EP0143021B1 - Aluminium coating process for the internal side of a colour television tube screen - Google Patents

Aluminium coating process for the internal side of a colour television tube screen Download PDF

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Publication number
EP0143021B1
EP0143021B1 EP84401895A EP84401895A EP0143021B1 EP 0143021 B1 EP0143021 B1 EP 0143021B1 EP 84401895 A EP84401895 A EP 84401895A EP 84401895 A EP84401895 A EP 84401895A EP 0143021 B1 EP0143021 B1 EP 0143021B1
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Prior art keywords
solution
layer
organic layer
aluminum
tube
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German (de)
French (fr)
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EP0143021A1 (en
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Gabriele Giancaterini
Francesco Pacifici
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Videocolor SA
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Videocolor SA
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
    • H01J29/02—Electrodes; Screens; Mounting, supporting, spacing or insulating thereof
    • H01J29/10—Screens on or from which an image or pattern is formed, picked up, converted or stored
    • H01J29/18—Luminescent screens
    • H01J29/28—Luminescent screens with protective, conductive or reflective layers

Definitions

  • the invention relates to a method of illuminating the internal face of the screen of a color television tube.
  • a cathode ray tube for color display in particular a television tube, has a glass front panel the internal face of which is covered with phosphors, that is to say luminescent substances which emit light when they are excited by electron beams produced by electron guns inside the tube.
  • phosphors are deposited on the glass in the form of bands or dots and are covered by a layer of aluminum. This layer, connected to ground, is intended to evacuate the incident electrons and to constitute a mirror reflecting forward the light emitted towards the rear of the tube. Since the phosphors form an irregular layer, if the aluminum were deposited directly on them, the reflection coefficient of this layer would be low, which would go against the aim sought.
  • the invention makes it possible to reduce the probability of the formation of such blisters.
  • the roughness of the surface of the layer of organic material covering the phosphors and the glass around these phosphors is obtained by spraying a solution, in particular an aqueous solution, or a suspension of ammonium tetraborate, preferably hydrated, [NH 4 HB 4 O 7 . x H 2 0].
  • the probability of blistering of the aluminum layer is particularly low and that the quantity of product to be sprayed onto the organic material can also be low, which reduces the cost of manufacturing.
  • boric anhydride residue B 2 0 3 which has the advantage of increasing the adhesion between aluminum and phosphorus and between aluminum and glass.
  • boric anhydride remains stable at maximum temperatures, generally of the order of 450 to 480 ° C, to which the tube is subjected during its manufacture and, at these temperatures, this material forms a paste of great viscosity which is distributed evenly between aluminum and glass and between the luminescent material and aluminum.
  • this property of improving the adhesion is not specific to ammonium tetraborate because, when, in accordance with a known technique, boric acid is used, a residue is also obtained after treatment.
  • boric anhydride 8 2 0 3
  • the quantity of product used can be very reduced, the residue, after heat treatment, is minimal. This minimization of the vitrified residue ensures better excitation of the phosphors (the residue forming a screen of reduced thickness for the electron beam) and greater reflection of light by the aluminum layer.
  • a color television tube comprises a thick glass envelope having a front panel 10 on the internal surface 11 of which are deposited the phosphors 12, in points or in bands, which are selectively excited by three electron beams (not shown) generated by three electron guns inside the glass bulb.
  • the color of each excited point triplet depends on the relative intensities of the electron beams.
  • a hole mask (not shown) is usually provided near the phosphors inside the vacuum tube.
  • the phosphors 12 are deposited directly on the internal surface 11 of the panel 10 and they are covered by a layer of aluminum 13 which has a double role: on the one hand to evacuate towards the mass the electrons striking the screen, and, on the other hand, reflect towards the front, that is to say towards the outside of the tube, the light emitted by the phosphors 12 towards the rear, that is to say towards the inside of the tube.
  • the aluminum is also deposited around the screen so that this peripheral part 14, which is very often outside the case of the television, is opaque. In this way the tube does not have a transparent part, unsightly for the spectator.
  • a layer 15 of organic material is deposited on the phosphors 12, comprising for example an emulsion of acrylic resins, polyvinyl alcohol and water.
  • This layer 15, arranged on the face of the phosphors receiving the electrons, has a smooth surface which makes it possible to obtain a substantially flat aluminum deposit 13.
  • the tube is subjected to a heat treatment so that the internal deposits reach a temperature above 350 ° C. for which the microcrystals 16 and the organic layer 15 decompose.
  • the gases resulting from this decomposition escape through the holes formed by the microcrystals 16. In this way the probability of blistering in the aluminum layer 13 ( Figure 2) is reduced.
  • the aqueous solution which is sprayed onto the surface of the organic layer 15 is an ammonium tetraborate solution, preferably hydrated ammonium tetraborate [NH4HB407 'xH 2 0].
  • This sprayed solution is then dried by blowing hot air or by different heating. At the end of this drying, microcrystals remain. Then, as already described, the aluminum layer 13 is deposited.
  • the microcrystals of hydrated ammonium tetraborate undergo a significant reduction in volume because the water H 2 0 and the ammonia NH 3 escape in gaseous form. This leaves only a residue 17 of boric anhydride B 2 0 3 of small volume. This minimum residual volume makes it possible to reduce as much as possible the surface of the holes which remains obscured, which gives easier passage to the gases resulting from the decomposition of the organic layer 15.
  • Figure 3 is a diagram illustrating these comparative tests and other tests.
  • the treatment temperature is plotted on the abscissa in d ° Celsius and the ordinate in%. weight loss of various layers.
  • Curve 20 relates to hydrated ammonium tetraborate, curve 21 represents the weight loss of boric acid, under the same concentration conditions.
  • Curve 22 shows the weight loss of the borax of chemical formula [Na 2 B 4 O 7 . 10H 2 0].
  • Curve 23 relates to the use of ammonium oxalate and curve 24 shows the weight loss as a function of the temperature of layer 15.
  • ammonium oxalate is an organic compound which evaporates completely and does not give rise to a residue making it possible to improve the adhesion between the phosphors and the aluminum layer and between glass and that layer of aluminum.
  • curve 23 shows, the ammonium oxalate evaporates quickly; the risk of blistering is therefore high.
  • borax [Na2B407 '10H 2 0] also decomposes faster than ammonium tetraborate (see curve 22). The risk of blistering is therefore higher. In addition, the residue left by borax does not have the bonding properties of residue B 2 0 3 .

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  • Formation Of Various Coating Films On Cathode Ray Tubes And Lamps (AREA)
  • Cathode-Ray Tubes And Fluorescent Screens For Display (AREA)

Description

L'invention est relative à un procédé d'aluminisation de la face interne de l'écran d'un tube de télévision en couleurs.The invention relates to a method of illuminating the internal face of the screen of a color television tube.

Un tube à rayons cathodiques pour la visualisation en couleurs, notamment un tube de télévision, présente un panneau frontal en verre dont la face interne est recouverte de phosphores, c'est-à-dire de substances luminescentes qui émettent de la lumière lorsqu'elles sont excitées par des faisceaux d'électrons produits par des canons à électrons à l'intérieur du tube. Ces phosphores sont déposés sur le verre sous forme de bandes ou de points et sont recouverts par une couche d'aluminium. Cette couche, connectée à la masse, est destinée à évacuer les électrons incidents et à constituer un miroir réfléchissant vers l'avant la lumière émise vers l'arrière du tube. Les phosphores formant une couche irrégulière, si l'on déposait directement l'aluminium sur ceux-ci le coefficient de réflexion de cette couche serait faible, ce qui irait à l'encontre du but recherché. C'est pourquoi sur les phosphores on dépose, avant la couche d'aluminium, une couche d'un matériau organique en solution (ou en émulsion dans l'eau) qui présente une surface lisse à l'opposé des phosphores et c'est sur cette surface lisse qu'on dépose ensuite l'aluminium. La matière organique est ensuite éliminée par traitement thermique à une température supérieure à 350 °C. Au cours de ce traitement, cette matière se décompose en divers gaz qui s'échappent à travers l'aluminium qui est relativement poreux du fait de sa faible épaisseur. Mais cette porosité de l'aluminium est en général insuffisante. C'est pourquoi il peut se former des cloques ou boursouflures qui altèrent la réflectivité, et des parties de la couche métallique peuvent même se détacher, et ainsi perturber le fonctionnement des canons à électrons et/ou bloquer des trous du masque généralement utilisé pour la sélection des couleurs.A cathode ray tube for color display, in particular a television tube, has a glass front panel the internal face of which is covered with phosphors, that is to say luminescent substances which emit light when they are excited by electron beams produced by electron guns inside the tube. These phosphors are deposited on the glass in the form of bands or dots and are covered by a layer of aluminum. This layer, connected to ground, is intended to evacuate the incident electrons and to constitute a mirror reflecting forward the light emitted towards the rear of the tube. Since the phosphors form an irregular layer, if the aluminum were deposited directly on them, the reflection coefficient of this layer would be low, which would go against the aim sought. This is why on the phosphors, a layer of an organic material in solution (or in emulsion in water) is deposited, before the aluminum layer, which has a smooth surface opposite to the phosphors and it is on this smooth surface we then deposit the aluminum. The organic matter is then removed by heat treatment at a temperature above 350 ° C. During this treatment, this material decomposes into various gases which escape through the aluminum which is relatively porous due to its small thickness. However, this porosity of aluminum is generally insufficient. This is why it is possible to form blisters or blisters which alter the reflectivity, and parts of the metallic layer can even detach, and thus disturb the functioning of the electron guns and / or block holes in the mask generally used for the color selection.

Pour remédier à cet inconvénient (la formation des cloques) on a déjà proposé (brevets US-A-3821 009 et US-A-4 339 475) de projeter sur la matière organique, une solution formant des cristaux destinés à percer la couche d'aluminium afin de faciliter l'échappement des gaz résultant de la décomposition de la matière organique.To remedy this drawback (the formation of blisters), it has already been proposed (US-A-3821 009 and US-A-4 339 475) to spray on the organic material, a solution forming crystals intended to pierce the layer of aluminum to facilitate the escape of gases resulting from the decomposition of organic matter.

Mais les produits utilisés jusqu'à présent pour rendre rugueuse la surface de la matière organique sur laquelle doit être déposée la couche d'aluminium n'ont pas donné entière satisfaction car on a constaté, après fabrication d'un grand nombre de tubes, qu'une proportion non négligeable de ceux-ci présentait encore des cloques de la couche d'aluminium.However, the products used until now to roughen the surface of the organic material on which the aluminum layer must be deposited have not been entirely satisfactory because it has been found, after manufacturing a large number of tubes, that 'a significant proportion of these still showed blisters of the aluminum layer.

L'invention permet de réduire la probabilité de formation de telles cloques.The invention makes it possible to reduce the probability of the formation of such blisters.

Elle est caractérisée en ce que la rugosité de la surface de la couche de matière organique recouvrant les phosphores et le verre autour de ces phosphores est obtenue par projection d'une solution, notamment aqueuse, ou d'une suspension de tétraborate d'ammonium, de préférence hydraté, [NH4HB4O7 . x H20].It is characterized in that the roughness of the surface of the layer of organic material covering the phosphors and the glass around these phosphors is obtained by spraying a solution, in particular an aqueous solution, or a suspension of ammonium tetraborate, preferably hydrated, [NH 4 HB 4 O 7 . x H 2 0].

On a constaté qu'avec le procédé selon l'invention la probabilité de formation de cloques de la couche d'aluminium est particulièrement faible et que la quantité de produit à projeter sur la matière organique peut également être faible, ce qui réduit le coût de fabrication.It has been found that with the process according to the invention the probability of blistering of the aluminum layer is particularly low and that the quantity of product to be sprayed onto the organic material can also be low, which reduces the cost of manufacturing.

En outre il subsiste, après traitement, un résidu d'anhydride borique B203 qui présente l'avantage d'augmenter l'adhérence entre l'aluminium et les phosphores et entre l'aluminium et le verre. En effet, l'anhydride borique reste stable aux températures maximales, généralement de l'ordre de 450 à 480 °C, auquel le tube est soumis au cours de sa fabrication et, à ces températures, ce matériau forme une pâte d'une grande viscosité qui se répartit de façon uniforme entre l'aluminium et le verre et entre le matériau luminescent et l'aluminium. Toutefois, cette propriété d'amélioration de l'adhérence n'est pas spécifique au tétraborate d'ammonium car, lorsqu'on utilise, conformément à une technique connue, de l'acide borique, on obtient aussi, après traitement, un résidu d'anhydride borique 8203,In addition, there remains, after treatment, a boric anhydride residue B 2 0 3 which has the advantage of increasing the adhesion between aluminum and phosphorus and between aluminum and glass. Indeed, boric anhydride remains stable at maximum temperatures, generally of the order of 450 to 480 ° C, to which the tube is subjected during its manufacture and, at these temperatures, this material forms a paste of great viscosity which is distributed evenly between aluminum and glass and between the luminescent material and aluminum. However, this property of improving the adhesion is not specific to ammonium tetraborate because, when, in accordance with a known technique, boric acid is used, a residue is also obtained after treatment. boric anhydride 8 2 0 3 ,

La diminution de la probabilité de formation de cloques de la couche d'aluminium et la diminution de la quantité de matériau projeté sur la matière organique résulte, selon les expériences effectuées par les inventeurs, des propriétés suivantes du tétraborate d'ammonium :

  • Après projection et séchage, les microcristaux, qui percent la couche d'aluminium, sont plus petits et mieux répartis qu'avec les corps utilisés antérieurement. Il en résulte un plus grand nombre de trous dans la couche d'aluminium et donc une meilleure évacuation des gaz, d'où un moindre risque de formation de cloques. A cette minimisation du risque de formation de cloques contribue aussi le fait que, lorsque la température s'élève, le tétraborate d'ammonium hydraté se décompose, notamment par évaporation de l'eau, de façon progressive, sans discontinuité ; au contraire avec l'acide borique ou l'oxalate d'ammonium. ou encore le composé Na2B407' 10H20, la décomposition est beaucoup plus rapide, la probabilité de formation de cloques étant d'autant plus grande que la vitesse de décomposition ou d'évaporation est importante.
The decrease in the probability of blistering of the aluminum layer and the decrease in the amount of material sprayed onto the organic matter results, according to the experiments carried out by the inventors, from the following properties of ammonium tetraborate:
  • After projection and drying, the microcrystals, which pierce the aluminum layer, are smaller and better distributed than with the bodies previously used. This results in a greater number of holes in the aluminum layer and therefore better evacuation of gases, hence a lower risk of blistering. This minimization of the risk of blistering also contributes to the fact that, when the temperature rises, the hydrated ammonium tetraborate decomposes, in particular by evaporation of the water, in a progressive manner, without discontinuity; on the contrary with boric acid or ammonium oxalate. or the compound Na2B407 '10H 2 0, the decomposition is much faster, the probability of blistering being all the greater the greater the speed of decomposition or evaporation.

Par ailleurs on notera que la quantité de produit utilisé pouvant être très réduite, le résidu, après traitement thermique, est minime. Cette minimisation du résidu vitrifié assure une meilleure excitation des phosphores (le résidu formant un écran d'épaisseur réduite pour le faisceau d'électrons) et une plus grande réflexion de la lumière par la couche d'aluminium.Furthermore, it will be noted that the quantity of product used can be very reduced, the residue, after heat treatment, is minimal. This minimization of the vitrified residue ensures better excitation of the phosphors (the residue forming a screen of reduced thickness for the electron beam) and greater reflection of light by the aluminum layer.

D'autres caractéristiques et avantages de l'invention apparaîtront avec la description de certains de ses modes de réalisation, celle-ci étant effectuée en se référant aux dessins ci-annexés sur lesquels :

  • la figure 1 est un schéma partiel en coupe d'un tube de télévision en couleurs en cours de fabrication.
  • la figure 2 est un schéma analogue à celui de la figure 1 après traitement thermique, et
  • la figure 3 est un diagramme comparatif.
Other characteristics and advantages of the invention will appear with the description of some of its embodiments, this being carried out with reference to the attached drawings in which:
  • Figure 1 is a partial sectional diagram of a color television tube during manufacture.
  • FIG. 2 is a diagram similar to that of FIG. 1 after heat treatment, and
  • Figure 3 is a comparative diagram.

Un tube de télévision en couleurs comprend une enveloppe en verre épais présentant un panneau frontal 10 sur la surface interne 11 duquel sont déposés les phosphores 12, en points ou en bandes, qui sont excités sélectivement par trois faisceaux d'électrons (non représentés) engendrés par trois canons à électrons à l'intérieur de l'ampoule de verre. La couleur de chaque triplet de points excité dépend des intensités relatives des faisceaux d'électrons. Pour qu'un faisceau d'électrons ne frappe qu'un phosphore de la couleur qu'il doit exciter on prévoit habituellement un masque à trous (non représenté) à proximité des phosphores à l'intérieur du tube sous vide.A color television tube comprises a thick glass envelope having a front panel 10 on the internal surface 11 of which are deposited the phosphors 12, in points or in bands, which are selectively excited by three electron beams (not shown) generated by three electron guns inside the glass bulb. The color of each excited point triplet depends on the relative intensities of the electron beams. In order for an electron beam to strike only a phosphorus of the color which it is to excite, a hole mask (not shown) is usually provided near the phosphors inside the vacuum tube.

Les phosphores 12 sont déposés directement sur la surface interne 11 du panneau 10 et ils sont recouverts par une couche d'aluminium 13 qui a un double rôle : d'une part évacuer vers la masse les électrons frappant l'écran, et, d'autre part, réfléchir vers l'avant, c'est-à-dire vers l'extérieur du tube, la lumière émise par les phosphores 12 vers l'arrière, c'est-à-dire vers l'intérieur du tube. L'aluminium est également déposé autour de l'écran afin que cette partie périphérique 14, qui est très souvent à l'extérieur du boîtier du téléviseur, soit opaque. De cette manière le tube ne présente pas de partie transparente, inesthétique pour le spectateur.The phosphors 12 are deposited directly on the internal surface 11 of the panel 10 and they are covered by a layer of aluminum 13 which has a double role: on the one hand to evacuate towards the mass the electrons striking the screen, and, on the other hand, reflect towards the front, that is to say towards the outside of the tube, the light emitted by the phosphors 12 towards the rear, that is to say towards the inside of the tube. The aluminum is also deposited around the screen so that this peripheral part 14, which is very often outside the case of the television, is opaque. In this way the tube does not have a transparent part, unsightly for the spectator.

Préalablement au dépôt de la couche d'aluminium on dépose sur les phosphores 12 une couche 15 d'une matière organique, comprenant par exemple une émulsion de résines acryliques, d'alcool polyvinylique et d'eau. Cette couche 15, disposée sur la face des luminophores recevant les électrons, présente une surface lisse qui permet d'obtenir un dépôt d'aluminium 13 sensiblement plat.Prior to the deposition of the aluminum layer, a layer 15 of organic material is deposited on the phosphors 12, comprising for example an emulsion of acrylic resins, polyvinyl alcohol and water. This layer 15, arranged on the face of the phosphors receiving the electrons, has a smooth surface which makes it possible to obtain a substantially flat aluminum deposit 13.

Sur cette surface lisse de la couche 15 on projette une solution d'une matière cristallisable qui, après séchage, forme des microcristaux 16 d'une hauteur plus importante que l'épaisseur de la couche d'aluminium 13 qui sera déposée afin que celle-ci présente des trous.On this smooth surface of the layer 15 a solution of a crystallizable material is projected which, after drying, forms microcrystals 16 of a height greater than the thickness of the aluminum layer 13 which will be deposited so that it these have holes.

Après dépôt de la couche d'aluminium 13 le tube est soumis à un traitement thermique de façon que les dépôts internes atteignent une température supérieure à 350 °C pour laquelle les microcristaux 16 et la couche organique 15 se décomposent. Les gaz résultant de cette décomposition s'échappent par les trous formés par les microcristaux 16. De cette manière la probabilité de formation de cloques dans la couche d'aluminium 13 (figure 2) est réduite.After the aluminum layer 13 has been deposited, the tube is subjected to a heat treatment so that the internal deposits reach a temperature above 350 ° C. for which the microcrystals 16 and the organic layer 15 decompose. The gases resulting from this decomposition escape through the holes formed by the microcrystals 16. In this way the probability of blistering in the aluminum layer 13 (Figure 2) is reduced.

Conformément à l'invention la solution aqueuse qui est projetée sur la surface de la couche organique 15 est une solution de tétraborate d'ammonium, de préférence le tétraborate d'ammonium hydraté [NH4HB407' xH20].According to the invention, the aqueous solution which is sprayed onto the surface of the organic layer 15 is an ammonium tetraborate solution, preferably hydrated ammonium tetraborate [NH4HB407 'xH 2 0].

Cette solution projetée est ensuite séchée par soufflage d'air chaud ou par un chauffage différent. A l'issue de ce séchage il subsiste des microcristaux 16. Ensuite, comme déjà décrit, on dépose la couche d'aluminium 13.This sprayed solution is then dried by blowing hot air or by different heating. At the end of this drying, microcrystals remain. Then, as already described, the aluminum layer 13 is deposited.

Au cours du traitement thermique les microcristaux de tétraborate d'ammonium hydraté subissent une réduction de volume importante car l'eau H20 et l'ammoniac NH3 s'échappent sous forme gazeuse. Il ne reste ainsi qu'un résidu 17 d'anhydride borique B203 de petit volume. Ce volume résiduel minimum permet de réduire au maximum la surface des trous qui reste occultée, ce qui donne un passage plus aisé aux gaz résultant de la décomposition de la couche organique 15.During the heat treatment, the microcrystals of hydrated ammonium tetraborate undergo a significant reduction in volume because the water H 2 0 and the ammonia NH 3 escape in gaseous form. This leaves only a residue 17 of boric anhydride B 2 0 3 of small volume. This minimum residual volume makes it possible to reduce as much as possible the surface of the holes which remains obscured, which gives easier passage to the gases resulting from the decomposition of the organic layer 15.

Ainsi la formation de cloques, tant sur l'écran proprement dit qu'autour de ce dernier, est moins probable avec un sel d'ammonium hydraté qu'avec les produits utilisés antérieurement.Thus the formation of blisters, both on the screen itself and around it, is less likely with a hydrated ammonium salt than with the products used previously.

Dans des essais comparatifs entre une solution d'acide borique et une solution de tétraborate d'ammonium on a relevé les résultats suivants :

  • pour un panneau frontal,
  • avec des solutions à 3 % dans les deux cas,
    Figure imgb0001
In comparative tests between a boric acid solution and an ammonium tetraborate solution, the following results were noted:
  • for a front panel,
  • with 3% solutions in both cases,
    Figure imgb0001

On constate ainsi que l'invention réduit considérablement le poids de résidus solides.It can thus be seen that the invention considerably reduces the weight of solid residues.

Au cours des essais comparatifs on a constaté que les soufflages de cloques sous la couche d'aluminium étaient principalement provoqués par une brutale perte en eau dans la solution d'acide borique. Entre 100 °C et 150 °C, cette perte brutale provoque un flux de vapeur d'eau responsable de la formation de cloques. Une solution selon l'invention, en concentrations comparables, subit une perte en eau beaucoup plus progressive.During the comparative tests it was found that the blowing of blisters under the aluminum layer was mainly caused by a sudden loss of water in the boric acid solution. Between 100 ° C and 150 ° C, this sudden loss causes a flow of water vapor responsible for the formation of blisters. A solution according to the invention, in comparable concentrations, undergoes a much more progressive loss of water.

La figure 3 est un diagramme illustrant ces essais comparatifs et d'autres essais. En abscisses on a porté la température de traitement en d° Celsius et en ordonnées, en %. la perte en poids des diverses couches. La courbe 20 se rapporte au tétraborate d'ammonium hydraté, la courbe 21 représente la perte de poids d'acide borique, dans les mêmes conditions de concentration. La courbe 22 montre la perte en poids du borax de formule chimique [Na2B4O7. 10H20]. La courbe 23 se rapporte à l'utilisation de l'oxalate d'ammonium et la courbe 24 montre la perte de poids en fonction de la température de la couche 15.Figure 3 is a diagram illustrating these comparative tests and other tests. The treatment temperature is plotted on the abscissa in d ° Celsius and the ordinate in%. weight loss of various layers. Curve 20 relates to hydrated ammonium tetraborate, curve 21 represents the weight loss of boric acid, under the same concentration conditions. Curve 22 shows the weight loss of the borax of chemical formula [Na 2 B 4 O 7 . 10H 2 0]. Curve 23 relates to the use of ammonium oxalate and curve 24 shows the weight loss as a function of the temperature of layer 15.

Les recherches effectuées par les inventeurs ont montré que l'oxalate d'ammonium est un composé organique qui s'évapore complètement et ne donne pas lieu à un résidu permettant d'améliorer l'adhérence entre les phosphores et la couche d'aluminium et entre le verre et cette couche d'aluminium. De plus, comme le montre la courbe 23 l'oxalate d'ammonium s'évapore rapidement ; le risque de formation de cloques est donc élevé.The research carried out by the inventors has shown that ammonium oxalate is an organic compound which evaporates completely and does not give rise to a residue making it possible to improve the adhesion between the phosphors and the aluminum layer and between glass and that layer of aluminum. In addition, as curve 23 shows, the ammonium oxalate evaporates quickly; the risk of blistering is therefore high.

L'acide borique laisse, après décomposition, un résidu B203 améliorant ladite adhérence. Le tétraborate d'ammonium laisse le même résidu. Toutefois, l'avantage de cette dernière substance par rapport à l'acide borique est, comme on peut le voir à l'examen des courbes 20 et 21, que la vitesse de décomposition du tétraborate d'ammonium est moins importante que la vitesse de décomposition de l'acide borique ; ainsi avec le tétraborate d'ammonium le risque de formation de cloques est moins élevé.Boric acid leaves, after decomposition, a residue B 2 0 3 improving said adhesion. The ammonium tetraborate leaves the same residue. However, the advantage of the latter substance over boric acid is, as can be seen from the examination of curves 20 and 21, that the rate of decomposition of ammonium tetraborate is less important than the rate of decomposition of boric acid; thus with ammonium tetraborate the risk of blistering is lower.

Enfin, le borax [Na2B407' 10H20] se décompose également plus rapidement que le tétraborate d'ammonium (voir courbe 22). Le risque de formation de cloques est ainsi plus élevé. De plus, le résidu laissé par le borax n'a pas les propriétés de collage du résidu B203.Finally, borax [Na2B407 '10H 2 0] also decomposes faster than ammonium tetraborate (see curve 22). The risk of blistering is therefore higher. In addition, the residue left by borax does not have the bonding properties of residue B 2 0 3 .

Claims (3)

1. Process for aluminizing the inner face of the screen of a cathode ray tube, especially for colour television, comprising depositing an organic layer (15) onto the luminescent elements and around the screen, then spraying, onto said organic layer, a solution or suspension forming microcrystals (16) upon drying which roughen the surface of said organic layer, subsequently depositing aluminium (13) onto said rough surface, and subjecting said tube to a thermal treatment so as to decompose said organic layer (15) in order to deflate it through the holes of said aluminium layer formed by said rough, characterized in that said solution or suspension applied onto said organic layer (15) being a solution of ammonium tetraborate, preferably of hydrated ammonium tetraborate [NH4HB4O7· xH20].
2. Process according to claim 1 characterized in that said solution is dried by blowing of hot air.
3. Process according to claim 1 or characterized in that said solution of ammonium tetraborate is an aqueous solution.
EP84401895A 1983-09-27 1984-09-21 Aluminium coating process for the internal side of a colour television tube screen Expired EP0143021B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8315338A FR2552584B1 (en) 1983-09-27 1983-09-27 METHOD FOR ALUMINIZING THE INTERNAL FACE OF THE SCREEN OF A COLORED TELEVISION TUBE
FR8315338 1983-09-27

Publications (2)

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EP0143021A1 EP0143021A1 (en) 1985-05-29
EP0143021B1 true EP0143021B1 (en) 1987-05-06

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EP (1) EP0143021B1 (en)
JP (1) JPH067455B2 (en)
DE (1) DE3463587D1 (en)
FR (1) FR2552584B1 (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA1267684A (en) * 1985-09-12 1990-04-10 Hiroshi Kato Beam-index type color cathode ray tube device
JPH0227636A (en) * 1988-07-15 1990-01-30 Sony Corp Formation of fluorescent surface of image receiving tube
EP0382554A3 (en) * 1989-02-10 1992-09-30 Matsushita Electric Industrial Co., Ltd. Method of forming a metal-backed layer and a method of forming an anode
US5264478A (en) * 1991-08-21 1993-11-23 Samsung Electron Devices Co., Ltd. Filming liquid composition for color braun tubes
JP2536409B2 (en) * 1993-06-08 1996-09-18 日本電気株式会社 Method for forming fluorescent screen of cathode ray tube
WO1999035192A1 (en) 1998-01-09 1999-07-15 Metabolix, Inc. Polymer compositions providing low residue levels and methods of use thereof
ITMI991155A1 (en) 1999-05-25 2000-11-25 Videocolor Spa METHOD FOR METALLIZING A LUMINESCENT SCREEN
KR100331452B1 (en) * 2000-05-29 2002-04-09 김순택 Method for forming phosphor screen decreasing residual carbon compound
JP2002343241A (en) * 2001-05-10 2002-11-29 Toshiba Corp Method of forming phosphor screen metal back and image display unit
JP4952974B2 (en) * 2005-11-18 2012-06-13 カシオ計算機株式会社 Lens cover and digital camera

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US2910376A (en) * 1957-03-27 1959-10-27 Rca Corp Method of aluminizing phosphor screens
US3821009A (en) * 1972-04-28 1974-06-28 Zenith Radio Corp Method of aluminizing a cathode-ray tube screen
US4025661A (en) * 1972-11-13 1977-05-24 Rca Corporation Method of making viewing-screen structure for a cathode-ray tube
US4123563A (en) * 1977-02-23 1978-10-31 Hitachi, Ltd. Process for the production of color television picture tubes
US4339475A (en) * 1979-03-23 1982-07-13 Hitachi, Ltd. Method of forming a fluorescent screen for cathode-ray tube

Also Published As

Publication number Publication date
EP0143021A1 (en) 1985-05-29
US4590092A (en) 1986-05-20
FR2552584A1 (en) 1985-03-29
JPS60150537A (en) 1985-08-08
FR2552584B1 (en) 1986-03-21
JPH067455B2 (en) 1994-01-26
DE3463587D1 (en) 1987-06-11

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