JP2004311034A

JP2004311034A - Method of removing devitrification of arc tube, method of manufacturing arc tube, and discharge lamp

Info

Publication number: JP2004311034A
Application number: JP2003098525A
Authority: JP
Inventors: Hitoshi Asayama; 仁浅山; Motozo Sakoda; 素三佐古田
Original assignee: Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Holdings Corp
Priority date: 2003-04-01
Filing date: 2003-04-01
Publication date: 2004-11-04
Anticipated expiration: 2023-04-01
Also published as: JP4272458B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for removing a devitrification for removing a devitrified part generated on the surface or the surface layer part of a luminous part caused by partially heating a boundary part by using a part heating means, e.g., a laser, a pencil burner etc. with miniaturization of an arc tube, a method of manufacturing an arc tube in which the loss of the transparency part is removed, an arc tube manufactured by the method, and a discharge lamp with the arc tube incorporated therein as a light source. <P>SOLUTION: A translucency insulating tube to be a material of the arc tube, which has a luminous part with a pair of electrodes provided therein and a sealing part formed at the end part of the luminous part, makes a part at which the luminous part is formed a predetermined part for forming the luminous part, partially irradiates the devitrified part generated on the surface of the predetermined part with a laser beam, and heats the devitrified part. Furthermore, while rotating the translucency insulating tube with a tube axis of the insulating tube as the center, an irradiation region with the laser beam is moved along the tube axis. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、主として放電ランプ用の発光管の製造方法に関し、特に、発光管の発光部に生じる失透部を除去する技術に関する。
【０００２】
【従来の技術】
近年、液晶プロジェクタなど、大型スクリーンに鮮明に投影するプロジェクタが種々検討されている。その中でも、小型のプロジェクタには、放電ランプの一種であるショートアーク型の高圧水銀ランプを光源としたものがある。
図８は、一例として、従来における小型の放電ランプに組み込まれる発光管の構造を示す概要図である。
【０００３】
同図にみられるように、小型の放電ランプに組み込まれる発光管１０は、長さ１０ｍｍ、最大外径１０ｍｍの回転楕円体状の発光部２１と、長さ２５ｍｍ、外径６ｍｍの円柱状の封止部３１，４１から構成される。
発光部２１は、内部に放電空間２２が設けられ、放電空間２２内に電極５２，６２が対向して配置され、水銀、金属ハロゲン化物、及び不活性ガスなどが封入される。そして、点灯時に内圧２００気圧に達する。
【０００４】
封止部３１は、発光管１０に形成される前の直管状の透光性絶縁管１１（例えば、石英ガラス管など）において封止部形成予定部３５を加熱して軟化させた状態で封止して形成される。また、封止部４１も、封止部３１と同様に形成される。
そして、発光管１０の小型化に伴い、発光管１０を点灯させた際に、発光部２１内に封入された高圧の封入ガスが電極軸の根元３８，４８に侵入して、クラックが生じやすくなる。これ故に、発光部２１と封止部３１との境界に位置する境界部３６を封止する際には、バーナー以外にもレーザーを使用して、気密性が高く、かつ歪みの少ない加工が施される。また、境界部４６についても同様である（例えば、特許文献１、特許文献２参照）。
【０００５】
【特許文献１】
特開２００２−２９８７３８号公報
【０００６】
【特許文献２】
特開２０００−２２３０３０号公報
【０００７】
【発明が解決しようとする課題】
しかしながら、発光管１０の小型化に伴い、例えば、レーザーやペンシルバーナーなどの様な局部加熱手段を使用して局部的に境界部３６を加熱したことで、境界部３６と発光部２１との間の温度勾配が大きくなり、発光部２１の表面または表層部に、白い靄がかかった様な部分（以下、失透部２３と呼称する）が顕著に見られるようになる。同様に、境界部４６に対しても失透部２４が顕著に見られるようになる。さらに、発光部２１の表面積に対して失透部２３または失透部２４の占める割合も、発光管１０が小型化すればする程、大きくなり、光学的損失が生じるという問題がある。
【０００８】
本発明は、前述の問題に鑑みてなされたものであり、発光部の表面または表層部に生じた失透部を除去する失透除去方法、失透部を除去した発光管の製造方法、当該製造方法で製造された発光管、及び当該発光管を光源として組み込まれた放電ランプを提供することを目的とする。
【０００９】
【課題を解決するための手段】
＜解決手段１＞
前述の問題を解決するにあたり、本発明に係わる発光管の失透除去方法は、一対の電極が内部に設けられた発光部と、前記発光部の端部に形成された封止部とを有する発光管の材料である透光性絶縁管において、前記発光部が形成される部分を発光部形成予定部として、前記発光部形成予定部の表面に生じた失透部に、レーザービームを局部的に照射して、前記失透部を加熱することとする。
【００１０】
これによって、発光部形成予定部の表面または表層部に生じた失透部を局部的に加熱して、結晶状態から過冷却液体状態を経てガラス状態に転移させて、失透を除去することが可能という効果がある。
＜解決手段２＞
さらに、解決手段１に記載の内容に加えて、前記透光性絶縁管の管軸を中心に、前記透光性絶縁管を回転させながら、レーザービームの照射領域を、前記管軸に沿って移動させることとしてもよい。
【００１１】
これによって、レーザービームの照射領域を固定した場合と比べて、同じ温度を長時間に渡って保たれることを抑止し、再度、失透が生じることを防止することが可能という効果がある。さらに、広範囲に渡って発光部形成予定部の表面または表層部に生じた失透部を除去することが可能という効果もある。
＜解決手段３＞
前述の問題を解決するにあたり、本発明に係わる発光管の失透除去方法は、一対の電極が内部に設けられた発光部と、前記発光部の端部に形成された封止部とを有する発光管において、前記発光部の表面に生じた失透部に、レーザービームを局部的に照射して、前記失透部を加熱することとする。
【００１２】
これによって、透光性絶縁管の代わりに発光管に対しても、解決手段１に記載の効果と同様の効果がある。
さらに、バーナーを使用して失透部を加熱した場合と比べて、加熱する範囲を小さくすることができ、発光管表面の熱の広がりを抑制でき、発光部に与える熱量を低く抑えることができる。とりわけ、失透部が生じる発光部の内部は高圧であり、バーナーを使用して失透部を加熱すると、内部に封入されている封入ガスの熱膨張などで、変形または破損が発光部に生じやすい。その点、レーザーを使用して失透部を加熱することで、内部に封入されている封入ガスの熱膨張を抑えることができ、変形または破損が発光部に生じにくくすることが可能という効果がある。
【００１３】
＜解決手段４＞
さらに、解決手段３に記載の内容に加えて、前記発光管の管軸を中心に、前記発光管を回転させながら、レーザービームの照射領域を、前記管軸に沿って移動させることとしてもよい。
これによって、透光性絶縁管の代わりに発光管に対しても、解決手段２に記載の効果と同様の効果がある。
【００１４】
＜解決手段５＞
前述の問題を解決するにあたり、本発明に係わる発光管の製造方法は、一対の電極が内部に設けられた発光部と、前記発光部の端部に形成された封止部とを有する発光管の製造方法であって、前記発光管の材料である透光性絶縁管において、前記発光部が形成される部分を発光部形成予定部とし、前記封止部が形成される部分を封止部形成予定部とし、前記発光部形成予定部と前記封止部形成予定部との境界に位置する部分を境界部として、前記電極を有する電極体を前記封止部形成予定部に挿入して、前記境界部を溶融封止した後に、前記封止部形成予定部の残余部を溶融封止すると共に、前記境界部を溶融封止した際に前記発光部形成予定部の表面に生じた失透部に、レーザービームを局部的に照射して、前記失透部を加熱することとする。
【００１５】
これによって、解決手段１に記載の効果と同様の効果がある。
さらに、バーナーで残余部を封止すると共に、レーザーを使用して失透部を加熱して除去することで、封止部が形成された後に、失透部を除去する場合と比べて、さらに、製造に要する時間を短縮することが可能という効果がある。
また、フッ酸を使用して失透部を除去した場合と比べて、発光管を冷却した後に、フッ酸に浸して洗浄する工程を要しない分、失透部までも除去して発光管を製造するまでの時間を短縮することが可能という効果がある。
【００１６】
＜解決手段６＞
前述の問題を解決するにあたり、本発明に係わる発光管の製造方法は、一対の電極が内部に設けられた発光部と、前記発光部の端部に形成された封止部とを有する発光管の製造方法であって、前記発光管の材料である透光性絶縁管において、前記発光部が形成される部分を発光部形成予定部とし、前記封止部が形成される部分を封止部形成予定部とし、前記発光部形成予定部と前記封止部形成予定部との境界に位置する部分を境界部として、前記電極を有する電極体を前記封止部形成予定部に挿入して、前記境界部を溶融封止し、前記封止部形成予定部の残余部を溶融封止して前記封止部が形成された後に、前記境界部を溶融封止した際に前記発光部形成予定部の表面に生じた失透部に、レーザービームを局部的に照射して、前記失透部を加熱することとする。
【００１７】
これによって、解決手段１に記載の効果と同様の効果がある。
＜解決手段７＞
さらに、解決手段５又は６に記載の内容に加えて、前記透光性絶縁管の管軸を中心に、前記透光性絶縁管を回転させながら、レーザービームの照射領域を、前記管軸に沿って移動させることとしてもよい。
【００１８】
これによって、解決手段２に記載の効果と同様の効果がある。
＜解決手段８＞
前述の問題を解決するにあたり、本発明に係わる発光管の製造方法は、一対の電極が内部に設けられた発光部と、前記発光部の端部に形成された封止部とを有する発光管の製造方法であって、前記封止部が形成された後に、前記封止部が形成される部分を溶融封止した際に前記発光部の表面に生じた失透部に、レーザービームを局部的に照射して、前記失透部を加熱することとする。
【００１９】
これによって、解決手段３に記載の効果と同様の効果がある。
＜解決手段９＞
さらに、解決手段８に記載の内容に加えて、前記発光管の管軸を中心に、前記発光管を回転させながら、レーザービームの照射領域を、前記管軸に沿って移動させることとしてもよい。
【００２０】
これによって、解決手段４に記載の効果と同様の効果がある。
【００２１】
【発明の実施の形態】
以下、本発明の実施の形態について、図面を参照しながら説明する。
＜放電ランプ＞
図１（ａ）は、本発明の実施の形態における発光管を光源とする放電ランプの構成を示す切り欠き斜視図であり、（ｂ）は、放電ランプの光源とする発光管の構造を示す概要図である。
【００２２】
図１（ａ）にみられるように、放電ランプ１００は、片方の封止部に口金１０１が装着された発光管１１０が、スペーサ１０２を介して反射鏡１０３のネック部に取り付けられて構成されている。そして、反射鏡１０３に設けられた貫通孔１０６を通して外側に引き出されたリード線１０４、及び端子１０５を介して、発光管１１０の電極に、電流が供給される。
【００２３】
なお、発光管１１０の放電アークの位置は、反射鏡１０３の光軸と一致する位置に調整されている。
＜発光管＞
図１（ｂ）にみられるように、放電ランプに組み込まれる発光管１１０は、回転楕円体状の発光部１２１と、円柱状の封止部１３１，１４１、電極体１５１，１６１とから構成される。
【００２４】
発光部１２１は、内部の放電空間１２２内に、電極１５２，１６２が対向して配置され、水銀、金属ハロゲン化物、及び不活性ガスなどが封入されている。
封止部１３１は、発光管１１０に形成される前の直管状の透光性絶縁管において封止部１３１が形成される予定の封止部形成予定部に電極体１５１を挿入して、封止部形成予定部を封止（例えばシュリンク封止）して形成される。また、封止部１４１も封止部１３１と同様に形成される。
【００２５】
ここで、シュリンク封止とは、真空引きした発光管１１０の封止部形成予定部を加熱して軟化させた部分を大気圧で収縮させて封止することを指す。
なお、透光性絶縁管には、石英ガラス、硼珪酸塩ガラスなどが挙げられる。
電極体１５１は、電極軸１５３にコイルが形成されてなるタングステン製の電極１５２と、モリブデン箔などの金属箔１５４と、モリブデン線などのリード線１５５とを接合して構成されている。また、電極体１６１も電極体１５１と同様に構成されている。
【００２６】
＜発光管の製造方法＞
図２乃至５は、実施の形態における発光管の製造方法を示す模式図である。
図２乃至５にみられるように、発光管１１０は、第１封止工程、第２封止工程を経て製造される。
＜封止装置＞
ここで、発光管１１０の製造方法について説明する前に、発光管を製造する際に使用される封止装置（不図示）について簡単に説明する。
【００２７】
発光管１１０を製造する際に使用される封止装置には、支持部、回転部、排気部、封入部、冷却部、送風部、噴出部、照射部、制御部などが備えられている。
支持部は、図２（ａ）に示される透光性絶縁管１１１の両端部をチャックで挟み込み、透光性絶縁管１１１を支持する。
回転部は、支持部で支持された透光性絶縁管１１１の管軸（以下、回転軸と呼称する）を中心として、透光性絶縁管１１１を一定速度（例えば、１４０ｒｐｍ）で回転させる。
【００２８】
排気部は、透光性絶縁管１１１の開口部１１３または開口部１１４を介して、透光性絶縁管１１１の内部の気体を排気する。
封入部は、透光性絶縁管１１１の開口部１１３または開口部１１４を介して、透光性絶縁管１１１の内部に、水銀、金属ハロゲン化物、及び不活性ガスなどを封入する。
【００２９】
冷却部は、液体窒素などの冷却媒体を使用して発光部形成予定部１２５を冷却する。
送風部は、透光性絶縁管１１１に窒素もしくは空気を吹き付けて透光性絶縁管１１１を冷却する。
噴出部は、図３（ａ）または図４（ｂ）に示される様に、酸素−水素、プロパンなどの燃焼性ガスを点火して、回転軸に沿って移動しながら、封止部形成予定部１３５または封止部形成予定部１４５に噴出する。
【００３０】
照射部は、図３（ｂ）または図５（ｂ）に示される様に、レーザー発振源１８１から発振されたレーザービームを反射鏡１８２，１８３で反射させて、反射させたレーザービームを集光レンズ１８４で集光して、レーザービームを照射する。さらに、反射鏡１８３および集光レンズ１８４を回転軸方向に沿って移動することで、レーザービームの照射領域を移動させて、図３（ａ）または図４（ｂ）に示される様に、境界部１３６または境界部１４６や、図３（ｂ）または図５（ｂ）に示される様に、失透部１２３または失透部１２４を照射する。以下、単に、照射部をレーザーと呼称する。
【００３１】
なお、レーザー発振源１８１には、赤外線レーザー、ガラスレーザー、炭酸ガスレーザーなどが挙げられる。
制御部は、支持部、回転部、排気部、封入部、冷却部、送風部、噴出部、照射部の動作を制御する。
以上の様に構成された封止装置を使用して発光管１１０を製造する製造方法について説明する。
【００３２】
＜発光部形成予定部成形工程＞
図２（ａ）にみられるように、発光管１１０の材料である透光性絶縁管１１１の中央部をバーナーで加熱して軟化させて（手順１−１）、透光性絶縁管１１１の一方の開口部１１３（または開口部１１４）を一時的に閉じる（手順１−２）。続いて、他方の開口部１１４（または開口部１１３）から透光性絶縁管１１１内に不活性ガスを吹き込み（手順１−３）、吹き込んだ不活性ガスの圧力で軟化させた部分を膨らませる（手順１−４）。そして、膨らんだ部分に金型を押し当て、その部分を回転楕円体状に成形して、発光部形成予定部１２５が形成される（手順１−５）。
【００３３】
＜第１封止工程＞
図２（ｂ）にみられるように、発光部形成予定部１２５が形成された透光性絶縁管１１１を垂直に立てた状態で、透光性絶縁管１１１の開口部１１３から封止部形成予定部１３５内に電極体１５１を挿入し（手順２−１）、その両端部をチャック１７１，１７２で挟み込み、透光性絶縁管１１１を保持する（手順２−２）。
【００３４】
なお、電極体１５１は、予め、電極１５２、金属箔１５４、及びリード線１５５を一体化させて組み立てられており、電極体１５１のリード線１５５の端部に六角形状のバネ１７３が取り付けられている。そして、この六角形状のバネ１７３の一部が封止部形成予定部１３５の上方部分の内面に圧接し、バネ１７３の弾性応力で、封止部形成予定部１３５内の所定位置に、電極体１５１が保持される。
【００３５】
図３（ａ）にみられるように、封止部形成予定部１３５に電極体１５１を挿入した後に、透光性絶縁管１１１を回転部で回転させる（手順２−３）。そして、透光性絶縁管１１１を回転させながら、発光部形成予定部１２５と封止部形成予定部１３５との境界に位置する境界部１３６を、バーナー１７５およびレーザー１７６を併用して、加熱し軟化させる（手順２−４）。そして、境界部１３６を軟化させた状態でシュリンク封止する（手順２−５）。
【００３６】
なお、図３（ａ）の左側に示したグラフ１９１にみられるように、レーザーを使用して局部的に加熱していくと、レーザービームの照射領域では、融点になる一方、レーザービームの照射領域から少し外れた位置では、失透温度範囲内になり、失透が生じる。以下、失透が生じやすい範囲を失透範囲と呼称する。
ここで、失透温度範囲とは、失透が生じやすい温度範囲を指し、軟化点に近い高温で、粘度が１０^４ポアズ（Ｐ）程度の温度範囲を指す。
【００３７】
なお、封止の際、透光性絶縁管１１１内は、アルゴンガスなどの不活性ガスで満たされている。
図３（ｂ）にみられるように、境界部１３６を封止した後に、もしくは封止中に、開口部１１３に向かってバーナー１７５を連続的に移動させながら（手順２−６ａ）、バーナー１７５を使用して、残余部１３７を順次加熱し軟化させる（手順２−７ａ）。そして、残余部１３７を軟化させた状態でシュリンク封止する（手順２−８ａ）。
【００３８】
その一方で、レーザー１７６の使用を一旦停止し（手順２−６ｂ）、境界部１３６を封止した際に発光部形成予定部１２５の表面または表層部に生じた失透部１２３に、レーザービームの照射領域を移動させる（手順２−７ｂ）。そして、発光部形成予定部１２５の中心より下側の位置から境界部１３６に向かって、または境界部１３６から発光部形成予定部１２５の中心より下側の位置に向かって、レーザービームの照射領域を徐々に移動させながら、レーザー１７６を使用して、失透部１２３を局部的に加熱して除去する（手順２−８ｂ）。
【００３９】
なお、レーザー１７６を使用して、失透部１２３を局部的に加熱して除去する際には、レーザービームの照射領域を上下に移動させながら照射するとしてもよい。
以上、残余部１３７を封止して、失透部１２３を除去して、封止部１３１が形成される。そして、送風部から窒素もしくは空気を吹き付けて、封止部１３１を冷却する。
【００４０】
＜第２封止工程＞
図４（ａ）にみられるように、封止部１３１が形成された透光性絶縁管１１１を上下反転させて、封止部１３１が下側に位置する様に透光性絶縁管１１１を垂直に立てた状態で、その両端部をチャック１７１，１７２で挟み込み、透光性絶縁管１１１を保持する（手順３−１）。
【００４１】
図４（ｂ）にみられるように、透光性絶縁管１１１の開口部１１４から水銀などの封入物を投入した後に（手順３−２）、第１封止工程で記した手順２−１，手順２−３〜手順２−５と同様の手順を行い、発光部形成予定部１２５と封止部形成予定部１４５との境界に位置する境界部１４６を封止する。
ここで、第２封止工程では、第１封止工程と比べて、発光部形成予定部１２５内に封入された水銀などの封入物が蒸気化しないように、発光部形成予定部１２５の下側または封止部１３１を液体窒素で冷却する点が異なる（手順３−３）。
【００４２】
なお、図４（ｂ）の左側に示したグラフ１９２にみられるように、第１封止工程と比べて、液体窒素で冷却することにより、温度勾配が、さらに大きくなり、失透範囲が、さらに大きくなる。
図５（ａ）にみられるように、第１封止工程で記した手順２−６ａ〜手順２−８ａ、および手順２−６ｂと同様の手順を行い、残余部１４７を封止して、封止部１４１が形成される。
【００４３】
ここで、第２封止工程では、第１封止工程と比べて、第１封止工程で記した手順２−８ｂを行わない点が異なる。
以上、封止部１３１，１４１が形成されて、発光部１２１が形成される。
図５（ｂ）にみられるように、封止部１４１が形成された後に、発光管を少し引き上げて、境界部１４６を封止した際に発光部形成予定部１２５の表面または表層部に生じた失透部１２４に対して、手順２−７ｂと同様の手順を行う。そして、発光部１２１の中心より下側の位置から境界部１４６に向かって、または境界部１４６から発光部１２１の中心より下側の位置に向かって、レーザービームの照射領域を徐々に移動させながら、レーザー１７６を使用して、失透部１２４を局部的に加熱して除去する（手順３−４）。
【００４４】
このとき、失透部１２３を局部的に加熱して除去した際と同様の条件で、レーザー１７６を使用して、失透部１２４を照射する。
以上、失透部１２４を除去して、透光性絶縁管１１１の両端部を切り落として、図１（ｂ）に示される様な発光管１１０が製造される。さらに、この後、発光管１１０に口金１０１などが取り付けられて放電ランプ１００が製造される。
【００４５】
＜具体例＞
ここで、長さ１０ｍｍ、最大外径１０ｍｍの回転楕円体状の発光部１２１と、長さ２５ｍｍ、外径６ｍｍの円柱状の封止部１３１，１４１とを有する発光管１１０が形成される場合を例に説明する。
また、発光管１１０の材料である透光性絶縁管１１１には、石英ガラス管を使用し、レーザー１７６には、石英に吸収され易い炭酸ガスレーザーを使用する。
【００４６】
なお、炭酸ガスレーザーの出力は９０Ｗ〜１１０Ｗ、ビームスポット径はφ３〜φ６とする。
手順２−４において、レーザービームの照射領域を２０秒の間固定して、境界部１３６を照射する。なお、このとき、境界部１３６は、約２０００℃に加熱される。
【００４７】
手順２−８ｂにおいて、最初、レーザービームの照射領域を２．５秒の間固定して、発光部形成予定部１２５のやや下側を照射する。その後、回転軸に沿って、レーザービームの照射領域を徐々に移動させながら、発光部形成予定部のやや下側から境界部１３６に向かって、速度０．３２ｍｍ／ｓｅｃで、照射範囲７．３ｍｍ（失透部１２３を含む範囲）を照射する。なお、このとき、失透部１２３は、１５００℃〜１６００℃に加熱される。
【００４８】
実際に、手順２−８ｂを行った結果、手順２−４で発光部形成予定部１２５の表面または表層部に生じた失透部１２３がきれいに除去されることが発明者等によって確認された。
＜まとめ＞
図６（ａ）は、境界部を封止する際の失透部の状態変化を示す模式図であり、（ｂ）は、失透部を除去する際の失透部の状態変化を示す模式図である。なお、図中において、Ｔ_ｍは融点を示し、Ｔ_ｇはガラス転移温度を示している。
【００４９】
図６（ａ）にみられるように、境界部を封止する際に、レーザービームの照射領域を所定の時間固定して局部的に加熱すると、ガラス状態から過冷却液体状態を経て液体状態に転移する。さらに、レーザービームの照射領域では、融点に達して、ガラス状態から過冷却液体状態を経て液体状態に転移する。しかし、レーザービームの照射領域を少し外れた失透範囲では、軟化点に近い高温に達して、失透温度範囲内に留まる時間が長くなり、結晶が析出される。そして、このまま冷やされて、結晶状態に転移して、失透部が生じると想定される。
【００５０】
図６（ｂ）にみられるように、失透部を除去する際に、透光性絶縁管の管軸に沿って、レーザービームの照射領域を移動させながら局部的に加熱すると、液体状態から過冷却液体状態を経てガラス状態に転移する。さらに、レーザービームの照射領域が近づくにつれて、失透部の温度が徐々に上がり、結晶状態から液体状態に転移する。また、遠ざかるにつれて、失透部の温度が徐々に下がり、失透温度範囲を短時間で通過して、液体状態から過冷却液体状態に転移する。そして、このまま冷やされて、ガラス状態に転移して、失透部が除去されると想定される。
【００５１】
＜その他＞
なお、発光部形成予定部成形工程で成形された透光性絶縁管１１１の代わりに、ロストワックス法、粉末プレス成形法、押し出しプレス成形法、凍結成形法、射出成形法、或いはゲル化成形法などによって予め発光部形成予定部１２５をも含めて成形された透光性絶縁管１１１を材料に、発光管１１０が製造されるとしてもよい。
【００５２】
なお、封止装置は、境界部を封止する際に使用するレーザーと、失透部を除去する際に使用するレーザーとを、それぞれ個別に備えるとしてもよい。また、異なるタイプのレーザーとしてもよい。
なお、発光部１２１の形状を回転楕円体状として説明したが、球体状などとしてもよく、その形状が特に限定されないことは言うまでもない。
【００５３】
なお、レーザー１７６のビームスポット径を、封止部１３１または封止部１４１の外径を目安に特定されるとしてもよい。例えば、外径／２〜外径の範囲内として、封止する際に最適とされるビームスポット径で失透も除去するとしてもよい。
なお、レーザー１７６は、連続発振としてもよいし、パルス発振としてもよい。
【００５４】
なお、残余部１３７を封止しながら手順２−８ｂを行う代わりに、封止部１３１が形成された後に手順２−８ｂを行うとしてもよい。
なお、手順２−８ｂを行わずに、手順３−４で、第２封止工程で生じた失透部１２４を除去する際に、第１封止工程で生じた失透部１２３も一緒に除去するとしてもよい。
【００５５】
なお、手順２−８ｂまたは手順３−４で示した失透除去方法を、発光管の製造方法とは切り離して単独の工程としてもよい。そして、製造された発光管に生じている失透部、又は製造される前の発光管の材料である透光性絶縁管に生じている失透部に適用して、失透部を除去するとしてもよい。
なお、失透部は、石英ガラス管を加熱した際に蒸気となった石英が、温度の低い部分に付着してできる、またはガラス状態から結晶状態に転移してできるなど種々の原因が考えられる。また、小型の放電ランプ特有の問題でもなく、大型の放電ランプでも同様に形成される。
【００５６】
図７は、一例として、大型の放電ランプの構成を示す外観図である。
同図にみられるように、外管２０１の端部に口金２０２が取り付けられた大型の放電ランプ２００においても、外管２０１に覆われる発光管２１０の表面に僅かながら失透部が生じる。そこで、手順２−８ｂまたは手順３−４で説明した失透除去方法を使用して、発光管２１０に生じる失透部を除去するとしてもよい。
【００５７】
【発明の効果】
以上の様に、本発明に係わる発光管の失透除去方法、及び製造方法は、発光部の表面または表層部に生じた失透部に、レーザービームを局部的に照射して、失透部を加熱する。このとき、前記透光性絶縁管の管軸を中心に、前記透光性絶縁管を回転させながら、レーザービームの照射領域を、前記管軸に沿って移動させて、前記失透部を結晶状態から過冷却液体状態を経てガラス状態に転移させる。
【００５８】
これにより、発光管の小型化に伴い、例えば、レーザーやペンシルバーナーなどの様な局部加熱手段を使用して局部的に境界部を加熱したことで、発光部の表面または表層部に生じた失透部を除去することができる。その結果、発光部の表面積に対して失透部の占める割合も、発光管が小型化すればする程、大きくなり、光学的損失が生じるという問題を解決することが可能という効果がある。
【図面の簡単な説明】
【図１】（ａ）は、本発明の実施の形態における発光管を光源とする放電ランプの構成を示す切り欠き斜視図であり、（ｂ）は、放電ランプの光源とする発光管の構造を示す概要図である。
【図２】実施の形態における発光管の製造方法を示す模式図その１である。
【図３】実施の形態における発光管の製造方法を示す模式図その２である。
【図４】実施の形態における発光管の製造方法を示す模式図その３である。
【図５】実施の形態における発光管の製造方法を示す模式図その４である。
【図６】（ａ）は、境界部を封止する際の失透部の状態変化を示す模式図であり、（ｂ）は、失透部を除去する際の失透部の状態変化を示す模式図である。
【図７】一例として、大型の放電ランプの構成を示す外観図である。
【図８】一例として、従来における小型の放電ランプに組み込まれる発光管の構造を示す概要図である。
【符号の説明】
１００放電ランプ
１０１口金
１０２スペーサ
１０３反射鏡
１０４リード線
１０５端子
１０６貫通孔
１０，１１０発光管
１１，１１１透光性絶縁管
１１３，１１４開口部
２１，１２１発光部
２２，１２２放電空間
２３，２４，１２３，１２４失透部
１２５発光部形成予定部
１３１，１４１封止部
１３５，１４５封止部形成予定部
３６，４６，１３６，１４６境界部
１３７，１４７残余部
３８，４８根元
１５１，１６１電極体
１５２，１６２電極
１５３，１６３電極軸
１５４，１６４金属箔
１５５，１６５リード線
１７１，１７２チャック
１７３，１７４バネ
１７５バーナー
１７６レーザー
１８１レーザー発振源
１８２，１８３反射鏡
１８４集光レンズ
２００放電ランプ
２０１外管
２０２口金
２１０発光管[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing an arc tube for a discharge lamp, and more particularly to a technique for removing a devitrified portion generated in a light emitting portion of an arc tube.
[0002]
[Prior art]
In recent years, various types of projectors, such as liquid crystal projectors, that project sharply on a large screen have been studied. Among them, some small projectors use a short arc type high pressure mercury lamp, which is a kind of discharge lamp, as a light source.
FIG. 8 is a schematic view showing, as an example, the structure of an arc tube incorporated in a conventional small discharge lamp.
[0003]
As shown in the figure, an arc tube 10 incorporated in a small discharge lamp has a spheroidal light emitting portion 21 having a length of 10 mm and a maximum outer diameter of 10 mm, and a columnar shape having a length of 25 mm and an outer diameter of 6 mm. It is composed of sealing portions 31 and 41.
The light emitting unit 21 has a discharge space 22 provided therein, electrodes 52 and 62 are arranged in the discharge space 22 to face each other, and mercury, a metal halide, an inert gas, and the like are sealed therein. Then, at the time of lighting, the internal pressure reaches 200 atm.
[0004]
The sealing portion 31 is sealed in a state in which the portion 35 to be sealed is softened by heating the portion 35 to be formed in the straight tubular transparent insulating tube 11 (for example, a quartz glass tube) before being formed in the arc tube 10. Stopped and formed. In addition, the sealing portion 41 is formed similarly to the sealing portion 31.
When the arc tube 10 is turned on with the downsizing of the arc tube 10, the high-pressure sealed gas sealed in the light emitting portion 21 enters the roots 38 and 48 of the electrode shaft, and cracks are easily generated. Become. For this reason, when sealing the boundary portion 36 located at the boundary between the light emitting portion 21 and the sealing portion 31, a laser is used in addition to the burner to perform processing with high airtightness and less distortion. Is done. The same applies to the boundary portion 46 (for example, see Patent Documents 1 and 2).
[0005]
[Patent Document 1]
JP 2002-298938 A
[0006]
[Patent Document 2]
JP 2000-223030 A
[0007]
[Problems to be solved by the invention]
However, with the miniaturization of the arc tube 10, for example, by locally heating the boundary portion 36 using a local heating means such as a laser or a pen silverer, the distance between the boundary portion 36 and the light emitting portion 21 is increased. The temperature gradient of the light-emitting portion 21 becomes large, and a portion such as a white haze (hereinafter, referred to as a devitrified portion 23) is remarkably observed on the surface or the surface layer portion of the light-emitting portion 21. Similarly, the devitrification part 24 becomes remarkable also at the boundary part 46. Further, the ratio of the devitrified portion 23 or the devitrified portion 24 to the surface area of the light-emitting portion 21 increases as the size of the arc tube 10 decreases, resulting in a problem that optical loss occurs.
[0008]
The present invention has been made in view of the above-described problems, and has a devitrification removing method for removing a devitrified portion generated on a surface or a surface layer portion of a light emitting portion, a method for manufacturing an arc tube from which a devitrified portion is removed, An object of the present invention is to provide an arc tube manufactured by a manufacturing method and a discharge lamp incorporating the arc tube as a light source.
[0009]
[Means for Solving the Problems]
<Solution 1>
In order to solve the above-described problem, a devitrification removing method for an arc tube according to the present invention includes a light-emitting portion having a pair of electrodes provided therein and a sealing portion formed at an end of the light-emitting portion. In the light-transmitting insulating tube which is a material of the arc tube, a portion where the light-emitting portion is formed is set as a light-emitting portion forming portion, and a laser beam is locally applied to a devitrified portion generated on the surface of the light-emitting portion forming portion. To heat the devitrified portion.
[0010]
Thereby, it is possible to locally heat the devitrified portion generated on the surface or the surface layer portion of the portion where the light emitting portion is to be formed, to transition from the crystalline state to the glass state through the supercooled liquid state, and to remove the devitrified portion. The effect is possible.
<Solution 2>
Furthermore, in addition to the contents described in the first solution, while rotating the light-transmitting insulating tube around the tube axis of the light-transmitting insulating tube, the irradiation area of the laser beam is moved along the tube axis. It may be moved.
[0011]
Thereby, compared to the case where the irradiation area of the laser beam is fixed, there is an effect that it is possible to prevent the same temperature from being maintained for a long time, and to prevent the devitrification from occurring again. Further, there is an effect that it is possible to remove a devitrified portion generated on a surface or a surface layer portion of a light emitting portion forming scheduled portion over a wide range.
<Solution 3>
In order to solve the above-described problem, a devitrification removing method for an arc tube according to the present invention includes a light-emitting portion having a pair of electrodes provided therein and a sealing portion formed at an end of the light-emitting portion. In the arc tube, the devitrified portion generated on the surface of the light emitting portion is locally irradiated with a laser beam to heat the devitrified portion.
[0012]
Thus, the same effect as described in the first solution can be obtained for the arc tube instead of the light-transmitting insulating tube.
Furthermore, compared to the case where the devitrified portion is heated using a burner, the heating range can be reduced, the spread of heat on the arc tube surface can be suppressed, and the amount of heat given to the light emitting portion can be suppressed. . In particular, the interior of the light emitting part where the devitrified part occurs is at a high pressure, and when the devitrified part is heated using a burner, deformation or damage occurs in the light emitting part due to thermal expansion of the sealed gas sealed inside. Cheap. In this regard, heating the devitrified portion using a laser can suppress the thermal expansion of the sealed gas sealed inside, making it less likely that deformation or damage will occur in the light emitting portion. is there.
[0013]
<Solution 4>
Furthermore, in addition to the contents described in the solution means 3, the laser beam irradiation area may be moved along the tube axis while rotating the arc tube around the tube axis of the arc tube. .
Thus, the same effect as described in the solution 2 can be obtained for the arc tube instead of the translucent insulating tube.
[0014]
<Solution 5>
In order to solve the above-described problem, a method for manufacturing an arc tube according to the present invention includes an arc tube having a light emitting portion having a pair of electrodes provided therein and a sealing portion formed at an end of the light emitting portion. In the light-transmitting insulating tube that is a material of the arc tube, a portion where the light emitting portion is formed is a light emitting portion forming scheduled portion, and a portion where the sealing portion is formed is a sealing portion. As a formation scheduled portion, a portion located at a boundary between the light emitting portion formation scheduled portion and the sealing portion formation scheduled portion as a boundary portion, an electrode body having the electrode is inserted into the sealing portion formation scheduled portion, After the boundary portion is melt-sealed, the remaining portion of the sealing portion formation scheduled portion is melt-sealed, and the devitrification generated on the surface of the light emitting portion formation portion when the boundary portion is melt-sealed. A laser beam is locally applied to the portion to heat the devitrified portion. .
[0015]
This has the same effect as the effect described in the first solution.
Furthermore, by sealing the remaining portion with a burner, and heating and removing the devitrified portion using a laser, after the sealed portion is formed, compared with the case where the devitrified portion is removed, This has the effect that the time required for manufacturing can be reduced.
In addition, compared to the case where the devitrified portion is removed using hydrofluoric acid, the arc tube is cooled and then immersed in hydrofluoric acid, so that the step of cleaning is not required. There is an effect that the time until manufacturing can be reduced.
[0016]
<Solution 6>
In order to solve the above-described problem, a method for manufacturing an arc tube according to the present invention includes an arc tube having a light emitting portion having a pair of electrodes provided therein and a sealing portion formed at an end of the light emitting portion. In the light-transmitting insulating tube that is a material of the arc tube, a portion where the light emitting portion is formed is a light emitting portion forming scheduled portion, and a portion where the sealing portion is formed is a sealing portion. As a formation scheduled portion, a portion located at a boundary between the light emitting portion formation scheduled portion and the sealing portion formation scheduled portion as a boundary portion, an electrode body having the electrode is inserted into the sealing portion formation scheduled portion, The boundary portion is melt-sealed, and after the sealing portion is formed by melting and sealing the remaining portion of the portion where the sealing portion is to be formed, the light-emitting portion is scheduled to be formed when the boundary portion is melt-sealed. A laser beam is locally applied to the devitrified portion generated on the surface of the portion to add the devitrified portion. To be.
[0017]
This has the same effect as the effect described in the first solution.
<Solution 7>
Furthermore, in addition to the contents described in the solution 5 or 6, while rotating the light-transmitting insulating tube around the tube axis of the light-transmitting insulating tube, the irradiation area of the laser beam is moved to the tube axis. It may be moved along.
[0018]
This has the same effect as the effect described in the second solution.
<Solution 8>
In order to solve the above-described problem, a method for manufacturing an arc tube according to the present invention includes an arc tube having a light emitting portion having a pair of electrodes provided therein and a sealing portion formed at an end of the light emitting portion. After the sealing portion is formed, a laser beam is locally applied to a devitrification portion generated on a surface of the light emitting portion when a portion where the sealing portion is formed is melt-sealed. And the devitrified portion is heated.
[0019]
This has the same effect as the effect described in Solution 3.
<Solution 9>
Furthermore, in addition to the contents described in the solution 8, the irradiation region of the laser beam may be moved along the tube axis while rotating the arc tube around the tube axis of the arc tube. .
[0020]
This has the same effect as the effect described in the solution 4.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
<Discharge lamp>
FIG. 1A is a cutaway perspective view showing a configuration of a discharge lamp using an arc tube as a light source according to an embodiment of the present invention, and FIG. 1B shows a structure of the arc tube as a light source of the discharge lamp. FIG.
[0022]
As shown in FIG. 1A, the discharge lamp 100 is configured such that an arc tube 110 having a cap 101 mounted on one sealing portion is attached to a neck portion of a reflecting mirror 103 via a spacer 102. ing. Then, current is supplied to the electrode of the arc tube 110 via the lead wire 104 drawn out through the through hole 106 provided in the reflecting mirror 103 and the terminal 105.
[0023]
The position of the discharge arc of the arc tube 110 is adjusted to a position that coincides with the optical axis of the reflecting mirror 103.
<Emission tube>
As shown in FIG. 1B, the arc tube 110 incorporated in the discharge lamp includes a spheroidal light emitting portion 121, cylindrical sealing portions 131 and 141, and electrode members 151 and 161. You.
[0024]
In the light emitting section 121, electrodes 152 and 162 are arranged in an internal discharge space 122 so as to face each other, and mercury, a metal halide, an inert gas, and the like are sealed therein.
The sealing portion 131 is formed by inserting the electrode body 151 into a portion where a sealing portion 131 is to be formed in the straight tubular light-transmitting insulating tube before being formed on the arc tube 110. It is formed by sealing (for example, shrink sealing) a portion where a stop portion is to be formed. In addition, the sealing portion 141 is formed similarly to the sealing portion 131.
[0025]
Here, shrink sealing refers to shrinking a portion of the evacuated tube 110, which has been evacuated and which has been softened by heating the portion for forming the sealing portion, by shrinking the portion at atmospheric pressure to seal the portion.
In addition, a quartz glass, a borosilicate glass, etc. are mentioned as a translucent insulating tube.
The electrode body 151 is configured by joining a tungsten electrode 152 having a coil formed on an electrode shaft 153, a metal foil 154 such as a molybdenum foil, and a lead wire 155 such as a molybdenum wire. The electrode body 161 has the same configuration as the electrode body 151.
[0026]
<Method of manufacturing arc tube>
2 to 5 are schematic diagrams illustrating a method for manufacturing the arc tube according to the embodiment.
As shown in FIGS. 2 to 5, the arc tube 110 is manufactured through a first sealing step and a second sealing step.
<Sealing device>
Here, before describing the method of manufacturing the arc tube 110, a sealing device (not shown) used for manufacturing the arc tube will be briefly described.
[0027]
The sealing device used when manufacturing the arc tube 110 includes a support unit, a rotating unit, an exhaust unit, a sealing unit, a cooling unit, a blowing unit, a blowing unit, an irradiation unit, a control unit, and the like.
The support section supports the light-transmitting insulating tube 111 by sandwiching both ends of the light-transmitting insulating tube 111 shown in FIG.
The rotating unit rotates the light-transmitting insulating tube 111 at a constant speed (for example, 140 rpm) around a tube axis (hereinafter, referred to as a rotation axis) of the light-transmitting insulating tube 111 supported by the support unit.
[0028]
The exhaust unit exhausts the gas inside the light-transmitting insulating tube 111 through the opening 113 or the opening 114 of the light-transmitting insulating tube 111.
The sealing portion seals mercury, a metal halide, an inert gas, and the like into the inside of the light-transmitting insulating tube 111 through the opening 113 or the opening 114 of the light-transmitting insulating tube 111.
[0029]
The cooling unit cools the light emitting unit formation scheduled portion 125 using a cooling medium such as liquid nitrogen.
The blower blows nitrogen or air onto the light-transmitting insulating tube 111 to cool the light-transmitting insulating tube 111.
As shown in FIG. 3 (a) or FIG. 4 (b), the ejection portion ignites a combustible gas such as oxygen-hydrogen or propane, and moves along the rotation axis to form a sealing portion. It is ejected to the portion 135 or the portion 145 to be formed with a sealing portion.
[0030]
The irradiating unit reflects the laser beam oscillated from the laser oscillation source 181 by the reflecting mirrors 182 and 183 and condenses the reflected laser beam as shown in FIG. 3B or 5B. The light is condensed by a lens 184 and irradiated with a laser beam. Further, by moving the reflecting mirror 183 and the condensing lens 184 along the rotation axis direction, the irradiation area of the laser beam is moved, and as shown in FIG. 3A or FIG. As shown in FIG. 3B or FIG. 5B, the devitrification part 123 or the devitrification part 124 is irradiated. Hereinafter, the irradiation unit is simply referred to as a laser.
[0031]
Note that the laser oscillation source 181 includes an infrared laser, a glass laser, a carbon dioxide laser, and the like.
The control unit controls operations of the support unit, the rotating unit, the exhaust unit, the sealing unit, the cooling unit, the blowing unit, the ejection unit, and the irradiation unit.
A method for manufacturing the arc tube 110 using the sealing device configured as described above will be described.
[0032]
<Light emitting part forming scheduled part forming step>
As shown in FIG. 2A, the central part of the light-transmitting insulating tube 111, which is the material of the arc tube 110, is softened by heating with a burner (procedure 1-1). One opening 113 (or opening 114) is temporarily closed (procedure 1-2). Subsequently, an inert gas is blown into the light-transmitting insulating tube 111 from the other opening 114 (or the opening 113) (step 1-3), and the portion softened by the pressure of the blown inert gas is expanded. (Procedure 1-4). Then, a mold is pressed against the swollen portion, and the portion is formed into a spheroidal shape, thereby forming the light emitting portion forming scheduled portion 125 (step 1-5).
[0033]
<First sealing step>
As shown in FIG. 2B, in a state where the light-transmitting insulating tube 111 on which the light-emitting portion forming scheduled portion 125 is formed is vertically set, a sealing portion is formed from the opening 113 of the light-transmitting insulating tube 111. The electrode body 151 is inserted into the scheduled portion 135 (procedure 2-1), and both ends are sandwiched between the chucks 171 and 172 to hold the translucent insulating tube 111 (procedure 2-2).
[0034]
The electrode body 151 is assembled by previously integrating the electrode 152, the metal foil 154, and the lead wire 155, and a hexagonal spring 173 is attached to the end of the lead wire 155 of the electrode body 151. I have. Then, a part of the hexagonal spring 173 presses against the inner surface of the upper part of the portion 135 to be formed with the sealing portion, and the elastic body of the spring 173 places the electrode body at a predetermined position in the portion 135 to be formed. 151 is held.
[0035]
As shown in FIG. 3A, after inserting the electrode body 151 into the portion 135 to be formed with the sealing portion, the light-transmitting insulating tube 111 is rotated by the rotating portion (step 2-3). Then, while rotating the light-transmitting insulating tube 111, the boundary portion 136 located at the boundary between the light-emitting portion forming scheduled portion 125 and the sealing portion forming scheduled portion 135 is heated by using the burner 175 and the laser 176 together. Soften (procedure 2-4). Then, the boundary portion 136 is shrink-sealed while being softened (procedure 2-5).
[0036]
As can be seen from a graph 191 shown on the left side of FIG. 3A, when the laser beam is locally heated, the melting point is reached in the laser beam irradiation region, while the laser beam irradiation region is heated. At a position slightly deviated from the region, the temperature falls within the devitrification temperature range, and devitrification occurs. Hereinafter, a range in which devitrification easily occurs is referred to as a devitrification range.
Here, the devitrification temperature range refers to a temperature range in which devitrification is likely to occur, and a high temperature close to the softening point and a viscosity of 10 ° C. ⁴ It refers to a temperature range of about Poise (P).
[0037]
At the time of sealing, the inside of the light-transmitting insulating tube 111 is filled with an inert gas such as an argon gas.
As seen in FIG. 3B, after the boundary 136 is sealed or during the sealing, the burner 175 is continuously moved toward the opening 113 (procedure 2-6a). Is used to sequentially heat and soften the remaining portion 137 (procedure 2-7a). Then, the remaining portion 137 is shrink-sealed while being softened (procedure 2-8a).
[0038]
On the other hand, the use of the laser 176 is temporarily stopped (procedure 2-6b), and when the boundary portion 136 is sealed, the laser beam is applied to the devitrified portion 123 generated on the surface or the surface layer of the light emitting portion forming scheduled portion 125. Is moved (procedure 2-7b). The irradiation area of the laser beam extends from a position below the center of the light-emitting unit forming section 125 toward the boundary 136 or from the boundary 136 to a position below the center of the light-emitting unit forming section 125. Is gradually moved, and the devitrification part 123 is locally heated and removed using the laser 176 (procedure 2-8b).
[0039]
Note that, when the devitrification part 123 is locally heated and removed using the laser 176, the irradiation may be performed while moving the irradiation area of the laser beam up and down.
As described above, the remaining portion 137 is sealed, the devitrified portion 123 is removed, and the sealing portion 131 is formed. Then, nitrogen or air is blown from the blowing unit to cool the sealing unit 131.
[0040]
<Second sealing step>
As shown in FIG. 4A, the light-transmitting insulating tube 111 on which the sealing portion 131 is formed is turned upside down, and the light-transmitting insulating tube 111 is positioned such that the sealing portion 131 is located on the lower side. In a state of standing vertically, both ends are sandwiched between the chucks 171 and 172 to hold the translucent insulating tube 111 (step 3-1).
[0041]
As shown in FIG. 4 (b), after filling an enclosure such as mercury from the opening 114 of the light-transmitting insulating tube 111 (procedure 3-2), the procedure 2-1 described in the first sealing step. A procedure similar to the procedure 2-3 to the procedure 2-5 is performed to seal the boundary part 146 located at the boundary between the light emitting part formation scheduled part 125 and the sealing part formation scheduled part 145.
Here, in the second sealing step, as compared with the first sealing step, the filling material such as mercury sealed in the light emitting part formation scheduled portion 125 is formed under the light emitting part formation scheduled part 125 so as not to vaporize. The difference is that the side or the sealing portion 131 is cooled with liquid nitrogen (procedure 3-3).
[0042]
In addition, as can be seen from the graph 192 shown on the left side of FIG. 4B, by cooling with liquid nitrogen, the temperature gradient is further increased and the devitrification range is reduced as compared with the first sealing step. It gets even bigger.
As shown in FIG. 5A, the same procedure as the procedure 2-6a to the procedure 2-8a and the procedure 2-6b described in the first sealing step is performed, and the remaining portion 147 is sealed. The sealing part 141 is formed.
[0043]
Here, the second sealing step is different from the first sealing step in that the procedure 2-8b described in the first sealing step is not performed.
As described above, the sealing portions 131 and 141 are formed, and the light emitting portion 121 is formed.
As shown in FIG. 5B, after the sealing portion 141 is formed, the arc tube is slightly lifted up, and when the boundary portion 146 is sealed, the light emitting tube is formed on the surface or the surface layer of the light emitting portion forming scheduled portion 125. The same procedure as the procedure 2-7b is performed on the devitrified portion 124. Then, while gradually moving the laser beam irradiation area from a position below the center of the light emitting unit 121 to the boundary 146 or from the boundary 146 to a position below the center of the light emitting unit 121. Then, the devitrification part 124 is locally heated and removed using a laser 176 (step 3-4).
[0044]
At this time, the devitrification part 124 is irradiated using the laser 176 under the same conditions as when the devitrification part 123 is locally heated and removed.
As described above, the devitrification part 124 is removed, and both ends of the light-transmitting insulating tube 111 are cut off, so that the arc tube 110 as shown in FIG. 1B is manufactured. Thereafter, the base 101 and the like are attached to the arc tube 110, and the discharge lamp 100 is manufactured.
[0045]
<Specific examples>
Here, when the light emitting tube 110 having a spheroidal light emitting portion 121 having a length of 10 mm and a maximum outer diameter of 10 mm and cylindrical sealing portions 131 and 141 having a length of 25 mm and an outer diameter of 6 mm is formed. Will be described as an example.
In addition, a quartz glass tube is used for the translucent insulating tube 111 which is a material of the arc tube 110, and a carbon dioxide laser which is easily absorbed by quartz is used for the laser 176.
[0046]
The output of the carbon dioxide laser is 90 W to 110 W, and the beam spot diameter is φ3 to φ6.
In step 2-4, the irradiation area of the laser beam is fixed for 20 seconds, and the boundary 136 is irradiated. At this time, the boundary 136 is heated to about 2000 ° C.
[0047]
In procedure 2-8b, first, the irradiation area of the laser beam is fixed for 2.5 seconds, and the lower side of the light emitting portion formation scheduled portion 125 is irradiated slightly. Thereafter, while gradually moving the irradiation area of the laser beam along the rotation axis, the irradiation range is 7.3 mm at a speed of 0.32 mm / sec from a slightly lower side of the light emitting portion formation planned portion toward the boundary portion 136. (A range including the devitrification portion 123). At this time, the devitrification part 123 is heated to 1500 to 1600 ° C.
[0048]
Actually, as a result of performing step 2-8b, the inventors and others confirmed that the devitrified portion 123 generated on the surface or the surface layer of the light emitting portion formation scheduled portion 125 in step 2-4 was removed cleanly.
<Summary>
FIG. 6A is a schematic diagram illustrating a state change of the devitrified portion when sealing the boundary portion, and FIG. 6B is a schematic diagram illustrating a state change of the devitrified portion when removing the devitrified portion. FIG. In the figure, T _m Indicates a melting point, and T _g Indicates the glass transition temperature.
[0049]
As shown in FIG. 6 (a), when sealing the boundary portion, when the irradiation area of the laser beam is fixed for a predetermined time and locally heated, the state changes from the glass state to the supercooled liquid state to the liquid state. Transfer. Further, in the laser beam irradiation area, the melting point is reached, and the state changes from a glass state to a liquid state through a supercooled liquid state. However, in the devitrification range slightly deviating from the laser beam irradiation region, the temperature reaches a high temperature close to the softening point, the time for staying within the devitrification temperature range becomes longer, and crystals are deposited. And it is assumed that it is cooled as it is and changes to a crystalline state, and a devitrified part is generated.
[0050]
As shown in FIG. 6 (b), when the devitrified portion is removed, when the region is locally heated while moving the irradiation region of the laser beam along the tube axis of the translucent insulating tube, the liquid state is changed from the liquid state. Transforms to a glassy state via a supercooled liquid state. Further, as the irradiation area of the laser beam approaches, the temperature of the devitrified portion gradually rises, and the state changes from a crystalline state to a liquid state. Further, as the distance increases, the temperature of the devitrification portion gradually decreases, and the liquid crystal passes through the devitrification temperature range in a short time, and changes from a liquid state to a supercooled liquid state. And it is assumed that it is cooled as it is and changes to a glass state, and the devitrification part is removed.
[0051]
<Others>
In place of the light-transmitting insulating tube 111 formed in the light-emitting portion forming scheduled portion forming step, a lost wax method, a powder press molding method, an extrusion press molding method, a freeze molding method, an injection molding method, or a gel molding method is used. The luminous tube 110 may be manufactured by using the light-transmitting insulating tube 111 formed in advance including the luminous portion forming scheduled portion 125 in advance.
[0052]
Note that the sealing device may separately include a laser used for sealing the boundary portion and a laser used for removing the devitrified portion. Also, different types of lasers may be used.
Although the shape of the light emitting portion 121 has been described as a spheroidal shape, the light emitting portion 121 may have a spherical shape or the like, and it goes without saying that the shape is not particularly limited.
[0053]
Note that the beam spot diameter of the laser 176 may be specified based on the outer diameter of the sealing portion 131 or 141. For example, the devitrification may be removed at a beam spot diameter that is optimized when sealing, with the outer diameter being in the range of the outer diameter / 2 to the outer diameter.
Note that the laser 176 may be a continuous wave laser or a pulsed laser.
[0054]
Note that, instead of performing the procedure 2-8b while sealing the remaining portion 137, the procedure 2-8b may be performed after the sealing portion 131 is formed.
When removing the devitrified portion 124 generated in the second sealing step in step 3-4 without performing step 2-8b, the devitrified portion 123 generated in the first sealing step is also removed. It may be removed.
[0055]
In addition, the devitrification removal method shown in the procedure 2-8b or the procedure 3-4 may be separated from the arc tube manufacturing method and may be a single step. Then, the method is applied to a devitrified portion generated in a manufactured arc tube or a devitrified portion generated in a light-transmitting insulating tube, which is a material of an arc tube before being manufactured, to remove the devitrified portion. It may be.
The devitrified portion may be caused by various causes, such as the formation of quartz that has become steam when the quartz glass tube is heated, which is attached to a low-temperature portion, or the transition from a glassy state to a crystalline state. . Further, the problem is not a problem peculiar to a small discharge lamp, and is similarly formed in a large discharge lamp.
[0056]
FIG. 7 is an external view showing a configuration of a large discharge lamp as an example.
As shown in the figure, even in a large-sized discharge lamp 200 in which a base 202 is attached to an end of an outer tube 201, a slight devitrification portion is formed on the surface of the arc tube 210 covered by the outer tube 201. Therefore, the devitrification part generated in the arc tube 210 may be removed by using the devitrification removal method described in the procedure 2-8b or the procedure 3-4.
[0057]
【The invention's effect】
As described above, the devitrification removing method of the arc tube and the manufacturing method according to the present invention are characterized in that the devitrification portion generated on the surface or the surface layer of the light emitting portion is locally irradiated with a laser beam, Heat. At this time, while rotating the light-transmitting insulating tube around the tube axis of the light-transmitting insulating tube, the irradiation area of the laser beam is moved along the tube axis to crystallize the devitrified portion. The state changes from a state to a glass state through a supercooled liquid state.
[0058]
As a result, with the miniaturization of the arc tube, for example, by locally heating the boundary using a local heating means such as a laser or a pen silverer, the loss generated on the surface or surface layer of the light emitting unit The transparent part can be removed. As a result, the ratio of the devitrification portion to the surface area of the light-emitting portion increases as the size of the arc tube decreases, and it is possible to solve the problem that optical loss occurs.
[Brief description of the drawings]
FIG. 1A is a cutaway perspective view showing a configuration of a discharge lamp using an arc tube as a light source according to an embodiment of the present invention, and FIG. 1B is a structure of the arc tube as a light source of the discharge lamp. FIG.
FIG. 2 is a first schematic view illustrating a method for manufacturing the arc tube in the embodiment.
FIG. 3 is a second schematic diagram illustrating the method for manufacturing the arc tube in the embodiment.
FIG. 4 is a third schematic diagram illustrating the method for manufacturing the arc tube in the embodiment.
FIG. 5 is a fourth schematic diagram showing the method for manufacturing the arc tube in the embodiment.
FIG. 6A is a schematic diagram showing a state change of a devitrified portion when sealing a boundary portion, and FIG. 6B is a schematic diagram showing a state change of a devitrified portion when removing a devitrified portion. FIG.
FIG. 7 is an external view showing a configuration of a large discharge lamp as an example.
FIG. 8 is a schematic view showing, as an example, the structure of an arc tube incorporated in a conventional small discharge lamp.
[Explanation of symbols]
100 discharge lamp
101 base
102 Spacer
103 Reflector
104 Lead wire
105 terminal
106 through hole
10,110 arc tube
11,111 translucent insulating tube
113,114 opening
21, 121 light emitting unit
22,122 discharge space
23, 24, 123, 124 devitrification part
125 Emitting part to be formed
131, 141 sealing part
135, 145 Sealing part formation scheduled part
36,46,136,146 border
137,147 Remaining part
38,48 root
151,161 electrode body
152,162 electrodes
153,163 Electrode axis
154,164 metal foil
155,165 lead wire
171,172 Chuck
173,174 spring
175 burner
176 laser
181 Laser oscillation source
182,183 Reflector
184 condenser lens
200 discharge lamp
201 outer tube
202 base
210 arc tube

Claims

A light-transmitting insulating tube that is a material of a light-emitting tube having a light-emitting portion having a pair of electrodes provided therein and a sealing portion formed at an end of the light-emitting portion, in which the light-emitting portion is formed; As a light-emitting part formation scheduled part,
A devitrification removing method for an arc tube, comprising locally irradiating a laser beam to a devitrified portion generated on a surface of a portion where the light emitting portion is to be formed, and heating the devitrified portion.

The laser beam irradiation area is moved along the tube axis while rotating the light-transmitting insulating tube around a tube axis of the light-transmitting insulating tube. A method for removing devitrification of an arc tube.

In a light emitting tube having a light emitting portion having a pair of electrodes provided therein and a sealing portion formed at an end of the light emitting portion,
A devitrification removing method for an arc tube, wherein a laser beam is locally applied to a devitrified portion generated on a surface of the light emitting portion to heat the devitrified portion.

4. The devitrification removal of the arc tube according to claim 3, wherein the laser beam irradiation area is moved along the tube axis while rotating the arc tube around the tube axis of the arc tube. 5. Method.

A method for manufacturing a light emitting tube having a light emitting portion having a pair of electrodes provided therein and a sealing portion formed at an end of the light emitting portion,
In the light-transmitting insulating tube, which is a material of the arc tube, a portion where the light emitting portion is formed is a scheduled light emitting portion formation portion, and a portion where the sealing portion is formed is a scheduled sealing portion formation scheduled portion, A portion located at the boundary between the portion formation scheduled portion and the sealing portion formation scheduled portion as a boundary portion,
After inserting the electrode body having the electrode into the portion where the sealing portion is to be formed, and melting and sealing the boundary portion,
Along with melting and sealing the remaining portion of the portion where the sealing portion is to be formed,
An arc tube characterized by locally irradiating a laser beam to a devitrified portion formed on the surface of the portion where the light emitting portion is to be formed when the boundary portion is melt-sealed, thereby heating the devitrified portion. Manufacturing method.

A method for manufacturing a light emitting tube having a light emitting portion having a pair of electrodes provided therein and a sealing portion formed at an end of the light emitting portion,
In the light-transmitting insulating tube, which is a material of the arc tube, a portion where the light emitting portion is formed is a scheduled light emitting portion formation portion, and a portion where the sealing portion is formed is a scheduled sealing portion formation scheduled portion, A portion located at the boundary between the portion formation scheduled portion and the sealing portion formation scheduled portion as a boundary portion,
An electrode body having the electrode is inserted into the portion where the sealing portion is to be formed, the boundary portion is melt-sealed, and the remaining portion of the portion where the sealing portion is to be formed is melt-sealed to form the sealing portion. After that,
An arc tube characterized by locally irradiating a laser beam to a devitrified portion formed on the surface of the portion where the light emitting portion is to be formed when the boundary portion is melt-sealed, thereby heating the devitrified portion. Manufacturing method.

The laser beam irradiation area is moved along the tube axis while rotating the light-transmitting insulating tube around a tube axis of the light-transmitting insulating tube. A method for manufacturing the arc tube according to the above.

A method for manufacturing a light emitting tube having a light emitting portion having a pair of electrodes provided therein and a sealing portion formed at an end of the light emitting portion,
After the sealing portion is formed, a laser beam is locally applied to the devitrification portion generated on the surface of the light emitting portion when the portion where the sealing portion is formed is melt-sealed, A method for manufacturing an arc tube, comprising heating a devitrified portion.

The method for manufacturing an arc tube according to claim 8, wherein the laser beam irradiation region is moved along the tube axis while rotating the arc tube around the tube axis of the arc tube.

An arc tube manufactured by the manufacturing method according to claim 5.

A discharge lamp using, as a light source, an arc tube manufactured by the manufacturing method according to claim 5.

A discharge lamp comprising an arc tube and a reflector, wherein the arc tube is an arc tube manufactured by the manufacturing method according to claim 5.

A manufacturing method according to any one of claims 5 to 9, wherein the discharge lamp includes an arc tube, an outer tube covering the arc tube, and a base attached to an end of the outer tube. A discharge lamp characterized in that it is an arc tube manufactured by: