、駆動部１４において発振部１３の第二の周波数２５の出力に応じた直流電圧＋Ｂを変換して正電位と負電位の交互のパルス波形を出力し、この駆動部１４の出力を入力した昇圧トランス１７の出力は、図１２（ｆ）に示すように昇圧トランス１７の巻線分布容量によってパルス波形から概正弦波形に歪んだ交流の高電圧で出力され、放電灯１２に高電圧が印加されて放電灯１２の点灯を維持していた。
【００２２】
なお、この出願の発明に関連する先行技術文献情報としては、例えば、特許文献１が知られている。
【００２３】
【特許文献１】
特開２００２−２７０４４１号公報
【００２４】
【発明が解決しようとする課題】
上記従来の構成では、トランスの閉磁路磁心７が、断面Ｅ字状の分割磁心６と平板状の分割磁心６を突合せて構成しているので、入力巻線１５と出力巻線１６との間の中脚９で漏れインダクタンスが大きくなり、また、巻線１を施したコイルボビン４を分割磁心６に装着しているので、巻線５と分割磁心６との間の間隔が大きくなり、漏れインダクタンスが大きくなっていた。
【００２５】
そして、漏れインダクタンスが大きくなると第二の共振点２３の共振周波数は漏れインダクタンスの大きさに反比例するために第二の共振点２３の共振周波数が低くなり、第一の共振点２２と第二の共振点２３との周波数の幅が小さくなるとともにインピーダンスの変化の傾きが大きくなっていた。
【００２６】
このため、発振部１３の第一の周波数および第二の周波数の値が制限されたり、その発振周波数のばらつきを小さくしなければならないといった課題を有していた。
【００２７】
また、第二の共振点２３の共振周波数を高い周波数にして第一の周波数と第二の周波数の幅を大きくする他の方法として、共振容量１９の値を小さくする方法があるが、トランスの漏れインダクタンスの値が大きいと複数個の容量素子１８を直列接続して共振容量１９を小さくする必要があり、設計面および製造面において作業が煩雑になるといった課題を有していた。
【００２８】
本発明は上記従来の課題を解決するもので、漏れインダクタンスを小さくして放電灯点灯装置等の設計自由度を高めたトランスを提供することを目的としている。
【００２９】
【課題を解決するための手段】
上記目的を達成するために本発明は以下の構成を有する。
【００３０】
本発明の請求項１に記載の発明は、特に、二つの分割磁心は巻軸部の上下端に鍔を設けるとともに鍔の側面に平面部を形成しており、一方の分割磁心の巻軸部の外周に入力巻線を巻回するとともに他方の分割磁心の巻軸部に出力巻線を巻回し、二つの分割磁心の平面部を突合せて閉磁路を形成しており、出力巻線を巻回した分割磁心の巻軸部の断面積を入力巻線を巻回した分割磁心の巻軸部の断面積以上とした構成である。
【００３１】
上記構成により、分割磁心に直接巻線を巻回して分割磁心の平面部を突合せて閉磁路を形成しているので、巻線と分割磁心との間に間隔がなくなり、漏れインダクタンスを小さくすることができる。
【００３２】
そして、出力巻線を巻回した分割磁心の巻軸部の断面積を入力巻線を巻回した分割磁心の巻軸部の断面積以上としているので、入力巻線を巻回した巻軸部より出力巻線を巻回した巻軸部の磁気抵抗を小さくすることができるので、入力巻線が発生した磁束を出力巻線を巻回した分割磁心に通しやすくすることができ、漏れインダクタンスを小さくすることができる。
【００３３】
本発明の請求項２に記載の発明は、特に、二つの分割磁心の上下端の鍔の断面積を同じ面積とした構成である。
【００３４】
上記構成により、分割磁心の上下端の鍔の断面積を同じ面積としているので、上下端の分割磁心の磁気抵抗のバランスをとることができ、いずれか一方の鍔から磁束が漏れることを抑制して漏れインダクタンスを小さくすることができる。
【００３５】
本発明の請求項３に記載の発明は、特に、二つの分割磁心の上下端の鍔の断面積を入力巻線を巻回した分割磁心の巻軸部の断面積以上とした構成である。
【００３６】
上記構成により、入力巻線を巻回した巻軸部より上下端部の磁気抵抗が小さくなり、入力巻線を巻回した磁脚部から上下端の鍔へ流れ込む磁束を通しやすくすることができ、入力巻線を巻回した磁脚から上下端鍔へ磁束が流れるときに磁束が漏れることを抑制して漏れインダクタンスを小さくすることができる。
【００３７】
本発明の請求項４に記載の発明は、特に、出力巻線を巻回した分割磁心の巻軸部の断面積を二つの分割磁心の上下端の鍔の断面積以上とした構成である。
【００３８】
上記構成により、巻軸部の上下端の鍔より出力巻線を巻回した巻軸部の磁気抵抗が小さくなり、巻軸部の上下端の鍔から出力巻線を巻回した巻軸部へ流れ込む磁束を通しやすくすることができ、巻軸部の上下端の鍔から出力巻線を巻回した巻軸部へ磁束が流れるときに磁束が漏れることを抑制して漏れインダクタンスを小さくすることができる。
【００３９】
本発明の請求項５に記載の発明は、特に、二つの分割磁心をＭｎ系のフェライト材で形成した構成である。
【００４０】
上記構成により、Ｍｎ系のフェライト材はコアロスが小さいので、効率の良いトランスを構成できる。
【００４１】
本発明の請求項６に記載の発明は、特に、二つの分割磁心をＮｉ系のフェライト材で形成した構成である。
【００４２】
上記構成により、Ｎｉ系のフェライト材は絶縁抵抗が高いので、巻線に入力する電圧または巻線が出力する電圧が高電圧の場合でも巻線と分割磁心の絶縁性を損なうことがなく、高電圧のトランスを構成することができる。
【００４３】
本発明の請求項７に記載の発明は、特に、二つの分割磁心は、一方の分割磁心をＭｎ系のフェライト材で形成し、他方の分割磁心をＮｉ系のフェライト材で形成した構成である。
【００４４】
上記構成により、一方の分割磁心をコアロスの小さいＭｎ系のフェライトコア材で形成し、他方の分割磁心を絶縁抵抗の高いＮｉ系のフェライト材で形成しているので、Ｎｉ系のフェライト材で形成した分割磁心に高電圧の巻線を巻回すれば、高電圧に対応した効率の良いトランスを構成できる。
【００４５】
本発明の請求項８に記載の発明は、特に、二つの分割磁心の少なくとも一方は、平面部を除いて絶縁樹脂で被覆した絶縁層を設けた構成である。
【００４６】
上記構成により、巻線と分割磁心との間に絶縁層があるので、巻線と分割磁心の絶縁性を向上することができる。
【００４７】
本発明の請求項９に記載の発明は、請求項１に記載の発明において、特に、二つの分割磁心の内少なくとも一方は、巻軸部の断面形状を円形状とした構成である。
【００４８】
上記構成により、巻軸部に導線を巻回するときに導線にかかる応力を小さくすることができる。
【００４９】
本発明の請求項１０に記載の発明は、特に、二つの分割磁心の内少なくとも一方は、巻軸部の断面形状を偏平形状とした構成である。
【００５０】
上記構成により、二つの分割磁心を突合せて閉磁路磁心を形成したときの底面積を小さくすることができる。
【００５１】
本発明の請求項１１に記載の発明は、特に、分割磁心の下端の鍔に、下端の鍔の側面から巻軸部までスリットを形成し、スリットから巻線の引き出し線を引き出した構成である。
【００５２】
上記構成により、巻線の巻軸部側の引き出し線を、分割磁心の下端の鍔に形成したスリットを通して引き出せば、巻線と引き出し線のクロスオーバーをなくすことができる。
【００５３】
本発明の請求項１２に記載の発明は、特に、二つの分割磁心の平面部と反対側の下端鍔に、下端鍔の底面を載置する載置部と、載置部と連成するとともに下端鍔の平面部と反対側の側面に巻線の引き出し線を接続する端子を有した厚肉部と、載置部および厚肉部と連成するとともに下端鍔の側面に沿わせた固定壁とを有した端子板を設けた構成である。
【００５４】
上記構成により、端子板に載置部および厚肉部とを連成するとともに下端鍔の側面に沿わせた固定壁を有しているので、分割磁心に端子板を容易に位置決めすることができる。
【００５５】
本発明の請求項１３に記載の発明は、特に、一方の端子板の載置部と固定壁とを一方の分割磁心の平面部より外方まで設け、一方の端子板の載置部に他方の分割磁心を載置した構成である。
【００５６】
上記構成により、一方の磁心を載置した端子板に、他方の分割磁心の下端の鍔を載置するだけで、二つの分割磁心の位置決めを容易に行うことができる。
【００５７】
【発明の実施の形態】
以下、本発明の一実施の形態におけるトランスについて図面を参照しながら説明する。
【００５８】
図１は本発明の一実施の形態におけるトランスの断面図、図２は同トランスの斜視図、図３は同トランスの分解斜視図である。
【００５９】
図１〜図３において、本発明の一実施の形態におけるトランスは、二つの分割磁心３１を突合せて閉磁路を形成した閉磁路磁心３２と、分割磁心３１に絶縁被膜付導線を巻回した巻線３３とを備えている。
【００６０】
そして、この二つの分割磁心３１は巻軸部３４の上下端に鍔３５を設けるとともに鍔３５の側面に平面部３６を形成しており、一方の分割磁心３１の巻軸部３４の外周に絶縁被膜付導線を数ターン程度巻回した入力巻線３７を施すとともに、他方の分割磁心３１の巻軸部３４に入力巻線３７の電線よりも細い絶縁被膜付導線を千数百ターン程度巻回した出力巻線３８を施し、二つの分割磁心３１の平面部３６を突合せて閉磁路を形成しており、出力巻線３８を巻回した分割磁心３１の巻軸部３４の断面積Ｃを入力巻線３７を巻回した分割磁心３１の巻軸部３４の断面積Ａ以上としている。
【００６１】
また、二つの分割磁心３１の上下端の鍔３５の断面積Ｂを同じ面積としており、二つの分割磁心３１の上下端の鍔３５の断面積Ｂを入力巻線３７を巻回した分割磁心３１の巻軸部３４の断面積Ａ以上にしている。
【００６２】
そして、出力巻線３８を巻回した分割磁心３１の巻軸部３４の断面積Ｃは、二つの分割磁心３１の上下端の鍔３４の断面積Ｂ以上にしている。
【００６３】
さらに、二つの分割磁心３１は、入力巻線３７を巻回した分割磁心３１をＭｎ系のフェライト材で形成し、出力巻線３８を巻回した分割磁心３１をＮｉ系のフェライト材で形成しており、平面部３６を除いた表面を数十μｍの厚みの絶縁樹脂（図示せず）で被覆した絶縁層３９を設けている。
【００６４】
また、二つの分割磁心３１の巻軸部３４の断面形状を円形状にしている。
【００６５】
そして、分割磁心３１の下端の鍔３５に、下端の鍔３５の側面から巻軸部３４までスリット４０を形成し、スリット４０から巻線３３の引き出し線４１を引き出している。
【００６６】
そして、二つの分割磁心３１の平面部３６と反対側の下端の鍔３５には、下端の鍔３５の底面を載置する載置部４２と、載置部４２と連成するとともに下端の鍔３５の平面部３６と反対側の側面に巻線３３の引き出し線４１を接続する端子４３を有した厚肉部４４と、載置部４２および厚肉部４４と連成するとともに下端の鍔３５の側面に沿わせた固定壁４５とを有した端子板４６を設けている。
【００６７】
また、一方の端子板４６の載置部４２と固定壁４５とを一方の分割磁心３１の平面部３６より外方まで設け、一方の端子板４６の載置部４２に他方の分割磁心３１を載置してトランスを構成したものである。
【００６８】
上記構成の本実施の形態のトランスについて以下その動作を説明する。
【００６９】
本実施の形態のトランスは、分割磁心３１に直接巻線３３を巻回して分割磁心３１の平面部３６を突合せて閉磁路を形成しているので、巻線３３と分割磁心３１との間に間隔がなくなり、漏れインダクタンスを小さくすることができる。
【００７０】
そして、出力巻線３８を巻回した分割磁心３１の巻軸部３４の断面積Ｃを入力巻線３７を巻回した分割磁心３１の巻軸部３４の断面積Ａ以上としているので、出力巻線３８を巻回した巻軸部３４より入力巻線３７を巻回した巻軸部３４の磁気抵抗が小さくなり、入力巻線３７の発生した磁束が出力巻線３８を巻回した分割磁心３１に通りやすくすることができ、漏れインダクタンスを小さくすることができる。
【００７１】
さらに、分割磁心３１の上下端の鍔３５の断面積Ｂを同じ面積としているので、上下端の分割磁心３１の磁気抵抗のバランスをとることができ、いずれか一方の鍔３５から磁束が漏れることを抑制して漏れインダクタンスを小さくすることができる。
【００７２】
また、二つの分割磁心３１の上下端の鍔３５の断面積Ｂを、入力巻線３７を巻回した分割磁心３１の巻軸部３４の断面積Ａ以上としているので、入力巻線３７を巻回した巻軸部３４より上下端の鍔３５の磁気抵抗が小さくなり、入力巻線３７を巻回した巻軸部３４から上下端の鍔３５へ流れ込む磁束を通しやすくすることができ、入力巻線３７を巻回した巻軸部３４から上下端の鍔３５へ磁束が流れるときに、磁束が漏れることを抑制して漏れインダクタンスを小さくすることができる。
【００７３】
そして、出力巻線３８を巻回した分割磁心３１の巻軸部３４の断面積Ｃを、二つの分割磁心３１の上下端の鍔３５の断面積Ｂ以上としているので、巻軸部３４の上下端の鍔３５より出力巻線３８を巻回した巻軸部３４の磁気抵抗を小さくすることができ、巻軸部３４の上下端の鍔３５から出力巻線３８を巻回した巻軸部３４へ流れ込む磁束を通しやすくすることができ、巻軸部３４の上下端の鍔３５から出力巻線３８を巻回した巻軸部３４へ磁束が流れるときに磁束が漏れることを抑制して漏れインダクタンスを小さくすることができる。
【００７４】
さらに、入力巻線３７を巻回した分割磁心３１をコアロスの少ないＭｎ系フェライト磁心で形成し、出力巻線３８を巻回した分割磁心３１を絶縁抵抗の高いＮｉ系のフェライト材で形成しているので、高電圧に対応した効率の良いトランスを構成できる。
【００７５】
このとき、分割磁心３１の上下端の鍔３５の断面積Ｂおよび出力巻線３８を巻回した分割磁心３１の巻軸部３４の断面積Ｃを、入力巻線３７を巻回した分割磁心３１の巻軸部３４の断面積Ａ以上としているので、Ｎｉ系フェライトコアの磁気抵抗増大による漏れ磁束の増大を抑制して、漏れインダクタンスが大きくなることを防止できる。
【００７６】
また、二つの分割磁心３１は、平面部３６を除いた表面を絶縁樹脂で被覆した絶縁層３９を設けているので、巻線３３と分割磁心３１の絶縁性を向上することができる。
【００７７】
そして、分割磁心３１の巻軸部３５の断面形状を円形状にしているので、巻軸部３４に導線を巻回するときに導線にかかる応力を小さくすることができる。
【００７８】
さらに、分割磁心３１の下端の鍔３５に、下端の鍔３５の側面から巻軸部３４までスリット４０を形成し、スリット４０から巻線３３の引き出し線４１を引き出しているので、巻線３３と引き出し線４１のクロスオーバーをなくすことができ、出力巻線３８に高電圧を発生したときの出力巻線３８と引き出し線４１の絶縁破壊を防止できる。
【００７９】
また、端子板４６に載置部４２および厚肉部４４とを連成するとともに下端の鍔３５の側面に沿わせた固定壁４５を有しているので、分割磁心３１に端子板４６を容易に位置決めすることができる。
【００８０】
そして、一方の端子板４６の載置部４２と固定壁４５とを一方の分割磁心３１の平面部３６より外方まで設け、一方の端子板４６の載置部４２に他方の分割磁心３１を載置しているので、一方の分割磁心３１を載置した端子板４６に、他方の分割磁心３１の下端の鍔３５を載置するだけで、二つの分割磁心３１の位置決めを容易に行うことができる。
【００８１】
次に、上記本発明の一実施の形態のトランスを放電灯点灯装置に用いた使用例について図面を参照して説明する。
【００８２】
図４は本発明の一実施の形態のトランスを用いた放電灯点灯装置のブロック図である。
【００８３】
同図において、放電灯４７の点灯を開始する第一の周波数５８と放電灯４７の点灯を維持する第二の周波数５９を切替えて正電位の高周波パルスを出力する発振部４８と、発振部４８の出力を入力するとともに発振部４８の出力に応じて直流電圧＋Ｂを変換して正電位のパルスと負電位のパルスを交互に出力する駆動部４９と、入力巻線３７と出力巻線３８を有し駆動部４９の出力を高電圧に昇圧して出力する昇圧トランス５０と、昇圧トランス５０の出力巻線３８の両端に容量素子５２を一つ接続した共振容量５３と、共振容量５３と並列に接続して昇圧トランス５０の出力巻線３８の両端と接続した放電灯４７と、放電灯４７に流れる電流を検出して発振部４８に第一の周波数５８と第二の周波数５９を切替える制御信号を出力する制御部５４とを有している。
【００８４】
上記本実施の形態におけるトランスは、放電灯点灯装置において昇圧トランス５０として用いられ、駆動部４９からの出力を入力巻線３７に入力し、入力巻線３７と出力巻線３８との巻数比倍の高電圧を出力したいわゆる他励方式の昇圧トランス５０として用いられる。
【００８５】
そして、本実施の形態のトランスを放電灯点灯装置の昇圧トランス５０に用いたときの、入力巻線３７側から見たときのインピーダンス周波数特性は図５の曲線５５に示すように、第一の共振点５６と第二の共振点５７を有している。
【００８６】
この第一の共振点５６は昇圧トランス５０の出力巻線３８と共振容量５３の並列共振による共振点であり、第二の共振点５７は昇圧トランス５０の出力巻線３８の漏れインダクタンスと共振容量の直列共振によるもので、第一の共振点から第二の共振点にかけてインピーダンスが小さくなっている。
【００８７】
次に、放電灯点灯装置の動作について、図６の本実施の形態におけるトランスを用いた放電灯点灯装置の要部波形図を用いて説明する。
【００８８】
図６（ａ）は発振部の第一の周波数の出力波形図、同図（ｂ）は発振部の第一の周波数における駆動部の出力波形図、同図（ｃ）は発振部の第一の周波数における昇圧トランスの出力波形図である。
【００８９】
同図において、放電灯４７の点灯開始時、図６（ａ）に示すように発振部４８が第一の周波数５８の正電位のパルスを出力する。
【００９０】
この第一の周波数５８は、放電灯４７の点灯開始時に駆動部４９側から昇圧トランス５０に大きな電力を供給するために、駆動部４９側のインピーダンスに対して昇圧トランス５０側のインピーダンスが小さくなるように、図５に示した曲線５５の第二の共振点５７に近づけた周波数に予め設定したものである。
【００９１】
そして、図６（ｂ）に示すように、駆動部４９において発振部４８の出力に応じて直流電圧＋Ｂを変換して正電位と負電位の交互のパルス波形を出力する。
【００９２】
この駆動部４９の出力を入力した昇圧トランス５０の出力波形は、図６（ｃ）に示すように、昇圧トランス５０の巻線分布容量によってパルス波形から概正弦波形に歪んだ交流の高電圧で出力され、放電灯４７に高電圧が印加されて放電灯４７が点灯する。
【００９３】
次に放電灯が点灯開始した後の放電灯点灯装置の動作を、図６（ｄ）の発振部の第二の周波数の出力波形図、同図（ｅ）の発振部の第二の周波数における駆動部の出力波形図、同図（ｆ）の発振部の第二の周波数における昇圧トランスの出力波形図を用いて説明する。
【００９４】
放電灯４７が点灯すると、制御部５４が放電灯４７に流れた電流を検出して発振部４８に制御信号を出力し、発振部４８は制御部５４からの制御信号に応じて図６（ｄ）に示すように発振周波数を第一の周波数５８から第二の周波数５９に切替えて出力する。
【００９５】
この第二の周波数５９は、放電灯４７が点灯すると、放電灯４７が負性特性であるので点灯開始時の大きな電力は必要なくなり、昇圧トランス５０のインピーダンスを大きくして駆動部４９側から昇圧トランス５０側への電力の供給を少なくするために、図５の曲線５５の第一の共振点５６に近づけた周波数に予め設定したものである。
【００９６】
そして、放電灯４７の点灯開始時と同様に、図６（ｅ）に示すように、駆動部４９において、発振部４８の第二の周波数５９の出力に応じて直流電圧＋Ｂを変換して正電位と負電位の交互のパルス波形に変換して出力し、この駆動部４９の出力を入力した昇圧トランス５０の出力は、図６（ｆ）に示すように昇圧トランス５０の巻線分布容量によってパルス波形から概正弦波形に歪んだ交流の高電圧で出力され、放電灯４７に高電圧が印加されて放電灯４７の点灯を維持している。
【００９７】
上記本実施の形態のトランスを用いた放電灯点灯装置は、本実施の形態のトランスが漏れインダクタンスを小さくできるので、図５の曲線５５に示すように、従来のトランスの曲線２１に比べて第二の共振点５７の共振周波数が高くなり、第一の周波数５８と第二の周波数５９の幅を大きくすることができる。
【００９８】
また、複数の容量素子を直列接続して共振容量を小さくすることをなくすことができる。
【００９９】
そして、第一の周波数５８と第二の周波数５９の幅を大きくすることができるので、発振部４８の発振周波数の第一の周波数５８と第二の周波数５９が制限されることを抑制することができ、その発振周波数のばらつきを小さく抑えることを緩和することができる。
【０１００】
また、第一の共振点５６と第二の共振点５７の周波数の幅が広くなり第一の共振点５６から第二の共振点５７までの周波数に対する昇圧トランス５０のインピーダンスの変化量、すなわちインピーダンス変化の傾きが緩やかになるので、発振部４８の発振周波数のばらつきの幅に対する昇圧トランス５０のインピーダンスの変化量を小さくすることができ、且つ、昇圧トランス５０の製造上のインピーダンスのばらつきの影響を小さくして、より精度良く放電灯４７へ供給する電力を制御することができる。
【０１０１】
また、複数の容量素子を直列接続して共振容量を小さくするといった煩雑な作業をなくすことができる。
【０１０２】
このように、本発明の一実施の形態におけるトランスは、分割磁心３１に直接巻線３３を巻回して、分割磁心３１の平面部３６を突合せて閉磁路を形成しているので、巻線３３と分割磁心３１との間に間隔がなくなり、漏れインダクタンスを抑制することができる。
【０１０３】
さらに、出力巻線３８を巻回した分割磁心３１の巻軸部３４の断面積Ｃを入力巻線３７を巻回した分割磁心３１の巻軸部３４の断面積Ａ以上としているので、入力巻線３７を巻回した巻軸部３４より出力巻線３８を巻回した巻軸部３４の磁気抵抗が小さくなり、入力巻線３７が発生した磁束を出力巻線３８を巻回した分割磁心３１に通しやすくすることができ、より漏れインダクタンスを小さくすることができる。
【０１０４】
尚、上記本実施の形態では、二つの分割磁心３１の一方をＭｎ系フェライト材で形成し、他方の分割磁心３１をＮｉ系フェライト材で形成した構成を説明したが、二つの分割磁心３１をＭｎ系のフェライト材で形成しても良く、Ｍｎ系のフェライト材はコアロスが小さいので、効率の良いトランスを構成できる。
【０１０５】
また、二つの分割磁心をＮｉ系のフェライト材で形成しても良く、Ｎｉ系のフェライト材は絶縁抵抗が高いので、巻線３３に入力する電圧または巻線３３が出力する電圧が高電圧の場合でも、巻線３３と分割磁心３１の絶縁性を損なうことがなく、高電圧のトランスを構成することができる。
【０１０６】
そして、本実施の形態では分割磁心３１の巻軸部３４の断面形状が円形状の構成を説明したが、図７の本発明の実施の形態におけるトランスの巻軸部の他の形状例を示す平面図に示すように、巻軸部３４の断面形状を偏平形状とすれば、二つの分割磁心３１を突合せて閉磁路磁心を形成したときの底面積を小さくすることができる。
【０１０７】
【発明の効果】
以上のように本発明によれば、二つの分割磁心は巻軸部の上下端に鍔を設けるとともに鍔の側面に平面部を形成しており、一方の分割磁心の巻軸部の外周に入力巻線を巻回するとともに他方の分割磁心の巻軸部に出力巻線を巻回しており、二つの分割磁心の平面部を突合せて閉磁路を形成しており、出力巻線を巻回した分割磁心の巻軸部の断面積を入力巻線を巻回した分割磁心の巻軸部の断面積以上とした構成である。
【０１０８】
これにより、分割磁心と巻線との間隔がなくなり漏れ磁束を少なくすることができるとともに、出力巻線を巻回した分割磁心に入力巻線が発生した磁束を通しやすくして漏れインダクタンスを小さくすることができ、漏れインダクタンスを抑制して放電灯点灯装置の設計自由度を高めたトランスを提供することができる。
【図面の簡単な説明】
【図１】本発明の一実施の形態におけるトランスの断面図
【図２】同トランスの斜視図
【図３】同トランスの分解斜視図
【図４】同トランスを用いた放電灯点灯装置のブロック図
【図５】同放電灯点灯装置のトランスの入力巻線側のインピーダンス周波数特性図
【図６】同放電灯点灯装置の要部波形図
【図７】本発明の一実施の形態におけるトランスの巻軸部の他の形状例を示した平面図
【図８】従来のトランスの断面図
【図９】従来のトランスの斜視図
【図１０】同トランスを用いた放電灯点灯装置のブロック図
【図１１】同放電灯点灯装置のトランスの入力巻線側のインピーダンス周波数特性図
【図１２】同放電灯点灯装置の要部波形図
【符号の説明】
３１分割磁心
３２閉磁路磁心
３３巻線
３４巻軸部
３５鍔
３６平面部
３７入力巻線
３８出力巻線
３９絶縁層
４０スリット
４１引き出し線
４２載置部
４３端子
４４厚肉部
４５固定壁
４６端子板[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a transformer used for a discharge lamp lighting device and the like.
[0002]
[Prior art]
Hereinafter, a conventional transformer will be described with reference to the drawings.
[0003]
FIG. 8 is a sectional view of a conventional transformer, and FIG. 9 is a perspective view of the transformer.
[0004]
8 and 9, a conventional transformer has two coil bobbins 4 having a through hole 2 at the center of a winding shaft 1 and flanges 3 provided at upper and lower ends, and a winding 5 wound around the outer periphery of the winding shaft 1. And a closed magnetic path core 7 inserted into the through hole 2 of the coil bobbin 4 and abutting the two divided magnetic cores 6 to form a closed magnetic path, and a terminal implanted at the ends of the two coil bobbins 4 and connected to the winding 5. 8 was provided.
[0005]
The closed magnetic path core 7 is formed by abutting a split core 6 having an E-shaped cross section and a flat split core 6 in which one middle leg 9 and two magnetic legs 10 are connected by a connecting leg 11. At this time, one magnetic leg 10 was inserted through the through hole 2 of one coil bobbin 4, and the other magnetic leg 10 was inserted through the through hole 2 of the other coil bobbin 4 to constitute a transformer.
[0006]
Next, an example of use of the above-mentioned conventional transformer in a discharge lamp lighting device will be described.
[0007]
FIG. 10 is a block diagram of a conventional discharge lamp lighting device using a transformer.
[0008]
In the figure, a conventional discharge lamp lighting device using a transformer switches between a first frequency 24 for starting lighting of the discharge lamp 12 and a second frequency 25 for maintaining lighting of the discharge lamp 12 to output a positive potential. An oscillating unit 13 that outputs a high-frequency pulse, and a driving unit that receives an output of the oscillating unit 13, converts a DC voltage + B according to the output of the oscillating unit 13, and alternately outputs a positive potential pulse and a negative potential pulse. , A step-up transformer 17 having an input winding 15 and an output winding 16 for boosting the output of the drive unit 14 to a high voltage and outputting the same, and a capacitive element 18 at both ends of the output winding 16 of the step-up transformer 17. The connected resonance capacitor 19, the discharge lamp 12 connected in parallel with the resonance capacitor 19 and connected to both ends of the output winding 16 of the step-up transformer 17, the current flowing through the discharge lamp 12 is detected, and the first Frequency 24 and the second It had a control unit 20 for outputting a control signal for switching the number 25.
[0009]
The above-mentioned conventional transformer is used as a step-up transformer 17 in a discharge lamp lighting device. An electric wire with an insulating coating, which is thinner than the wire 15, is used after being applied for about one thousand and several hundred turns. The output from the drive unit 14 is input to the input winding 15, and the turn ratio of the input winding 15 to the output winding 16 is twice as high. It has been used as a so-called separately excited step-up transformer 17 that outputs a voltage.
[0010]
When a conventional transformer is used as a step-up transformer of a discharge lamp lighting device, the impedance frequency characteristic when viewed from the input winding 15 side is, as shown by a curve 21 in FIG. It had a second resonance point 23.
[0011]
The first resonance point 22 is a resonance point due to parallel resonance between the output winding 16 of the step-up transformer 17 and the resonance capacitor 19, and the second resonance point 23 is the leakage inductance of the output winding 16 of the transformer and the resonance capacitance 19. Due to series resonance, the impedance decreases from the first resonance point 22 to the second resonance point 23.
[0012]
Next, the operation of the discharge lamp lighting device will be described with reference to a waveform diagram of a main part of the discharge lamp lighting device using the conventional transformer shown in FIG.
[0013]
12A is an output waveform diagram of the oscillation unit at the first frequency, FIG. 12B is an output waveform diagram of the driving unit at the first frequency of the oscillation unit, and FIG. FIG. 5 is an output waveform diagram of the boosting transformer at different frequencies.
[0014]
12, when the discharge lamp 12 starts to be lit, the oscillating unit 13 outputs a positive potential pulse having a first frequency 24 as shown in FIG.
[0015]
Since the first frequency 24 supplies a larger power to the boosting transformer 17 from the driving unit 14 at the start of lighting of the discharge lamp 12, the impedance of the boosting transformer 17 becomes smaller than the impedance of the driving unit 14. As described above, the frequency is set in advance to a frequency approaching the second resonance point 23 of the curve 21 shown in FIG.
[0016]
Then, as shown in FIG. 12B, the driving unit 14 converts the DC voltage + B according to the output of the oscillation unit 13 and outputs an alternating pulse waveform of a positive potential and a negative potential.
[0017]
The output waveform of the step-up transformer 17 to which the output of the drive unit 14 is input is an AC high voltage distorted from a pulse waveform to a substantially sinusoidal waveform by the winding distribution capacitance of the step-up transformer 17 as shown in FIG. The output is applied and a high voltage is applied to the discharge lamp 12, and the discharge lamp 12 is turned on.
[0018]
Next, the operation of the discharge lamp lighting device after the discharge lamp 12 starts lighting will be described with reference to the output waveform diagram of the second frequency of the oscillating unit in FIG. This will be described with reference to an output waveform diagram of the drive unit at the frequency of FIG. 4 and an output waveform diagram of the boosting transformer at the second frequency of the oscillation unit of FIG.
[0019]
When the discharge lamp 12 is turned on, the control unit 20 detects the current flowing through the discharge lamp and outputs a control signal to the oscillation unit 13. The oscillation unit 13 responds to the control signal from the control unit 20 as shown in FIG. As shown, the oscillation frequency is switched from the first frequency 24 to the second frequency 25 and output.
[0020]
When the discharge lamp 12 is turned on, the second frequency 25 does not require a large power at the start of lighting because the discharge lamp 12 has a negative characteristic. In order to reduce the supply of power to the transformer 17, the frequency is set in advance to a frequency close to the first resonance point 22 of the curve 21 in FIG.
[0021]
12 (e), the driving unit 14 converts the DC voltage + B corresponding to the output of the second frequency 25 of the oscillating unit 13 into the positive potential as shown in FIG. The output of the step-up transformer 17 to which the output of the driving unit 14 is input is approximately changed from the pulse waveform by the winding distribution capacitance of the step-up transformer 17 as shown in FIG. A high voltage of an AC voltage distorted into a sine waveform was output, and a high voltage was applied to the discharge lamp 12 to keep the discharge lamp 12 lit.
[0022]
As prior art document information related to the invention of this application, for example, Patent Document 1 is known.
[0023]
[Patent Document 1]
JP-A-2002-270441
[0024]
[Problems to be solved by the invention]
In the above-described conventional configuration, the closed magnetic path core 7 of the transformer is formed by abutting the E-shaped cross-section divided core 6 and the plate-shaped divided core 6 so that the input winding 15 and the output winding 16 And the coil bobbin 4 on which the winding 1 is provided is mounted on the split core 6, so that the distance between the winding 5 and the split core 6 increases, and the leakage inductance increases. Was getting bigger.
[0025]
When the leakage inductance increases, the resonance frequency of the second resonance point 23 is inversely proportional to the magnitude of the leakage inductance, so that the resonance frequency of the second resonance point 23 decreases. As the width of the frequency from the resonance point 23 became smaller, the slope of the change in impedance became larger.
[0026]
Therefore, there are problems that the values of the first frequency and the second frequency of the oscillating unit 13 are limited, and that variations in the oscillating frequencies must be reduced.
[0027]
Another method for increasing the resonance frequency of the second resonance point 23 to increase the width of the first frequency and the second frequency is to reduce the value of the resonance capacitor 19. If the value of the leakage inductance is large, it is necessary to connect the plurality of capacitive elements 18 in series to reduce the resonance capacitance 19, which has a problem that the work becomes complicated in terms of design and manufacturing.
[0028]
An object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to provide a transformer in which the leakage inductance is reduced to increase the degree of freedom in designing a discharge lamp lighting device and the like.
[0029]
[Means for Solving the Problems]
In order to achieve the above object, the present invention has the following configuration.
[0030]
In the invention according to claim 1 of the present invention, in particular, the two divided magnetic cores are provided with flanges at the upper and lower ends of a core portion and a flat portion is formed on a side surface of the flange, and the core portion of one divided magnetic core is provided. The input winding is wound around the outer circumference of the core, and the output winding is wound around the core of the other split core, and the flat portions of the two split cores are joined to form a closed magnetic circuit. In this configuration, the cross-sectional area of the wound core portion of the rotated divided core is equal to or larger than the cross-sectional area of the wound shaft portion of the divided core around which the input winding is wound.
[0031]
According to the above configuration, since a closed magnetic circuit is formed by winding the winding directly on the divided core and abutting the flat portions of the divided core, there is no space between the winding and the divided core, thereby reducing leakage inductance. Can be.
[0032]
Since the cross-sectional area of the core of the split core around which the output winding is wound is equal to or larger than the cross-sectional area of the core of the split core where the input winding is wound, the core around which the input winding is wound Since the magnetic resistance of the winding shaft around which the output winding is wound can be reduced, the magnetic flux generated by the input winding can easily pass through the split core around which the output winding is wound, and the leakage inductance can be reduced. Can be smaller.
[0033]
The invention described in claim 2 of the present invention is particularly configured such that the cross-sectional areas of the upper and lower ends of the two divided magnetic cores have the same area.
[0034]
With the above configuration, since the sectional areas of the upper and lower ends of the split cores have the same area, it is possible to balance the magnetic resistance of the upper and lower ends of the split core, and to suppress the leakage of magnetic flux from one of the split ends. Thus, the leakage inductance can be reduced.
[0035]
The invention described in claim 3 of the present invention is particularly configured such that the cross-sectional area of the upper and lower ends of the two divided magnetic cores is equal to or larger than the cross-sectional area of the core of the divided magnetic core around which the input winding is wound.
[0036]
With the above configuration, the magnetic resistance at the upper and lower ends is smaller than the winding shaft portion around which the input winding is wound, and the magnetic flux flowing from the magnetic leg around which the input winding is wound to the upper and lower flanges can be easily passed. In addition, when the magnetic flux flows from the magnetic leg around which the input winding is wound to the upper and lower end flanges, the leakage of the magnetic flux can be suppressed, and the leakage inductance can be reduced.
[0037]
The invention described in claim 4 of the present invention is particularly configured such that the sectional area of the winding shaft portion of the divided magnetic core around which the output winding is wound is equal to or larger than the sectional area of the upper and lower flanges of the two divided magnetic cores.
[0038]
With the above-described configuration, the magnetic resistance of the winding shaft portion around which the output winding is wound from the upper and lower flanges of the winding shaft portion is reduced, and from the upper and lower flanges of the winding shaft portion to the winding shaft around which the output winding is wound. It is possible to make the flowing magnetic flux easy to pass, and it is possible to reduce the leakage inductance by suppressing the leakage of the magnetic flux when the magnetic flux flows from the upper and lower flanges of the winding shaft to the winding shaft around which the output winding is wound. it can.
[0039]
The invention described in claim 5 of the present invention is particularly configured such that the two split magnetic cores are formed of a Mn-based ferrite material.
[0040]
According to the above configuration, since the Mn-based ferrite material has a small core loss, an efficient transformer can be formed.
[0041]
The invention according to claim 6 of the present invention is particularly configured such that the two split cores are formed of a Ni-based ferrite material.
[0042]
According to the above configuration, the Ni-based ferrite material has a high insulation resistance. Therefore, even when the voltage input to the winding or the voltage output from the winding is high, the insulation between the winding and the split core is not impaired. A voltage transformer can be configured.
[0043]
The invention according to claim 7 of the present invention is particularly configured such that one of the two divided cores is formed of a Mn-based ferrite material and the other is formed of a Ni-based ferrite material. .
[0044]
According to the above configuration, one of the divided cores is formed of a Mn-based ferrite core material having a small core loss, and the other divided core is formed of a Ni-based ferrite material having a high insulation resistance. By winding a high voltage winding around the divided magnetic core, an efficient transformer corresponding to the high voltage can be constructed.
[0045]
The invention described in claim 8 of the present invention has a configuration in which at least one of the two divided magnetic cores is provided with an insulating layer covered with an insulating resin except for a plane portion.
[0046]
According to the above configuration, since the insulating layer is provided between the winding and the split core, the insulation between the winding and the split core can be improved.
[0047]
According to a ninth aspect of the present invention, in the first aspect, at least one of the two divided magnetic cores has a configuration in which the cross-sectional shape of the winding shaft is circular.
[0048]
According to the above configuration, it is possible to reduce stress applied to the conductor when the conductor is wound around the winding shaft portion.
[0049]
The invention according to claim 10 of the present invention has a configuration in which at least one of the two divided magnetic cores has a flat cross-sectional shape of the winding shaft portion.
[0050]
According to the above configuration, the bottom area when the closed magnetic circuit core is formed by abutting the two divided magnetic cores can be reduced.
[0051]
The invention according to claim 11 of the present invention is particularly configured such that a slit is formed on the lower end flange of the divided magnetic core from the side surface of the lower end flange to the winding shaft portion, and a wire for leading the winding is drawn out of the slit. .
[0052]
With the above configuration, if the lead wire on the winding shaft side of the winding is drawn out through the slit formed in the flange at the lower end of the divided magnetic core, crossover between the winding and the drawing wire can be eliminated.
[0053]
The invention according to claim 12 of the present invention is, in particular, a mounting portion for mounting the bottom surface of the lower end flange on the lower end flange opposite to the plane portion of the two split magnetic cores, and the mounting portion is coupled with the mounting portion. A thick portion having a terminal for connecting a lead wire of a winding to a side surface opposite to the flat portion of the lower end flange, and a fixed wall coupled to the mounting portion and the thick portion and along the side surface of the lower end flange. And a terminal plate having the following.
[0054]
According to the above configuration, since the mounting portion and the thick portion are coupled to the terminal plate and the fixed plate is provided along the side surface of the lower end flange, the terminal plate can be easily positioned on the divided magnetic core. .
[0055]
In the invention according to claim 13 of the present invention, in particular, the mounting portion of one terminal plate and the fixed wall are provided from the flat portion of one of the divided magnetic cores to the outside, and the mounting portion of one terminal plate is provided on the other side. Is mounted.
[0056]
According to the above configuration, the positioning of the two divided cores can be easily performed only by placing the flange at the lower end of the other divided core on the terminal plate on which one of the cores is mounted.
[0057]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a transformer according to an embodiment of the present invention will be described with reference to the drawings.
[0058]
FIG. 1 is a sectional view of a transformer according to an embodiment of the present invention, FIG. 2 is a perspective view of the transformer, and FIG. 3 is an exploded perspective view of the transformer.
[0059]
1 to 3, a transformer according to an embodiment of the present invention includes a closed magnetic circuit core 32 in which two divided magnetic cores 31 are joined to form a closed magnetic circuit, and a winding in which a conductive wire with an insulating coating is wound around the divided magnetic cores 31. And a line 33.
[0060]
The two divided magnetic cores 31 are provided with flanges 35 at the upper and lower ends of the core portion 34 and form flat portions 36 on the side surfaces of the flange 35, and the outer periphery of the core portion 34 of one of the divided cores 31 is insulated. The input winding 37 is formed by winding the coated conductor about several turns, and the insulation-coated conductor thinner than the electric wire of the input winding 37 is wound around the winding shaft portion 34 of the other divided magnetic core 31 for about 1,000 turns. A closed magnetic circuit is formed by abutting the flat portions 36 of the two split magnetic cores 31, and the cross-sectional area C of the winding shaft portion 34 of the split magnetic core 31 around which the output winding 38 is wound is input. The sectional area A of the winding shaft portion 34 of the divided magnetic core 31 around which the winding 37 is wound is equal to or larger than A.
[0061]
Further, the sectional area B of the upper and lower flanges 35 of the two divided magnetic cores 31 has the same area, and the sectional area B of the upper and lower flanges 35 of the two divided magnetic cores 31 is the divided magnetic core 31 on which the input winding 37 is wound. Is larger than or equal to the cross-sectional area A of the winding shaft portion 34.
[0062]
The cross-sectional area C of the winding shaft portion 34 of the divided magnetic core 31 around which the output winding 38 is wound is greater than the cross-sectional area B of the upper and lower ends of the two divided magnetic cores 31.
[0063]
Further, the two divided cores 31 are formed by forming the divided core 31 around the input winding 37 with a Mn-based ferrite material, and forming the divided core 31 around the output winding 38 with a Ni-based ferrite material. An insulating layer 39 is provided in which the surface excluding the flat portion 36 is covered with an insulating resin (not shown) having a thickness of several tens of μm.
[0064]
Further, the cross-sectional shape of the winding shaft portion 34 of the two divided magnetic cores 31 is circular.
[0065]
A slit 40 is formed in the flange 35 at the lower end of the divided magnetic core 31 from the side surface of the flange 35 at the lower end to the winding shaft portion 34, and the lead wire 41 of the winding 33 is drawn out of the slit 40.
[0066]
The lower flange 35 on the opposite side of the flat portion 36 of the two divided magnetic cores 31 has a mounting portion 42 on which the bottom surface of the lower flange 35 is mounted, and a lower portion flange coupled with the mounting portion 42. A thick portion 44 having a terminal 43 for connecting the lead wire 41 of the winding 33 to a side surface opposite to the flat portion 36 of the mounting portion 35, and a flange 35 at the lower end which is coupled to the mounting portion 42 and the thick portion 44. A terminal plate 46 having a fixed wall 45 along the side surface of the terminal plate 46 is provided.
[0067]
The mounting portion 42 of one terminal plate 46 and the fixed wall 45 are provided outside the flat portion 36 of one of the divided magnetic cores 31, and the other divided magnetic core 31 is mounted on the mounting portion 42 of one of the terminal plates 46. The transformer is mounted on the transformer.
[0068]
The operation of the transformer of the present embodiment having the above configuration will be described below.
[0069]
In the transformer according to the present embodiment, the winding 33 is wound directly around the divided core 31 and the flat portion 36 of the divided core 31 is joined to form a closed magnetic path. The gap is eliminated, and the leakage inductance can be reduced.
[0070]
Since the cross-sectional area C of the core 34 of the divided magnetic core 31 around which the output winding 38 is wound is equal to or larger than the cross-sectional area A of the core 34 of the divided magnetic core 31 around which the input winding 37 is wound. The magnetic reluctance of the winding shaft portion 34 on which the input winding 37 is wound becomes smaller than that of the winding shaft portion 34 on which the wire 38 is wound, and the magnetic flux generated by the input winding 37 becomes the divided magnetic core 31 on which the output winding 38 is wound. The leakage inductance can be reduced.
[0071]
Furthermore, since the sectional areas B of the upper and lower flanges 35 at the upper and lower ends of the divided magnetic core 31 have the same area, the magnetic resistance of the upper and lower divided cores 31 can be balanced, and the magnetic flux leaks from either one of the flanges 35. And the leakage inductance can be reduced.
[0072]
Further, since the sectional area B of the upper and lower flanges 35 of the two divided magnetic cores 31 is set to be equal to or larger than the sectional area A of the core portion 34 of the divided magnetic core 31 around which the input winding 37 is wound, the input winding 37 is wound. The magnetic resistance of the flange 35 at the upper and lower ends is smaller than that of the rotated winding shaft portion 34, and the magnetic flux flowing from the winding shaft portion 34 around which the input winding 37 is wound to the upper and lower flanges 35 can be easily passed. When magnetic flux flows from the winding shaft portion 34 around which the wire 37 is wound to the flange 35 at the upper and lower ends, it is possible to suppress the leakage of the magnetic flux and reduce the leakage inductance.
[0073]
Since the cross-sectional area C of the core portion 34 of the divided magnetic core 31 around which the output winding 38 is wound is equal to or larger than the cross-sectional area B of the flange 35 at the upper and lower ends of the two divided magnetic cores 31, The magnetic resistance of the bobbin 34 around which the output winding 38 is wound from the end flange 35 can be reduced, and the bobbin 34 around which the output winding 38 is wound from the upper and lower flanges 35 of the bobbin 34. To prevent the magnetic flux from leaking when the magnetic flux flows from the upper and lower flanges 35 at the upper and lower ends of the winding shaft 34 to the winding shaft 34 around which the output winding 38 is wound. Can be reduced.
[0074]
Further, the split core 31 wound with the input winding 37 is formed of a Mn-based ferrite core with a small core loss, and the split core 31 wound with the output winding 38 is formed of a Ni-based ferrite material having a high insulation resistance. Therefore, an efficient transformer corresponding to a high voltage can be configured.
[0075]
At this time, the sectional area B of the flange 35 at the upper and lower ends of the divided magnetic core 31 and the sectional area C of the winding shaft portion 34 of the divided magnetic core 31 around which the output winding 38 is wound are divided by the divided magnetic core 31 around which the input winding 37 is wound. Is larger than the cross-sectional area A of the winding portion 34, it is possible to suppress an increase in leakage magnetic flux due to an increase in the magnetic resistance of the Ni-based ferrite core, and to prevent an increase in leakage inductance.
[0076]
Further, since the two divided cores 31 are provided with the insulating layer 39 whose surface except for the flat portion 36 is covered with an insulating resin, the insulation between the winding 33 and the divided cores 31 can be improved.
[0077]
And since the cross-sectional shape of the winding part 35 of the divided magnetic core 31 is circular, the stress applied to the conducting wire when winding the conducting wire around the winding part 34 can be reduced.
[0078]
Further, a slit 40 is formed in the flange 35 at the lower end of the divided magnetic core 31 from the side surface of the flange 35 at the lower end to the winding shaft portion 34, and the lead wire 41 of the winding 33 is drawn out from the slit 40. Crossover of the lead wire 41 can be eliminated, and dielectric breakdown between the output winding 38 and the lead wire 41 when a high voltage is generated in the output winding 38 can be prevented.
[0079]
Further, since the mounting portion 42 and the thick portion 44 are coupled to the terminal plate 46 and the fixed wall 45 is formed along the side surface of the lower end flange 35, the terminal plate 46 can be easily attached to the divided magnetic core 31. Can be positioned.
[0080]
Then, the mounting portion 42 of one terminal plate 46 and the fixed wall 45 are provided outside the flat portion 36 of the one divided magnetic core 31, and the other divided magnetic core 31 is mounted on the mounting portion 42 of the one terminal plate 46. The two divided magnetic cores 31 can be easily positioned simply by mounting the flange 35 at the lower end of the other divided magnetic core 31 on the terminal plate 46 on which the one divided magnetic core 31 is mounted. Can be.
[0081]
Next, an example of use of the transformer according to the embodiment of the present invention in a discharge lamp lighting device will be described with reference to the drawings.
[0082]
FIG. 4 is a block diagram of a discharge lamp lighting device using a transformer according to one embodiment of the present invention.
[0083]
In the figure, an oscillating unit 48 that switches between a first frequency 58 for starting the lighting of the discharge lamp 47 and a second frequency 59 for maintaining the lighting of the discharge lamp 47 to output a high-frequency pulse of a positive potential, And a drive unit 49 for converting the DC voltage + B according to the output of the oscillation unit 48 and alternately outputting a positive potential pulse and a negative potential pulse, and an input winding 37 and an output winding 38. A step-up transformer 50 for boosting the output of the drive unit 49 to a high voltage and outputting the same; a resonance capacitor 53 having one capacitive element 52 connected to both ends of an output winding 38 of the step-up transformer 50; And the discharge lamp 47 connected to both ends of the output winding 38 of the step-up transformer 50, and a control for detecting the current flowing through the discharge lamp 47 and switching the first frequency 58 and the second frequency 59 to the oscillation unit 48. Control to output signal And a 54.
[0084]
The transformer according to the present embodiment is used as a step-up transformer 50 in a discharge lamp lighting device, inputs an output from a driving unit 49 to an input winding 37, and turns the input winding 37 and an output winding 38 by a turns ratio. Is used as a so-called separately excited step-up transformer 50 that outputs a high voltage.
[0085]
When the transformer of the present embodiment is used for the step-up transformer 50 of the discharge lamp lighting device, the impedance frequency characteristic when viewed from the input winding 37 side is, as shown by a curve 55 in FIG. It has a resonance point 56 and a second resonance point 57.
[0086]
The first resonance point 56 is a resonance point due to the parallel resonance of the output winding 38 of the step-up transformer 50 and the resonance capacitor 53, and the second resonance point 57 is the leakage inductance and the resonance capacitance of the output winding 38 of the step-up transformer 50. , The impedance decreases from the first resonance point to the second resonance point.
[0087]
Next, the operation of the discharge lamp lighting device will be described with reference to a waveform diagram of a main part of the discharge lamp lighting device using the transformer according to the present embodiment in FIG.
[0088]
6A is an output waveform diagram of the oscillation unit at the first frequency, FIG. 6B is an output waveform diagram of the driving unit at the first frequency of the oscillation unit, and FIG. FIG. 7 is an output waveform diagram of the step-up transformer at the frequency of FIG.
[0089]
6, when the discharge lamp 47 starts to be lit, the oscillating unit 48 outputs a positive potential pulse having a first frequency 58 as shown in FIG.
[0090]
Since the first frequency 58 supplies a large amount of power from the driving unit 49 to the boosting transformer 50 at the start of lighting of the discharge lamp 47, the impedance of the boosting transformer 50 becomes smaller than the impedance of the driving unit 49. As described above, the frequency is set in advance to a frequency close to the second resonance point 57 of the curve 55 shown in FIG.
[0091]
Then, as shown in FIG. 6B, the driving unit 49 converts the DC voltage + B according to the output of the oscillation unit 48 and outputs an alternating pulse waveform of a positive potential and a negative potential.
[0092]
The output waveform of the step-up transformer 50 to which the output of the drive unit 49 is input is an AC high voltage distorted from a pulse waveform to a substantially sinusoidal waveform due to the winding distribution capacitance of the step-up transformer 50 as shown in FIG. The output is applied and a high voltage is applied to the discharge lamp 47 so that the discharge lamp 47 is turned on.
[0093]
Next, the operation of the discharge lamp lighting device after the discharge lamp starts lighting will be described with reference to the output waveform diagram of the second frequency of the oscillating unit in FIG. 6D and the second frequency of the oscillating unit in FIG. This will be described with reference to the output waveform diagram of the drive unit and the output waveform diagram of the boosting transformer at the second frequency of the oscillation unit in FIG.
[0094]
When the discharge lamp 47 is turned on, the control unit 54 detects the current flowing through the discharge lamp 47 and outputs a control signal to the oscillation unit 48. The oscillation unit 48 responds to the control signal from the control unit 54 as shown in FIG. As shown in ()), the oscillation frequency is switched from the first frequency 58 to the second frequency 59 and output.
[0095]
When the discharge lamp 47 is turned on, the second frequency 59 does not require a large amount of power at the start of lighting because the discharge lamp 47 has a negative characteristic. In order to reduce the power supply to the transformer 50, the frequency is set in advance to a frequency close to the first resonance point 56 of the curve 55 in FIG.
[0096]
6 (e), the driving unit 49 converts the DC voltage + B according to the output of the second frequency 59 of the oscillating unit 48 into a positive voltage as in the case of starting the lighting of the discharge lamp 47. The output of the step-up transformer 50, which has been converted into an alternate pulse waveform of a potential and a negative potential, and the output of the drive unit 49 has been input, depends on the winding distribution capacitance of the step-up transformer 50 as shown in FIG. The output is output at a high AC voltage distorted from a pulse waveform to a substantially sine waveform, and a high voltage is applied to the discharge lamp 47 to maintain the lighting of the discharge lamp 47.
[0097]
Since the discharge lamp lighting device using the transformer of the present embodiment can reduce the leakage inductance of the transformer of the present embodiment, as shown by a curve 55 in FIG. The resonance frequency of the second resonance point 57 increases, and the width between the first frequency 58 and the second frequency 59 can be increased.
[0098]
In addition, it is possible to eliminate a case where a plurality of capacitance elements are connected in series to reduce the resonance capacitance.
[0099]
Since the width of the first frequency 58 and the second frequency 59 can be increased, it is possible to suppress the first frequency 58 and the second frequency 59 of the oscillation frequency of the oscillation unit 48 from being limited. Therefore, it is possible to reduce the variation in the oscillation frequency.
[0100]
Further, the frequency width between the first resonance point 56 and the second resonance point 57 is widened, and the amount of change in the impedance of the step-up transformer 50 with respect to the frequency from the first resonance point 56 to the second resonance point 57, that is, the impedance Since the slope of the change is gentle, the amount of change in the impedance of the step-up transformer 50 with respect to the width of the variation in the oscillation frequency of the oscillation unit 48 can be reduced, and the influence of the variation in the impedance in the manufacture of the step-up transformer 50 can be reduced. By reducing the size, the power supplied to the discharge lamp 47 can be controlled more accurately.
[0101]
Further, it is possible to eliminate a complicated operation such as connecting a plurality of capacitance elements in series to reduce the resonance capacitance.
[0102]
As described above, in the transformer according to the embodiment of the present invention, the winding 33 is directly wound around the divided core 31 and the flat portion 36 of the divided core 31 is abutted to form a closed magnetic circuit. There is no space between the core and the split magnetic core 31, and the leakage inductance can be suppressed.
[0103]
Further, since the cross-sectional area C of the core 34 of the divided core 31 around which the output winding 38 is wound is equal to or larger than the cross-sectional area A of the core 34 of the divided core 31 around which the input winding 37 is wound, The magnetic resistance of the winding shaft portion 34 on which the output winding 38 is wound becomes smaller than that of the winding shaft portion 34 on which the wire 37 is wound, and the magnetic flux generated by the input winding 37 is divided by the divided magnetic core 31 around which the output winding 38 is wound. The leakage inductance can be further reduced.
[0104]
In the present embodiment, a configuration in which one of the two divided cores 31 is formed of a Mn-based ferrite material and the other divided core 31 is formed of a Ni-based ferrite material has been described. It may be formed of a Mn-based ferrite material, and since the Mn-based ferrite material has a small core loss, an efficient transformer can be formed.
[0105]
Further, the two split cores may be formed of a Ni-based ferrite material. Since the Ni-based ferrite material has a high insulation resistance, the voltage input to the winding 33 or the voltage output from the winding 33 is a high voltage. Even in this case, a high-voltage transformer can be configured without impairing the insulation between the winding 33 and the split magnetic core 31.
[0106]
In the present embodiment, the configuration in which the cross-sectional shape of the winding part 34 of the divided magnetic core 31 is circular is described, but another example of the shape of the winding part of the transformer in the embodiment of the present invention in FIG. 7 is shown. As shown in the plan view, when the cross-sectional shape of the winding shaft portion 34 is a flat shape, the bottom area when the two divided magnetic cores 31 are butted to form a closed magnetic circuit core can be reduced.
[0107]
【The invention's effect】
As described above, according to the present invention, the two split magnetic cores are provided with flanges at the upper and lower ends of the winding shaft portion and form flat portions on the side surfaces of the flange, and the input is applied to the outer periphery of the winding shaft portion of one split magnetic core. The output winding is wound around the winding part of the other divided core while winding the winding, and the flat part of the two divided cores is joined to form a closed magnetic circuit, and the output winding is wound. In this configuration, the sectional area of the core portion of the divided core is equal to or larger than the sectional area of the core portion of the divided core wound with the input winding.
[0108]
As a result, the distance between the split core and the winding is eliminated, so that the leakage magnetic flux can be reduced, and the magnetic flux generated by the input winding can easily pass through the split core around which the output winding is wound, thereby reducing the leakage inductance. Thus, it is possible to provide a transformer in which the leakage inductance is suppressed and the degree of freedom in designing the discharge lamp lighting device is increased.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a transformer according to an embodiment of the present invention.
FIG. 2 is a perspective view of the transformer.
FIG. 3 is an exploded perspective view of the transformer.
FIG. 4 is a block diagram of a discharge lamp lighting device using the transformer.
FIG. 5 is an impedance frequency characteristic diagram of an input winding side of a transformer of the discharge lamp lighting device.
FIG. 6 is a waveform diagram of a main part of the discharge lamp lighting device.
FIG. 7 is a plan view showing another example of the shape of the winding shaft of the transformer according to the embodiment of the present invention;
FIG. 8 is a sectional view of a conventional transformer.
FIG. 9 is a perspective view of a conventional transformer.
FIG. 10 is a block diagram of a discharge lamp lighting device using the transformer.
FIG. 11 is an impedance frequency characteristic diagram on the input winding side of a transformer of the discharge lamp lighting device.
FIG. 12 is a waveform diagram of a main part of the discharge lamp lighting device.
[Explanation of symbols]
31 split core
32 closed magnetic core
33 winding
34 reel
35 Tsuba
36 flat part
37 Input winding
38 output winding
39 Insulation layer
40 slits
41 Leader
42 Mounting part
43 terminals
44 Thick part
45 Fixed wall
46 Terminal board

Claims

A closed magnetic path core in which a closed magnetic path is formed by abutting two divided magnetic cores, and a winding in which a conductive wire with an insulating coating is wound around the divided magnetic core, and the two divided cores are provided with flanges at upper and lower ends of a winding shaft portion. A flat portion is formed on the side surface of the flange, and an input winding is wound around the outer periphery of a winding shaft portion of one of the divided magnetic cores, and an output winding is wound around the winding shaft portion of the other divided magnetic core. A closed magnetic path is formed by abutting the flat portions of the two divided cores, and the cross-sectional area of a core portion of the divided core wound with the output winding is divided by the input winding. Transformer with a core area larger than the cross-sectional area of the core.

2. The transformer according to claim 1, wherein the sectional areas of the upper and lower flanges of the two divided magnetic cores have the same area.

2. The transformer according to claim 1, wherein a cross-sectional area of upper and lower flanges of the two divided cores is equal to or larger than a cross-sectional area of a winding shaft portion of the divided core around which the input winding is wound. 3.

2. The transformer according to claim 1, wherein a cross-sectional area of a winding shaft portion of the divided magnetic core around which the output winding is wound is equal to or greater than a cross-sectional area of upper and lower ends of two divided magnetic cores. 3.

2. The transformer according to claim 1, wherein the two split cores are formed of a Mn-based ferrite material.

2. The transformer according to claim 1, wherein the two split cores are formed of a Ni-based ferrite material.

2. The transformer according to claim 1, wherein the two split cores are formed by using one of the split cores with a Mn-based ferrite material and the other split core with a Ni-based ferrite material. 3.

2. The transformer according to claim 1, wherein at least one of the two divided magnetic cores is provided with an insulating layer covered with an insulating resin except for a plane portion.

2. The transformer according to claim 1, wherein at least one of the two divided cores has a circular cross section of the winding shaft.

2. The transformer according to claim 1, wherein at least one of the two divided magnetic cores has a flat cross-sectional shape of a winding shaft portion.

2. The transformer according to claim 1, wherein a slit is formed in a flange at a lower end of the divided magnetic core from a side surface of the flange at the lower end to a winding shaft portion, and a lead wire of a winding is drawn from the slit.

A mounting portion for mounting the bottom surface of the lower flange on the lower end flange opposite to the flat portion of the two divided magnetic cores, and a mounting portion coupled to the mounting portion and wound on a side surface opposite to the flat portion of the lower end flange. A terminal plate having a thick portion having a terminal for connecting a lead line of the wire, and a fixed wall coupled to the placing portion and the thick portion and along a side surface of the lower end flange is provided. The transformer according to claim 1.

The mounting part of one terminal board and the fixed wall are provided from the plane part of one of the divided cores to the outside, and the other divided core is mounted on the mounting part of one of the terminal boards. Transformer.