EP0556480B1 - Method for applying thin coatings on large curved surfaces, especially cathode ray tube screen, by a centrifugal coating process - Google Patents

Method for applying thin coatings on large curved surfaces, especially cathode ray tube screen, by a centrifugal coating process Download PDF

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Publication number
EP0556480B1
EP0556480B1 EP92121666A EP92121666A EP0556480B1 EP 0556480 B1 EP0556480 B1 EP 0556480B1 EP 92121666 A EP92121666 A EP 92121666A EP 92121666 A EP92121666 A EP 92121666A EP 0556480 B1 EP0556480 B1 EP 0556480B1
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EP
European Patent Office
Prior art keywords
coated
disc
coating
cathode ray
ray tube
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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EP92121666A
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German (de)
French (fr)
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EP0556480A1 (en
Inventor
Nanning Dr. Arfsten
Hermann Piehlke
Reinhard Kaufmann
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Schott AG
Carl Zeiss AG
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Carl Zeiss AG
Schott Glaswerke AG
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J9/00—Apparatus or processes specially adapted for the manufacture, installation, removal, maintenance of electric discharge tubes, discharge lamps, or parts thereof; Recovery of material from discharge tubes or lamps
    • H01J9/20—Manufacture of screens on or from which an image or pattern is formed, picked up, converted or stored; Applying coatings to the vessel
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D1/00—Processes for applying liquids or other fluent materials
    • B05D1/002—Processes for applying liquids or other fluent materials the substrate being rotated
    • B05D1/005—Spin coating
    • 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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J9/00—Apparatus or processes specially adapted for the manufacture, installation, removal, maintenance of electric discharge tubes, discharge lamps, or parts thereof; Recovery of material from discharge tubes or lamps
    • H01J9/20—Manufacture of screens on or from which an image or pattern is formed, picked up, converted or stored; Applying coatings to the vessel
    • H01J9/22—Applying luminescent coatings
    • H01J9/221—Applying luminescent coatings in continuous layers
    • H01J9/223—Applying luminescent coatings in continuous layers by uniformly dispersing of liquid

Definitions

  • the outer surface of the screen of a picture tube is usually mirror-like and has a very high electrical resistance.
  • the bare, smooth surface often causes annoying reflections, and the high electrical resistance leads to electrostatic charging of the screen surface during operation of the tube.
  • an antistatic or anti-reflective coating by applying one or more thin layers, for which numerous methods are known. It is widespread, for example, to apply an alcoholic solution of organosilicon compounds, in particular silicon alcoholates, together with organotitanium compounds in a thin layer to adjust the refractive index, which after drying and baking form an SiO2 film that has antistatic and antireflective properties . Sometimes several layers, possibly with different refractive indices, are applied after each intermediate drying and then baked together. Excellent layers of anti-reflective effects can be created, especially with multiple layers.
  • spin coating is used in particular as a coating method for producing thin layers on large domed bodies.
  • the coating solution is applied to the object to be coated, distributed by rotating the object to be coated and any excess is thrown off at the edges.
  • the centrifugal process is simple in terms of process technology and also works very quickly, but in particular in the outer and corner areas of large-area screens, different layer thicknesses can occur, which can cause undesirable effects, for example interference.
  • the screen surface to be coated to be arranged facing downwards in an inclined drum, which has an opening facing upwards, then spraying the coating solution on the screen surface and, while rotating by means of a warm air blower, part of the liquid film formed in and around the center of the screen by targeted blowing with warm air to dry.
  • a warm air blower part of the liquid film formed in and around the center of the screen by targeted blowing with warm air to dry.
  • the object of the invention is to find a method for spin coating in which very homogeneous coatings can be achieved even with large bodies, in which only a relatively small outlay on equipment is required and in which the consumption of coating material can be kept low.
  • the generation of a particularly uniform layer thickness over the entire surface to be coated is achieved in that a disc approximately adapted to the shape of the surface to be coated with approximately the spin speed is used in the same direction during the spinning process at a distance of 1-10 mm above the surface to be coated the surface to be coated can rotate. If the distance between the pane and the surface to be coated is less than 1 mm, the outlay on equipment rises sharply due to the high precision that is then required. If the distance of the rotating disk from the surface to be coated is greater than 10 mm, inhomogeneities in the layer thickness could occur, particularly in the case of large parts to be coated. A distance of 2-4 mm for the disk is preferred. Furthermore, it is preferred if the rotating disk follows the contour of the edge at the edges of the surface to be coated, ie is drawn down about 0.5-2 cm deep at a distance of 1 to 10 mm around the edges of the object to be coated.
  • the addition of the coating solution takes place most advantageously during the rotation through a central opening in the disk rotating concentrically to the coating surface.
  • the known addition of the coating solution during the rotation has the advantage that very little coating solution is used.
  • the size of the central opening is largely uncritical, but in practice it is preferred not to let the diameter of this opening be larger than 15 cm, preferably not larger than 3 cm.
  • the smallest diameter of the feed opening is limited by the need to let the coating agent or a nozzle supplying the coating agent pass through. Of course, it is also possible to close the opening after the coating solution has been supplied.
  • the nozzle can also be firmly connected to the disk and connected to a feed system for the coating solution via a rotating seal.
  • the distance of the pane from the surface to be coated should be 1-10 mm, preferably 2-4 mm, whereby an approximately the shape of the pane to be coated is achieved. It is further preferred if, for a given average distance of the pane in the area under stress, the difference in the distance of the pane between the shortest and furthest distance from the top surface to be coated is at most 4 mm. It is further preferred if the distance of the pane from the coating surface in the outer third of the edge area is between 1 and 4, preferably 2 and 3 mm.
  • the speeds at which the disk and the surface to be coated rotate during spin coating are known per se and range from less than 300 revolutions / minute to about 1,500 revolutions. About 500-700 revolutions / minute are preferred.
  • the speed of the rotating disc should not differ significantly from the speed at which the surface to be coated rotates. It is preferred if the rotating disk and the surface to be coated run at the same speed, which is also the simplest solution to implement in terms of apparatus. However, it is also entirely possible to allow speed differences of up to about 10%.
  • Figure 1 shows a cathode ray tube 1, which is held in a holding device 2 and 2 '.
  • the screen page 3 to be coated faces upwards.
  • the disc is a short distance above the surface to be coated 4 arranged, which essentially follows the shape of the surface to be coated.
  • the disc 4 is provided with a nozzle 5, around which the disc 4 is rotatable and which at the same time forms the central opening 6 for the supply of the coating material.
  • the disc 4 is provided on its sides with a collar 7 which overlaps the outer edges of the surface 3 to be coated.
  • the picture tube 1 with the holder 2 and 2 and the disk 4 are preferably rotated synchronously about the axis 9 and the coating solution is introduced onto the surface 3 through the central opening 6 coating surface 3 completely uniform coating film.
  • FIG. 2 shows a top view of a disk 24 with a centrally arranged feed opening 26 for applying the coating solution.
  • a disc is provided, which is provided with a collar and is thus drawn 0.5 cm around the edge of the surface to be coated.
  • the disc is provided with a central opening of 0.2-1 cm in diameter for the supply of the coating agent.
  • the axes of rotation of screen 1 and disc 4 are of course concentric. Now the screen and screen are rotated in the same direction at 800 revolutions / minute and 5 ml of coating solution are added at once through the central opening.
  • the coating solution has the composition: 32 g (OCH3) 4Si (OCH3) 4, 88 ml of ethanol, 1 ml of HCL and 27 ml of H2O.
  • the disk and screen are rotated for about 10 seconds, the screen is removed from the holding device, it is dried at 150 ° C. and then the coating is baked at 400-450 ° C.
  • the layer produced on the screen surface had a thickness of 91 nm ⁇ 2 nm over the entire area.
  • the coating solution can also be dried on the screen surface if the picture tube is still clamped in the holder, for example by the pane is tilted away and the entire pane surface is blown with warm or hot air.
  • the screen can rotate or stand still. After the first layer has dried, corresponding further layers can be applied, so that a layer package is obtained which is finally baked together in one firing process. In this way, an excellent anti-reflective coating or antistatic finish can be achieved.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Application Of Or Painting With Fluid Materials (AREA)
  • Formation Of Various Coating Films On Cathode Ray Tubes And Lamps (AREA)
  • Chemically Coating (AREA)

Abstract

A process for centrifugal coating of large-surface, arched elements, especially of cathode-ray-tube displays or screens, in which during the centrifugal coating, a disk matched to approximately the shape of the surface to be coated is rotated at a distance of 1 to 10 mm above the surface to be coated at approximately the centrifugal speed equidirectional with the surface to be coated.

Description

Üblicherweise ist die äußere Oberfläche des Bildschirms einer Bildröhre spiegelblank und besitzt einen sehr hohen elektrischen Widerstand. Die blanke, glatte Oberfläche verursacht häufig störende Reflexe, und der hohe elektrische Widerstand führt zu einer elektrostatischen Aufladung der Bildschirmoberfläche während des Betriebs der Röhre. Um diese Nachteile zu vermeiden, ist es bekannt, durch Aufbringen einer oder mehrerer dünner Schichten die Oberfläche des Bildschirms antistatisch oder antireflektierend auszurüsten, wozu zahlreiche Methoden bekannt sind. Weit verbreitet ist es z.B., auf die Bildschirmoberfläche eine alkoholische Lösung von siliziumorganischen Verbindungen, insbesondere Siliziumalkoholaten, gegebenenfalls zusammen mit titanorganischen Verbindungen zur Anpassung des Brechungsindex in dünner Schicht aufzubringen, die nach Trocknen und Ausheizen einen SiO₂-Film bilden, der antistatische und antireflexive Eigenschaften aufweist. Mitunter werden auch mehrere Schichten, gegebenenfalls mit unterschiedlichen Brechungsindices, nach jeweiligem Zwischentrocknen aufgebracht und anschließend gemeinsam eingebrannt. Insbesondere mit mehreren Schichten lassen sich ganz ausgezeichnete antireflexive Wirkungen erzeugen.The outer surface of the screen of a picture tube is usually mirror-like and has a very high electrical resistance. The bare, smooth surface often causes annoying reflections, and the high electrical resistance leads to electrostatic charging of the screen surface during operation of the tube. In order to avoid these disadvantages, it is known to provide the surface of the screen with an antistatic or anti-reflective coating by applying one or more thin layers, for which numerous methods are known. It is widespread, for example, to apply an alcoholic solution of organosilicon compounds, in particular silicon alcoholates, together with organotitanium compounds in a thin layer to adjust the refractive index, which after drying and baking form an SiO₂ film that has antistatic and antireflective properties . Sometimes several layers, possibly with different refractive indices, are applied after each intermediate drying and then baked together. Excellent layers of anti-reflective effects can be created, especially with multiple layers.

Bei der Ausbildung der Schichten ist es besonders wichtig, daß diese über die gesamte Fläche des zu beschichtenden Gegenstandes eine gleichmäßige Dicke aufweisen. Als Beschichtungsverfahren zum Erzeugen dünner Schichten auf großflächigen gewölbten Körpern kommt insbesondere das Schleuderbeschichten zur Anwendung. Bei diesem Verfahren wird die Beschichtungslösung auf den zu beschichtenden Gegenstand aufgegeben, durch Rotation des zu beschichtenden Gegenstandes verteilt und ein etwaiger Überschuß an den Rändern abgeschleudert. Das Schleuderverfahren ist verfahrenstechnisch einfach und arbeitet auch sehr schnell, jedoch können insbesondere im Außen-und Eckenbereich großflächiger Bildschirme unterschiedliche Schichtdicken auftreten, die unerwünschte Wirkungen, z.B. Interferenz, hervorrufen können. Zur Erzeugung einer gleichmäßigen Schichtdicke ist es z.B. aus EP-A- 286 129 bekannt, die zu beschichtende Bildschirmoberfläche nach unten weisend in einer schräg gestellten Trommel anzuordnen, die eine nach oben weisende Öffnung besitzt, anschließend die Bildschirmoberfläche mit der Beschichtungslösung zu besprühen und während des Rotierens durch ein Warmluftgebläse einen Teil des gebildeten Flüssigkeitsfilmes in und um das Zentrum des Bildschirms durch gezieltes Anblasen mit Warmluft zu trocknen. Ein solches Verfahren ist verhältnismäßig aufwendig. Aus JP 2-12736 A ist ein Verfahren bekannt, bei dem der zu beschichtende Bildschirm mit der zu beschichtenden Fläche nach oben weisend in einen Trog eingesetzt wird, dessen Halteplatten für den Bildschirm so gestaltet sind, daß sie praktisch eine Fortsetzung der Bildschirmoberfläche bilden. Ferner ist in dieser Schrift beschrieben, mit Abstand über der Bildschirmoberfläche zwei bis etwa zur Mitte verlaufende diagonal angeordnete sehr hohe Stege vorzusehen, die während der Beschichtung synchron mit der Bildröhre rotieren. Durch diese Anordnungen soll eine gleichmäßige Schichtdicke der aufgebrachten Schicht erreicht werden. Diese Verfahren arbeiten jedoch, insbesondere bei großen Bildschirmen, nicht immer zufriedenstellend.When forming the layers, it is particularly important that they have a uniform thickness over the entire surface of the object to be coated. Spin coating is used in particular as a coating method for producing thin layers on large domed bodies. In this method, the coating solution is applied to the object to be coated, distributed by rotating the object to be coated and any excess is thrown off at the edges. The centrifugal process is simple in terms of process technology and also works very quickly, but in particular in the outer and corner areas of large-area screens, different layer thicknesses can occur, which can cause undesirable effects, for example interference. To produce a uniform layer thickness, it is known, for example from EP-A-286 129, the screen surface to be coated to be arranged facing downwards in an inclined drum, which has an opening facing upwards, then spraying the coating solution on the screen surface and, while rotating by means of a warm air blower, part of the liquid film formed in and around the center of the screen by targeted blowing with warm air to dry. Such a process is relatively complex. From JP 2-12736 A a method is known in which the screen to be coated is inserted with the surface to be coated facing upwards into a trough, the support plates for the screen of which are designed so that they practically form a continuation of the screen surface. Furthermore, it is described in this document to provide two diagonally arranged, very high webs running at a distance above the screen surface which rotate synchronously with the picture tube during the coating. These arrangements are intended to achieve a uniform layer thickness of the applied layer. However, these methods do not always work satisfactorily, especially with large screens.

Die Aufgabe der Erfindung besteht darin, ein Verfahren zum Schleuderbeschichten zu finden, bei dem auch bei großflächigen Körpern sehr homogene Beschichtungen erzielt werden können, bei dem nur ein verhältnismäßig geringer apparativer Aufwand erforderlich ist und bei dem der Verbrauch von Beschichtungsmaterial gering gehalten werden kann.The object of the invention is to find a method for spin coating in which very homogeneous coatings can be achieved even with large bodies, in which only a relatively small outlay on equipment is required and in which the consumption of coating material can be kept low.

Diese Aufgabe wird durch das in Patentanspruch 1 beschriebene Verfahren gelöst.This object is achieved by the method described in claim 1.

Die Erzeugung einer besonders gleichmäßigen Schichtdicke über die gesamte zu beschichtende Fläche wird dadurch erreicht, daß man während des Schleudervorganges im Abstand von 1 - 10 mm über der zu beschichtenden Oberfläche eine in etwa der Form der zu beschichtenden Oberfläche angepaßte Scheibe mit etwa der Schleuderdrehzahl gleichsinnig mit der zu beschichtenden Oberfläche rotieren läßt. Wird der Abstand der Scheibe zu der zu der beschichtenden Oberfläche kleiner als 1 mm, so steigt der apparative Aufwand wegen der dann erforderlichen hohen Präzision stark an, darüber hinaus kann es im rauhen Alltagsbetrieb zu Störungen kommen. Wird der Abstand der rotierenden Scheibe von der zu beschichtenden Oberfläche größer als 10 mm, so könnten, insbesondere bei großen zu beschichtenden Teilen, Inhomogenitäten in der Schichtdicke auftreten. Bevorzugt wird ein Abstand für die Scheibe von 2-4 mm. Weiterhin wird es bevorzugt, wenn die rotierende Scheibe an den Rändern der zu beschichtenden Oberfläche der Kontur des Randes folgt, d.h. etwa 0,5-2 cm tief in einem Abstand von 1 bis 10 mm um die Kanten des zu beschichtenden Gegenstandes heruntergezogen ist.The generation of a particularly uniform layer thickness over the entire surface to be coated is achieved in that a disc approximately adapted to the shape of the surface to be coated with approximately the spin speed is used in the same direction during the spinning process at a distance of 1-10 mm above the surface to be coated the surface to be coated can rotate. If the distance between the pane and the surface to be coated is less than 1 mm, the outlay on equipment rises sharply due to the high precision that is then required. If the distance of the rotating disk from the surface to be coated is greater than 10 mm, inhomogeneities in the layer thickness could occur, particularly in the case of large parts to be coated. A distance of 2-4 mm for the disk is preferred. Furthermore, it is preferred if the rotating disk follows the contour of the edge at the edges of the surface to be coated, ie is drawn down about 0.5-2 cm deep at a distance of 1 to 10 mm around the edges of the object to be coated.

Die Zugabe der Beschichtungslösung erfolgt am vorteilhaftesten während der Rotation durch eine zentrale Öffnung in der konzentrisch zu der beschichtenden Oberfläche rotierende Scheibe. Die an sich bekannte Zugabe der Beschichtungslösung während der Rotation hat den Vorteil, daß ganz besonders wenig Beschichtungslösung verbraucht wird. Die Größe der zentralen Öffnung ist weitgehend unkritisch, in der Praxis wird jedoch bevorzugt, den Durchmesser dieser Öffnung nicht größer als 15 cm, bevorzugt nicht größer als 3 cm, werden zu lassen. Der kleinste Durchmesser der Zufuhröffnung wird durch die Notwendigkeit, das Beschichtungsmittel bzw. einen das Beschichtungsmittel zuführenden Stutzen durchtreten zu lassen, begrenzt. Natürlich ist es auch möglich, nach der Zufuhr der Beschichtungslösung die Öffnung zu verschließen.
Der Stutzen kann auch fest mit der Scheibe verbunden und über eine rotierende Dichtung an ein Zuführsystem für die Beschichtungslösung angeschlossen sein. Der Abstand der Scheibe von der zu beschichtenden Oberfläche soll 1-10 mm, bevorzugt 2-4 mm betragen, wodurch eine in etwa der Form der zu beschichtenden Oberfläche angepaßte Scheibenform erzielt wird. Es wird weiterhin bevorzugt, wenn bei einem gegebenen mittleren Abstand der Scheibe in dem beanspuchten Bereich die Differenz des Abstandes der Scheibe zwischen dem kürzesten und weitesten Abstand von der zu beschichtenden Obenfläche maximal 4 mm beträgt. Weiterhin wird es bevorzugt, wenn der Abstand der Scheibe zu der beschichtenden Oberfläche im äußeren Drittel des Randbereichs zwischen 1 und 4, bevorzugt 2 und 3 mm beträgt.The addition of the coating solution takes place most advantageously during the rotation through a central opening in the disk rotating concentrically to the coating surface. The known addition of the coating solution during the rotation has the advantage that very little coating solution is used. The size of the central opening is largely uncritical, but in practice it is preferred not to let the diameter of this opening be larger than 15 cm, preferably not larger than 3 cm. The smallest diameter of the feed opening is limited by the need to let the coating agent or a nozzle supplying the coating agent pass through. Of course, it is also possible to close the opening after the coating solution has been supplied.
The nozzle can also be firmly connected to the disk and connected to a feed system for the coating solution via a rotating seal. The distance of the pane from the surface to be coated should be 1-10 mm, preferably 2-4 mm, whereby an approximately the shape of the pane to be coated is achieved. It is further preferred if, for a given average distance of the pane in the area under stress, the difference in the distance of the pane between the shortest and furthest distance from the top surface to be coated is at most 4 mm. It is further preferred if the distance of the pane from the coating surface in the outer third of the edge area is between 1 and 4, preferably 2 and 3 mm.

Die Drehzahlen, mit denen Scheibe und zu beschichtende Oberfläche während der Schleuderbeschichtung rotieren, sind an sich bekannt und reichen von unter 300 Umdrehungen/Minute bis zu etwa 1.500 Umdrehungen. Bevorzugt werden etwa 500-700 Umdrehungen/Minute. Die Drehzahl der rotierenden Scheibe sollte von der Drehzahl, mit der die zu beschichtende Oberfläche rotiert, nicht wesentlich abweichen. Bevorzugt wird es, wenn die rotierende Scheibe und die zu beschichtende Oberfläche mit gleicher Drehzahl laufen, das ist auch die apparativ am einfachsten zu verwirklichende Lösung. Es ist jedoch durchaus auch möglich, Drehzahldifferenzen bis zu etwa 10 % zuzulassen.The speeds at which the disk and the surface to be coated rotate during spin coating are known per se and range from less than 300 revolutions / minute to about 1,500 revolutions. About 500-700 revolutions / minute are preferred. The speed of the rotating disc should not differ significantly from the speed at which the surface to be coated rotates. It is preferred if the rotating disk and the surface to be coated run at the same speed, which is also the simplest solution to implement in terms of apparatus. However, it is also entirely possible to allow speed differences of up to about 10%.

Die Erfindung wird anhand der Abbildung weiter erläutert. Es zeigen

Figur 1
in schematischer Weise einen Schnitt durch eine eingespannte Bildröhre mit darüber angeordneter rotierender Scheibe und
Figur 2
eine Aufsicht auf eine rotierende Scheibe mit zentraler Öffnung.
The invention is further illustrated by the figure. Show it
Figure 1
in a schematic way a section through a clamped picture tube with a rotating disc and
Figure 2
a top view of a rotating disc with a central opening.

Figur 1 zeigt eine Kathodenstrahlbildröhre 1, die in einer Haltevorrichtung 2 und 2′ gehaltert ist. Die zu beschichtende Bildschirmseite 3 weist nach oben. In geringem Abstand oberhalb der zu beschichtenden Oberfläche ist die Scheibe 4 angeordnet, die im wesentlichen der Form der zu beschichtenden Oberfläche folgt. Die Scheibe 4 ist mit einem Stutzen 5 versehen, um den die Scheibe 4 drehbar ist und der gleichzeitig die zentrale Öffnung 6 für die Zufuhr des Beschichtungsmaterials bildet. Die Scheibe 4 ist an ihren Seiten mit einem Kragen 7 versehen, der die Außenkanten der zu beschichtenden Fläche 3 überlappt. Zum Schleuderbeschichten läßt man die Bildröhre, 1 mit der Halterung 2 und 2-sowie die Scheibe 4 bevorzugt synchron um die Achse 9 rotieren und gibt durch die zentrale Öffnung 6 die Beschichtungslösung auf die Oberfläche 3. Es bildet sich ein bis in die Randbereiche der zu beschichtenden Fläche 3 völlig gleichmäßiger Beschichtungsfilm aus. Die Antriebsmechanismen für die in der Halterung 2 und 2′ eingespannte Bildröhre 1 sowie für die Scheibe 4 sind nicht besonders dargestellt. Statt über den Stutzen 5 kann die Scheibe natürlich auch in geeigneter Weise an den Halterungen 2 und 2- befestigt sein und von dort mit angetrieben werden. Figur 2 zeigt eine Aufsicht auf eine Scheibe 24 mit einer zentral angeordneten Zufuhröffnung 26 zum Aufbringen der Beschichtungslösung.Figure 1 shows a cathode ray tube 1, which is held in a holding device 2 and 2 '. The screen page 3 to be coated faces upwards. The disc is a short distance above the surface to be coated 4 arranged, which essentially follows the shape of the surface to be coated. The disc 4 is provided with a nozzle 5, around which the disc 4 is rotatable and which at the same time forms the central opening 6 for the supply of the coating material. The disc 4 is provided on its sides with a collar 7 which overlaps the outer edges of the surface 3 to be coated. For spin coating, the picture tube 1 with the holder 2 and 2 and the disk 4 are preferably rotated synchronously about the axis 9 and the coating solution is introduced onto the surface 3 through the central opening 6 coating surface 3 completely uniform coating film. The drive mechanisms for the clamped in the holder 2 and 2 'picture tube 1 and for the disc 4 are not shown in particular. Instead of via the connector 5, the disc can of course also be attached to the brackets 2 and 2- in a suitable manner and driven from there. FIG. 2 shows a top view of a disk 24 with a centrally arranged feed opening 26 for applying the coating solution.

Beispiel: Eine Kathodenstrahlbildröhre mit den Abmessungen 25 × 32 cm² wird in eine Vorrichtung ähnlich Figur 1 eingespannt. Im Abstand von 2 mm von der zu beschichtenden Oberfläche wird eine Scheibe, die mit einem Kragen versehen ist und dadurch 0,5 cm um die Kante der zu beschichtenden Oberfläche herumgezogen ist, angeordnet. Die Scheibe ist mit einer zentralen Öffnung von 0,2-1 cm Durchmesser zur Zufuhr des Beschichtungsmittels versehen. Die Drehachsen von Bildschirm 1 und Scheibe 4 sind selbstverständlich konzentrisch. Nun werden Scheibe und Bildschirm gleichsinnig mit 800 Umdrehungen/Minute in Rotation versetzt und durch die zentrale Öffnung wird 5 ml Beschichtungslösung auf einmal zugegeben. Die Beschichtungslösung hat die Zusammensetzung: 32 g (OCH₃)₄Si(OCH₃)₄, 88 ml Ethanol, 1 ml HCL und 27 ml H₂O.Example: A cathode ray tube with the dimensions 25 × 32 cm² is clamped in a device similar to FIG. 1. At a distance of 2 mm from the surface to be coated, a disc is provided, which is provided with a collar and is thus drawn 0.5 cm around the edge of the surface to be coated. The disc is provided with a central opening of 0.2-1 cm in diameter for the supply of the coating agent. The axes of rotation of screen 1 and disc 4 are of course concentric. Now the screen and screen are rotated in the same direction at 800 revolutions / minute and 5 ml of coating solution are added at once through the central opening. The coating solution has the composition: 32 g (OCH₃) ₄Si (OCH₃) ₄, 88 ml of ethanol, 1 ml of HCL and 27 ml of H₂O.

Nach der Zugabe der Beschichtungslösung läßt man Scheibe und Bildschirm noch zirka 10. sec. rotieren, entnimmt den Bildschirm der Haltevorrichtung, trocknet ihn bei 150 °C und brennt anschließend die Beschichtung bei 400-450°C ein. Die auf der Bildschirmoberfläche erzeugte Schicht hatte über die gesamte Fläche eine Dicke von 91 nm ± 2 nm. Die Trocknung der Beschichtungslösung auf der Bildschirmoberfläche kann auch erfolgen, wenn die Bildröhre noch in der Halterung eingespannt ist, indem z.B. die Scheibe weggekippt und die gesamte Scheibenoberfläche mit Warm-oder Heißluft angeblasen wird. Der Bildschirm kann dabei rotieren oder stillstehen. Nach dem Trocknen der ersten Schicht können entsprechende weitere Schichten aufgebracht werden, so daß man ein Schichtenpaket erhält, das abschließend gemeinsam in einem Brennvorgang eingebrannt wird. Auf diese Weise läßt sich eine ganz vorzügliche Entspiegelung oder antistatische Ausrüstung erreichen.After the addition of the coating solution, the disk and screen are rotated for about 10 seconds, the screen is removed from the holding device, it is dried at 150 ° C. and then the coating is baked at 400-450 ° C. The layer produced on the screen surface had a thickness of 91 nm ± 2 nm over the entire area. The coating solution can also be dried on the screen surface if the picture tube is still clamped in the holder, for example by the pane is tilted away and the entire pane surface is blown with warm or hot air. The screen can rotate or stand still. After the first layer has dried, corresponding further layers can be applied, so that a layer package is obtained which is finally baked together in one firing process. In this way, an excellent anti-reflective coating or antistatic finish can be achieved.

Claims (5)

  1. Process for producing thin coatings on large-surface curved bodies, in particular cathode ray tube screens, by centrifugal coating, characterized in that during the centrifugal procedure a disc (4) matched approximately to the shape of the surface to be coated is rotated approximately at the speed of centrifuging in the same direction as the surface (3) to be coated, at a spacing of 1 to 10 mm above the surface to be coated.
  2. Process according to Claim 1, characterized in that the disc (4) is rotated at a spacing of 2 to 4 mm above the surface (3) to be coated.
  3. Process according to Claim 1 or 2, characterized in that a disc which is drawn down approximately 0.5 to 2 cm and at a spacing of 1 to 10 mm around the edges of the surface (3) to be coated is rotated.
  4. Process according to at least one of Claims 1 to 3, characterized in that the coating solution is added during rotation through a central opening (6) in the disc (4), which is not larger than 15 cm.
  5. Process according to at least one of Claims 1 to 4, characterized in that the centrifuging procedure is carried out at a speed of 300 to 1500 revolutions per minute.
EP92121666A 1992-02-15 1992-12-19 Method for applying thin coatings on large curved surfaces, especially cathode ray tube screen, by a centrifugal coating process Expired - Lifetime EP0556480B1 (en)

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DE4204637A DE4204637C1 (en) 1992-02-15 1992-02-15
DE4204637 1992-02-15

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EP0556480A1 EP0556480A1 (en) 1993-08-25
EP0556480B1 true EP0556480B1 (en) 1994-09-14

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JP (1) JP2592034B2 (en)
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DE19545573A1 (en) * 1995-12-07 1997-06-12 Leybold Ag Even deposition of lacquer on substrate

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US3824955A (en) * 1972-05-15 1974-07-23 A Marks Apparatus for coating television viewing tubes
JP2653429B2 (en) * 1986-10-16 1997-09-17 株式会社東芝 Bulb holder for cathode ray tube
JP2695823B2 (en) * 1987-04-10 1998-01-14 株式会社東芝 Method for forming a thin film on the outer surface of the display surface of a cathode ray tube
JPH0654634B2 (en) * 1988-02-08 1994-07-20 株式会社東芝 Coating device
JPH07109747B2 (en) * 1988-06-30 1995-11-22 旭硝子株式会社 Surface treatment device for panel face for ground pipe
FR2636546B1 (en) * 1988-09-15 1991-03-15 Sulzer Electro Tech METHOD AND DEVICE FOR THE UNIFORMLY REGULAR APPLICATION OF A RESIN LAYER ON A SUBSTRATE
JPH0294335A (en) * 1988-09-30 1990-04-05 Mitsubishi Electric Corp Manufacture of antistatic process type catode-ray tube
JPH02195629A (en) * 1989-01-25 1990-08-02 Hitachi Ltd Rotary coating method for cathode-ray tube panel face processing liquid
JP2760551B2 (en) * 1989-03-15 1998-06-04 株式会社東芝 Method for forming thin film on outer surface of face of cathode ray tube
JPH03152827A (en) * 1989-11-08 1991-06-28 Toshiba Corp Method of forming thin film on face outer surface of cathode-ray tube
JPH0675367B2 (en) * 1989-12-05 1994-09-21 旭硝子株式会社 Surface treatment method and device for panel face for cathode ray tube

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ES2060445T3 (en) 1994-11-16
JP2592034B2 (en) 1997-03-19
EP0556480A1 (en) 1993-08-25
DE4204637C1 (en) 1993-03-11
US5314715A (en) 1994-05-24
JPH0612981A (en) 1994-01-21
ATE111634T1 (en) 1994-09-15
DE59200507D1 (en) 1994-10-20

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