JP3863299B2 - Glass bulb for cathode ray tube - Google Patents

Description

【００４３】
一方、ボールインパクトテストにおいては、パネルの外表面に圧縮応力層があるため、衝撃部にヘルツクラック状の小さな打痕が生じるだけでガラスにクラックを生じさせない反発の発生率が増加する傾向を見せた。圧縮応力値σ_ＫＣの絶対値が大きいほどこの傾向が見られた。
【００４４】
このような表面圧縮応力層を有するガラスバルブが陰極線管として組み立てられ、内部を真空にした際、外表面に発生する応力σは、線形弾性体に関する応力の重ね合わせの原理からして、真空応力σ_Ｖと表面圧縮応力σ_ＫＣの和、すなわちσ＝σ_Ｖ＋σ_ＫＣとして表せる。
【００４５】
陰極線管の製造工程や使用時に破壊が生じない保証として、前述の耐圧強度試験において、内外圧力差がＣ気圧の場合に耐えうるようにしなければならない。内外圧力差としてＣ気圧を与えた場合、陰極線管ガラスバルブの表面に発生している応力の大きさはσ＝Ｃσ_Ｖ＋σ_ＫＣに変化している。
【００４６】
したがって、ガラスバルブが構造的に有する破壊強度をσ_ＳＧ、大気圧における最大引張真空応力をσ_{ＶＴｍａｘ}とすれば、破壊しない条件としては、Ｃσ_{ＶＴｍａｘ}＋σ_ＫＣ＜σ_ＳＧとなる。
【００４７】
一方、物理強化により薄肉化、軽量化するとして、σ_SG／Ｃ＜σ_VTmaxなる条件を満足しなければならないから、結局σ _SG ／Ｃ＜σ_VTmax＜（σ_SG−σ_KC）／Ｃとなる。すなわち、１＜Ｃ・σ_VTmax／σ_SG＜１−σ_KC／σ_SGなる関係をσ_VTmaxとσ_KCが満足することが、物理強化をおこなって安全に軽量化しうる条件となると判明した。
【００４８】
カラーテレビジョン用陰極線管の製造工程においては、パネルとファンネルとは、封着部の強度を向上させる目的で、旭硝子社製品ＡＳＦ１３０７のようなＰｂＯ−Ｂ_２Ｏ_３−ＺｎＯ−ＢａＯ−ＳｉＯ_２系の結晶性ハンダガラスを用い、約４４０℃で３５分間焼成して封着し、ガラスバルブとして一体化した構造にする。
【００４９】
しかし、このようなハンダガラス焼成体が有する曲げ強度は、パネルやハンダガラスの約７０％しかない。そこで、封着部からの破壊を防止する必要上、封着部近傍のパネルおよびファンネルの肉厚を厚くし、封着部に発生する真空引張応力を通常６０ｋｇ／ｃｍ^２程度に抑えている。
【００５０】
ところで、上記カラーテレビジョン用陰極線管の製造工程で、結晶性ハンダガラスを用い約４４０℃で３５分間焼成し封着して室温まで冷却する際に、パネルに形成した圧縮応力が５％程度緩和される。本発明においては、前記の圧縮応力の緩和を加味して圧縮応力を形成しているため、パネルとファンネルとを封着してカラーテレビジョン用陰極線管を製造した後にも充分な圧縮応力が残留し、強化されている。
【００５１】
パネルの軽量化は、フェース部またはスカート部のいずれかを薄肉化しても得られるが、スカート部を薄肉化する場合、パネルとファンネルとの封着部の引張真空応力の増加を招き、封着部からの破壊発生が問題となる。すなわち、軽量化はフェース部を薄肉化して達成するのが好ましい。
【００５２】
いま、フェース部の外面の曲率および内面の曲率を一定にしたまま、どちらか一方を平行移動し薄肉化を達成するものとする。
【００５３】
アスペクト比が４：３または１６：９のテレビジョン向け陰極線管用のガラスバルブの短軸または長軸上のフェース部の画像表示端部の近傍に発生する最大引張真空応力σ_{ＶＴｍａｘ}は、フェース部中央の肉厚のほぼ２乗に反比例して増減する。したがって、σ_{ＶＴｍａｘ}＝σ_ＳＧ／Ｃを与えるフェース部中央肉厚をｔ_０とすると、肉厚をｔ_１にした場合の最大引張真空応力は、ほぼσ_{ＶＴｍａｘ}＝（ｔ_０／ｔ_１）^２σ_ＳＧ／Ｃの関係を有する。
【００５４】
前述したように、物理強化により圧縮応力σ_ＫＣを有するガラスバルブについて、許容されるσ_{ＶＴｍａｘ}の範囲はσ_ＳＧ／Ｃ＜σ_{ＶＴｍａｘ}＜（σ_ＳＧ−σ_ＫＣ）／Ｃであるから、σ_ＳＧ／（σ_ＳＧ−σ_ＫＣ）＜（ｔ_１／ｔ_０）^２＜１となる。つまり、前式の範囲でフェース部中央肉厚ｔ_１を薄くすることにより、陰極線管の爆縮を招かず軽量化を達成できる。
【００５５】
【実施例】
（実施例１）
本実施例においては、図１に示すようなカラーテレビジョン用陰極線管に通常使用されるものでＣ＝３で設計されており、表２に示されるような特性を有し、表３に記載された組成（単位：重量％）からなるガラス材料を用いてガラスバルブを作成した。図１の各部品については、ガラスバルブ２の応力分布およびフェース部７の肉厚が薄肉化しているのを除いて、従来と同様であるのでその説明を省略する。なお、表２、表３における「名称」はいずれも商品名（旭硝子社製）である。
【００５６】
前記ガラスバルブはアスペクト比が４：３で、対角径６８ｃｍの有効画面を有する２９インチ型テレビジョン用の従来品と同一形状、同一寸法の外形をしている。また、フェース部の内面を、設計時にフェース部とネックの中心軸を結ぶ管軸に沿って外方向に平行移動して薄肉化し、フェース部中央肉厚が１４ｍｍの従来品から１３ｍｍに変更した構造になっている。
【００５７】
【表２】

【００５８】
【表３】

【００５９】
ガラスバルブの内部を排気し真空にすると、フェース部外面の有効画面端の短軸上に最大引張真空応力σ_{ＶＴｍａｘ}を形成する。その値を表４に示す。
【００６０】
【表４】

【００６１】
この値は、フェース部中央肉厚が１４ｍｍの従来品において８４ｋｇ／ｃｍ^２であったが、フェース部中央肉厚を１３ｍｍに薄肉化した場合９７ｋｇ／ｃｍ^２まで増加した。
【００６２】
次に、この薄肉化したパネルを成型後の徐冷時に冷却速度と保持温度を操作し、パネルの外面と内面とにほぼ一様に種々のσ_ＫＣの値を有する圧縮応力層を形成した。これらのσ_ＫＣの値は表４のケース３からケース７に示した。
【００６３】
このようにして、パネル表面に形成された圧縮応力値σ_ＫＣと強度との関係を確認するため、強化されたパネルとファンネルとを封着しガラスバルブを形成後、耐圧強度テストと排気後防爆加工をおこない、前述のミサイルテストとボールインパクトテストにより防爆試験で評価した。
【００６４】
フェース部中央肉厚が１４ｍｍのパネルを用いた従来品のガラスバルブの場合、耐圧強度は約３．０ｋｇ／ｃｍ^２であった。これに対し、フェース部中央肉厚が１３ｍｍの薄肉化されたパネルを用いた未強化ガラスバルブの場合、耐圧強度は２．６ｋｇ／ｃｍ^２に低下した。この両者の破壊強度σ_ＳＧを求めると約２５０ｋｇ／ｃｍ^２であった。
【００６５】
また、薄肉化された強化ガラスバルブについて耐圧強度を求めると、表４に示したように、ほぼσ_ＳＧ＝Ｐ・σ_ＶＴ＋σ_ＫＣの関係が成り立つ。圧縮応力σ_ＫＣの絶対値が増加するにつれて、耐圧強度Ｐの値が大きくなることが判った。しかし、σ_{ＶＴｍａｘ}＜（σ_ＳＧ−σ_ＫＣ）／３を満たさないケース３の場合、耐圧強度は２．９ｋｇ／ｃｍ^２となり、Ｃ＝３．０（ｋｇ／ｃｍ^２）を保証できなかった。
【００６６】
次にミサイルテストをおこない爆縮発生率の差異を求めたが、圧縮応力の絶対値が大きくなるにつれて、フェース部有効面端にあらかじめ入れられたスクラッチが伸びた亀裂の進展を阻止する効果によって安定する傾向を示した。
【００６７】
さらに、ボールインパクトテストをおこない、ミサイルテストと同様爆縮発生率の差異を求めた。ケース２にみられるように未強化ガラスバルブではコーナー部打点（有効画面端より２５ｍｍ内側）で爆縮が発生したが、圧縮応力σ_ＫＣの絶対値が増加するにつれて爆縮発生率が低下し、また亀裂の発生を阻止する効果によって反発の発生率が増加する傾向を示した。
【００６８】
（実施例２）
本実施例においては、ガラスバルブの構造的因子が与える影響、設定された耐圧強度Ｃの影響を確認するため、アスペクト比がほぼ１６：９で、対角径が７６ｃｍの有効画面を有する横長の３２インチ型テレビジョン向け陰極線管用ガラスバルブについて、実施例１と同様の評価をおこなった。
【００６９】
この３２インチ型テレビジョン用の従来パネルのフェース部中央肉厚は１４．５ｍｍでＣ＝３であるが、Ｃ＝２．８としフェース部中央肉厚を１４．０ｍｍ、１３．５ｍｍ、１３．０ｍｍとして薄肉化し、さらにＣ＝２．５としフェース部中央肉厚を１２．５ｍｍとして薄肉化した。本実施例においてもフェース部外面の有効面端短軸上に最大引張真空応力σ_{ＶＴｍａｘ}を形成しており、このガラスバルブについて耐圧強度試験をおこなって測定した破壊強度σ_ＳＧはほぼ２６０ｋｇ／ｃｍ^２であった。また強化によりパネル表面に形成した圧縮応力値σ_ＫＣの値は表５に示した。
【００７０】
【表５】

【００７１】
耐圧強度に関しては、表５に示すとおり、薄肉化されたガラスバルブで、σ_{ＶＴｍａｘ}＞（σ_ＳＧ−σ_ＫＣ）／Ｃとなるケース４は耐圧強度２．８ｋｇ／ｃｍ^２未満となり不充分であった。しかもミサイルテスト、ボールインパクトテストにおいても爆縮が発生した。
【００７２】
一方、圧縮応力σ_ＫＣ≦−３０ｋｇ／ｃｍ^２ であり、σ_{ＶＴｍａｘ}＜（σ_ＳＧ−σ_ＫＣ）／Ｃを満足しているケース３、ケース５、ケース６については耐圧強度２．８ｋｇ／ｃｍ^２を超えかつ圧縮応力層がもたらす亀裂進展阻止の効果により、ミサイルテスト、ボールインパクトテストにおいても爆縮が発生せず安定している。さらにＣを２．５としたケース７においても耐圧強度、ミサイルテスト、ボールインパクトテストとも安全が確認された。
【００７３】
またケース２にみられるように、未強化でσ_{ＶＴｍａｘ}＜（σ_ＳＧ−σ_ＫＣ）／Ｃを満足しながらボールインパクトテストで爆縮が発生する場合に対して、圧縮応力σ_ＫＣを付加したケース３では爆縮が発生せず、ボールの反発の発生率も増加した。
【００７４】
（実施例３）
本実施例では、実施例１と同様のアスペクト比が４：３で、対角径６８ｃｍの有効画面を有する２９インチ型テレビジョン用のパネルを用い、表６に示すように圧縮応力σ_ＫＣ（ｋｇ／ｃｍ^２）がパネルの外表面においてスカート部よりもフェース部の方で大きくなるようにした。
【００７５】
この場合、パネルを徐冷点から歪点へ冷却する際に、主にフェース部に冷却風が当たるようにし、フェース部がスカート部より急冷されるようにして製造した。
【００７６】
【表６】

【００７７】
サンプル１はスカート部の圧縮応力がフェース部の圧縮応力より大きい例であり、サンプル２〜４はスカート部の圧縮応力がフェース部の圧縮応力の６２％、６０％、５８％の例である。冷却後の捻れ（μｍ）については、パネルの４隅のスカート部の端部を結ぶ２本の対角線について、パネル中央におけるフェース部表面からの高さの差を測定して求めた。各サンプルは、１００個ずつのパネルについて測定した。捻れの平均値で比較すると、サンプル１の捻れが約１００μｍであるのに対し、サンプル２〜４のそれは各々サンプル１の４分の１以下に改善された。
【００７８】
【発明の効果】
本発明は、陰極線管用ガラスバルブのガラス成型後の徐冷時の冷却速度と保持温度を操作することにより、安定的な圧縮応力が得られる物理強化をおこない、その圧縮応力の大きさを許容できる範囲内で特定することにより、ガラスバルブの肉厚を従来品より薄くし、爆縮を招かず軽量化したガラスバルブを実現できるという優れた効果を有する。また、特に薄くしても強度的に影響の小さいフェース部の肉厚を薄肉化して軽量化できるという効果も有する。
【図面の簡単な説明】
【図１】陰極線管の部分断面図。
【図２】従来の２８インチ型陰極線管用ガラスバルブの応力分布図。
【図３】従来の各種陰極線管用ガラスバルブの破壊強度を示すグラフ。
【符号の説明】
１：陰極線管
２：ガラスバルブ
３：パネル
４：ファンネル
５：ネック
６：スカート部
７：フェース部
８：防爆補強バンド
１０：封着部
１２：蛍光膜
１３：アルミニウム膜
１４：シャドウマスク
１５：スタッドピン
１６：内装ダッグ
１７：電子銃[0001]
BACKGROUND OF THE INVENTION
The present invention is mainly used for televisions and the like.Cathode ray tubeGlass bal forToRelated.
[0002]
[Prior art]
As shown in the partial sectional view of FIG. 1, a cathode ray tube 1 used for a television or the like basically has a panel for displaying an image.Le 3, Funnel to install the deflection coilLe 4And a net for storing the electron gun 175It consists of a glass bulb 2 made of
[0003]
6 in FIG.HaCart part, 7 shows videoSufuAce part, 8 is an explosion-proof reinforcement band to maintain strength, 10 is a panelLe 3And funneLe 412 is a fluorescent film that emits fluorescence when irradiated with an electron beam, 13 is an aluminum film that prevents the return of fluorescence, 14 is a shadow mask that defines the irradiation position of the electron beam, 15 Is the shadow mask 14TheCart part 6ofA stud pin 16 for fixing to the inner surface is an internal doug for preventing high charging by the electron beam of the shadow mask 14 and conducting grounding to the outside. A is the net.5Center axis and panelLe 3The tube axis which connects the center of is shown.
[0004]
A glass bulb of a cathode ray tube as a vacuum vessel generates stress (hereinafter referred to as vacuum stress) because atmospheric pressure is applied to the outer surface, but tensile stress (sign of +) that is imposed on an asymmetric structure different from a spherical shell. 2) exists in a relatively wide range as shown in FIG. 2 together with the compressive stress (sign of-). Here, σ in FIG._RIs the stress along the paper, σ_TIndicates a stress component perpendicular to the paper surface. The number along the stress distribution in the figure indicates the stress value at that position.
[0005]
There is a two-dimensional stress distribution on the surface of the glass bulb, and the maximum tensile vacuum stress is usually the panel.ofThe edge of the image display surface of the face or the panelLePresent on the side wall. Therefore, if the cathode rayforIf the tensile vacuum stress of the glass bulb is large and the structural strength is not sufficient, static fatigue failure due to atmospheric pressure occurs and the cathode ray tube does not function. Further, in the cathode ray tube manufacturing process, particularly when the exhaust gas is kept at a high temperature of about 380 ° C. and exhausted, a thermal stress is generated in the thermal process and is added to the vacuum stress. There is a danger of causing severe implosion by reaction and causing damage to the surroundings.
[0006]
As a guarantee to prevent such destruction, # 150 emery paper is used in consideration of the strength of scratches on the glass surface generated during the assembly process of the glass bulb and the cathode ray tube and the practical service life of the cathode ray tube. A uniformly damaged glass bulb is pressurized with air pressure or water pressure and an external pressure load test is conducted to determine the internal / external pressure difference when it breaks, and the pressure difference can withstand 3 atmospheres or more.
[0007]
As shown in FIG. 2, the structural fracture strength of the glass bulb subjected to such scratches is two-dimensional because the vacuum stress existing on the outer surface of the glass bulb depends on the structure of the glass bulb. It is not decided uniquely. Various televisions made from the same materialbroadcastFor receivingIn cathode ray tubesThe breaking strength of the glass bulb is shown in FIG. 3, but at most 190 kg / cm², Average 250 kg / cm²It is only about the extent.
[0008]
On the other hand, when considering fatigue fracture due to vacuum stress, the maximum tensile vacuum stress σ_VTmaxTherefore, in order to obtain a cathode ray tube glass bulb having a strength of 3 pressures or more, which is a guaranteed value of the pressure resistance, the linearity of the elastic body is high. 3.0σ because of its compatibility with glass bulbs_VTmax<Σ_SGIt is sufficient to satisfy the conditions. That is, σ_VTmax<Σ_SGSince / 3, conventionally, as shown in FIG._VTmax60-90kg / cm²The geometrical structure of the glass bulb, such as the wall thickness and shape, is determined so as to keep it at a minimum.
[0009]
[Problems to be solved by the invention]
However, to guarantee the compressive strength, σ_VTmax60-90 kg / cm as described above²For example, a cathode ray tube for a color television having an effective screen (viewing area) having an aspect ratio of 4: 3 (horizontal: vertical).ofPanels used for glass bulbsLeSince the weight increases in proportion to the maximum outer diameter of approximately 2.0 to 2.4, the productivity of large-sized cathode ray tubes, especially the productivity of glass bulbs, is extremely reduced, and the material cost is greatly increased. Results in an increase.
[0010]
As a solution to such a problem, for example, the surface of the glass bulb can be strengthened by ion exchange treatment to reduce the weight. In this method, alkali ions in the glass are replaced with ions larger than that at a temperature lower than the annealing region, and a compressive stress is created on the surface by increasing the volume. For example, Na₂5-8% O, K₂SiO containing about 5 to 9% of O₂-SrO-BaO-Al₂O₃-ZnO₂ SystemLass (Asahi GlassCompany5001 glass)Panel consisting ofWas kept at about 450 ° C.₃It is obtained by immersing in a melt of about 4 to 6 hours.
[0011]
Through this process, the panelof1500 ~ 3000kg / cm on the surface²Compression with a size of about 10 to 30 μmstressA layer is formed. In the case of this strengthening method, a large tensile stress layer is not formed inside the glass, but the thickness of the obtained compressive stress layer isTheIs thin. As shown in Table 1, the depth is the same as or less than the depth of scratching by # 150 emery paper. Therefore, during manufacture or useCompressionIt is fully conceivable that scratches that penetrate through the stress layer are considered. In this case, there is a problem that the strengthening effect disappears.
[0012]
It is also known that the glass surface can be strengthened by air cooling strengthening. This is because the glass is heated to a temperature slightly lower than the softening point, and then cooled rapidly by blowing air, so that the glass surface is 500-1000 kg / cm.²This is a method of forming a compressive stress layer of a degree.
[0013]
In other words, since the surface is rapidly cooled while being kept in a temperature range where softening of the glass is somewhat caused, it is accompanied by slight deformation after the treatment, so that the dimensional accuracy is strictly required.ofPanelLeThere is a big problem as a strengthening method. Also compressionstresslayerofCompressive stress inside the glass simultaneously with formationvalueA tensile stress layer having a size half the absolute value of is formed. Therefore, when a crack propagates into the glass, it self-destructs in an attempt to release the stored tensile strain energy, so in a vacuum vessel such as a cathode ray tube, a tensile stress layer that is too large from the point of implosion becomes a problem. .
[0014]
The object of the present invention is to relieve the drawbacks of the prior art and to strengthen the surface of the glass bulb while ensuring safety so as not to cause implosion of the cathode ray tube, and the relationship with the compression stress value of the surface. , A cathode ray tube that is lighter than beforeforTo provide a new glass bulb.
[0015]
[Means for Solving the Problems]
  The present invention relates to a glass bulb for a cathode ray tube comprising a panel having a substantially rectangular face portion, a funnel and a neck. At least the panel of the glass bulb is subjected to compressive stress σ by physical strengthening._KCA compressive stress layer having the compressive stress σ._KCIs σ_KC≦ −30kg / cm²And the breaking strength σ of the glass bulb_SGAnd the maximum tensile vacuum stress σ, which is the maximum value of the tensile stress generated when atmospheric pressure is applied to the surface of the glass bulb whose vacuum is inside_VTmax1 <C · σ_VTmax/ Σ_SG≦ 1- (σ_KC/ Σ_SG(However,C is the pressure strength that satisfies the safety requirements for the glass bulb usage environment.2 ≦ C ≦ 4Initial setting value determined in the range of)
  When the surface shape of the inner and outer surfaces of the face portion is constant and the wall thickness is changed, σ_VTmax= Σ_SGThe wall thickness at the center of the face that is / C is t₀The thickness t at the center of the face₁Is σ_SG/ (Σ_SG−σ_KC) ≤ (t₁/ T₀)², 0.64 ≦ (t₁/ T₀)²There is provided a glass bulb for a cathode ray tube, characterized by having a relationship <1.
[0016]
In the present invention, (t₁/ T₀)²Is 0.64 ≦ (t₁/ T₀)²<1 is preferable. If it is smaller than 0.64, the thickness of the face portion becomes thin, and implosion tends to occur. T₁= T₀In this case, it is impossible to reduce the thickness and weight.
[0017]
In the present invention, the maximum value σ of the tensile stress_VTmaxIs 70-150kg / cm²This is a value determined by the structure of the glass, and can be set to a value equal to or larger than the conventional value.
[0018]
The compressive stress σ_KCSpecifically, -30kg / cm²The following is preferable in order to effectively reduce the weight of the glass tube for the cathode ray tube, increase the pressure resistance, and suppress the implosion occurrence rate. Compressive stress σ_KCThe smaller the better, the better for strengthening the glass bulb for the cathode ray tube.²It is difficult to make it below the level, and as a practical lower limit -300 kg / cm²It is good to do it.
[0019]
  The value of C corresponds to the environment in which the glass bulb is used and is equal to the pressure difference that can be withstood so as to satisfy the required safety and the like, and the pressure strength (P in Tables 4 and 5). Initial setting (unit: kg / cm²).That is, C is a value that is initially set at the time of design as a pressure strength (safety strength) that satisfies the safety suitable for the environment in which the glass bulb is used, and P is manufactured based on such an initial set value C. It is the pressure strength (breaking strength) obtained by measuring the glass bulb.For a setting of a certain value of C, a certain value of σ is set so as to satisfy the conditional expression as in the present invention._KCIs set, as a result, the pressure strength P is improved and C ≦ P. σ_VTmax, Σ_SGIs a value substantially determined by the shape of the glass bulb.
[0020]
That is, for a specific C, a specific σ that satisfies the conditional expression_KC, Σ_VTmax, Σ_SGCan be determined. The range of C is required to satisfy 2 ≦ C ≦ 4, whereby a glass bulb can be manufactured with a wider range of pressure strength P than conventional.
[0021]
Σ for C <2_SG/ C (= σ_VTmax) Is too big,Unsuitable because it tends to cause spontaneous implosion due to delayed fracture._VTmaxIs too small, that is, σ_KCWill be too large, and an excessive σ_KCIt is not suitable to form the film because it causes a deterioration in productivity and is not practical. Further, when C = 3, the pressure strength P is 3 or more, and a glass bulb having a guaranteed pressure strength of 3 or more can be provided, which is preferable.
[0022]
In the present invention, the panelLeIf the part where the maximum tensile vacuum stress is generated is the outer surface of the face,LeIt is preferable to make the compressive stress of the face portion larger than the compressive stress of the skirt portion in order to prevent crack extension on the glass surface due to the maximum tensile vacuum stress and prevent implosion. In this case, the compressive stress of the skirt portion is 50% or more and less than 100% of the compressive stress of the face portion.
[0023]
If the compressive stress of the skirt is greater than that of the face,LeDeformation due to twisting cannot be prevented. If the compressive stress in the skirt is less than 50% of the compressive stress in the face, the skirt will not be strengthened, soTheThere is a problem in that it is necessary to increase the thickness, and weight reduction cannot be achieved.
[0024]
A panel in which the compressive stress of the face portion is larger than the compressive stress of the skirt portion.LeUntil the glass temperature drops to the strain point.LeManufactured mainly by applying cooling air to the face. In this way, the panelLeThe face portion is cooled more rapidly than the skirt portion, and a large compressive stress is formed.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
The present inventionLe,FunneLeAndOrCompression with a size and thickness that does not lead to implosion of the cathode ray tube due to physical strengthening on the surface of the glass bulb for the cathode ray tube having the glass bulbstressLayer (compressive stress σ by reinforcement σ_KCIn the present invention, the tensile stress isPositiveThe compression stress is expressed asnegativeRepresented by the value of. ). Especially panelsMake it impracticalDimensional accuracyofThe compression stress σ_KCThe maximum tensile vacuum stress σ determined by the mechanical properties of the glass bulb and the glass bulb structure_VTmaxA cathode ray tube glass bulb that is lighter in weight and has a structure that increases the allowable range of the conventional one.
[0026]
As a particularly preferred embodiment of the present invention, the compressive stress σ_KCThe absolute value of is the structurally intrinsic fracture strength σ of the glass._SGFor | σ_KC| ≦ σ_SGThe maximum value of tensile vacuum stress σ_VTmaxIs σ_SG/ C <σ_VTmax<(Σ_SG−σ_KC) / C.
[0027]
In the present invention, the maximum value σ of the tensile stress_VTmaxThe shape and thickness of the panelTheDepending on the distribution of the face, it may exist on the short axis of the effective screen end on the outer surface of the face part or on the long axis. The short axis and long axis areTheAn axis that passes through the center point of the outer surface of the casing and is parallel to the short side of the panel, andBifuIt means an axis that passes through the center point of the outer surface of the ace part and is parallel to the long side of the panel.
[0028]
Further, the compressive stress σ_KCThe panelLe skirtIt is preferable that the face part is larger than the part.Is paNell'sSkirt part(Side wall)By quickly cooling the face part and forming a compressive stress layer,skirtThis is because the deformation of the face portion accompanying the shrinkage and solidification of the portion can be suppressed and the curvature accuracy of the inner surface of the face portion can be improved.
[0029]
If the skirt is cooled more strongly and faster than the face,LeDuring cooling and solidification, the face portion causes a large deformation along with the movement when the skirt portion contracts. Therefore, face partofBecause the accuracy of the internal curvature fluctuates and becomes unstable,NapaColor using flannelCathode wire for televisionIn the case of a tube, the landing characteristics of the electron beam become poor, and a stable color image cannot be obtained.
[0030]
According to a preferred embodiment of the present invention, PaIt is possible to minimize the deformation of the face portion due to the contracting action accompanying the cooling and solidification of the skirt portion of the flannel.
[0031]
As described above, the present invention has a large compressive stress value but sufficient compression.stressLayer thicknessTheIon-exchange strengthening method that does not provide heat resistance, or wind-cooling strengthening that results in excessive tensile stress inside the glass, resulting in implosion of the cathode ray tube, or when internal tensile stress is suppressed, and compression stress cannot be stably obtained. It is not based on the method, but physical strengthening that obtains a stable compressive stress is performed by manipulating the cooling rate and holding temperature during slow cooling after glass molding.
[0032]
The inventors of the present invention have been able to realize a glass bulb that is lighter without implosion by reducing the wall thickness of the glass bulb by specifying the magnitude of the allowable compressive stress through experiments. AlsoTheThe shape of the ace portion may be any of spherical, cylindrical, and aspherical shapes. However, the present invention has a great advantage when applied to an HDTV (High Definition TV) panel having a large aspect ratio and an aspherical surface.
[0033]
In physical strengthening, when the glass is rapidly cooled from the high temperature range near the softening point, the surface rapidly shrinks and solidifies, but the interior is still in a state of expansion with sufficient fluidity, and the temporary strain is instantaneously generated by the flow. It will ease. When further cooled, the interior will also shrink, but its movement is limited by the presence of a solidified surface layer. As a result, when the temperature of the glass decreases to room temperature and reaches a sufficient equilibrium state, a large compressive stress layer and a tensile stress layer are formed on the surface and remain as residual stress.
[0034]
Occurs at this timecompressionThe magnitude of the stress depends on the time required for the glass surface to drop from the annealing temperature to the strain point. The earlier the cooling, the greater the difference in shrinkage from the inside. Compressive stress σ_KCIs generated. However, at the same time, σ_KT= −σ_KCA tensile stress of the magnitude of / 2 is inevitably formed.
[0035]
A television with a maximum outer diameter of 15 cm or morebroadcastFor receiving cathode ray tubes, PaNeLeSkirt partofTighten the outer surface with a metal explosion-proof band, etc.REven if an impact of a magnitude that is conceivable for handling is applied to the cathode ray tube, the cathode ray tube is not destroyed and safety is ensured.
[0036]
In addition, even if the cathode ray tube glass bulb is broken due to impact, in order to ensure the safety of the user, the UL safety standard of the United States applies the impact to the cathode ray tube and the amount of glass scattered at that time. Safety is judged by the following two types of methods, such as determining whether it is acceptable or not.
[0037]
oneTheAt the top and bottom of the long side near the effective screen display edge of the case partScratch 10cm long with diamond cutterAfter putting up to 20JThe face part is impacted by a missile-like steel object so as to give the energy. A test that breaks the cathode ray tube by the impact and makes a pass / fail judgment based on the size of the glass pieces scattered at that time.testis called.
[0038]
The other is 7 steel balls with a diameter of 50 mm.JEnergyInThe ball impact is a test in which the ball is dropped in a pendulum shape on the effective screen of the ace part, and a pass / fail judgment is made based on the size of the glass pieces scattered at that time.testis called.
[0039]
In these destructive tests, when rapid implosion occurs, the amount of scattered glass increases and the probability of failing is high. In addition, a test called the guillotine method has been carried out to confirm safety, and an upright steel rod is placed on the upper part of the funnel from the top of the cabinet containing the cathode ray tube.JIt gives an impact of a certain degree of energy.
[0040]
The guillotine methodtelevisionIt is a test that forcibly damages and destroys a set by applying a large amount of energy shock, and it cannot be said that the shock that occurs in normal daily life is assumed. Therefore, the guillotine methodTableExcept for the front-reinforced valve with safety glass or the like bonded to the surface, it was deleted from the US safety standard in 1992 and is not adopted in the present invention.
[0041]
In the present invention, by physical strengtheningcompressionIn order to confirm the impact of the presence of the stress layer on the safety, σ_KTThe allowable range was obtained. Panels in Table 1LeThe depth of the damage | wound generate | occur | produced when it injures using various damage methods is shown. missiletestThen, as shown in Table 1, the depth of the scratch to be entered with the diamond cutter is at most 140 μm, while the compression is compressed.stressLayer thicknessTheGlassthicknessAlmost1/6The compressive stress value σ_KCThe larger the absolute value of, the greater the degree of inhibition of crack growth from scratch and the tendency to stabilize.
[0042]
[Table 1]

[0043]
Meanwhile, ball impacttestIn the panelofSince there was a compressive stress layer on the outer surface, only a small Hertz crack-shaped dent was generated at the impact portion, and the incidence of repulsion that did not cause cracks in the glass increased. Compressive stress value σ_KCThis tendency was seen as the absolute value of became larger.
[0044]
When a glass bulb having such a surface compressive stress layer is assembled as a cathode ray tube and the inside is evacuated, the stress σ generated on the outer surface is a vacuum stress based on the principle of superposition of stresses on a linear elastic body. σ_VAnd surface compressive stress σ_KCSum, i.e., σ = σ_V+ Σ_KCIt can be expressed as
[0045]
As a guarantee that the cathode ray tube will not be broken during the manufacturing process or use, it must be able to withstand when the pressure difference between the inside and outside is C atm in the pressure strength test described above. When C atmospheric pressure is given as the internal / external pressure difference, the magnitude of the stress generated on the surface of the cathode ray tube glass bulb is σ = Cσ_V+ Σ_KCHas changed.
[0046]
Therefore, the breaking strength structurally possessed by the glass bulb is σ_SG, The maximum tensile vacuum stress at atmospheric pressure σ_VTmaxAs a condition for not destroying, Cσ_VTmax+ Σ_KC<Σ_SGIt becomes.
[0047]
  On the other hand, σ_SG/ C <σ_VTmaxBecause you have to satisfyσ _SG / C <σ_VTmax<(Σ_SG−σ_KC) / C. That is, 1 <C · σ_VTmax/ Σ_SG<1-σ_KC/ Σ_SGThe relationship σ_VTmaxAnd σ_KCIt has been found that satisfying the above conditions is a condition that can be physically reduced and lightened safely.
[0048]
In the manufacturing process of color television cathode ray tubes, the panels and funnels are sealed.PartAsahi Glass for the purpose of improving the strength ofCompanyMadeGoodsPbO-B like ASF1307₂O₃-ZnO-BaO-SiO₂A series of crystalline solder glass is used, which is fired and sealed at about 440 ° C. for 35 minutes to form an integrated glass bulb structure.
[0049]
However, the bending strength of such a solder glass fired product isLeOnly about 70% of solder glass. Therefore, it is necessary to prevent destruction from the sealing part, and the panel near the sealing part.andThe funnel wall thickness is increased, and the vacuum tensile stress generated at the sealed part is usually 60 kg / cm.²It is suppressed to the extent.
[0050]
By the way, in the manufacturing process of the cathode ray tube for a color television, when the crystalline solder glass is baked and sealed at about 440 ° C. for 35 minutes and cooled to room temperature, the panel is used.LeThe formed compressive stress is relaxed by about 5%. In the present invention, since the compressive stress is formed in consideration of the relaxation of the compressive stress,AndFunnelWhenEven after a cathode ray tube for a color television is manufactured by sealing, a sufficient compressive stress remains and is strengthened.
[0051]
PanelLeWeight reductionTheAce clubHacartPartIt can be obtained by thinning either one,skirtWhen thinning parts, panels and funnelsWhenThis causes an increase in the tensile vacuum stress at the sealed portion, and the occurrence of breakage from the sealed portion becomes a problem. That is, weight reductionHaThinning the case partTheIt is preferable to achieve this.
[0052]
NowTheWith the curvature of the outer surface and the curvature of the inner surface of the ace portion kept constant, one of them is translated to achieve thinning.
[0053]
Television with an aspect ratio of 4: 3 or 16: 9ForCathode ray tubeForFace on short or long axis of glass bulbPartMaximum tensile vacuum stress σ generated near the edge of the image display_VTmaxIncreases or decreases in inverse proportion to the square of the wall thickness at the center of the face. Therefore, σ_VTmax= Σ_SGThe thickness of the center of the face that gives / C is t₀Then, the wall thickness is t₁The maximum tensile vacuum stress is approximately σ_VTmax= (T₀/ T₁)²σ_SG/ C relationship.
[0054]
As mentioned above, compressive stress σ by physical strengthening_KCFor glass bulbs with_VTmaxThe range is σ_SG/ C <σ_VTmax<(Σ_SG−σ_KC) / C, so σ_SG/ (Σ_SG−σ_KC) <(T₁/ T₀)²<1. That is, the face center thickness t within the range of the previous formula₁By reducing the thickness, weight reduction can be achieved without causing implosion of the cathode ray tube.
[0055]
【Example】
(Example 1)
In this embodiment, it is normally used for a cathode ray tube for a color television as shown in FIG. 1 and is designed with C = 3, and has the characteristics shown in Table 2. A glass bulb was prepared using a glass material having the composition (unit: wt%). For each part in FIG. 1, the stress distribution of the glass bulb 2 andBifuExcept that the thickness of the ace portion 7 is reduced, it is the same as the conventional one, and the description thereof is omitted. “Name” in Tables 2 and 3 is the product name (Asahi Glass).CompanyMade).
[0056]
The glass bulb has an aspect ratio of 4: 3, and has the same shape and dimensions as a conventional product for a 29-inch television having an effective screen with a diagonal diameter of 68 cm. AlsoTheWhen designing the inner surface of the casingNiAcePartAnd neckofcenteraxisThe face is thinned by parallel translation outward along the tube axis connectingPartIt has a structure in which the central thickness is changed from a conventional product of 14 mm to 13 mm.
[0057]
[Table 2]

[0058]
[Table 3]

[0059]
When the inside of the glass bulb is evacuated and evacuated, the maximum tensile vacuum stress σ on the minor axis of the effective screen edge on the outer surface of the face part_VTmaxForm. The values are shown in Table 4.
[0060]
[Table 4]

[0061]
This value isTheAcePart84kg / cm in the conventional product with a center thickness of 14mm²But facePart97kg / cm when the wall thickness is reduced to 13mm²Increased to.
[0062]
Next, the cooling rate and holding temperature are controlled during the slow cooling of the thinned panel after molding,WhenInsideWhenAlmost uniformly various σ_KCA compressive stress layer having a value of These σ_KCThe values of are shown in Case 3 to Case 7 in Table 4.
[0063]
In this way, the compressive stress value σ formed on the panel surface_KCIn order to confirm the relationship between strength and strength, a reinforced panel and a funnel are sealed to form a glass bulb, and then a pressure resistance test and an explosion-proof process are performed after exhaust.,Missile mentioned abovetestAnd ball impacttestAccording to the explosion-proof test.
[0064]
FacePartIn the case of a conventional glass bulb using a panel with a center wall thickness of 14 mm, the pressure resistance is about 3.0 kg / cm.²Met. In contrast, facePartIn the case of an untempered glass bulb using a thinned panel with a central wall thickness of 13 mm, the pressure resistance is 2.6 kg / cm.²Declined. Fracture strength σ of both_SGIs about 250kg / cm²Met.
[0065]
Further, when the pressure resistance of the thinned tempered glass bulb was obtained, as shown in Table 4, it was almost σ._SG= P · σ_VT+ Σ_KCThe relationship holds. Compressive stress σ_KCIt has been found that the value of the pressure strength P increases as the absolute value of increases. However, σ_VTmax<(Σ_SG−σ_KC) In case 3 not satisfying / 3, the pressure strength is 2.9 kg / cm.²C = 3.0 (kg / cm²) Could not be guaranteed.
[0066]
Next, a missile test was conducted to determine the difference in implosion rate. As the absolute value of the compressive stress increased,PartScratches preliminarily placed at the edge of the effective surface showed a tendency to stabilize due to the effect of preventing the growth of cracks.
[0067]
In addition, a ball impact test was performed, and the difference in implosion rate was obtained as in the missile test. As seen in Case 2, implosion occurred at the corner spot (25 mm inside the effective screen edge) in the untempered glass bulb, but the compressive stress σ_KCThe rate of implosion decreased as the absolute value of was increased, and the rate of repulsion increased due to the effect of preventing cracking.
[0068]
(Example 2)
In the present example, in order to confirm the influence of the structural factors of the glass bulb and the influence of the set pressure strength C, the horizontally long screen having an effective screen with an aspect ratio of approximately 16: 9 and a diagonal diameter of 76 cm. 32-inch televisionCathode ray tubeThe glass bulb for evaluation was evaluated in the same manner as in Example 1.
[0069]
The face of the conventional panel for this 32-inch televisionPartThe central wall thickness is 14.5 mm and C = 3, but C = 2.8PartCenter thickness is 14.0mm13.5mm13.0mmAnd thinned, and C = 2.5PartThe central thickness was reduced to 12.5 mm. Also in this example, the maximum tensile vacuum stress σ on the short axis of the effective surface edge of the outer surface of the face part._VTmaxThe fracture strength σ measured by performing a pressure strength test on this glass bulb._SGIs approximately 260kg / cm²Met. Also, the compressive stress value σ formed on the panel surface by strengthening_KCThe values are shown in Table 5.
[0070]
[Table 5]

[0071]
Regarding the pressure strength, as shown in Table 5, with a thinned glass bulb, σ_VTmax> (Σ_SG−σ_KC) / C, case 4 has a compressive strength of 2.8 kg / cm²It was less than enough. Moreover, implosion occurred in missile tests and ball impact tests.
[0072]
On the other hand, compressive stress σ_KC≦ −30kg / cm² And, Σ_VTmax<(Σ_SG−σ_KC) For case 3, 5 and 6 satisfying / C, the pressure strength is 2.8 kg / cm.²In addition, the effect of preventing the crack growth caused by the compressive stress layer is stable in the missile test and ball impact test without implosion. In case 7 where C was 2.5, safety was confirmed in the pressure strength, missile test, and ball impact test.
[0073]
In addition, as seen in Case 2, σ_VTmax<(Σ_SG−σ_KC) / C in the case where implosion occurs in the ball impact test while satisfying / C, the compressive stress σ_KCIn case 3 with the addition of, implosion did not occur and the rate of ball repulsion increased.
[0074]
(Example 3)
In this embodiment, a panel for a 29-inch television having an effective screen with an aspect ratio of 4: 3 and a diagonal diameter of 68 cm is the same as that of the first embodiment.LeAnd compressive stress σ as shown in Table 6_KC(Kg / cm²)LeOn the outer surface, the face portion is larger than the skirt portion.
[0075]
In this case, the panelLeWhen cooling from the slow cooling point to the strain point, the face portion was cooled so that the cooling air was mainly applied, and the face portion was rapidly cooled from the skirt portion.
[0076]
[Table 6]

[0077]
Sample 1 is an example in which the compressive stress in the skirt portion is larger than the compressive stress in the face portion, and Samples 2 to 4 are examples in which the compressive stress in the skirt portion is 62%, 60%, and 58% of the compressive stress in the face portion. For twist (μm) after cooling, the skirts at the four corners of the panelPartFaces in the center of the panel for two diagonal lines connecting the endsTableIt was determined by measuring the difference in height from the surface. Each sample was measured on 100 panels. Compared with the average value of twist, the twist of sample 1 is about 100 μm, whereas that of samples 2 to 4 is1/4The following has been improved.
[0078]
【The invention's effect】
The present invention performs physical strengthening to obtain a stable compressive stress by manipulating the cooling rate and holding temperature at the time of slow cooling after glass molding of the glass bulb for a cathode ray tube, and allows the magnitude of the compressive stress. By specifying within the range, the glass bulb has an excellent effect that the thickness of the glass bulb is made thinner than that of the conventional product, and a lightweight glass bulb can be realized without causing implosion. In addition, even if it is particularly thin, it has little effect on strength.TheThere is also an effect that the thickness of the ace portion can be reduced by reducing the thickness.
[Brief description of the drawings]
[Figure 1]shadowThe fragmentary sectional view of an polar tube.
Fig. 2 Conventional 28 inchTypeThe stress distribution figure of the glass bulb for cathode ray tubes.
FIG. 3 is a graph showing the breaking strength of various conventional glass tubes for cathode ray tubes.
[Explanation of symbols]
1: Cathode ray tube
2: Glass bulb
3: PanelLe
4: FunneLe
5: NetThe
6: SuCart
7: FAce club
8: Explosion-proof reinforcement band
10: Sealing part
12: Fluorescent film
13: Aluminum film
14: Shadow mask
15: Stud pin
16: Interior doug
17: Electron gun

Claims (1)

In a glass tube for a cathode ray tube comprising a panel having a substantially rectangular face portion, a funnel and a neck,
A compression stress layer having a compression stress σ _KC is formed on at least the panel of the glass bulb by physical strengthening, and the compression stress σ _KC is σ _KC ≦ −30 kg / cm ² ,
Further, between the breaking strength σ _SG of the glass bulb and the maximum tensile vacuum stress σ _VTmax which is the maximum value of the tensile stress generated when atmospheric pressure is applied to the surface of the glass bulb whose inside is vacuum, 1 < C · σ _VTmax / σ _SG ≦ 1- (σ _KC / σ _SG ) (where C is a pressure strength that satisfies the safety conditions that match the glass bulb's usage environment, and is determined within the range of 2 ≦ C ≦ 4. (Initial setting value )
When the thickness of the face portion center is t ₀ such that σ _VTmax = σ _SG / C when the inner and outer surface shapes of the face portion are constant and the wall thickness is changed, The thickness t ₁ has a relationship of σ _SG / (σ _SG −σ _KC ) ≦ (t ₁ / t ₀ ) ² , 0.64 ≦ (t ₁ / t ₀ ) ² <1 A glass bulb for a cathode ray tube.

Images