JP2004171998A

JP2004171998A - Color cathode-ray tube

Info

Publication number: JP2004171998A
Application number: JP2002338042A
Authority: JP
Inventors: Takuya Mashita; 拓也真下; Toru Takahashi; 亨高橋; Hiroyuki Oda; 裕之織田; Takeshi Nakayama; 剛士中山
Original assignee: Toshiba Corp
Current assignee: Toshiba Corp
Priority date: 2002-11-21
Filing date: 2002-11-21
Publication date: 2004-06-17

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color cathode-ray tube having sufficient mask curved-surface strength and providing good image quality by reducing a positional displacement between a main mask and an auxiliary mask. <P>SOLUTION: A shadow mask 7 is formed by superimposing a main mask 14 and an auxiliary mask 20 on each other. The main mask faces approximately the overall surface of a phosphor screen, and has a porous portion approximately in a rectangle in which a lot of electron beam passing holes are formed. The auxiliary mask is superimposed/fixed on/to the porous portion of the main mask, and has a porous portion which has a lot of electron beam passing holes corresponding to the electron beam passing holes of the main mask, respectively. The main mask and the auxiliary mask are welded to each other at a lot of welding points. The welding points are located from one end to the other end of the porous portion of the auxiliary mask and form a plurality of lines of welding points. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
この発明は、シャドウマスクを備えたカラー陰極線管、およびその製造方法に関する。
【０００２】
【従来の技術】
一般に、カラー陰極線管は、内面に蛍光体スクリーンが形成されたパネルを有する外囲器と、この外囲器内で蛍光体スクリーンに対向して設けられたほぼ矩形状のシャドウマスクと、を備えている。シャドウマスクの蛍光体スクリーンと対向する有孔面には、電子ビーム通過孔として多数の開孔が所定の配列で形成されている。そして、シャドウマスクは、各開孔により電子銃から放出された３電子ビームを選別し、蛍光体スクリーンを構成する３色蛍光体層に入射させる機能を備えている。
【０００３】
近年、外光反射が少なく且つ画像歪を軽減して視認性を高めるため、カラー陰極線管のパネル外面の曲率半径を１０，０００ｍｍ以上と実質的に平坦としたフラット管が主流となりつつある。通常、蛍光体スクリーンと対向するシャドウマスクの有孔面は、パネルの内面形状に対応した形状に形成されている。そのため、フラット管のシャドウマスクは、従来のカラー陰極線管に対して曲率が小さくなり、ほぼ平坦化している。
【０００４】
ところが、このような曲率の小さなシャドウマスクを用いた場合、以下の問題が生じる。
通常、シャドウマスクは板厚が０．２ｍｍ程度の金属板によって形成されている。このような薄板で形成された大画面用のシャドウマスクは、有孔面の曲率が小さい場合、自重または外力によって変形し、マスク曲面を維持することが難しい。すなわち、有孔面の曲率を小さくすると、マスク曲面の保持力（以下、マスク曲面強度）が低下する。特に、マスク曲面強度の低下は有孔面中心すなわち画面センター近傍が最も顕著となる。
【０００５】
そして、マスク曲面強度が低い場合、製造中、あるいは輸送中の微小な外力によってシャドウマスクの有孔面が変形してしまう。この場合、シャドウマスクの電子ビーム通過孔とパネル内面との距離関係が変動し、電子銃から放出された電子ビームが所定の蛍光体層にランディングせず、色ずれの原因となる。
【０００６】
また、マスク曲面強度の低下は、シャドウマスクが変形まで到達しないまでも、テレビジョンセットに組み込んだ際、音声などの振動により、マスク有孔面が共振しやすくなり、画面上に不要な明暗を映し出してしまう。
【０００７】
このような問題を解決する手段として、補助マスクによりシャドウマスクのマスク曲面強度を向上させる試みがなされている。例えば、特許文献１に開示されたカラー陰極線管によれば、シャドウマスクは、蛍光体スクリーンのほぼ全体に対応する主マスクと、帯状の補助マスクとを有し、補助マスクは主マスクの短軸を含む領域に重ねて設けられている。補助マスクを主マスクに固定することにより、フラット化および高解像度化に伴うマスク曲面強度の劣化を防ぐことができる。従って、外力によるマスク曲面の変形を防止し、色ずれを防ぐことが可能となる。
【０００８】
【特許文献１】
特開２００２−１９７９８９号公報
【０００９】
【発明が解決しようとする課題】
このような主マスクとこれに重ねた補助マスクとを有したシャドウマスクでは、主マスクと補助マスクとの固定の度合い（以下、貼り合せ強度と称する）が低いと、両者の密着度が低下してマスク曲面強度の向上を図ることが困難となる。
【００１０】
また、貼り合せ強度が低いと、製造中あるいは輸送中に外力が加わった際、主マスクに対して補助マスクがずれてしまう。すると、主マスクの電子ビーム通過孔と補助マスクの電子ビーム通過孔とにずれが生じて、補助マスクが主マスクの電子ビーム通過孔である開孔を狭めたり、場合によっては閉じてしまう。この場合、開孔を通過する電子ビームが減少し、蛍光体スクリーンの発光が低下する。その結果、部分的に画像の輝度が低下してしまうという問題が生じる。
【００１１】
一方、シャドウマスクに最も外力が加わるのは、シャドウマスクをプレス成形により曲面状に成形する製造工程時である。そのため、補助マスクのずれを防止するには、主マスクおよび補助マスクをそれぞれプレス成形した後、互いに貼り合せことが望ましい。しかしながら、各マスクに形成された多数の開孔を完全に一致させる必要があるため、主マスクおよび補助マスクを高い精度で位置合わせすることが要求され、曲面形状に成形されたマスク同士の位置合わせは極めて困難となる。したがって、平坦な主マスクおよび補助マスクを貼り合せた後、プレス成形により曲面状に成形しなければならない。
【００１２】
また、特許文献１のように主マスクと補助マスクとの形状が大きく異なる場合、主マスクと補助マスクとがほぼ同一形状の場合に比べ、プレス成形するときに各マスクに加わる力が大きく相違する。そのため、プレス成形に伴う補助マスクの位置ずれを防止するためには、貼り合せ強度を一層高くする必要がある。
【００１３】
この発明は以上の点に鑑みなされたもので、その目的は、十分なマスク曲面強度を有しているとともに主マスクと補助マスクとの位置ずれを抑制し、良好な画像品位を有したカラー陰極線管を提供することにある。
【００１４】
【課題を解決するための手段】
上記目的を達成するため、この発明の態様に係るカラー陰極線管は、内面に蛍光体スクリーンが設けられたパネルと、上記蛍光体スクリーンに向かって電子ビームを放出する電子銃と、上記パネルの内側に上記蛍光体スクリーンと対向して配置されているとともに、互いに直交しているとともに管軸と直交した長軸および短軸を有したほぼ矩形状のシャドウマスクと、を備え、
上記シャドウマスクは、上記蛍光体スクリーンのほぼ全面と対向しているとともに多数の電子ビーム通過孔が形成されたほぼ矩形状の有孔部を有する主マスクと、上記主マスクの短軸を含む領域に重ねて固定されているとともに上記短軸方向を長手方向とした帯状の補助マスクと、を備えている。
上記補助マスクは、上記主マスクの有孔部に重ねて固定されているとともに上記主マスクの電子ビーム通過孔に対応した多数の電子ビーム通過孔を有する有孔部を備え、上記主マスクおよび補助マスクは多数の溶接点で溶接され、上記溶接点は、上記補助マスクの有孔部の一端から他端まで列状に配置され、複数の溶接点列を形成している。
【００１５】
上記構成のカラー陰極線管によれば、溶接点列に対して垂直な方向に生じる外力に対して貼り合せ強度が強く、主マスクと補助マスクのズレを抑制することができる。
【００１６】
また、この発明の形態に係るカラー陰極線管によれば、補助マスクは、主マスクの有孔部に重ねて固定されているとともに上記主マスクの電子ビーム通過孔に対応した多数の電子ビーム通過孔を有する有孔部と、有孔部の短軸方向両端から延出し、上記主マスクの無孔部およびスカート部にそれぞれ重ねて固定された無孔部およびスカート部と、を備え、補助マスクの無孔部およびスカート部の少なくとも一方は、上記主マスクの無孔部およびスカート部の少なくとも一方に複数の溶接点で溶接され、上記長軸方向の溶接点間隔が上記短軸方向の溶接点間隔よりも短いことを特徴としている。
【００１７】
【発明の実施の形態】
以下図面を参照しながら、この発明の実施の形態に係るカラー陰極線管について詳細に説明する。
図１および図２に示すように、カラー陰極線管はガラスで形成された外囲器９を備え、この外囲器は、周縁部にスカート部２を有した矩形状のパネル１と、パネル１のスカート部２に接合されたファンネル３と、ファンネル３の小径部から伸びたネック４とを有している。パネル１の外面は、曲率半径が１００，０００ｍｍと実質的に平坦となっている。パネル１の内面には蛍光体スクリーン５が形成されている。そして、外囲器９は、パネル１の中心およびネック４の中心を通る管軸Ｚ、管軸と直交して延びた長軸（水平軸）Ｘ、並びに、管軸および長軸と直交して延びた短軸（垂直軸）Ｙを有している。
【００１８】
外囲器９内には、色選別電極であるシャドウマスク構体６が蛍光体スクリーン５に対向して配置されている。このシャドウマスク構体６は、電子ビーム通過孔となる開孔が多数形成されたシャドウマスク７と、シャドウマスク７の周辺部が固定された断面Ｌ字形の矩形枠状のマスクフレーム８と、を有している。このシャドウマスク構体６は、マスクフレーム８の側壁に設けられた弾性支持体３０をパネル１のスカート部２に埋設されたスタッドピン３２に係止することで、パネル１の内側に支持されている。なお、シャドウマスク７に形成された電子ビーム通過孔の開孔形状は、用途に応じて矩形状または円形状に形成される。
【００１９】
ネック４内には長軸Ｘに沿ってインライン配列された３本の電子ビーム９Ｒ、９Ｇ、９Ｂを放出する電子銃１０が配置されている。そして、上記カラー陰極線管では、電子銃１０から放出された電子ビーム９Ｒ、９Ｇ、９Ｂをファンネル３の外側に取り付けられた偏向ヨーク１１により偏向し、シャドウマスク構体６を介して、蛍光体スクリーン５を水平、垂直走査することで画像を表示する。
【００２０】
次に、シャドウマスク７の構成について詳細に説明する。図３ないし図５に示すように、シャドウマスク７は、主マスク１４と、この主マスクの一部に重複して固定された補助マスク２０と、を備え、部分的に２重構造に構成されている。
【００２１】
主マスク１４は、板厚０．１５〜０．２５ｍｍの金属板で構成され、パネル１の内面と対向して配置されるとともに所定の曲面形状に形成されたほぼ矩形状のマスク主面３８と、マスク主面の周縁から管軸Ｚ方向に沿って電子銃側に延出したスカート部１７と、を一体に備えている。マスク主面３８は、電子ビーム通過孔として機能する多数の開孔１２が形成された矩形状の有孔部１３と、有効部を囲むように位置しているとともに開孔を持たないほぼ矩形枠状の無孔部１６と、を有している。
【００２２】
主マスク１４の各開孔１２は、有孔部１３の長軸Ｘ方向を幅方向とするほぼ矩形状に形成されている。そして、これらの開孔１２は、それぞれ有孔部の短軸Ｙ方向に沿って直線状に延びた開孔列が、長軸Ｘ方向に約０．４〜０．６ｍｍの配列ピッチＰＨで多数配列されるように設けられている。各開孔列は、複数個の開孔１２をブリッジ１５を介して短軸Ｙ方向にほぼ直線状に配置して構成されている。各開孔１２は、主マスク１４の蛍光体スクリーン側の表面に開口したほぼ矩形状の大孔と、電子銃側の表面に開口したほぼ矩形状の小孔と、を連通した連通孔により形成されている。
【００２３】
図３ないし図５に示すように、補助マスク２０は長い帯状に形成され、主マスク１４の外面側、つまり、蛍光体スクリーン５側の表面上で、有孔部１３の短軸Ｙを含む領域に重ねて固定されている。そして、補助マスク２０は、その長軸方向が、主マスク１４の短軸Ｙと一致して設けられている。
【００２４】
補助マスク２０は、長軸Ｘ方向に沿った幅ＬＨ１が主マスク１４の有孔部１３の長軸方向長ＬＨ２よりも小さく、また、短軸Ｙ方向に沿った長さは主マスク１４の同方向長さとほぼ等しく形成されている。補助マスク２０は、板厚０．１５〜０．２５ｍｍの金属板で構成され、電子ビーム通過孔としての多数の開孔４２が形成された有孔部２１と、有孔部２１の外側で補助マスクの長手方向両端部に位置した無孔部２３と、更に、各無孔部２３から管軸Ｚ方向へ延出した一対のスカート部２４と、を一体に備えている。有孔部２１の開孔４２は、主マスク１４の開孔１２に対応して形成されている。
【００２５】
そして、補助マスク２０は、その有孔部２１、無孔部２３、スカート部２４が主マスク１４の有孔部１３、無孔部１６およびスカート部１７とそれぞれ重なった状態で主マスクに固定されている。これにより、主マスク１４の短軸Ｙ上の領域は全て２重構造となっている。
【００２６】
図６に示すように、補助マスク２０は、多数の溶接点４６でレーザ溶接することにより、主マスク１４に固定されている。ここで、シャドウマスク７の製造工程について簡単に説明する。図７に示すように、主マスク用の平坦なマスク基材４０および補助マスク用の平坦なマスク基材４５をそれぞれ用意し、各マスク基材の有孔部に開孔を形成する。そして、これらのマスク基材を重ね合わせ、位置合わせした後、レーザ溶接により互いに固定する。
【００２７】
その後、互いに固定されたマスク基材４０、４５を同時にプレス成形する。この場合、まず、平坦な状態のマスク基材４０、４５をプレス装置の上型５０と下型５４との間に位置決めして配置する。次に、上型５０のブランクホルダ５１を下降して、ブランクホルダと下型５４のダイ５５とにより、マスク基材４０、４５の周辺部、つまり、スカート部形成部分を挟持する。
【００２８】
マスク基材４０、４５の周辺部を挟持した状態で、上型５０のポンチ５３を下降させ、マスク主面部分を所定の曲面に張り出し加工する。その後、ブランクホルダ５１とダイ５５とを離してマスク基材４０、４５の周辺部を開放する。次に、ポンチ５３とノックアウト５７を押し下げ、マスク基材４０、４５の周辺部をダイ５５とポンチ５３との隙間に引き込むことによりほぼ直角に折り曲げ、スカート部１７、２４を形成する。その後、全ての型を元に戻し、成形されたシャドウマスク７を取り出す。
【００２９】
このようなプレス成形時、シャドウマスク７に最も大きな外力が作用する。そして、シャドウマスク７を張り出して曲面を形成する際、補助マスク２０には、図８の矢印ように、有孔部２１中心に向かう長軸Ｘ方向の力と有孔部周辺に向かう短軸Ｙ方向の力が加わる。短軸Ｙから長軸Ｘ方向の距離が一定の領域では、長軸Ｘ方向に作用する力がほぼ同一となる。
【００３０】
そこで、このような外力に対する補助マスク２０の位置ずれを防止するには、図６に示すように、短軸Ｙ方向に沿って補助マスク２０の有孔部端から有孔部端まで列状に設けた溶接点４６で溶接されていることが最も有効となる。他の方法では、補助マスク２０に対して不均一な力が加わりやすく、主マスク１４に対する補助マスクの位置ずれズレを抑制することが困難となる。これは、長軸Ｘ方向、短軸Ｙ方向のいずれについても同様の効果がある。溶接点が有孔部端まで配置されていないと、補助マスク２０の位置ずれが不均一に発生することが発明者らの実験で確認された。
【００３１】
そこで、本実施の形態によれば、図６に破線で示すように、溶接点４６は、短軸Ｙ方向に延びる複数の溶接点列および長軸Ｘ方向に延びる複数の溶接点列を形成するように設けられている。短軸Ｙ方向の各溶接点列は、補助マスク２０の有孔部２１の一端から他端まで延び、長軸Ｘ方向の各溶接点列は、補助マスクの一端から他端まで、つまり、一側から他側まで延びている。なお、長軸Ｘ方向の溶接点列は、補助マスク２０の各無孔部２３およびスカート部２４にも設けられている。
【００３２】
また、溶接点列の列間隔、および各溶接点列における溶接点間隔を有孔部２１全面で一定にして主マスクおよび補助マスクを溶接し、プレス成形時の補助マスク短軸Ｙ上の位置ずれ量を測定した。その結果を図９に示す。短軸Ｙ方向に沿った補助マスク２０の有孔部幅をＨ（図６参照）すると、長軸ＸからＨ／２離れた有孔部端における補助マスクの位置ずれ量に対して、長軸ＸからＨ／３離れた位置でのずれ量は約１／４であり、補助マスク中心で位置ずれは生じなかった。
【００３３】
つまり、補助マスク２０に加わる力は、有孔部２１端で最も大きく有孔部中心で最も小さいことが判る。従って、位置ずれを抑制するためには、補助マスク２０の有孔部２１中心よりも有孔部端に溶接点４６を多く配置した方が良い。
【００３４】
そして、補助マスク２０の有孔部２１中心から短軸Ｙ方向に少なくともＨ／４離れた位置を基準とした場合、補助マスク２０の有孔部中心を通り長軸Ｘに平行な軸から短軸Ｙ方向にＨ／４以上離れた領域に設けられた溶接点列の列間隔および溶接点列の溶接点間隔を、補助マスク２０の有孔部中心を通り長軸Ｘに平行な軸から短軸Ｙ方向にＨ／４以下離れた領域に設けられた溶接列よりも短くし設定されている。また、補助マスク２０の長軸Ｘ方向に沿った幅をＷとすると、短軸Ｙから長軸Ｘ方向にＷ／４以上離れた領域の溶接点を長軸Ｘ方向にＷ／４以下離れた領域の溶接点よりも多くすることが望ましい。これは、長軸Ｘ方向、短軸Ｙ方向のどちらについても同様の効果がある。
【００３５】
また、図１０に示すように、短軸Ｙ方向に沿って延びた補助マスク２０の側縁２０ａと、短軸Ｙ方向に延びているとともに側縁２０ａに最も隣接した有孔部最外に溶接列２５との間隔をｄとし、この間隔ｄがそれぞれ１０．０ｍｍ、２．５ｍｍ、１．０ｍｍに設定されたマスクを用いて、最外領域の補助マスク２０の位置ずれ量を測定した。その結果、表１に示すように、間隔ｄが１０．０ｍｍのマスク（１）では位置ずれ量が４０μｍであったのに対し、間隔ｄが２．５ｍｍのマスク（２）、および間隔ｄが１．０ｍｍのマスク（３）では、それぞれ位置ずれ量が１０μｍ、４μｍと７５％以下にまで減少した。このことから、有孔部２１端から溶接点列までの間隔ｄが補助マスク最外領域での位置ずれに大きく影響することが確認された。そこで、有孔部２１端から距離が２．５ｍｍ以下の領域に溶接点を設けることが好ましい。
【００３６】
【表１】

【００３７】
一方、溶接点列の列間隔は２０ｍｍ以上とすると、溶接点列の間で主マスク１４と補助マスク２０とが離れてしまい、擬似的にマスク板厚を厚くすることができないことが確認された。従って、溶接点列の列間隔は２０ｍｍ以下であることが望ましい。
【００３８】
また、溶接点列における溶接点間隔については、長軸Ｘ方向に延びた溶接点列における溶接点間隔が異なる複数のシャドウマスクを用意し、プレス成形時における補助マスク２０の短軸Ｙ方向有孔部端での補助マスク２０の位置ずれ量を測定し、調査した。
【００３９】
その結果、表２に示すように、溶接点間隔が１５ｍｍのマスク（４）と７．５ｍｍのマスク（５）とでは大きな差はなく、溶接点間隔が２ｍｍのマスク（６）のとき、補助マスク２０の位置ずれ量が著しく減少した。従って、溶接点間隔は２ｍｍ以下とすることが望ましい。
【００４０】
【表２】

【００４１】
また、表３に示すように、補助マスク２０の無孔部２３およびスカート部２４の溶接点４６は、長軸Ｘ方向の溶接点間隔が短軸Ｙ方向の溶接点間隔よりも短い場合、長軸Ｘ方向の溶接点間隔が短軸Ｙ方向の溶接点間隔よりも長い場合に比較して、短軸Ｙ方向の有孔部端での補助マスク２０の位置ずれ量が小さいことが確認された。従って、無孔部２３およびスカート部２４の溶接点４６は、長軸Ｘ方向の溶接点間隔が短軸Ｙ方向の溶接点間隔よりも短く設定されていることが望ましい。
【００４２】
【表３】

【００４３】
以上のように構成されたカラー陰極線管によれば、主マスク１４に重ねて補助マスク２０を設けることにより、シャドウマスク７の最も変形しやすい画面中央近傍の変形を抑制することが可能となり、結果的にマスク曲面強度を向上させることができる。また、主マスクおよび補助マスクは多数の溶接点で溶接され、溶接点は補助マスクの有孔部端から端まで列状に配置されている。そのため、外力に対して主マスクと補助マスクの貼り合せ強度が向上し、主マスクと補助マスクの位置ずれを抑制することができるとともに、シャドウマスクの機械的強度を向上させることができる。これにより、シャドウマスクの変形や、振動による画像の劣化を防止し、画像品位の向上したカラー陰極線管を得ることができる。
【００４４】
なお、この発明は上述した実施の形態に限定されることなく、この発明の範囲内で種々変形可能である。例えば、上述した実施の形態において、補助マスク２０を主マスク１４の蛍光体スクリーン側に配置した構成について説明したが、図１１に示すように、補助マスク２０は主マスク１４の電子銃側に配置してもよい。また、補助マスクは１枚に限らず複数設けてもよい。
【００４５】
また、上述した実施の形態において、シャドウマスクの溶接点列は、長軸方向に延びた溶接点列および短軸方向に延びた溶接点列を含む構成としたが、これに限らず、長軸方向および短軸方向のいずれか一方に延びる溶接点列のみを含む構成としてもよい。更に、上述した実施の形態において、補助マスクの無孔部およびスカート部を主マスクの無孔部およびスカート部にそれぞれ溶接する構成としたが、無孔部および有孔部の少なくとも一方が主マスクに溶接されていればよい。
【００４６】
【発明の効果】
以上詳述したように、本発明によれば、十分なマスク曲面強度を有しているとともに主マスクと補助マスクとの位置ずれを抑制し、良好な画像品位を有したカラー陰極線管を提供することができる。
【図面の簡単な説明】
【図１】この発明の実施の形態に係るカラー陰極線管の長軸を含む断面図。
【図２】上記カラー陰極線管の短軸を含む断面図。
【図３】上記カラー陰極線管におけるシャドウマスクを示す斜視図および電子ビーム通過孔を示す平面図。
【図４】図３に示すシャドウマスクの長軸方向に沿った断面図。
【図５】図３に示すシャドウマスクの短軸方向に沿った断面図。
【図６】上記シャドウマスクの平面図、側面図、および溶接点を示す平面図。
【図７】上記シャドウマスクのプレス成形に用いるプレス装置を示す断面図。
【図８】上記プレス成形時にシャドウマスクに作用する力を模式的に示す図。
【図９】上記シャドウマスクの中心からの距離と補助マスクの位置ずれ量との関係を示す図。
【図１０】上記補助マスクの側縁と最外縁の溶接点列との関係を模式的に示す図。
【図１１】この発明の他の実施の形態におけるシャドウマスクを示す断面図。
【符号の説明】
１…パネル
５…蛍光体スクリーン
６…シャドウマスク構体
７…シャドウマスク
８…マスクフレーム
９Ｂ、９Ｇ、９Ｒ…電子ビーム
１０…電子銃
１４…主マスク
２０…補助マスク
１２、４２…開孔
１３、２１…有孔部
４６…溶接点[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a color cathode ray tube having a shadow mask and a method for manufacturing the same.
[0002]
[Prior art]
In general, a color cathode ray tube includes an envelope having a panel having a phosphor screen formed on an inner surface thereof, and a substantially rectangular shadow mask provided in the envelope so as to face the phosphor screen. ing. On the perforated surface of the shadow mask facing the phosphor screen, a large number of openings are formed in a predetermined arrangement as electron beam passage holes. The shadow mask has a function of selecting three electron beams emitted from the electron gun through the respective apertures and causing the three electron beams to enter the three-color phosphor layer constituting the phosphor screen.
[0003]
2. Description of the Related Art In recent years, flat tubes having a substantially flat radius of curvature of 10,000 mm or more on the outer surface of a panel of a color cathode ray tube have become mainstream in order to increase visibility by reducing external light reflection and reducing image distortion. Usually, the perforated surface of the shadow mask facing the phosphor screen is formed in a shape corresponding to the inner shape of the panel. For this reason, the flat tube shadow mask has a smaller curvature than the conventional color cathode ray tube and is almost flattened.
[0004]
However, when such a shadow mask having a small curvature is used, the following problem occurs.
Usually, the shadow mask is formed of a metal plate having a thickness of about 0.2 mm. When the curvature of the perforated surface is small, the shadow mask for a large screen formed of such a thin plate is deformed by its own weight or an external force, and it is difficult to maintain the mask curved surface. In other words, when the curvature of the perforated surface is reduced, the holding power of the mask curved surface (hereinafter, mask curved surface strength) decreases. In particular, the decrease in the mask curved surface strength is most remarkable at the center of the perforated surface, that is, near the center of the screen.
[0005]
When the mask curved surface strength is low, the perforated surface of the shadow mask is deformed by a small external force during manufacturing or transportation. In this case, the distance relationship between the electron beam passage hole of the shadow mask and the inner surface of the panel fluctuates, and the electron beam emitted from the electron gun does not land on a predetermined phosphor layer, causing a color shift.
[0006]
In addition, even if the shadow mask does not reach the deformation, when the mask is incorporated into a television set, vibrations such as sound will cause the perforated surface of the mask to resonate easily, causing unnecessary shadows on the screen. It will be projected.
[0007]
As means for solving such a problem, attempts have been made to improve the strength of the mask curved surface of the shadow mask by using an auxiliary mask. For example, according to the color cathode ray tube disclosed in Patent Document 1, the shadow mask has a main mask corresponding to almost the entire phosphor screen and a band-shaped auxiliary mask, and the auxiliary mask is a short axis of the main mask. Are provided so as to overlap with the region including. By fixing the auxiliary mask to the main mask, it is possible to prevent deterioration of the mask curved surface strength due to flattening and high resolution. Therefore, deformation of the mask curved surface due to external force can be prevented, and color shift can be prevented.
[0008]
[Patent Document 1]
JP-A-2002-197989
[Problems to be solved by the invention]
In a shadow mask having such a main mask and an auxiliary mask superposed thereon, if the degree of fixation between the main mask and the auxiliary mask (hereinafter, referred to as bonding strength) is low, the degree of adhesion between the two is reduced. Therefore, it is difficult to improve the strength of the mask curved surface.
[0010]
Further, if the bonding strength is low, the auxiliary mask is shifted with respect to the main mask when an external force is applied during manufacturing or transportation. Then, a shift occurs between the electron beam passage hole of the main mask and the electron beam passage hole of the auxiliary mask, and the auxiliary mask narrows or closes the opening that is the electron beam passage hole of the main mask. In this case, the electron beam passing through the aperture decreases, and the light emission of the phosphor screen decreases. As a result, there arises a problem that the brightness of the image is partially reduced.
[0011]
On the other hand, the external force is most applied to the shadow mask during a manufacturing process in which the shadow mask is formed into a curved surface by press molding. Therefore, in order to prevent the displacement of the auxiliary mask, it is desirable to press-mold the main mask and the auxiliary mask and then bond them together. However, since it is necessary to perfectly match a large number of apertures formed in each mask, it is required to align the main mask and the auxiliary mask with high accuracy, and the alignment of the masks formed into a curved shape is required. Becomes extremely difficult. Therefore, after laminating a flat main mask and an auxiliary mask, they must be formed into a curved surface by press molding.
[0012]
Further, when the shapes of the main mask and the auxiliary mask are greatly different from each other as in Patent Literature 1, the force applied to each mask at the time of press molding is greatly different from the case where the main mask and the auxiliary mask have substantially the same shape. . Therefore, in order to prevent displacement of the auxiliary mask due to press molding, it is necessary to further increase the bonding strength.
[0013]
The present invention has been made in view of the above points, and it is an object of the present invention to provide a color cathode ray which has a sufficient mask curved surface strength, suppresses displacement between a main mask and an auxiliary mask, and has good image quality. To provide tubes.
[0014]
[Means for Solving the Problems]
To achieve the above object, a color cathode ray tube according to an aspect of the present invention includes a panel having a phosphor screen provided on an inner surface thereof, an electron gun for emitting an electron beam toward the phosphor screen, and an inner side of the panel. A substantially rectangular shadow mask having a major axis and a minor axis orthogonal to each other and orthogonal to the tube axis and arranged opposite to the phosphor screen,
The shadow mask is a main mask having a substantially rectangular perforated portion in which a large number of electron beam passage holes are formed, facing a substantially entire surface of the phosphor screen, and a region including a short axis of the main mask. And a band-shaped auxiliary mask which is fixed in a superimposed manner and has the short axis direction as a longitudinal direction.
The auxiliary mask is provided with a hole having a large number of electron beam passage holes corresponding to the electron beam passage holes of the main mask, the hole being fixed so as to overlap with the hole of the main mask. The mask is welded at a number of welding points, and the welding points are arranged in a row from one end to the other end of the perforated portion of the auxiliary mask to form a plurality of welding point rows.
[0015]
According to the color cathode ray tube having the above-described configuration, the bonding strength is strong against an external force generated in a direction perpendicular to the welding point row, and the displacement between the main mask and the auxiliary mask can be suppressed.
[0016]
Further, according to the color cathode ray tube according to the embodiment of the present invention, the auxiliary mask is fixed so as to overlap the perforated portion of the main mask and has a large number of electron beam passage holes corresponding to the electron beam passage holes of the main mask. And a skirt portion extending from both ends in the short axis direction of the perforated portion and fixed by being overlapped with and fixed to the non-porous portion and the skirt portion of the main mask, respectively. At least one of the non-porous portion and the skirt portion is welded to at least one of the non-porous portion and the skirt portion of the main mask at a plurality of welding points, and the long-axis direction welding point interval is the short-axis direction welding point interval. Shorter.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a color cathode ray tube according to an embodiment of the present invention will be described in detail with reference to the drawings.
As shown in FIGS. 1 and 2, the color cathode ray tube includes an envelope 9 formed of glass, and the envelope has a rectangular panel 1 having a skirt portion 2 at a peripheral portion, and a panel 1 having a skirt portion 2. And a neck 4 extending from a small-diameter portion of the funnel 3. The outer surface of the panel 1 is substantially flat with a radius of curvature of 100,000 mm. A phosphor screen 5 is formed on the inner surface of the panel 1. The envelope 9 has a tube axis Z passing through the center of the panel 1 and the center of the neck 4, a long axis (horizontal axis) X extending perpendicular to the tube axis, and perpendicular to the tube axis and the long axis. It has an extended short axis (vertical axis) Y.
[0018]
In the envelope 9, a shadow mask structure 6, which is a color selection electrode, is disposed so as to face the phosphor screen 5. The shadow mask structure 6 has a shadow mask 7 in which a large number of openings serving as electron beam passing holes are formed, and a rectangular frame-shaped mask frame 8 having an L-shaped cross section to which the periphery of the shadow mask 7 is fixed. are doing. The shadow mask structure 6 is supported inside the panel 1 by engaging an elastic support 30 provided on a side wall of the mask frame 8 with a stud pin 32 embedded in the skirt portion 2 of the panel 1. . The opening shape of the electron beam passage hole formed in the shadow mask 7 is formed in a rectangular shape or a circular shape depending on the use.
[0019]
An electron gun 10 that emits three

electron beams

9R, 9G, and 9B arranged in-line along the major axis X is disposed in the neck 4. In the color cathode ray tube, the

electron beams

9R, 9G, and 9B emitted from the electron gun 10 are deflected by a deflection yoke 11 attached to the outside of the funnel 3, and the phosphor screen 5 is passed through a shadow mask structure 6. The image is displayed by scanning horizontally and vertically.
[0020]
Next, the configuration of the shadow mask 7 will be described in detail. As shown in FIGS. 3 to 5, the shadow mask 7 includes a main mask 14 and an auxiliary mask 20 that is fixed to a part of the main mask so as to partially overlap the shadow mask 7. ing.
[0021]
The main mask 14 is formed of a metal plate having a plate thickness of 0.15 to 0.25 mm, is disposed to face the inner surface of the panel 1, and has a substantially rectangular mask main surface 38 formed in a predetermined curved shape. And a skirt portion 17 extending from the periphery of the mask main surface to the electron gun side along the tube axis Z direction. The mask main surface 38 has a rectangular perforated portion 13 in which a large number of apertures 12 functioning as electron beam passage holes are formed, and a substantially rectangular frame which is located so as to surround the effective portion and has no aperture. And a non-porous portion 16 in the shape of a circle.
[0022]
Each opening 12 of the main mask 14 is formed in a substantially rectangular shape whose width direction is the long axis X direction of the perforated portion 13. Each of the apertures 12 has a large number of aperture rows extending linearly along the short axis Y direction of the perforated portion at an arrangement pitch PH of about 0.4 to 0.6 mm in the long axis X direction. It is provided so that it may be arranged. Each aperture row is configured by arranging a plurality of apertures 12 via a bridge 15 in a substantially straight line in the short axis Y direction. Each opening 12 is formed by a communication hole that connects a substantially rectangular large hole opened on the surface of the main mask 14 on the phosphor screen side and a substantially rectangular small hole opened on the surface on the electron gun side. Have been.
[0023]
As shown in FIGS. 3 to 5, the auxiliary mask 20 is formed in a long strip shape, and an area including the short axis Y of the perforated portion 13 on the outer surface side of the main mask 14, that is, on the surface on the phosphor screen 5 side. It is fixed to overlap. The auxiliary mask 20 is provided such that its major axis direction coincides with the minor axis Y of the main mask 14.
[0024]
The auxiliary mask 20 has a width LH1 along the major axis X direction smaller than the major axis length LH2 of the perforated portion 13 of the main mask 14, and a length along the minor axis Y direction of the main mask 14. It is formed substantially equal to the length in the direction. The auxiliary mask 20 is made of a metal plate having a thickness of 0.15 to 0.25 mm, and has a plurality of apertures 21 in which a large number of apertures 42 as electron beam passage holes are formed. A non-porous portion 23 located at both ends in the longitudinal direction of the mask, and a pair of skirt portions 24 extending from each non-porous portion 23 in the tube axis Z direction are integrally provided. The opening 42 of the perforated portion 21 is formed corresponding to the opening 12 of the main mask 14.
[0025]
The auxiliary mask 20 is fixed to the main mask in a state where the perforated portion 21, the non-perforated portion 23, and the skirt portion 24 respectively overlap the perforated portion 13, the non-perforated portion 16, and the skirt portion 17 of the main mask 14. ing. As a result, the region on the minor axis Y of the main mask 14 has a double structure.
[0026]
As shown in FIG. 6, the auxiliary mask 20 is fixed to the main mask 14 by laser welding at a number of welding points 46. Here, the manufacturing process of the shadow mask 7 will be briefly described. As shown in FIG. 7, a flat mask base material 40 for the main mask and a flat mask base material 45 for the auxiliary mask are prepared, and an opening is formed in a perforated portion of each mask base material. Then, these mask base materials are overlapped and aligned, and then fixed to each other by laser welding.
[0027]
Then, the mutually fixed

mask base materials

40 and 45 are simultaneously press-molded. In this case, first, the

mask base materials

40 and 45 in a flat state are positioned and arranged between the upper die 50 and the lower die 54 of the press device. Next, the blank holder 51 of the upper die 50 is lowered, and the peripheral portions of the

mask base materials

40 and 45, that is, the skirt portion forming portion are held between the blank holder and the die 55 of the lower die 54.
[0028]
With the peripheral portions of the

mask base materials

40 and 45 held therebetween, the punch 53 of the upper die 50 is lowered, and the main surface of the mask is overhanged to a predetermined curved surface. Thereafter, the blank holder 51 and the die 55 are separated from each other, and the peripheral portions of the

mask base materials

40 and 45 are opened. Next, the punch 53 and the knockout 57 are pushed down, and the peripheral portions of the

mask base materials

40 and 45 are drawn into the gap between the die 55 and the punch 53 to be bent substantially at right angles to form the

skirt portions

17 and 24. Thereafter, all the molds are returned to the original state, and the formed shadow mask 7 is taken out.
[0029]
During such press forming, the largest external force acts on the shadow mask 7. When the curved surface is formed by projecting the shadow mask 7, the force in the long axis X direction toward the center of the perforated portion 21 and the short axis Y toward the periphery of the perforated portion are applied to the auxiliary mask 20 as shown by an arrow in FIG. A directional force is applied. In a region where the distance in the long axis X direction from the short axis Y is constant, the forces acting in the long axis X direction are substantially the same.
[0030]
Therefore, in order to prevent the displacement of the auxiliary mask 20 due to such external force, as shown in FIG. 6, the auxiliary mask 20 is arranged in a row from the perforated end to the perforated end along the short axis Y direction. It is most effective that welding is performed at the provided welding point 46. In other methods, a non-uniform force is likely to be applied to the auxiliary mask 20, and it is difficult to suppress the misalignment of the auxiliary mask with respect to the main mask 14. This has the same effect in both the major axis X direction and the minor axis Y direction. It has been confirmed by the experiments of the inventors that the misalignment of the auxiliary mask 20 occurs non-uniformly unless the welding point is arranged to the end of the perforated portion.
[0031]
Therefore, according to the present embodiment, as shown by the broken lines in FIG. 6, the welding points 46 form a plurality of welding point arrays extending in the short axis Y direction and a plurality of welding point arrays extending in the long axis X direction. It is provided as follows. Each welding point sequence in the short axis Y direction extends from one end to the other end of the perforated portion 21 of the auxiliary mask 20, and each welding point sequence in the long axis X direction extends from one end to the other end of the auxiliary mask. Extending from one side to the other. The welding point sequence in the long axis X direction is also provided on each non-porous portion 23 and skirt portion 24 of the auxiliary mask 20.
[0032]
In addition, the main mask and the auxiliary mask are welded while keeping the interval between the welding point rows and the interval between the welding points in each welding point row constant over the entire surface of the perforated portion 21, and the positional shift on the auxiliary mask short axis Y during press forming. The amount was measured. The result is shown in FIG. Assuming that the width of the perforated portion of the auxiliary mask 20 along the short axis Y direction is H (see FIG. 6), the position of the auxiliary mask at the end of the perforated portion H / 2 away from the long axis X is longer than the long axis The amount of displacement at a position H / 3 away from X was about 1/4, and no displacement occurred at the center of the auxiliary mask.
[0033]
That is, it can be seen that the force applied to the auxiliary mask 20 is largest at the end of the perforated portion 21 and smallest at the center of the perforated portion. Therefore, in order to suppress the displacement, it is better to arrange more welding points 46 at the perforated end than at the center of the perforated portion 21 of the auxiliary mask 20.
[0034]
When a position at least H / 4 away from the center of the perforated portion 21 of the auxiliary mask 20 in the short axis Y direction is used as a reference, the axis passing through the center of the perforated portion of the auxiliary mask 20 and being parallel to the long axis X is The distance between the welding point rows and the welding point distance between the welding point rows provided in a region separated by H / 4 or more in the Y direction are determined by changing the axis passing through the center of the perforated portion of the auxiliary mask 20 and parallel to the major axis X to the minor axis. The length is set shorter than the welding row provided in a region separated by H / 4 or less in the Y direction. Further, assuming that the width along the major axis X direction of the auxiliary mask 20 is W, a welding point in a region away from the minor axis Y by W / 4 or more in the major axis X direction is separated by W / 4 or less in the major axis X direction. It is desirable to have more than the welding points in the area. This has the same effect in both the major axis X direction and the minor axis Y direction.
[0035]
Further, as shown in FIG. 10, a side edge 20a of the auxiliary mask 20 extending along the short axis Y direction is welded to the outermost perforated portion which extends in the short axis Y direction and is closest to the side edge 20a. The distance from the row 25 was set to d, and the amount of misalignment of the auxiliary mask 20 in the outermost region was measured using a mask in which the distance d was set to 10.0 mm, 2.5 mm, and 1.0 mm, respectively. As a result, as shown in Table 1, the displacement amount of the mask (1) having the interval d of 10.0 mm was 40 μm, whereas the mask (2) having the interval d of 2.5 mm and the interval d were 40 μm. In the case of the mask (3) of 1.0 mm, the amount of displacement decreased to 10 μm, 4 μm, and 75% or less. From this, it was confirmed that the distance d from the end of the perforated portion 21 to the row of welding points greatly affected the displacement in the outermost region of the auxiliary mask. Therefore, it is preferable to provide a welding point in a region whose distance from the end of the perforated portion 21 is 2.5 mm or less.
[0036]
[Table 1]

[0037]
On the other hand, when the row interval between the welding point rows was set to 20 mm or more, it was confirmed that the main mask 14 and the auxiliary mask 20 were separated between the welding point rows, and it was impossible to artificially increase the mask plate thickness. . Therefore, it is desirable that the interval between the welding point rows is 20 mm or less.
[0038]
Further, as for the welding point interval in the welding point sequence, a plurality of shadow masks having different welding point intervals in the welding point sequence extending in the long axis X direction are prepared, and the short-axis Y direction hole of the auxiliary mask 20 at the time of press forming. The amount of misalignment of the auxiliary mask 20 at the edge was measured and investigated.
[0039]
As a result, as shown in Table 2, there is no large difference between the mask (4) having a welding point interval of 15 mm and the mask (5) having a welding point interval of 7.5 mm. The amount of displacement of the mask 20 was significantly reduced. Therefore, the welding point interval is desirably 2 mm or less.
[0040]
[Table 2]

[0041]
Further, as shown in Table 3, the welding point 46 of the non-porous portion 23 and the skirt portion 24 of the auxiliary mask 20 is long when the welding point interval in the long axis X direction is shorter than the welding point interval in the short axis Y direction. It was confirmed that the displacement amount of the auxiliary mask 20 at the end of the perforated portion in the short axis Y direction was smaller than when the welding point interval in the axis X direction was longer than the welding point interval in the short axis Y direction. . Therefore, it is desirable that the welding point 46 of the non-porous portion 23 and the skirt portion 24 is set such that the welding point interval in the long axis X direction is shorter than the welding point interval in the short axis Y direction.
[0042]
[Table 3]

[0043]
According to the color cathode ray tube configured as described above, by providing the auxiliary mask 20 so as to overlap the main mask 14, it is possible to suppress the deformation of the shadow mask 7 near the center of the screen where deformation is most likely to occur. It is possible to improve the mask curved surface strength. Further, the main mask and the auxiliary mask are welded at a number of welding points, and the welding points are arranged in a row from the end of the perforated portion of the auxiliary mask. Therefore, the bonding strength between the main mask and the auxiliary mask with respect to an external force is improved, the displacement between the main mask and the auxiliary mask can be suppressed, and the mechanical strength of the shadow mask can be improved. Thereby, it is possible to prevent the deformation of the shadow mask and the deterioration of the image due to the vibration, and to obtain a color cathode ray tube with improved image quality.
[0044]
The present invention is not limited to the above-described embodiment, but can be variously modified within the scope of the present invention. For example, in the above-described embodiment, the configuration in which the auxiliary mask 20 is disposed on the phosphor screen side of the main mask 14 has been described. However, as shown in FIG. 11, the auxiliary mask 20 is disposed on the electron gun side of the main mask 14. May be. The number of auxiliary masks is not limited to one, and a plurality of auxiliary masks may be provided.
[0045]
Further, in the above-described embodiment, the welding point sequence of the shadow mask is configured to include the welding point sequence extending in the long axis direction and the welding point sequence extending in the short axis direction. A configuration including only a welding point sequence extending in one of the direction and the short axis direction may be adopted. Further, in the above-described embodiment, the non-porous portion and the skirt portion of the auxiliary mask are welded to the non-porous portion and the skirt portion of the main mask, respectively. It is sufficient if they are welded.
[0046]
【The invention's effect】
As described above in detail, according to the present invention, a color cathode ray tube having a sufficient mask curved surface strength, suppressing a displacement between a main mask and an auxiliary mask, and having a good image quality is provided. be able to.
[Brief description of the drawings]
FIG. 1 is a sectional view including a major axis of a color cathode ray tube according to an embodiment of the present invention.
FIG. 2 is a sectional view including a short axis of the color cathode ray tube.
FIG. 3 is a perspective view showing a shadow mask and a plan view showing an electron beam passage hole in the color cathode ray tube.
FIG. 4 is a cross-sectional view along the major axis direction of the shadow mask shown in FIG.
FIG. 5 is a sectional view of the shadow mask shown in FIG. 3 along the minor axis direction.
FIG. 6 is a plan view, a side view, and a plan view showing welding points of the shadow mask.
FIG. 7 is a sectional view showing a press device used for press-forming the shadow mask.
FIG. 8 is a diagram schematically showing a force acting on a shadow mask during the press molding.
FIG. 9 is a diagram showing the relationship between the distance from the center of the shadow mask and the amount of displacement of the auxiliary mask.
FIG. 10 is a diagram schematically showing a relationship between a side edge of the auxiliary mask and an outermost edge welding point sequence.
FIG. 11 is a sectional view showing a shadow mask according to another embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Panel 5 ... Phosphor screen 6 ... Shadow mask structure 7 ... Shadow mask 8 ...

Mask frame

9B, 9G, 9R ... Electron beam 10 ... Electron gun 14 ... Main mask 20 ...

Auxiliary mask

12, 42 ...

Openings

13, 21 ... perforated part 46 ... welding point

Claims

A panel provided with a phosphor screen on the inner surface,
An electron gun that emits an electron beam toward the phosphor screen,
A substantially rectangular shadow mask having a major axis and a minor axis orthogonal to each other and orthogonal to the tube axis are arranged inside the panel so as to face the phosphor screen,
The shadow mask is a main mask having a substantially rectangular perforated portion in which a large number of electron beam passage holes are formed, facing a substantially entire surface of the phosphor screen, and a region including a short axis of the main mask. And a band-shaped auxiliary mask that is fixed to be overlapped with the above and has the short axis direction as a longitudinal direction,
The auxiliary mask includes a perforated portion having a large number of electron beam passing holes corresponding to the electron beam passing holes of the main mask and fixed to overlap with the perforated portion of the main mask,
The main mask and auxiliary mask are welded at a number of welding points,
The color cathode ray tube, wherein the welding points are arranged in a row from one end to the other end of the perforated portion of the auxiliary mask to form a plurality of welding point rows.

The color cathode ray tube according to claim 1, wherein the welding point sequence including the plurality of welding points extends in at least one of the major axis direction and the minor axis direction.

3. The color cathode ray tube according to claim 1, wherein the welding point sequence including the plurality of welding points is arranged at intervals of 20 mm or less.

Assuming that the width of the perforated portion in the major axis direction of the auxiliary mask is W, it is provided in a region that is at least W / 4 or more in the major axis direction away from an axis passing through the center of the perforated portion of the auxiliary mask and parallel to the short axis. The distance between the welding point rows extending in the short axis direction is provided in a region separated from the axis passing through the center of the perforated portion of the auxiliary mask and parallel to the short axis by W / 4 or less in the long axis direction. The color cathode ray tube according to any one of claims 1 to 3, wherein the length is shorter than a distance between the welding point rows extending in the short axis direction.

Assuming that the width of the perforated portion in the minor axis direction of the auxiliary mask is H, the auxiliary mask is provided in a region that is at least H / 4 in the minor axis direction from an axis passing through the center of the perforated portion of the auxiliary mask and parallel to the major axis. The distance between the rows of welding points extending in the long axis direction is provided in a region which is located at a distance of H / 4 or less in a short axis direction from an axis passing through the center of the perforated portion of the auxiliary mask and parallel to the long axis. The color cathode ray tube according to any one of claims 1 to 4, wherein the distance between the welding point rows extending in the axial direction is shorter.

The color cathode ray tube according to any one of claims 1 to 5, wherein an interval between the welding points is 2 mm or less in each of the welding point sequences including the plurality of welding points.

Assuming that the width of the perforated portion in the major axis direction of the auxiliary mask is W, it is provided in a region that is at least W / 4 or more in the major axis direction away from an axis passing through the center of the perforated portion of the auxiliary mask and parallel to the short axis. The distance between the welding points in each of the welding point trains provided in the region of the welding point trains provided in the region which is longer than W / 4 or less in the major axis direction from the axis passing through the center of the perforated portion of the auxiliary mask and parallel to the minor axis in the major axis direction. 2. The color cathode ray tube according to claim 1, wherein the distance is shorter than a welding point interval.

Assuming that the width of the perforated portion in the short axis direction of the auxiliary mask is H, the auxiliary mask is provided in a region separated by H / 4 or more in the short axis direction from an axis passing through the center of the perforated portion of the auxiliary mask and parallel to the long axis. The distance between the welding points in each welding point sequence is the distance between the welding points in each welding point sequence provided in a region separated by H / 4 or less in the short axis direction from an axis passing through the center of the perforated portion of the auxiliary mask and parallel to the long axis. 2. A color cathode ray tube according to claim 1, wherein said color cathode ray tube is shorter.

A panel provided with a phosphor screen on the inner surface,
An electron gun that emits an electron beam toward the phosphor screen,
A substantially rectangular shadow mask having a major axis and a minor axis orthogonal to each other and orthogonal to the tube axis are arranged inside the panel so as to face the phosphor screen,
The shadow mask is a main mask having a substantially rectangular perforated portion in which a large number of electron beam passage holes are formed, facing a substantially entire surface of the phosphor screen, and a region including a short axis of the main mask. And a band-shaped auxiliary mask that is fixed to be overlapped with the above and has the short axis direction as a longitudinal direction,
The auxiliary mask includes a perforated portion having a large number of electron beam passing holes corresponding to the electron beam passing holes of the main mask and fixed to overlap with the perforated portion of the main mask,
The main mask and auxiliary mask are welded at a number of welding points,
The color cathode ray tube according to claim 1, wherein the welding point includes a welding point arranged at a distance of 2.5 mm or less from an outermost portion of the perforated portion of the auxiliary mask.

A panel provided with a phosphor screen on the inner surface,
An electron gun that emits an electron beam toward the phosphor screen,
A substantially rectangular shadow mask having a major axis and a minor axis orthogonal to each other and orthogonal to the tube axis are arranged inside the panel so as to face the phosphor screen,
The shadow mask is substantially a rectangular hole having a large number of electron beam passage holes formed therein, which is opposed to substantially the entire surface of the phosphor screen, and a non-porous portion is formed around the hole. A main mask having a skirt portion formed by bending the non-porous portion in the tube axis direction,
A belt-shaped auxiliary mask fixed and overlapped with the area including the minor axis of the main mask and having the minor axis direction as the longitudinal direction,
The auxiliary mask is fixed so as to overlap the perforated portion of the main mask, and has a plurality of electron beam passing holes corresponding to the electron beam passing holes of the main mask, and a short axis of the perforated portion. A non-porous portion and a skirt portion that extend from both ends in the direction and are respectively fixed on the non-porous portion and the skirt portion of the main mask.
At least one of the non-porous portion and the skirt portion of the auxiliary mask is welded to at least one of the non-porous portion and the skirt portion of the main mask at a plurality of welding points,
A color cathode ray tube, wherein a distance between the welding points in the long axis direction is shorter than a distance between the welding points in the short axis direction.