JP3655686B2

JP3655686B2 - Noble gas discharge lamp and document irradiation device

Info

Publication number: JP3655686B2
Application number: JP01408196A
Authority: JP
Inventors: 一也伊藤
Original assignee: Ushio Denki KK; NEC Lighting Ltd
Current assignee: Ushio Denki KK; Hotalux Ltd
Priority date: 1996-01-30
Filing date: 1996-01-30
Publication date: 2005-06-02
Anticipated expiration: 2016-01-30
Also published as: JPH09213281A

Description

【０００１】
【発明の属する技術分野】
この発明は希ガス放電灯及び原稿照射装置に関し、特にファクシミリ，イメ−ジスキャナ，コピ−機などのＯＡ機器における原稿照射装置に適用される希ガス放電灯の軸方向の光特性及び原稿照射装置の読み取り精度の改良に関する。
【０００２】
【従来の技術】
一般に、原稿照射装置は、例えば図１４に示すように、放電灯１からの放射光を原稿面Ｐに照射し、原稿面Ｐからの反射光をＣＣＤ素子よりなるラインセンサ−Ｓにて受光するように構成されている。
【０００３】
この装置に適用される放電灯としては、装置の稼働態勢に応じて直ちに点灯し、かつその光量も極めて短時間に所定の光量以上例えば１００％程度にまで達することが要求されており、図１５〜図１６（図１５の展開図）に示す希ガス放電灯が提案されている。
【０００４】
同図において、希ガス放電灯１は、両端が封止され、管径が例えば５〜１０ｍｍ程度の直管形のガラスバルブよりなる外囲器２と、この外囲器２の内面に例えば開口部（アパ−チャ部２ａ）を有するように形成された蛍光体よりなる発光層３と、外囲器２の外周面に、それの長手方向に沿って適宜の間隔を保って形成された一対の帯状の外部電極４，５とから構成されており、外囲器内の密閉空間には例えばキセノンガスを主成分とする希ガスが封入されている。尚、外囲器２はガラスバルブの他、セラミックスなどにて形成することもできるし、又、希ガスはキセノンの他、クリプトン，ネオン，ヘリウムなども使用できるし、これらを適宜に混合することもできる。
【０００５】
この希ガス放電灯１は、例えば図１７に示す点灯装置によって点灯される。この点灯装置は、例えば直流電源Ｅと、一般的なインバ−タ回路ＩＮＶと、直流電源Ｅとインバ−タ回路ＩＮＶの一次側との間に接続された第１のスイッチング手段例えばトランジスタＳＷ１と、インバ−タ回路ＩＮＶの二次側に接続された希ガス放電灯１と、トランジスタＳＷ１のベ−スとグランドとの間に抵抗を介して接続された第２のスイッチング手段例えばトランジスタＳＷ２と、このトランジスタＳＷ２のベ−スにクロック信号を供給するクロック発生部ＣＧと、クロック発生部ＣＧからのクロック信号のデュ−ティ比を変更するための可変抵抗器ＶＲとから構成されている。例えばクロック信号のデュ−ティ比が１００％の場合にはトランジスタＳＷ１が連続的に導通状態となって図１８ａに示す高周波電圧が、又、デュ−ティ比が１００％以下になると、そのデュ−ティ比に応じて間欠的に導通状態となって図１８ｂに示す高周波電圧がそれぞれ希ガス放電灯１の外部電極４，５に印加される。
【０００６】
そして、同点灯装置において、例えば周波数が２８０Ｈｚのクロック信号のデュ−ティ比を１００％に設定すると、トランジスタＳＷ１は連続的な導通状態となり、インバ−タ回路ＩＮＶからは図１８ａに示すような高周波高電圧（例えば２８ＫＨｚで２７００Ｖｏ−ｐ）が出力され、外部電極４，５に印加される。すると、外部電極４，５の軸方向の全体に亘って、外囲器内にキセノンガスの放電が生じる。発光層３は、この放電に基づくキセノンガスの励起線によって刺激されて発光する。この光は、主として外部電極４，５の間の光放出部（アパ−チャ部）２ａから放出される。又、例えばクロック信号のデュ−ティ比を１００％以下に設定すると、トランジスタＳＷ１は間欠的な導通状態となり、インバ−タ回路ＩＮＶからは図１８ｂに示すような高周波高電圧が出力され、光放出部２ａから放出される光量はデュ−ティ比に応じて減少（調光）される。
【０００７】
特に、この希ガス放電灯１には水銀が用いられていないために、上述のいずれの点灯態様であっても、点灯後における光量の立ち上がりが急峻であり、ほぼ点灯と同時に光量が設定値近くにまで達するという特徴を有している。従って、この希ガス放電灯１を図１４に示す原稿照射装置に適用した場合には、原稿の読み取り品位を高めることができるものである。
【０００８】
【発明が解決しようとする課題】
ところで、ＯＡ機器における原稿の読み取り品位は、例えば原稿面Ｐの照度に影響され、照度が高いほど読み取り精度が高くなることから、極力、希ガス放電灯１の光量を増加することが求められている。
【０００９】
この希ガス放電灯１においては、希ガスの封入圧力を高くすることによって光量を増加させることができるものの、あまり高くすると、光にチラツキが発生して逆に原稿の読み取り精度が損なわれるようになる。
【００１０】
このチラツキ現象は、希ガスの封入圧力が高くなることによって、外部電極４，５間に縞状の放電が視認されるようになり、しかも、放電が軸方向にランダムに移動するために生ずるものと推測される。
【００１１】
しかしながら、図１４に示す原稿照射装置においては、希ガス放電灯１を点灯してから例えば２秒後における照度分布（軸方向の配光パタ−ン）が記憶され、同一の配光パタ−ンで光量のレベルに変動が生じた場合には記憶デ−タに基づいて補正が行なわれる関係で、原稿の読み取り品位を高精度に維持することができるものの、上述のように、光のチラツキによって配光パタ−ンが軸方向で局部的に崩れたり，短い周期で崩れたり，或いは光量の変動が大きくなったりした場合には、最早、記憶デ−タに基づく補正が不可能となり、原稿の読み取り精度も損なわれることになる。
【００１２】
特に、光のチラツキは放電電流，外部電極に印加される電圧などに影響されることから、例えばクロック発生部ＣＧからのクロック信号のデュ−ティ比が小さくなるほど、換言すれば、調光率が大きく（光量が小さく）なるほど放電電流が減少する。このために、放電の生成部位が不安定となり、光のチラツキが顕著に現われる結果、原稿の読み取り精度も一層に損なわれるという問題がある。
【００１３】
それ故に、本発明の目的は、簡単な構成によって外部電極間に安定した放電を生成でき、光のチラツキを効果的に抑制できる上、原稿の読み取り品位を改善し得る希ガス放電灯及び原稿照射装置を提供することにある。
【００１４】
【課題を解決するための手段】
従って、本発明は、上述の目的を達成するために、内面に発光層を有する外囲器の外周面に一対の帯状の外部電極を離隔して配置し、かつ外囲器内に希ガスを封入してなり、前記一対の帯状の外部電極双方の対向したいずれかの側縁部に、前記外部電極の軸方向に延在する、三角形状，台形状を含む矩形状，半円形状のいずれかの形状であって、ほぼ全長に亘って所定のピッチで設定した異形部が形成されていることを特徴とする。
【００１５】
又、本発明の第２の発明は、内面に発光層を有する外囲器の外周面に一対の帯状の外部電極を離隔して配置し、外囲器内に希ガスを封入してなり、前記一対の外部電極におけるそれぞれの側縁部であって、前記外部電極の軸方向に延在する、三角形状，台形状を含む矩形状，半円形状のいずれかの形状であって、ほぼ全長に亘って所定のピッチで設定した異形部が形成されていることを特徴とする。
【００１６】
さらに、本発明の第３の発明は、内面に発光層を有する外囲器の外周面に一対の帯状の外部電極を離隔して配置し、かつ外囲器内に希ガスを封入してなる希ガス放電灯からの放射光を原稿面に照射し、反射光をセンサにて受光する原稿照射装置において、前記一対の帯状の外部電極双方の対向したいずれかの側縁部に、前記外部電極の軸方向に延在する、三角形状，台形状を含む矩形状，半円形状のいずれかの形状であって、ほぼ全長に亘って所定のピッチで設定した異形部が形成されていることを特徴とする。
【００１７】
【発明の実施の形態】
次に、本発明の第１の実施例について図１〜図３を参照して説明する。尚、図１５〜図１６に示す従来例と同一部分には同一の参照符号を付し、その詳細な説明は省略する。本実施例の特徴部分は、希ガス放電灯１の外周面に配置した一対の外部電極４，５におけるそれぞれの側縁部４ａ，４ｂ，５ａ，５ｂにほぼ全長に亘って周期性を有する三角形状の異形部６を形成したことである。特に、外部電極４，５は外囲器２の外周面に、対向するそれぞれの異形部６が最短距離となるように配置することが望ましい。
【００１８】
この外部電極４，５における三角形状の異形部６は、外囲器２としてのガラスバルブの外径が例えば８ｍｍの場合には幅が８ｍｍ，異形部６のピッチが４ｍｍ，異形部６の高さが１．５ｍｍ程度の寸法に設定することが望ましいが、希ガス放電灯，点灯装置の仕様によっては適宜に変更できる。
【００１９】
又、この外部電極４，５は、例えばアルミニウム，銅，銀などのように導電性に優れ、かつ不透光性の金属部材にて構成されており、特に、ガラスバルブに接する側の面に光反射性を付与することが望ましい。これら外部電極の一方の面には、接着層などが形成されており、ガラスバルブ２の外周面にはこの接着層を利用して固定・配置されている。
【００２０】
この実施例によれば、外部電極４，５のそれぞれの側縁部４ａ，４ｂ，５ａ，５ｂには周期性を有する三角形状の異形部６が形成されているために、例えば図１７に示す点灯装置で始動させる際に、異形部６の先端部分の電位傾度が他の部分より高くなり、放電が安定に生成される上、その生成部位も安定化される。従って、動作状態における光のチラツキを効果的に抑制できる。このために、原稿照射装置での補正操作を最小限に抑えることができ、十分の読み取り精度を得ることができる。
【００２１】
又、従来の電極構造では光量を増加させるために希ガスの封入圧を高く設定すると、縞状の放電が視認されるようになって原稿照射装置の読み取り精度が損なわれるという問題があったが、この実施例では、そのような封入圧に設定しても、視認し得るような縞状の放電の発生はなく、チラツキも発生しない。このために、希ガスの封入圧を高く設定できた分だけ、希ガス放電灯の光量を効果的に増加でき、原稿照射装置の読み取り精度をより一層高めることができる。
【００２２】
図４は、本発明の第２の実施例を示すものであって、光放出部２ａ側における外部電極４，５の側縁部４ａ，５ａは互いに平行な直線状に形成されており、非光放出部側の側縁部４ｂ，５ｂは周期性を有する三角形状の異形部６がほぼ全長に亘って形成されている。尚、異形部６と直線部との形成部位は、互いに入れ替えることもできる。
【００２３】
この実施例によれば、第１の実施例と同様に縞状の放電に基づく光のチラツキを効果的に抑制できるものの、調光状態においては、チラツキを抑制できる点灯条件の幅が若干狭くなる傾向にある。
【００２４】
特に、外部電極４，５の一方の側縁部４ａ，５ａは直線状に形成されているために、その直線部を利用して、それぞれの外部電極を外囲器２の外周面に平行状態となるように容易に配置することができる。
【００２５】
図５〜図６は、本発明の第３の実施例を示すものであって、外部電極４，５におけるそれぞれの側縁部４ａ，４ｂ，５ａ，５ｂにはほぼ全長に亘って周期性を有する矩形状の異形部６Ａが形成されている。特に、外部電極４，５は外囲器２の外周面に、対向するそれぞれの異形部６Ａが最短距離となるように配置することが望ましい。尚、この異形部６Ａは、先端部の幅が狭くなる台形状も含むものであり、むしろ台形状に形成することが望ましい。
【００２６】
この外部電極４，５における矩形状の異形部６Ａは、外囲器２としてのガラスバルブの外径が例えば８ｍｍの場合には幅が８ｍｍ，異形部６Ａのピッチが４ｍｍ，異形部６Ａの高さが１．５ｍｍ程度の寸法に設定することが望ましいが、希ガス放電灯，点灯装置の仕様によっては適宜に変更できる。
【００２７】
この実施例によれば、第１の実施例とほぼ同様に光のチラツキを効果的に抑制することができる。
【００２８】
図７〜図８は、本発明の第４の実施例を示すものであって、基本的には図５〜図６に示す実施例と同様である。異なる点は、光放出部２ａ側における外部電極４，５の側縁部４ａ，５ａのみを互いに平行な直線状に形成したことである。尚、異形部６Ａと直線部との形成部位は、側縁部４ａ，５ａに異形部６Ａを、側縁部４ｂ，５ｂに直線部をそれぞれ形成するように互いに入れ替えることもできる。
【００２９】
この実施例によれば、第２の実施例と同様に光のチラツキを効果的に抑制できる上、それぞれの外部電極を外囲器２の外周面に、直線部を利用して容易に平行状態となるように配置することができる。
【００３０】
図９は、本発明の第５の実施例を示すものであって、外部電極４，５におけるそれぞれの側縁部４ａ，４ｂ，５ａ，５ｂにはほぼ全長に亘って周期性を有する半円形状の異形部６Ｂが形成されている。特に、外部電極４，５は外囲器２の外周面に、対向するそれぞれの異形部６Ｂが最短距離となるように配置することが望ましい。尚、この異形部６Ｂは、扁平状の半円形状も含むものである。
【００３１】
この外部電極４，５における矩形状の異形部６Ｂは、外囲器２としてのガラスバルブの外径が例えば８ｍｍの場合には幅が８ｍｍ，異形部６Ｂのピッチが４ｍｍ，異形部６Ｂの高さが１．５ｍｍ程度の寸法に設定することが望ましいが、希ガス放電灯，点灯回路の仕様によっては適宜に変更できる。
【００３２】
この実施例によれば、第１の実施例とほぼ同様に光のチラツキを効果的に抑制することができる。
【００３３】
図１０は、本発明の第６の実施例を示すものであって、基本的には図９に示す実施例と同様である。異なる点は、光放出部２ａ側における外部電極４，５の側縁部４ａ，５ａのみを互いに平行な直線状に形成したことである。尚、異形部６Ｂと直線部との形成部位は、側縁部４ａ，５ａに異形部６Ｂを、側縁部４ｂ，５ｂに直線部をそれぞれ形成するように互いに入れ替えることもできる。
【００３４】
この実施例によれば、第２の実施例と同様に光のチラツキを効果的に抑制できる上、それぞれの外部電極を外囲器２の外周面に、直線部を利用して容易に平行状態となるように配置することができる。
【００３５】
図１１は、本発明の第７の実施例を示すものであって、図１〜図３に示す希ガス放電灯１を原稿照射装置に適用したものである。希ガス放電灯１は、それの光放出部２ａから放出される光が原稿面Ｐに照射され、原稿面Ｐからの反射光がＣＣＤ素子などよりなるラインセンサ−Ｓにて受光されるように構成・配置されている。尚、この原稿照射装置には、第２〜第６の実施例に示す希ガス放電灯を適宜に適用することもできる。
【００３６】
この実施例によれば、外部電極４，５のそれぞれの側縁部４ａ，４ｂ，５ａ，５ｂには周期性を有する三角形状の異形部６が形成されているために、例えば図１７に示す点灯回路で始動させる際に、異形部６の先端部分の電位傾度が他の部分より高くなり、放電が安定に生成される上、その生成部位も安定化される。従って、動作状態における光のチラツキを効果的に抑制できる。このために、原稿照射装置での補正操作を最小限に抑えることができ、読み取り精度を高めることができる。
【００３７】
特に、希ガス放電灯１における希ガスの封入圧を、光のチラツキが発生しない程度に高くすれば、その分だけ光量を増加させることができ、読み取り品位をさらに高精度化し得る。
【００３８】
尚、本発明は、何ら上記実施例にのみ制約されることなく、例えば外部電極の異形部はそれぞれの外部電極の一方又は両方の側縁部に形成する他、いずれかの外部電極の少なくとも一つの側縁部に形成することもできる。又、外部電極を外囲器の外周面に配置するに当たって、予め透光性シ−トに所望形状の外部電極を相互に離隔するように貼着しておけば、外部電極の外囲器への貼り付け作業を能率化できる。又、外囲器内の発光層はアパ−チャ−部が形成されるように形成する他、内面全体に形成することもできるし、或いは光反射層と組合せることもできる。さらに、希ガス放電灯は、その外面を例えば熱収縮性を有する絶縁部材などにて被覆することもできる。
【００３９】
【実施例】
次に、第１の実験例について説明する。図１〜図３に示す希ガス放電灯１において、外径が８ｍｍ，全長が３００ｍｍの鉛ガラスよりなるガラスバルブ２の外周面に、両側縁部に周期性を有する三角形状の異形部６を形成し、かつ異形部６の幅が８ｍｍ，異形部６のピッチが４ｍｍ，異形部６の高さが１．５ｍｍに設定されたアルミニウム箔よりなる一対の外部電極４，５をほぼ全長に亘って接着する。尚、この希ガス放電灯における発光層には白色発光する三波長形の蛍光体が使用されており、又、キセノンガスの封入圧は７０トル及び８０トルに設定されている。
【００４０】
この希ガス放電灯の光放出部２ａの法線方向に８ｍｍ離隔した位置に照度計を配置し、図１７に示す点灯装置を使用して定格動作させて光特性を測定したところ、いずれの封入圧のものにも縞状の放電は視認できず、光のチラツキも観測できなかった。又、光放出部２ａの中央部分の初期照度は封入圧が７０トルのものが１００００（Ｌｘ）、８０トルのものが１２０００（Ｌｘ）であった。しかしながら、外部電極の幅が全長に亘って８ｍｍで、キセノンガスの封入圧が７０トル及び８０トルに設定された図１５〜図１６に示す構造の従来例の照度は、本発明品と同様であったが、封入圧が８０トルのものは定格電圧ではチラツキが発生し、２８２０Ｖ程度にまで電圧を高めなければチラツキの発生を抑えることができなかった。
【００４１】
次に、第２の実験例について説明する。キセノンガスの封入圧が７０トルで、外径が８ｍｍ，全長が１８０ｍｍの鉛ガラスよりなるガラスバルブ２の外周面に、図１〜図３，図４，図１５〜図１６に示す形状の外部電極を配置し、図１７に示す点灯装置にて定格（２７００Ｖｏ−ｐ）にて点灯させ、定格電圧を徐々に下げていき、光のチラツキが発生する電圧を測定したところ、図１２に示す結果が得られた。
【００４２】
図１２
同図から明らかなように、本発明品はいずれも従来例に比べて光のチラツキ発生電圧が低くなっている。このために、電源電圧に大幅な変動があっても、光のチラツキ発生を抑えることができ、原稿照射装置における読み取り品位を高く維持できる。
【００４３】
次に、第３の実験例について説明する。第２の実験例に使用した希ガス放電灯を、インバ−タ回路ＩＮＶの出力電圧が２７００Ｖ，発振周波数が２８ＫＨｚに、クロック発生部ＣＧのクロック信号の周波数が２８０Ｈｚにそれぞれ設定された図１７に示す点灯装置に組み合わせ、可変抵抗ＶＲを調整することによりクロック信号のデュ−ティ比を１００％〜１０％までの範囲で変化させてＰＷＭ（ＰｈａｓｅＷｉｄｔｈＭｏｄｕｌａｔｉｏｎ）調光し、光のチラツキの発生状況を観察したところ、図１３に示す結果が得られた。尚、インバ−タ回路の出力電圧は一定である。
【００４４】
図１３
同図から明らかなように、本発明１及び本発明２はいずれもデュ−ティ比が２０％までチラツキの発生は認められなかったが、１０％で非ハ−ネス側（各外部電極の端部に接続されたリ−ド線の非接続側）にチラツキの発生が認められた。しかしながら、従来例ではデュ−ティ比が４０％で非ハ−ネス側にチラツキが発生し、２０％でガラスバルブ全体にチラツキが拡大した。従って、本発明では調光率が広い範囲でも原稿照射装置への適用が可能であるが、従来例ではその使用範囲がかなり制約されるという不利がある。
【００４５】
【発明の効果】
以上のように、本発明によれば、一対の外部電極双方の対向したいずれかの側縁部には電位傾度が局部的に高くなるような、外部電極の軸方向に延在する三角形状，台形状を含む矩形状，半円形状のいずれかの形状であって、ほぼ全長に亘って所定のピッチで設定した異形部を形成したことされているために、放電の生成部位が安定化する。特に、異形部を周期性を有する三角形状，台形状を含む矩形状，半円形状などの形状に構成すると共に、外部電極のほぼ全長に亘って形成したことにより、光のチラツキ発生を効果的に抑制でき、原稿照射装置での読み取り精度を高めることができる。
【００４６】
又、外部電極の適宜の軸方向に延在する側縁部には三角形状，台形状を含む矩形状，半円形状のいずれかの形状であって、ほぼ全長に亘って所定のピッチで設定した異形部が形成されているために、希ガスの封入圧を高く設定しても、縞状の放電に起因するチラツキは発生しない。従って、希ガス放電灯の光量を効果的に増加でき、原稿照射装置の読み取り精度をより一層高めることができる。
【００４７】
さらには、外部電極のいずれかの軸方向に延在する側縁部には三角形状，台形状を含む矩形状，半円形状のいずれかの形状であって、ほぼ全長に亘って所定のピッチで設定した異形部が形成されているために、放電が安定に生成される。従って、放電電流が大幅に減少するような調光範囲でもチラツキが発生しない安定した放電を維持できる。
【図面の簡単な説明】
【図１】本発明の第１の実施例を示す側面図。
【図２】図１の中央部分における縦断面図。
【図３】図１の展開図。
【図４】本発明の第２の実施例を示す側面図。
【図５】本発明の第３の実施例を示す側面図。
【図６】図５の展開図。
【図７】本発明の第４の実施例を示す側面図。
【図８】図７の展開図。
【図９】本発明の第５の実施例を示す側面図。
【図１０】本発明の第６の実施例を示す側面図。
【図１１】本発明の第７の実施例を示す原稿照射装置の概略図。
【図１２】外部電極の構造とチラツキ発生電圧との関係を示す図。
【図１３】クロック信号のデュ−ティ比とチラツキ発生状況との関係を示す図。
【図１４】従来の原稿照射装置の概略図。
【図１５】従来の原稿照射装置に使用される放電灯の断面図。
【図１６】図１５の展開図。
【図１７】点灯装置の電気回路図。
【図１８】図１７に示すインバ−タ回路の出力電圧の波形図であって、（ａ）はクロック信号のデュ−ティ比が１００％のときの出力波形図、（ｂ）はデュ−ティ比が１００％未満のときの出力波形図。
【符号の説明】
１希ガス放電灯
２外囲器（ガラスバルブ）
２ａ光放出部
３発光層
４，５外部電極
４ａ，５ａ，４ｂ，５ｂ側縁部
６，６Ａ，６Ｂ異形部
Ｓセンサ−
Ｐ原稿面[0001]
BACKGROUND OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rare gas discharge lamp and an original irradiating apparatus, and more particularly to an axial optical characteristic of a rare gas discharge lamp applied to an original irradiating apparatus in office automation equipment such as a facsimile, an image scanner, and a copying machine. It relates to improvement of reading accuracy.
[0002]
[Prior art]
In general, as shown in FIG. 14, for example, the original irradiating apparatus irradiates the original surface P with the radiated light from the discharge lamp 1, and receives the reflected light from the original surface P with a line sensor-S comprising a CCD element. It is configured as follows.
[0003]
As a discharge lamp applied to this apparatus, it is required that the lamp is immediately turned on in accordance with the operating state of the apparatus, and the light quantity thereof reaches a predetermined light quantity or more, for example, to about 100% in an extremely short time. A rare gas discharge lamp shown in FIG. 16 (development of FIG. 15) has been proposed.
[0004]
In the figure, a rare gas discharge lamp 1 has an envelope 2 made of a straight tube-type glass bulb having both ends sealed and a tube diameter of, for example, about 5 to 10 mm, and an opening on the inner surface of the envelope 2. The light emitting layer 3 made of a phosphor formed so as to have a portion (aperture portion 2a) and a pair formed on the outer peripheral surface of the envelope 2 at an appropriate interval along the longitudinal direction thereof. A rare gas mainly composed of xenon gas, for example, is enclosed in a sealed space in the envelope. The envelope 2 can be formed of ceramics or the like in addition to a glass bulb, and the rare gas can be xenon, krypton, neon, helium, or the like, and these can be mixed appropriately. You can also.
[0005]
The rare gas discharge lamp 1 is turned on by, for example, a lighting device shown in FIG. The lighting device includes, for example, a DC power supply E, a general inverter circuit INV, and a first switching means, for example, a transistor SW1, connected between the DC power supply E and the primary side of the inverter circuit INV. A rare gas discharge lamp 1 connected to the secondary side of the inverter circuit INV, second switching means, for example, a transistor SW2, connected via a resistor between the base of the transistor SW1 and the ground, and this The clock generator CG supplies a clock signal to the base of the transistor SW2, and a variable resistor VR for changing the duty ratio of the clock signal from the clock generator CG. For example, when the duty ratio of the clock signal is 100%, the transistor SW1 is continuously turned on so that the high frequency voltage shown in FIG. 18a is reached, and when the duty ratio becomes 100% or less, the duty ratio is reduced. The high-frequency voltage shown in FIG. 18 b is intermittently applied according to the tee ratio and applied to the external electrodes 4 and 5 of the rare gas discharge lamp 1, respectively.
[0006]
In the same lighting device, for example, when the duty ratio of a clock signal having a frequency of 280 Hz is set to 100%, the transistor SW1 is in a continuous conduction state, and the inverter circuit INV has a high frequency as shown in FIG. 18a. A high voltage (for example, 2700 Vo-p at 28 KHz) is output and applied to the external electrodes 4 and 5. Then, a discharge of xenon gas occurs in the envelope over the entire axial direction of the external electrodes 4 and 5. The light emitting layer 3 emits light by being stimulated by the xenon gas excitation line based on this discharge. This light is mainly emitted from the light emission part (aperture part) 2 a between the external electrodes 4 and 5. For example, when the duty ratio of the clock signal is set to 100% or less, the transistor SW1 becomes intermittently conductive, and the inverter circuit INV outputs a high frequency high voltage as shown in FIG. The amount of light emitted from the section 2a is reduced (dimmed) according to the duty ratio.
[0007]
In particular, since no mercury is used in the rare gas discharge lamp 1, the rise of the amount of light after lighting is steep even in any of the above-described lighting modes, and the amount of light is close to the set value almost simultaneously with lighting. It has the feature of reaching up to. Therefore, when this rare gas discharge lamp 1 is applied to the document irradiation apparatus shown in FIG. 14, the reading quality of the document can be improved.
[0008]
[Problems to be solved by the invention]
By the way, the reading quality of the original in the OA device is affected by, for example, the illuminance of the original surface P, and the higher the illuminance, the higher the reading accuracy. Therefore, it is required to increase the light quantity of the rare gas discharge lamp 1 as much as possible. Yes.
[0009]
In this rare gas discharge lamp 1, although the amount of light can be increased by increasing the sealing pressure of the rare gas, if it is too high, flickering occurs in the light, and conversely the reading accuracy of the document is impaired. Become.
[0010]
This flickering phenomenon is caused by the fact that the discharge of stripes is visually recognized between the external electrodes 4 and 5 due to the increase in the pressure of the rare gas, and the discharge moves randomly in the axial direction. It is guessed.
[0011]
However, in the document irradiation apparatus shown in FIG. 14, the illuminance distribution (axial light distribution pattern), for example, 2 seconds after the rare gas discharge lamp 1 is turned on is stored, and the same light distribution pattern is stored. If the light level varies, the correction is performed based on the stored data, so that the reading quality of the original can be maintained with high accuracy. However, as described above, If the light distribution pattern collapses locally in the axial direction, collapses in a short cycle, or changes in the amount of light increase, correction based on the stored data is no longer possible, and Reading accuracy is also impaired.
[0012]
In particular, since the flickering of light is affected by the discharge current, the voltage applied to the external electrode, and the like, for example, the smaller the duty ratio of the clock signal from the clock generation unit CG is, in other words, the dimming rate is The discharge current decreases as the value increases (the amount of light decreases). For this reason, there is a problem that the generation site of the discharge becomes unstable and the flickering of light appears remarkably, and as a result, the reading accuracy of the document is further impaired.
[0013]
Therefore, an object of the present invention is to generate a stable discharge between external electrodes with a simple configuration, effectively suppress flickering of light, and improve an original reading quality and an original irradiation. To provide an apparatus.
[0014]
[Means for Solving the Problems]
Therefore, in order to achieve the above-mentioned object, the present invention disposes a pair of strip-shaped external electrodes on the outer peripheral surface of an envelope having a light emitting layer on the inner surface, and introduces a rare gas into the envelope. Any one of a triangular shape, a rectangular shape including a trapezoidal shape, and a semicircular shape, which is enclosed and extends in the axial direction of the external electrode at any facing side edge of both the pair of strip-shaped external electrodes. It is the shape, Comprising: The odd-shaped part set by the predetermined pitch is formed over substantially full length, It is characterized by the above-mentioned.
[0015]
The second invention of the present invention comprises a pair of strip-shaped external electrodes spaced apart on the outer peripheral surface of the envelope having a light emitting layer on the inner surface, and a rare gas is enclosed in the envelope. Each side edge of the pair of external electrodes , extending in the axial direction of the external electrode, and having any one of a triangular shape, a rectangular shape including a trapezoidal shape, and a semicircular shape. wherein the profiled section which is set at a predetermined pitch is formed over the.
[0016]
Further, according to a third aspect of the present invention, a pair of strip-like external electrodes are arranged separately on the outer peripheral surface of an envelope having a light emitting layer on the inner surface, and a rare gas is enclosed in the envelope. In a document irradiating apparatus that irradiates a surface of a document with radiated light from a rare gas discharge lamp and receives reflected light with a sensor, the external electrode is disposed on one of the opposing side edges of the pair of strip-shaped external electrodes. A deformed portion extending in the axial direction is formed in a triangular shape, a rectangular shape including a trapezoidal shape, or a semicircular shape, and is set at a predetermined pitch over almost the entire length. Features.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Next, a first embodiment of the present invention will be described with reference to FIGS. The same parts as those of the conventional example shown in FIGS. 15 to 16 are denoted by the same reference numerals, and detailed description thereof is omitted. The characteristic part of the present embodiment is that the side edges 4a, 4b, 5a and 5b of the pair of external electrodes 4 and 5 arranged on the outer peripheral surface of the rare gas discharge lamp 1 have a periodicity over almost the entire length. That is, the deformed portion 6 is formed. In particular, the external electrodes 4 and 5 are desirably arranged on the outer peripheral surface of the envelope 2 so that the respective deformed portions 6 facing each other have the shortest distance.
[0018]
The triangular deformed portion 6 of the external electrodes 4 and 5 has a width of 8 mm when the outer diameter of the glass bulb as the envelope 2 is, for example, 8 mm, the pitch of the deformed portion 6 is 4 mm, and the height of the deformed portion 6 is high. Is preferably set to a dimension of about 1.5 mm, but can be appropriately changed depending on the specifications of the rare gas discharge lamp and the lighting device.
[0019]
In addition, the external electrodes 4 and 5 are made of a non-transparent metal member such as aluminum, copper, silver, etc., and are particularly formed on the surface in contact with the glass bulb. It is desirable to impart light reflectivity. An adhesive layer or the like is formed on one surface of these external electrodes, and is fixed and arranged on the outer peripheral surface of the glass bulb 2 using this adhesive layer.
[0020]
According to this embodiment, the side edge portions 4a, 4b, 5a and 5b of the external electrodes 4 and 5 are formed with the triangular shaped deformed portion 6 having periodicity. When starting with the lighting device, the potential gradient of the tip portion of the deformed portion 6 becomes higher than that of the other portions, so that the discharge is stably generated and the generation site is also stabilized. Therefore, flickering of light in the operating state can be effectively suppressed. For this reason, the correction operation in the document irradiation apparatus can be minimized, and sufficient reading accuracy can be obtained.
[0021]
In addition, the conventional electrode structure has a problem in that when the rare gas filling pressure is set high in order to increase the amount of light, the striped discharge becomes visible and the reading accuracy of the document irradiating apparatus is impaired. In this embodiment, even when the sealing pressure is set, there is no generation of stripe-like discharge that can be visually recognized, and no flickering occurs. For this reason, the amount of light of the rare gas discharge lamp can be effectively increased by the amount by which the rare gas sealing pressure can be set high, and the reading accuracy of the document irradiation apparatus can be further enhanced.
[0022]
FIG. 4 shows a second embodiment of the present invention, wherein the side edges 4a and 5a of the external electrodes 4 and 5 on the light emitting portion 2a side are formed in a straight line parallel to each other. In the side edges 4b and 5b on the light emitting part side, a triangular shaped deformed part 6 having periodicity is formed over almost the entire length. In addition, the formation site | part of the deformed part 6 and a linear part can also mutually be replaced.
[0023]
According to this embodiment, the flicker of light based on the striped discharge can be effectively suppressed as in the first embodiment, but the range of lighting conditions capable of suppressing the flicker is slightly narrowed in the dimming state. There is a tendency.
[0024]
In particular, since one side edge 4a, 5a of the external electrodes 4, 5 is formed in a straight line shape, each external electrode is parallel to the outer peripheral surface of the envelope 2 by using the straight line portion. Can be easily arranged.
[0025]
5 to 6 show a third embodiment of the present invention, in which the side edges 4a, 4b, 5a and 5b of the external electrodes 4 and 5 have periodicity over almost the entire length. A rectangular deformed portion 6A is formed. In particular, it is desirable that the external electrodes 4 and 5 are arranged on the outer peripheral surface of the envelope 2 so that the respective deformed portions 6A facing each other have the shortest distance. The deformed portion 6A includes a trapezoid shape in which the width of the tip portion is narrow, and is preferably formed in a trapezoid shape.
[0026]
The rectangular deformed portion 6A of the external electrodes 4 and 5 has a width of 8 mm, a pitch of the deformed portion 6A of 4 mm, and a height of the deformed portion 6A when the outer diameter of the glass bulb as the envelope 2 is 8 mm, for example. Is preferably set to a dimension of about 1.5 mm, but can be appropriately changed depending on the specifications of the rare gas discharge lamp and the lighting device.
[0027]
According to this embodiment, light flicker can be effectively suppressed in substantially the same manner as in the first embodiment.
[0028]
7 to 8 show a fourth embodiment of the present invention, which is basically the same as the embodiment shown in FIGS. The difference is that only the side edges 4a and 5a of the external electrodes 4 and 5 on the light emitting portion 2a side are formed in a straight line parallel to each other. In addition, the formation part of 6 A of deformed parts and a linear part can also be mutually replaced so that 6 A of deformed parts may be formed in the side edge parts 4a and 5a, and a linear part may be formed in the side edge parts 4b and 5b, respectively.
[0029]
According to this embodiment, flickering of light can be effectively suppressed as in the second embodiment, and each external electrode can be easily parallelized to the outer peripheral surface of the envelope 2 by using a linear portion. It can arrange so that.
[0030]
FIG. 9 shows a fifth embodiment of the present invention, in which the side edges 4a, 4b, 5a and 5b of the external electrodes 4 and 5 are semicircles having periodicity over almost the entire length. A deformed portion 6B having a shape is formed. In particular, it is desirable that the external electrodes 4 and 5 are arranged on the outer peripheral surface of the envelope 2 so that the respective deformed portions 6B facing each other have the shortest distance. The deformed portion 6B includes a flat semicircular shape.
[0031]
When the outer diameter of the glass bulb as the envelope 2 is 8 mm, for example, the rectangular deformed portion 6B of the external electrodes 4 and 5 has a width of 8 mm, a pitch of the deformed portions 6B of 4 mm, and a height of the deformed portion 6B. Is preferably set to a dimension of about 1.5 mm, but can be appropriately changed depending on the specifications of the rare gas discharge lamp and the lighting circuit.
[0032]
According to this embodiment, light flicker can be effectively suppressed in substantially the same manner as in the first embodiment.
[0033]
FIG. 10 shows a sixth embodiment of the present invention, which is basically the same as the embodiment shown in FIG. The difference is that only the side edges 4a and 5a of the external electrodes 4 and 5 on the light emitting portion 2a side are formed in a straight line parallel to each other. In addition, the formation site | part of the irregular shape part 6B and a linear part can also be mutually replaced so that the irregular shape part 6B may be formed in the side edge parts 4a and 5a, and a linear part may be formed in the side edge parts 4b and 5b, respectively.
[0034]
According to this embodiment, flickering of light can be effectively suppressed as in the second embodiment, and each external electrode can be easily parallelized to the outer peripheral surface of the envelope 2 by using a linear portion. It can arrange so that.
[0035]
FIG. 11 shows a seventh embodiment of the present invention, in which the rare gas discharge lamp 1 shown in FIGS. 1 to 3 is applied to a document irradiation apparatus. The rare gas discharge lamp 1 is irradiated with light emitted from its light emitting portion 2a on the document surface P, and reflected light from the document surface P is received by a line sensor S composed of a CCD element or the like. Configured and arranged. The noble gas discharge lamp shown in the second to sixth embodiments can be appropriately applied to the document irradiation apparatus.
[0036]
According to this embodiment, the side edge portions 4a, 4b, 5a and 5b of the external electrodes 4 and 5 are formed with the triangular shaped deformed portion 6 having periodicity. When starting with a lighting circuit, the electric potential gradient of the front-end | tip part of the deformed part 6 becomes higher than another part, a discharge is produced | generated stably, and the production | generation site | part is also stabilized. Therefore, flickering of light in the operating state can be effectively suppressed. For this reason, the correction operation in the document irradiation apparatus can be minimized, and the reading accuracy can be improved.
[0037]
In particular, if the enclosure pressure of the rare gas in the rare gas discharge lamp 1 is increased to such an extent that light flicker does not occur, the amount of light can be increased by that amount, and the reading quality can be further improved in accuracy.
[0038]
The present invention is not limited to the above-described embodiments. For example, the deformed portion of the external electrode is formed on one or both side edges of each external electrode, and at least one of the external electrodes. It can also be formed on one side edge. In addition, when the external electrodes are arranged on the outer peripheral surface of the envelope, if the external electrodes having a desired shape are attached to the translucent sheet in advance so as to be separated from each other, the external electrodes can be transferred to the envelope. The pasting work can be streamlined. Further, the light emitting layer in the envelope can be formed on the entire inner surface in addition to forming the aperture portion, or can be combined with the light reflecting layer. Furthermore, the outer surface of the rare gas discharge lamp can be covered with, for example, an insulating member having heat shrinkability.
[0039]
【Example】
Next, a first experimental example will be described. In the rare gas discharge lamp 1 shown in FIG. 1 to FIG. 3, triangular deformed portions 6 having periodicity at both side edges are formed on the outer peripheral surface of a glass bulb 2 made of lead glass having an outer diameter of 8 mm and a total length of 300 mm. A pair of external electrodes 4, 5 made of aluminum foil is formed over the entire length, and the width of the deformed portion 6 is 8 mm, the pitch of the deformed portion 6 is 4 mm, and the height of the deformed portion 6 is 1.5 mm. And glue. The light emitting layer of this rare gas discharge lamp uses a three-wavelength phosphor that emits white light, and the xenon gas sealing pressure is set to 70 torr and 80 torr.
[0040]
An illuminance meter was placed at a position 8 mm apart in the normal direction of the light emitting portion 2a of the rare gas discharge lamp, and the light characteristics were measured using the lighting device shown in FIG. The striped discharge was not visible even under pressure, and no flickering of light was observed. The initial illuminance at the central portion of the light emitting portion 2a was 10,000 (Lx) when the sealing pressure was 70 torr and 12000 (Lx) when the sealing pressure was 80 torr. However, the illuminance of the conventional example shown in FIGS. 15 to 16 in which the width of the external electrode is 8 mm over the entire length and the sealed pressure of xenon gas is set to 70 torr and 80 torr is the same as that of the product of the present invention. However, when the sealing pressure was 80 torr, flickering occurred at the rated voltage, and flickering could not be suppressed unless the voltage was increased to about 2820V.
[0041]
Next, a second experimental example will be described. On the outer peripheral surface of the glass bulb 2 made of lead glass having a sealed pressure of xenon gas of 70 Torr, an outer diameter of 8 mm, and an overall length of 180 mm, the exterior of the shape shown in FIGS. The electrode was placed, and the lighting device shown in FIG. 17 was lit at the rating (2700 Vo-p), the rated voltage was gradually lowered, and the voltage at which the light flickering was measured. The result shown in FIG. was gotten.
[0042]
FIG.
As is clear from the figure, the light flicker generation voltage of each of the products of the present invention is lower than that of the conventional example. For this reason, even if the power supply voltage fluctuates greatly, the occurrence of flickering of light can be suppressed, and the reading quality of the document irradiation apparatus can be maintained high.
[0043]
Next, a third experimental example will be described. The rare gas discharge lamp used in the second experimental example is shown in FIG. 17 in which the output voltage of the inverter circuit INV is set to 2700 V, the oscillation frequency is set to 28 KHz, and the frequency of the clock signal of the clock generator CG is set to 280 Hz. In combination with the lighting device shown, and adjusting the variable resistor VR, the duty ratio of the clock signal is changed in the range of 100% to 10%, and PWM (Phase Width Modulation) light control is performed, and the occurrence of light flickering As a result, the results shown in FIG. 13 were obtained. Note that the output voltage of the inverter circuit is constant.
[0044]
FIG.
As is clear from the figure, no flickering was observed up to a duty ratio of 20% in both Invention 1 and Invention 2, but at 10% the non-harness side (end of each external electrode) Flickering was observed on the non-connected side of the lead wire connected to the section. However, in the conventional example, when the duty ratio was 40%, flickering occurred on the non-harness side, and at 20%, the flickering spread throughout the glass bulb. Therefore, the present invention can be applied to the document irradiating apparatus even in a wide range of the light control rate, but the conventional example has a disadvantage that its use range is considerably limited.
[0045]
【The invention's effect】
As described above, according to the present invention, the triangular shape extending in the axial direction of the external electrode such that the potential gradient is locally increased at any of the opposing side edges of the pair of external electrodes , Since the deformed portion is formed in a rectangular shape or a semicircular shape including a trapezoidal shape and set at a predetermined pitch over almost the entire length, the generation site of discharge is stabilized. . In particular, the irregular part is formed into a shape such as a triangular shape with periodicity, a rectangular shape including a trapezoidal shape, a semicircular shape, etc., and is formed over almost the entire length of the external electrode, thereby effectively generating light flickering. And the reading accuracy with the document irradiation apparatus can be improved.
[0046]
In addition, the side edge of the external electrode extending in the appropriate axial direction has a triangular shape, a rectangular shape including a trapezoidal shape, or a semicircular shape, and is set at a predetermined pitch over almost the entire length. Since the deformed portion is formed, flicker due to striped discharge does not occur even when the noble gas sealing pressure is set high. Therefore, the amount of light of the rare gas discharge lamp can be effectively increased, and the reading accuracy of the document irradiation apparatus can be further enhanced.
[0047]
Furthermore, the side edge portion extending in the axial direction of any one of the external electrodes has a triangular shape, a rectangular shape including a trapezoidal shape, or a semicircular shape, and has a predetermined pitch over almost the entire length. Since the deformed portion set in (1) is formed, the discharge is stably generated. Therefore, it is possible to maintain a stable discharge without flicker even in a dimming range where the discharge current is greatly reduced.
[Brief description of the drawings]
FIG. 1 is a side view showing a first embodiment of the present invention.
FIG. 2 is a longitudinal sectional view in the central portion of FIG.
FIG. 3 is a development view of FIG. 1;
FIG. 4 is a side view showing a second embodiment of the present invention.
FIG. 5 is a side view showing a third embodiment of the present invention.
6 is a development view of FIG. 5. FIG.
FIG. 7 is a side view showing a fourth embodiment of the present invention.
FIG. 8 is a development view of FIG. 7;
FIG. 9 is a side view showing a fifth embodiment of the present invention.
FIG. 10 is a side view showing a sixth embodiment of the present invention.
FIG. 11 is a schematic view of a document irradiation apparatus showing a seventh embodiment of the present invention.
FIG. 12 is a diagram showing the relationship between the structure of the external electrode and the flicker generation voltage.
FIG. 13 is a diagram showing a relationship between a duty ratio of a clock signal and a flicker occurrence state.
FIG. 14 is a schematic diagram of a conventional document irradiation apparatus.
FIG. 15 is a cross-sectional view of a discharge lamp used in a conventional document irradiation apparatus.
16 is a development view of FIG.
FIG. 17 is an electric circuit diagram of a lighting device.
18 is a waveform diagram of an output voltage of the inverter circuit shown in FIG. 17, where (a) is an output waveform diagram when the duty ratio of the clock signal is 100%, and (b) is a duty waveform. The output waveform diagram when the ratio is less than 100%.
[Explanation of symbols]
1 Noble gas discharge lamp 2 Envelope (glass bulb)
2a Light emitting part 3 Light emitting layer 4, 5 External electrode 4a, 5a, 4b, 5b Side edge part 6, 6A, 6B Deformed part S Sensor
P Original side

Claims

A pair of strip-shaped external electrodes are arranged apart from each other on the outer peripheral surface of the envelope having a light emitting layer on the inner surface, and a rare gas is sealed in the envelope, so that both of the pair of strip-shaped external electrodes are opposed to each other. Any one of a triangular shape extending in the axial direction of the external electrode, a rectangular shape including a trapezoidal shape, and a semicircular shape is formed on one of the side edges , and substantially at a predetermined pitch over the entire length. A rare gas discharge lamp characterized in that a set deformed portion is formed.

A pair of strip-shaped external electrodes are arranged separately on the outer peripheral surface of the envelope having a light emitting layer on the inner surface, and a rare gas is enclosed in the envelope, and each side edge portion of the pair of external electrodes And the deformed portion extending in the axial direction of the external electrode, having a triangular shape, a rectangular shape including a trapezoidal shape, or a semicircular shape, which is set at a predetermined pitch over substantially the entire length. A rare gas discharge lamp characterized in that is formed.

A pair of strip-shaped external electrodes are arranged apart from each other on the outer peripheral surface of the envelope having a light emitting layer on the inner surface, and the emitted light from the rare gas discharge lamp in which the rare gas is sealed in the envelope In the document irradiation device that receives the reflected light by the sensor and extends in the axial direction of the external electrode on either side edge of both of the pair of strip-shaped external electrodes , An original irradiating apparatus having a rectangular shape including a trapezoidal shape or a semicircular shape, and having a deformed portion set at a predetermined pitch over substantially the entire length.