EP0110458B1 - Cathode ray tube with a luminescent screen, process for manufacturing a screen for such a tube and television picture projection tube with such a screen - Google Patents

Cathode ray tube with a luminescent screen, process for manufacturing a screen for such a tube and television picture projection tube with such a screen Download PDF

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Publication number
EP0110458B1
EP0110458B1 EP19830201591 EP83201591A EP0110458B1 EP 0110458 B1 EP0110458 B1 EP 0110458B1 EP 19830201591 EP19830201591 EP 19830201591 EP 83201591 A EP83201591 A EP 83201591A EP 0110458 B1 EP0110458 B1 EP 0110458B1
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EP
European Patent Office
Prior art keywords
screen
support
layer
tube
cells
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
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EP19830201591
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German (de)
French (fr)
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EP0110458A1 (en
Inventor
Valère Dominique Louis Duchenois
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Laboratoires dElectronique Philips SAS
Koninklijke Philips NV
Original Assignee
Laboratoires dElectronique et de Physique Appliquee
Philips Gloeilampenfabrieken NV
Koninklijke Philips Electronics NV
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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
    • H01J9/22—Applying luminescent coatings
    • H01J9/227—Applying luminescent coatings with luminescent material discontinuously arranged, e.g. in dots or lines
    • H01J9/2271—Applying luminescent coatings with luminescent material discontinuously arranged, e.g. in dots or lines by photographic processes
    • 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
    • H01J29/24—Supports for luminescent material

Definitions

  • the present invention relates to a cathode ray tube provided with a luminescent screen comprising a support having luminescent material, support which is provided with a configuration of cells filled with luminescent material, cells which have the form of juxtaposed tubes extending in the support and whose walls are reflective.
  • the invention also relates to a method for manufacturing a screen intended for such a tube and to the tube for projecting television images provided with such a screen.
  • Obtaining a high gloss is one of the qualities sought for a cathode ray tube screen, in particular when this screen is that of a projection television picture tube. It is well known that greater brightness of a tube can be obtained by increasing the thickness of the luminescent layer constituting the screen and simultaneously giving greater energy (greater beam current and / or more accelerating voltage high) to the electron beam ensuring the bombardment of said layer. However, this increase in brightness is accompanied by an increase in the diameter of the light spot on the screen. This is due to the lateral scattering of the light generated in the insulating layer. This increase in the diameter of the light spot results in a notable reduction in the contrast and the resolution of the image represented.
  • Such a structure has several disadvantages.
  • the beam electrons make a notable angle with the axes of the tubular cells of the screen, the beam electrons only bombard a small part of the luminescent material due to a weak penetration of the beam or to a phenomenon of shading by the walls of these cells. Part of the luminescent material is not exposed to electron bombardment. It also follows that the bombardment of the luminescent material on the surface of the screen is not uniform and that the luminescent material in each of the cells is used incompletely. As a result, the resolution, contrast and maximum image brightness are not uniform over the entire surface of the screen. In addition, the heat dissipation is not sufficient when the heat generation is too high, which is among other things the case of tubes intended for the projection of television images.
  • the invention aims to increase the brightness of the image without reducing the resolution and the contrast, in the case of flat screens, or concave or convex screens.
  • the invention also aims to make the resolution, contrast and maximum image brightness of such a tube uniform over the entire screen surface.
  • Another object of the invention consists in improving the brightness of the screen by providing the screen with means preventing an increase in the temperature of the layer caused by the heat developed in the luminescent layer, so that the luminescence of said layer is not reduced.
  • a luminescent screen of the kind described in the first paragraph is characterized in that the axes of the cells converge essentially towards the center of deflection of the electron beam.
  • the screen operates in transmission, that is to say that the luminescence light is emitted through the support.
  • the support comprises two glass panes, which are transparent to light and which are both with faces parallel and parallel to each other and constitute a double wall in the envelope of the tube, the cells of the screen opening out. on the inner wall of the tube support, the same cells being provided at this outlet with a transparent metallic layer to electrons and reflecting light, the double wall being provided with means for admitting and discharging a cooling fluid circulating between the two glass panes of the double wall.
  • the screen and its support are flat or even concave on the side of the electronic scanning or else, the walls of the cells are highly conductive or not of heat and in particular metallic.
  • the screen operates in reflection.
  • the support is opaque, the cells of the screen emitting luminescence light on the receiving side of the electron beam on the screen, a tube which is provided with means for projecting images, while the support is provided means for cooling said screen.
  • the screen and its support are planar or convex on the side of the incidence of the electron beam on the screen.
  • the walls of the cells can be highly conductive of heat and in particular metallic.
  • the associated optical system comprises, centered on the axis of the tube, a concave mirror facing the screen and a plate for correcting the aberrations of this mirror placed behind the screen.
  • the electrolytic growth of metal walls in the empty lacquer parts of said first layer is replaced by the growth of walls of electrically insulating material by the use of known techniques of the cathaphoresis or anaphoresis genus, transport grains of said insulating material on the support taking place using electrostatic forces resulting from the electric field established between the screen support and an electrode parallel to the free surface of said first layer, the growth being followed by sintering at high temperature to improve the mechanical strength of the deposit.
  • This wall constituent material is for example Si0 2 , AI 2 0 3 , MgO or even better, to improve the thermal conductivity, BeO.
  • the screen support is made of a material which is itself photosensitive in the field of ultraviolet radiation, which avoids having to cover it with a layer of lacquer sensitive to ultraviolet radiation.
  • This material is for example a photosensitive glass and the process proceeds practically in the same way, except that the cells are formed directly in the support without the need for growth by electrolysis or other of the walls of these cells.
  • the point of convergence of the axes of the cells on the axis of the screen is coincident, during the positioning of said screen in the future cathode ray tube, with the center of deflection of the scanning electron beam of said tube.
  • This latter embodiment leads directly to devices which can be used for the projection on the screen, outside the tube, of television images.
  • Figure 1 shows how the relative brightness of a layer of luminescent material varies as a function of temperature. For a temperature of 80 ° C, the gloss has decreased by 50%. It is for this reason that to obtain a high gloss it is necessary to remove from the luminescent material the heat released by an electron bombardment.
  • FIG. 2 which relates to a cathode ray tube according to the prior art, with a flat screen represented in section by a plane of symmetry, indicates under the reference numeral 11, the envelope of the tube with its conical part 12 and the neck 13.
  • This neck is provided with an electronic cannon and a deflection system, both of which are described below in FIG. 4.
  • the electron beam is 10.
  • the electron beams of the electron gun whose trajectories are supposed to be rectilinear come, after deflection, apparently from point A, which is called the center of deflection of the beam.
  • the electron beams reach the screen 14 which is deposited on a wall of the envelope 11 of said tube.
  • this screen is provided with cells in the form of small tubes, of which, for the simplicity of the drawing, only three are shown, namely under the numbers 15 , 16.17.
  • the screen is lined inside the cathode ray tube with a multitude of these small tubes juxtaposed to each other.
  • the axes of these tubes 18, 19, 21 respectively are parallel to each other and to the axis of the cathode ray tube itself 21.
  • the section of these tubes is substantially equal to that on the screen of the scanning beam 10.
  • Figure 3 relates to a cathode ray tube according to the invention.
  • the screen 14 which is deposited on the inner wall of the casing 11, is produced in another way. It always includes cells filled in the form of juxtaposed tubes of small diameter but whose axes are not parallel to each other. To simplify the figure, only three of these tubes, in particular 28, 22, 23 are shown.
  • the electron beam is deflected in three directions 24, 25 and 26.
  • These tubes are in the form of a cone or a cylinder and have axes 27, 21, 29 which are oriented so that they pass practically by the center of curvature A. It follows that all the luminescent material contained in the tubes is excited by the bombardment of electrons. In addition, the luminescent material is cooled.
  • the envelope of the tube is provided with a double wall 31, in which a coolant circulates, the admission of which is ensured by the tube 32 and the evacuation by the tube 33.
  • FIG. 4 relates to a cathode ray tube for projecting television images in the case of a convex screen associated with its projection optics.
  • FIG. 4 we find the elements 11, 12, 13 and 21 of FIG. 1.
  • This tube consists of an envelope 11 formed from the neck of the tube 13, of length 250 mm and diameter 36 mm, and of the cone of the tube 12 of length 150 mm and diameter of 150 mm at its widest part.
  • this last part although generally conical over its entire length, may have a shorter conical part followed by a cylindrical part.
  • an electron gun composed of a thermionic cathode with indirect heating and a number of cylindrical anodes 110 making it possible to accelerate the electrons.
  • the focusing is of the electrostatic or magnetic type using the external coils.
  • the tube has deflection coils 120 for scanning along the X and Y axes.
  • the screen 41 has a convex shape and is applied to a screen support 40 disposed in the cone of the tube. As in the first embodiment, this screen is provided with cells filled with luminescent material.
  • These cells including for the simplicity of the figure, only three are represented, namely 42, 43, and 44, are small tubes in the form of a truncated cone or cylinder whose axes respectively 45, 21, 47 pass practiqeument through the center of deflection A.
  • the directions of the beam of electrons according to which the bombardment of these tubes takes place are 35, 36, 37.
  • the section of the electron beam in the convex plane 48 of the screen turns out to be practically equal to the right of each tube to the section of said tube in the same plane.
  • maximum excitation of the luminescent material in the tube is ensured.
  • the cathode ray tube is provided with an optic for projecting the screen of the face 48.
  • This optic is for example an optic of the known art known as Schmidt, which is constituted by the concave mirror 49, placed on the inner wall of the tube and by the plate 50 for the aberration correction and which is placed at the entrance of the tube behind the screen.
  • the dimensions of the rectangular screen 41 are 36 mm x 48 mm.
  • the radius of curvature of the convex screen is equal to half the radius of curvature of mirror 49.
  • This mirror 49 is pierced in its center with an opening of 35 mm in diameter to allow the electron beam to wait for the 'screen.
  • the beam current of the tube is approximately 2m A peak for a high voltage of up to 50 K. or so, which represents 100 watts dissipated on the screen.
  • a cooling device In order to cool the screen, as in the first embodiment, it is provided with a cooling device.
  • This comprises a cooling liquid circulation system in a double wall consisting of the support 40 of the screen and a wall 51, which is welded in a watertight manner to the periphery of the support 40, the admission and evacuation of liquid being effected by means of the tubes 52 and 53 opening towards the outside of the envelope 11 of the tube.
  • the cooling circuit using a fluid at a temperature of 25 ° C, for example tap water, with a flow rate of 1.5 liters / minute makes it possible to ensure that the temperature of the screen does not exceed 100 ° C.
  • the manufacturing process will successively use these two characteristics to proceed with the very development of the screen and the tube.
  • the use of the optics associated with the tube to participate in the steps of the method makes it possible to have an image where the different possible optical defects are reduced (aberrations, convergence, etc.).
  • the luminescent material must have a massive structure, its deposition can be carried out by epitaxial growth in the vapor phase, or even by means of a cathodic or plasma spraying or even by spraying of liquid.
  • the substrate In the case of a screen used in transmission, the substrate must be transparent, for example made of glass or crystals.
  • the first of the preceding steps is then modified, the metal deposit then being an electrically conductive and optically transparent oxide deposit.
  • Deposits of SnO 2 or In 2 0 3 of around 300 Angtroms of thickness and resistivity of around 400 ohms / square correspond to this use.
  • a new stage then presents itself: on the face where the luminescent product appears, a thin film of nitrocellulose is deposited, in liquid medium, on which, by vacuum evaporation, a thin metallic layer of 1000 A is deposited, for example aluminum .
  • Heat treatment is carried out with air, at around 350 ° C., in order to burn the thin nitrocellulose film so that the thin metal layer remains alone, which makes it possible to obtain a configuration of sealed cells filled with luminescent product.
  • This thin metallic layer is transparent to the electrons in the electron beam but reflects the light from the luminescent product when the latter emits its luminescence light.
  • a second variant after obtaining the hollow parts 84 to 88 of FIG. 6, these are filled by cathaphoresis or anaphoresis of an insulating material using the electrostatic forces resulting from an electric field applied between the support screen 40 and an electrode parallel to 48 and located between 48 and point A.
  • the growth of the latter is followed by sintering at high temperature, the process then proceeds as follows the first variant.
  • the material used, constituting these walls is for example Si0 2 , AlpO 3 , MgO or, even better, to improve the thermal conductivity, BeO.
  • the screen support 40 is not necessarily electrically conductive. It is thicker than in FIG. 6. It has for example the thickness of 41 and, moreover, it is made up of a material itself photosensitive to ultraviolet rays, so that it is not necessary to cover with a layer of lacquer sensitive to ultraviolet radiation. This material is for example a photosensitive glass. After forming a mask on the surface of the glass, the parts of which transparent to ultraviolet rays correspond to the openings of the desired alveoli, the latter is exposed using a point source of ultraviolet radiation which, just as before, is placed at point A, the process taking place in a similar manner except that the cells are formed directly in the support without the need for growth by electrolysis or other of the walls of these cells.

Description

La présente invention concerne un tube à rayons cathodiques muni d'un écran luminescent comportant un support présentant un matériau luminescent, support qui est muni d'une configuration d'alvéoles remplies du matériau luminescent, alvéoles qui présentent la forme de tubes juxtaposés s'étendant dans le support et dont les parois sont réflectrices. L'invention est également relative à un procédé pour la fabrication d'un écran destiné à un tel tube et au tube de projection d'images de télévision muni d'un tel écran.The present invention relates to a cathode ray tube provided with a luminescent screen comprising a support having luminescent material, support which is provided with a configuration of cells filled with luminescent material, cells which have the form of juxtaposed tubes extending in the support and whose walls are reflective. The invention also relates to a method for manufacturing a screen intended for such a tube and to the tube for projecting television images provided with such a screen.

L'obtention d'une grande brillance est l'une des qualités recherchées pour un écran de tube à rayons cathodiques, notamment lorsque cet écran est celui d'un tube image de télévision à projection. Il est bien connu qu'une plus grande brillance d'un tube peut être obtenue en augmentant l'épaisseur de la couche luminescente constituant l'écran et en donnant simultanément une plus grande énergie (plus grand courant de faisceau et/ou tension accélératrice plus élevée) au faisceau d'électrons assurant le bombardement de ladite couche. Toutefois, cette augmentation de la brillance s'accompagne d'une augmentation du diamètre de la tache lumineuse sur l'écran. Cela est dû à la diffusion latérale de la lumiè're engendrée dans la couche isolante. Cette augmentation du diamètre de la tache lumineuse se traduit par une diminution notable du conraste et de la résolution de l'image représentée. Une autre limitation de la brillance provient du fait que d'une part, le bombardement électronique de la couche de matière luminescente s'accompagne d'un échauffement de celle-ci, celui-ci étant d'autant plus intense que l'énergie du faisceau est plus élevée et que, d'autre part, l'émission de lumière est généralement une fonction décroissante de la température du matériau luminescent. Cette décroissance de la brillance en fonction de la température apparaît par exemple en valeur relative

Figure imgb0001
sur la figure 1 publiée par la firme Sony à Chicago, le 4 juin 1979 au cours de la conférence "IEEE Spring Conference on Consumers Elec- tronics" et reproduite ci-après dans la description de l'invention. Un tube à rayons cathodiques du genre est connu du brevet US-A-2.996.634, dans lequel est proposé un écran plan pour un tube à rayons cathodiques où le matériau luminescent est appliqué dans des alvéoles tubulaires, dont les axes longitudinaux sont perpendiculaires à la fenêtre image. Les parois de ces alvéoles sont opaques ou réflectrices de façon à éliminer des phénomènes de diffusion latérale. De ce fait, l'épaisseur de la couche de matériau luminescent peut être augmentée, tout comme l'énergie du faisceau d'électrons et par conséquent également la brillance sans affecter le contraste ou la résolution d'image. De plus, il y a lieu de noter que, sans que ce soit apparemment le but cherché par l'invention, une telle structure permet une meilleure évacuation, par la fenêtre image, de la chaleur développée par le bombardement électronique du matériau luminescent. En effet, cette évacuation s'effectue d'autant plus facilement que la surface de contact des grains de matériau luminescent avec la fenêtre image est plus grande. Cela est présentement le cas du fait que la surface est augmentée de celle des parois des petites alvéoles remplies de matériau luminescent. Cette structure permet donc de limiter l'augmentation de la température du matériau luml- nescent et la baisse concomittante de la brillance.Obtaining a high gloss is one of the qualities sought for a cathode ray tube screen, in particular when this screen is that of a projection television picture tube. It is well known that greater brightness of a tube can be obtained by increasing the thickness of the luminescent layer constituting the screen and simultaneously giving greater energy (greater beam current and / or more accelerating voltage high) to the electron beam ensuring the bombardment of said layer. However, this increase in brightness is accompanied by an increase in the diameter of the light spot on the screen. This is due to the lateral scattering of the light generated in the insulating layer. This increase in the diameter of the light spot results in a notable reduction in the contrast and the resolution of the image represented. Another limitation of the gloss comes from the fact that on the one hand, the electronic bombardment of the layer of luminescent material is accompanied by a heating of the latter, this being all the more intense as the energy of the beam is higher and that, on the other hand, the light emission is generally a decreasing function of the temperature of the luminescent material. This decrease in gloss as a function of temperature appears for example in relative value
Figure imgb0001
 in FIG. 1 published by the firm Sony in Chicago, on June 4, 1979 during the conference "IEEE Spring Conference on Consumers Electronic" and reproduced below in the description of the invention. A cathode ray tube of this kind is known from US Pat. No. 2,996,634, in which a flat screen is proposed for a cathode ray tube where the luminescent material is applied in tubular cells, the longitudinal axes of which are perpendicular to the image window. The walls of these cells are opaque or reflective so as to eliminate phenomena of lateral diffusion. Therefore, the thickness of the luminescent material layer can be increased, as can the energy of the electron beam and therefore also the brightness without affecting the contrast or image resolution. In addition, it should be noted that, without this apparently being the aim sought by the invention, such a structure allows better evacuation, through the image window, of the heat developed by the electron bombardment of the luminescent material. In fact, this evacuation takes place all the more easily the larger the contact surface of the luminescent material grains with the image window. This is currently the case because the surface is increased by that of the walls of the small cells filled with luminescent material. This structure therefore makes it possible to limit the increase in the temperature of the luminescent material and the concomitant decrease in gloss.

Une telle structure présente plusieurs désavantages. Lorsque les faisceaux d'électrons font un angle notable avec les axes des alvéoles tubulaires de l'écran, les électrons du faisceau ne bombardent qu'une petite partie du matériau luminescent dû à une faible pénétration du faisceau ou à un phénomène d'ombrage par les parois de ces alvéoles. Une partie du matériau luminescent n'est pas exposée au bombardement d'électrons. Il s'ensuit également que le bombardement du matériau luminescent sur la surface de l'écran n'est pas uniforme et que la matériau luminescent dans chacune des alvéoles est utilisé incomplètement. De ce fait, la résolution, le contraste et la brillance maximale d'image ne sont pas uniformes sur toute la surface de l'écran. De plus, l'évacuation de chaleur n'est pas suffisante lorsque le dégagement de chaleur est trop élevé, ce qui est entre autres le cas de tubes destinés à la projection d'images de télévision.Such a structure has several disadvantages. When the electron beams make a notable angle with the axes of the tubular cells of the screen, the beam electrons only bombard a small part of the luminescent material due to a weak penetration of the beam or to a phenomenon of shading by the walls of these cells. Part of the luminescent material is not exposed to electron bombardment. It also follows that the bombardment of the luminescent material on the surface of the screen is not uniform and that the luminescent material in each of the cells is used incompletely. As a result, the resolution, contrast and maximum image brightness are not uniform over the entire surface of the screen. In addition, the heat dissipation is not sufficient when the heat generation is too high, which is among other things the case of tubes intended for the projection of television images.

L'invention vise à augmenter la brillance de l'image sans réduire la résolution et le contraste, dans le cas d'écrans plans, ou d'écrans concaves ou convexes. L'invention vise également à rendre la résolution, le contraste et la brillance maximale d'image d'un tel tube uniformes sur toute la surface d'écran. Un autre but de l'invention consiste à améliorer la brillance de l'écran en munissant l'écran de moyens empêchant une augmentation de la température de la couche provoquée par la chaleur développée dans la couche luminescente, de sorte que la luminescence de ladite couche ne soit pas réduite.The invention aims to increase the brightness of the image without reducing the resolution and the contrast, in the case of flat screens, or concave or convex screens. The invention also aims to make the resolution, contrast and maximum image brightness of such a tube uniform over the entire screen surface. Another object of the invention consists in improving the brightness of the screen by providing the screen with means preventing an increase in the temperature of the layer caused by the heat developed in the luminescent layer, so that the luminescence of said layer is not reduced.

Conformément à l'invention, un écran< luminescent du genre décrit dans le premier alinéa est caractérisé en ce que les axes des alvéoles convergent essentiellement vers le centre de déflexion du faisceau d'électrons. Selon une première forme de réalisation, l'écran fonctionne en transmission, c'est-à-dire que la lumière de luminescence est émise à travers le support. Dans ce cas, le support comporte deux glaces en verre, qui sont transparentes à la lumière et qui sont toutes les deux à faces parallèles et parallèles entre elles et constituent une double paroi dans l'enveloppe du tube, les alvéoles de l'écran débouchant sur la paroi intérieure du support du tube, les mêmes alvéoles étant munies à ce débouché d'une couche métallique transparente aux électrons et réfléchissante de la lumière, la double paroi étant munie de moyens d'admission et d'évacuation d'un fluide de refroidissement circulant entre les deux glaces en verre de la double paroi.According to the invention, a luminescent screen of the kind described in the first paragraph is characterized in that the axes of the cells converge essentially towards the center of deflection of the electron beam. According to a first embodiment, the screen operates in transmission, that is to say that the luminescence light is emitted through the support. In this case, the support comprises two glass panes, which are transparent to light and which are both with faces parallel and parallel to each other and constitute a double wall in the envelope of the tube, the cells of the screen opening out. on the inner wall of the tube support, the same cells being provided at this outlet with a transparent metallic layer to electrons and reflecting light, the double wall being provided with means for admitting and discharging a cooling fluid circulating between the two glass panes of the double wall.

Selon des variantes de cette première forme de réalisation, l'écran et son support sont plans ou encore concaves du côté du balayage électronique ou bien, les parois des alvéoles sont fortement conductrices ou non de la chaleur et notamment métalliques.According to variants of this first embodiment, the screen and its support are flat or even concave on the side of the electronic scanning or else, the walls of the cells are highly conductive or not of heat and in particular metallic.

Selon une seconde forme de réalisation, l'écran fonctionne en réflexion. Le support est opaque, les alvéoles de l'écran émettant de la lumière de luminescence du côté de la réception du faisceau d'électrons sur l'écran, tube qui est muni de moyens de projection d'images, alors que le support est muni de moyens de refroidissement dudit écran.According to a second embodiment, the screen operates in reflection. The support is opaque, the cells of the screen emitting luminescence light on the receiving side of the electron beam on the screen, a tube which is provided with means for projecting images, while the support is provided means for cooling said screen.

Selon des variantes de cette seconde forme de réalisation, l'écran et son support sont plans ou convexes du côté de l'incidence du faisceau d'électrons sur l'écran. De plus, les parois des alvéoles peuvent être fortement conductrices de la chaleur et notamment métalliques.According to variants of this second embodiment, the screen and its support are planar or convex on the side of the incidence of the electron beam on the screen. In addition, the walls of the cells can be highly conductive of heat and in particular metallic.

Parmi ces dernières variantes, l'une d'elles présente la particularitée que le système optique associé comporte, centrés sur l'axe du tube, un miroir concave tourné vers l'écran et une lame correctrice des aberrations de ce miroir placée derrière l'écran.Among these latter variants, one of them has the particularity that the associated optical system comprises, centered on the axis of the tube, a concave mirror facing the screen and a plate for correcting the aberrations of this mirror placed behind the screen.

L'invention est également relative à un procédé de fabrication de l'écran luminescent fractionné en alvéoles, qui sont remplies de matériau luminescent et qui sont sous forme de tubes, dont les axes convergent sensiblement vers un même point placé sur l'axe de l'écran, caractérisé en ce qu'il comprend les étapes suivantes:

  • - dépôt, sur l'une des faces du support qui est conductrice électriquement naturellement ou par revêtement d'une couche conductrice, d'une première couche de laque photosensible aux rayons ultraviolets, l'épaisseur de cette couche étant égale à la profondeur des alvéoles d'écran que l'on désire;
  • - séchage et polymérisation de cette première couche;
  • - dépôt, sur cette première couche, d'une deuxième couche de laque photosensible'à la lumière blanche ou à une lumière monochromatique;
  • - projection à l'aide d'une optique de grandissement inférieur à 1 de lumière blanche ou monochromatique sur cette deuxième couche de l'image d'une configuration d'alvéoles réalisée sur un masque de grandes dimensions, la configuration d'alvéoles étant homothétique dans le rapport du grandissement de l'optique de la configuration d'alvéoles constituée par les ouvertures des alvéoles sur la surface d'écran;
  • - développement de ladite deuxième couche ainsi insolée;
  • - insolation au travers du masque obtenu de ladite première couche de laque à l'aide d'une source ponctuelle de rayonnement ultraviolet disposée en face de ladite couche sur l'axe du support, et à la place du centre de déflexion du faisceau;
  • - développement de la première couche ainsi insolée, séchage et cuisson;
  • - croissance électrolytique de murs métalliques dans les parties vides de laque de ladite première couche, le champ électrique provoquant le transport de métal étant établi entre la face conductrice du support et une électrode parallèle à la surface libre de ladite première couche;
  • - dissolution de la résine restante;
  • - si besoin, mise en place sur les parois internes latérales et éventuellement communes avec le support d'écran d'une couche de matériau réflecteur;
  • - remplissage des alvéoles créées de matériau luminescent;
  • - dépôt éventuel sur la surface des alvéoles d'une fine couche électriquement conductrice et optiquement réflectrice.
The invention also relates to a method of manufacturing the luminescent screen divided into cells, which are filled with luminescent material and which are in the form of tubes, the axes of which converge substantially towards the same point placed on the axis of the screen, characterized in that it comprises the following steps:
  • deposit on one of the faces of the support which is naturally electrically conductive or by coating a conductive layer with a first layer of lacquer photosensitive to ultraviolet rays, the thickness of this layer being equal to the depth of the cells screen that you want;
  • - drying and polymerization of this first layer;
  • - Depositing, on this first layer, a second layer of lacquer photosensitive to white light or to monochromatic light;
  • - projection using a magnification optic of less than 1 of white or monochromatic light on this second layer of the image of a configuration of cells produced on a large mask, the configuration of cells being homothetic in the ratio of the magnification of the optics of the configuration of cells formed by the openings of the cells on the screen surface;
  • - Development of said second layer thus exposed;
  • - sunshine through the mask obtained from said first layer of lacquer using a point source of ultraviolet radiation placed opposite said layer on the axis of the support, and in place of the center of deflection of the beam;
  • - development of the first layer thus exposed, drying and cooking;
  • - electrolytic growth of metal walls in the empty lacquer parts of said first layer, the electric field causing the transport of metal being established between the conductive face of the support and an electrode parallel to the free surface of said first layer;
  • - dissolution of the remaining resin;
  • - if necessary, installation on the internal side walls and possibly common with the screen support of a layer of reflective material;
  • - filling the cells created with luminescent material;
  • - possible deposit on the surface of the cells of a thin electrically conductive and optically reflective layer.

Selon une variante de ce procédé, la croissance électrolytique de murs métalliques dans les parties vides de laque de ladite première couche est remplacée par la croissance de murs en matériau électriquement isolant par la mise en oeuvre de techniques connues du genre cathaphorèse ou anaphorèse, le transport des grains dudit matériau isolant sur le support se faisant à l'aide de forces électrostatiques résultant du champ électrique établi entre le support d'écran et une électrode parallèle à la surface libre de ladite première couche, la croissance étant suivie d'une frittage à haute température pour l'amélioration de la solidité mécanique du dépôt. Ce matériau constitutif de paroi est par exemple Si02, AI203, MgO ou encore mieux, pour améliorer la conductibilité thermique, BeO.According to a variant of this method, the electrolytic growth of metal walls in the empty lacquer parts of said first layer is replaced by the growth of walls of electrically insulating material by the use of known techniques of the cathaphoresis or anaphoresis genus, transport grains of said insulating material on the support taking place using electrostatic forces resulting from the electric field established between the screen support and an electrode parallel to the free surface of said first layer, the growth being followed by sintering at high temperature to improve the mechanical strength of the deposit. This wall constituent material is for example Si0 2 , AI 2 0 3 , MgO or even better, to improve the thermal conductivity, BeO.

Selon une autre variante, le support d'écran est en un matériau lui-même photosensible dans le domaine du rayonnement ultraviolet, ce qui évite d'avoir à le recouvrir d'une couche de laque sensible au rayonnement ultraviolet. Ce matériau est par exemple un verre photosensible et le procédé se déroule pratiquement de la même façon, sauf que les alvéoles se trouvent formées directement dans le support sans besoin de croissance par électrolyse ou autres des parois de ces alvéoles. Le point de convergence des axes des alvéoles sur l'axe de l'écran est confondu, lors de la mise en place dudit écran dans le futur tube cathodique, avec le centre de déflexion du faisceau d'électrons de balayage dudit tube.According to another variant, the screen support is made of a material which is itself photosensitive in the field of ultraviolet radiation, which avoids having to cover it with a layer of lacquer sensitive to ultraviolet radiation. This material is for example a photosensitive glass and the process proceeds practically in the same way, except that the cells are formed directly in the support without the need for growth by electrolysis or other of the walls of these cells. The point of convergence of the axes of the cells on the axis of the screen is coincident, during the positioning of said screen in the future cathode ray tube, with the center of deflection of the scanning electron beam of said tube.

Cette dernière forme de réalisation aboutit de façon directe à des dispositifs utilisables pour la projection sur l'écran, extérieur au tube, d'images de télévision.This latter embodiment leads directly to devices which can be used for the projection on the screen, outside the tube, of television images.

La description ci-après, en se référant aux dessins annexés, le tout donné à titre d'exemple non limitatif, fera bien comprendre comment l'invention peut être réalisée.

  • La figure 1 montre une courbe indiquant en valeur relative un exemple de la variation de la brillance d'une couche de matériau luminescent en fonction de la température.
  • La figure 2 est une coupe partielle d'une tube à rayons cathodiques d'un genre connu, présentant un écran plan qui est formé à partir d'alvéoles en forme de petits tubes juxtaposés et perpendiculaires au support d'écran, à parois opaques ou réflectrices, chaque tube étant rempli d'une épaisseur de matériau luminescent.
  • La figure 3 représente en coupe un tube à rayons cathodiques selon une première forme de réalisation de l'invention présentant un écran plan.
  • La figure 4 représente en coupe un tube à rayons cathodiques pour la projection d'images de télévision selon une seconde forme de réalisation de l'invention présentant un écran convexe associé à son optique de projection.
  • Les figures 5 et 6 illustrent le procédé pour la construction de l'écran d'un tube conforme à l'invention.
The description below, with reference to the accompanying drawings, all given by way of non-limiting example, will make it clear how the invention can be implemented.
  • FIG. 1 shows a curve indicating in relative value an example of the variation of the brightness of a layer of luminescent material as a function of the temperature.
  • Figure 2 is a partial section of a tube to cathode rays of a known kind, having a flat screen which is formed from cells in the form of small tubes juxtaposed and perpendicular to the screen support, with opaque or reflecting walls, each tube being filled with a thickness of material luminescent.
  • Figure 3 shows in section a cathode ray tube according to a first embodiment of the invention having a flat screen.
  • Figure 4 shows in section a cathode ray tube for the projection of television images according to a second embodiment of the invention having a convex screen associated with its projection optics.
  • Figures 5 and 6 illustrate the method for the construction of the screen of a tube according to the invention.

La figure 1 indique la façon dont la brillance relative

Figure imgb0002
d'une couche de matériau luminescent varie en fonction de la température. Pour une température de 80°C, la brillance a diminué de 50%. C'est pour cette raison que pour obtenir une grande brillance il est nécessaire d'évacuer du matériau luminescent la challeur dégagée par un bombardement d'électrons.Figure 1 shows how the relative brightness
Figure imgb0002
 of a layer of luminescent material varies as a function of temperature. For a temperature of 80 ° C, the gloss has decreased by 50%. It is for this reason that to obtain a high gloss it is necessary to remove from the luminescent material the heat released by an electron bombardment.

La figure 2, qui est relative à un tube à rayons cathodiques selon l'art antérieur, à écran plan représenté en coupe par un plan de symétrie, indique sous le chiffre de référence 11, l'enveloppe du tube avec sa partie conique 12 et le col 13. Ce col est muni d'un canon électronique et d'un système de déflexion qui, tous les deux, sont décrits ci-après sur la figure 4. Le faisceau d'électrons est 10. Les faisceaux d'électrons du canon électronique dont les trajectoires sont supposées rectilignes proviennent, après déflexion, apparemment du point A, qui est appelé le centre de déflexion du faisceau. Les faisceaux d'électrons atteignent l'écran 14 qui est déposé sur une paroi de l'enveloppe 11 dudit tube. Selon l'état de la technique connu du brevet US-A-2.996.634, cet écran est muni d'alvéoles sous forme de petits tubes, dont, pour la simplicité du dessin, seules trois sont représentées, à savoir sous les numéros 15,16,17. Il faut imaginer qu'en réalité l'écran est tapissé à l'intérieur du tube cathodique d'une multitude de ces petits tubes juxtaposés les uns aux autres. Les axes de ces tubes respectivement 18, 19, 21 sont parallèles entre eux et à l'axe du tube cathodique lui-même 21. La section de ces tubes est sensiblement égale à celle sur l'écran du faisceau de balayage 10. Parmi les trajectoires d'électrons articulées en A, on peut distinguer suivant les positions du faisceau entre celles qui sont peu inclinées sur les axes des tubes et celles qui, par contre, présentent une inclinaison notable. Les trajectoires peu inclinées par rapport à l'axe du tube, comme 22, permettent aux électrons de pénétrer profondément dans les alvéoles remplies de matériau luminescent et d'engendrer ainsi la luminescence de tout le matériau contenu dans l'alvéole. En revanche, lorsqu'une trajectoire, comme un trajectoire 23 est suivie, les électrons ne pénètrent que superficiellement dans les alvéoles et n'excitent donc qu'une partie du matériau luminescent contenu dans l'alvéole. Le matériau luminescent dans la partie hachurée 24 n'est pas exposé au bombardement d'électrons. Ainsi, suivant l'angle de déviation du faisceau d'électrons, le volume et le matériau luminescent excité diffèrent et, de ce fait, la brillance locale sur l'écran.FIG. 2, which relates to a cathode ray tube according to the prior art, with a flat screen represented in section by a plane of symmetry, indicates under the reference numeral 11, the envelope of the tube with its conical part 12 and the neck 13. This neck is provided with an electronic cannon and a deflection system, both of which are described below in FIG. 4. The electron beam is 10. The electron beams of the electron gun whose trajectories are supposed to be rectilinear come, after deflection, apparently from point A, which is called the center of deflection of the beam. The electron beams reach the screen 14 which is deposited on a wall of the envelope 11 of said tube. According to the state of the art known from US-A-2,996,634, this screen is provided with cells in the form of small tubes, of which, for the simplicity of the drawing, only three are shown, namely under the numbers 15 , 16.17. You have to imagine that in reality the screen is lined inside the cathode ray tube with a multitude of these small tubes juxtaposed to each other. The axes of these tubes 18, 19, 21 respectively are parallel to each other and to the axis of the cathode ray tube itself 21. The section of these tubes is substantially equal to that on the screen of the scanning beam 10. Among the electron trajectories articulated at A, we can distinguish according to the beam positions between those which are slightly inclined on the axes of the tubes and those which, on the other hand, have a significant inclination. The paths which are slightly inclined relative to the axis of the tube, like 22, allow the electrons to penetrate deep into the cells filled with luminescent material and thus generate the luminescence of all the material contained in the cell. On the other hand, when a trajectory, such as a trajectory 23 is followed, the electrons only penetrate superficially into the cells and therefore only excite part of the luminescent material contained in the cell. The luminescent material in the hatched portion 24 is not exposed to electron bombardment. Thus, depending on the angle of deflection of the electron beam, the volume and the excited luminescent material differ and, as a result, the local brightness on the screen.

La figure 3 est relative à un tube à rayons cathodiques conforme à l'invention. Sur cette figure, on retrouve les éléments 10, 11, 12, 13, 21 de la figure 2, mais l'écran 14, qui est déposé sur la paroi intérieure de l'enveloppe 11, est réalisé d'une autre façon. Il comporte toujours des alvéoles remplies sous forme de tubes juxtaposés de petit diamètre mais dont les axes ne sont pas parallèles entre eux. Pour simplifier la figure, seuls trois de ces tubes, notamment 28, 22, 23 sont représentés. Le faisceau d'électrons est dévié dans les trois directions 24, 25 et 26. Ces tubes sont sous forme d'un cône ou d'un cylindre et présentent des axes 27, 21, 29 qui sont orientés de façon qu'ils passent pratiquement par le centre de courbure A. Il s'ensuit que tout le matériau luminescent contenu dans les tubes est excité par le bombardement d'électrons. De plus, le matériau luminescent est refroidi. A cet effet, l'enveloppe du tube est munie d'une double paroi 31, dans laquelle circule un liquide de refroidissement dont l'admission est assurée par le tube 32 et l'évacuation par le tube 33.Figure 3 relates to a cathode ray tube according to the invention. In this figure, we find the elements 10, 11, 12, 13, 21 of Figure 2, but the screen 14, which is deposited on the inner wall of the casing 11, is produced in another way. It always includes cells filled in the form of juxtaposed tubes of small diameter but whose axes are not parallel to each other. To simplify the figure, only three of these tubes, in particular 28, 22, 23 are shown. The electron beam is deflected in three directions 24, 25 and 26. These tubes are in the form of a cone or a cylinder and have axes 27, 21, 29 which are oriented so that they pass practically by the center of curvature A. It follows that all the luminescent material contained in the tubes is excited by the bombardment of electrons. In addition, the luminescent material is cooled. For this purpose, the envelope of the tube is provided with a double wall 31, in which a coolant circulates, the admission of which is ensured by the tube 32 and the evacuation by the tube 33.

La figure 4 est relative à un tube cathodique pour projection d'images de télévision dans le cas d'un écran convexe associé à son optique de projection. Sur cette figure, on retrouve les éléments 11, 12, 13 et 21 de la figure 1.FIG. 4 relates to a cathode ray tube for projecting television images in the case of a convex screen associated with its projection optics. In this figure, we find the elements 11, 12, 13 and 21 of FIG. 1.

Ce tube est constitué d'une enveloppe 11 formée du col du tube 13, de longueur 250 mm et de diamètre 36 mm, et du cône du tube 12 de longueur 150 mm et de diamètre de 150 mm dans sa partie la plus large. Comme le nom l'indique cette dernière partie bien que généralement conique sur toute sa longueur peut présenter une partie conique plus courte suivie d'une partie cylindrique.This tube consists of an envelope 11 formed from the neck of the tube 13, of length 250 mm and diameter 36 mm, and of the cone of the tube 12 of length 150 mm and diameter of 150 mm at its widest part. As the name suggests, this last part, although generally conical over its entire length, may have a shorter conical part followed by a cylindrical part.

Dans le col du tube 13 est disposé un canon à électrons composé d'une cathode thermoïonique à chauffage indirect et d'un certain nombre d'anodes cylindriques 110 permettant d'accélérer les électrons. La focalisation est de type électrostatique ou de type magnétique à l'aide des bobines extérieures. Le tube possède des bobines de déflexion 120 pour assurer le balayage selon les axes X et Y. L'écran 41 présente une forme convexe et est appliqué sur un support d'écran 40 disposé dans le cône du tube. Tout comme dans la première forme de réalisation, cet écran est muni d'alvéoles remplies de matériau luminescent. Ces alvéoles, dont pour la simplicité de la figure, seules trois sont représentées, à savoir 42, 43, et 44, sont de petits tubes sous forme de tronc de cône ou cylindre dont les axes respectivement 45, 21, 47 passent pratiqeument par le centre de déflexion A. Les directions du faisceau d'électrons selon lesquelles s'effectue le bombardement de ces tubes sont 35, 36, 37. La section du faisceau d'électrons dans le plan convexe 48 de l'écran s'avère pratiquement égale au droit de chaque tube à la section dudit tube dans le même plan. Ainsi, tout comme selon la première forme de réalisation, une excitation maximale du matériau luminescent dans le tube est assurée. Le tube à rayons cathodiques est muni d'une optique de projection de l'écran de la face 48. Cette optique est par exemple une optique de l'art connu dit de Schmidt, qui est constituée par le miroir concave 49, disposé sur la paroi intérieure du tube et par la plaque 50 pour la correction d'aberration et qui est placée à l'entrée du tube derrière l'écran. Les dimensions de l'écran 41 rectangulaire sont de 36 mm x 48 mm. Le rayon de courbure de l'écran convexe est égal à la moitié du rayon de courbure de miroir 49. Ce miroir 49 est percé en son centre d'une ouverture de 35 mm de diamètre pour permettre au faisceau d'électrons d'attendre l'écran. Le courant de faisceau du tube est environ de 2m A crète pour une haute tension pouvant atteindre 50 K.voits, ce qui représente 100 watts dissipés sur l'écran.In the neck of the tube 13 is arranged an electron gun composed of a thermionic cathode with indirect heating and a number of cylindrical anodes 110 making it possible to accelerate the electrons. The focusing is of the electrostatic or magnetic type using the external coils. The tube has deflection coils 120 for scanning along the X and Y axes. The screen 41 has a convex shape and is applied to a screen support 40 disposed in the cone of the tube. As in the first embodiment, this screen is provided with cells filled with luminescent material. These cells, including for the simplicity of the figure, only three are represented, namely 42, 43, and 44, are small tubes in the form of a truncated cone or cylinder whose axes respectively 45, 21, 47 pass practiqeument through the center of deflection A. The directions of the beam of electrons according to which the bombardment of these tubes takes place are 35, 36, 37. The section of the electron beam in the convex plane 48 of the screen turns out to be practically equal to the right of each tube to the section of said tube in the same plane. Thus, just as according to the first embodiment, maximum excitation of the luminescent material in the tube is ensured. The cathode ray tube is provided with an optic for projecting the screen of the face 48. This optic is for example an optic of the known art known as Schmidt, which is constituted by the concave mirror 49, placed on the inner wall of the tube and by the plate 50 for the aberration correction and which is placed at the entrance of the tube behind the screen. The dimensions of the rectangular screen 41 are 36 mm x 48 mm. The radius of curvature of the convex screen is equal to half the radius of curvature of mirror 49. This mirror 49 is pierced in its center with an opening of 35 mm in diameter to allow the electron beam to wait for the 'screen. The beam current of the tube is approximately 2m A peak for a high voltage of up to 50 K. or so, which represents 100 watts dissipated on the screen.

Afin de refroidir l'écran, tout comme dans la première forme de réalisation, celui-ci est muni d'un dispositif de refroidissement. Celui-ci comporte un système de circulation de liquide de refroidissement dans une paroi double constitué du support 40 de l'écran et d'une paroi 51, qui est soudée d'une façon étanche à l'eau à la périphérie du support 40, l'admission et l'évacuation de liquide s'effectuant à l'aide des tubes 52 et 53 débouchant vers l'extérieur de l'enveloppe 11 du tube. Le circuit de refroidissement utilisant un fluide à la température de 25°C, par exemple l'eau de ville, avec un débit de 1,5 litre/minute permet de faire que la température de l'écran ne dépasse pas 100°C.In order to cool the screen, as in the first embodiment, it is provided with a cooling device. This comprises a cooling liquid circulation system in a double wall consisting of the support 40 of the screen and a wall 51, which is welded in a watertight manner to the periphery of the support 40, the admission and evacuation of liquid being effected by means of the tubes 52 and 53 opening towards the outside of the envelope 11 of the tube. The cooling circuit using a fluid at a temperature of 25 ° C, for example tap water, with a flow rate of 1.5 liters / minute makes it possible to ensure that the temperature of the screen does not exceed 100 ° C.

Les figures 5 et 6 illustrent le procédé pour la réalisation de l'écran d'un tube à rayons cathodiques conforme à l'invention. Le procédé est illustré dans le cas d'un écran convexe. Ce procédé est analogue dans le cas d'un écran plan. Le procédé découle des points suivants: le tube lorsqu'il est terminé, a, entre autres, deux caractéristiques importantes:

  • - il a une optique associée qui reprend la lumière émise par le produit luminescent lorsque le tube est en fonctionnement;
  • - il a un canon à électrons émettant un faisceau d'électrons dont les trajectoires sont considérées comme concourant au point A centre de déflexion du faisceau.
Figures 5 and 6 illustrate the method for producing the screen of a cathode ray tube according to the invention. The process is illustrated in the case of a convex screen. This process is analogous in the case of a flat screen. The process follows from the following points: the tube when it is finished has, among other things, two important characteristics:
  • - it has an associated optic which picks up the light emitted by the luminescent product when the tube is in operation;
  • - it has an electron gun emitting an electron beam, the trajectories of which are considered to be concurrent at point A, center of deflection of the beam.

Pour obtenir le tube le mieux adapté au but de l'invention, le procédé de fabrication va utiliser successivement ces deux caractéristiques pour procéder à l'élaboration même de l'écran et du tube. L'utilisation de l'optique associée au tube pour participer aux étapes du procédé permet de disposer d'une image où les différents défauts optiques possibles sont diminués (aberrations, convergence, ...).To obtain the tube best suited to the purpose of the invention, the manufacturing process will successively use these two characteristics to proceed with the very development of the screen and the tube. The use of the optics associated with the tube to participate in the steps of the method makes it possible to have an image where the different possible optical defects are reduced (aberrations, convergence, etc.).

Selon que le tube fonctionne en réflexion ou en transmission les étapes du procédé sont légèrement différentes.Depending on whether the tube operates in reflection or in transmission, the process steps are slightly different.

Sur la figure 5 apparaissent le support 40 et le système de circulation de liquide de refroidissement déjà représenté sur la figure 4. C'est sur la face convexe 61 du support 40 qu'est réalisé l'écran. Le matériau de ce support présente une grande conductibilité thermique, de sorte que l'évacuation de la chaleur développée dans l'écran par le bombardement d'électrons est assurée. Du fait que selon l'une des variantes du procédé illustré ci-après dans le cas d'un fonctionnement en réflexion, la face 61 doit être électriquement conductrice, si le support choisi n'est pas métallique, par exemple un verre ou une céramique, on effectue alors le dépôt par évaporation sous vide d'une couche mince métallique, par exemple du nickel-chrome. Pendant un premier temps, le procédé consiste à réaliser, au dessus de 61 et concentriquement à cette surface, un masque à haute résolution et sans distorsion avec des parties opaques et transparentes, dont la géométrie en configuration d'alvéoles correspond à celle de la face 48 de l'écran représenté sur la figure 4. Pour réaliser ce masque, la méthode comprend les étapes suivantes:

  • - Le support est enduit d'une couche 41 de 5 à 6 Ilm d'une première laque photosensible aux rayons UV, telle la laque Shipley8 AZ 1350 du type positif. Cette laque est déposée par centrifugation.
  • - La surface de cette première laque est recou- verte d'une couche mince de 0,5 pm environ d'une deuxième laque 62 sensible à la lumière visible.
  • - Avec l'optique du tube on projette sur la deuxième couche de laque 62 l'image réduite de la configuration d'alvéoles désirée et on réalise l'insolation.
  • - On effectue le développement de la couche de laque 62 insolée. On obtient, reproduisant la configuration d'alvéoles, un masque qui épouse parfaitement la forme par exemple convexe du support 40. Sur la figure 6 les parties opaques et transparentes de ce masque sont les parties respectivement d'une part 71, 72, 73, 74 et 75 et d'autre part 76, 77, 78, 79.
  • - Le support est ensuite disposé dans un second dispositif d'insolation émettant un rayonnement UV produit par exemple par un arc court. Le support est placé de telle sort que le rayonnement UV produit par l'arc court provienne du point A qui sera par la suite le point de déflexion du faisceau électronique. Dans le cas du tube décrit ce point A se trouve à 130 mm de l'écran. On obtient des zones où la laque est polymérisée, et qui ont leurs axes concourant au point A. Sur la figure 6, les faisceaux de rayons ultraviolets d'insolation sont respectivement 81, 82, 83, 84. Les parties de laque exposées et les parties de laque non exposées sont respectivement d'une part 85, 86, 87, 88 et d'autre part 89, 90, 91, 92, 93.
  • - Les zones ainsi polymérisées sont enlevées à l'aide d'une révélateur UV tel le révélateur Shipley "microposit developper". On obtient ainsi le négatif de la configuration d'alvéoles recherchée.
  • - En se servant de la couche métallique déposée initialement comme électrode, ou du support métallique lui-même, on effectue, par croissance électrolytique, un dépôt métallique de Cu ou Au ou Ag ou Ni, dans les parties en creux de la couche épaisse de 5 pm environ formée par la première laque (telles que 85 à 88 de la figure 6). Le dépôt métallique est réalisé jusqu'à ce qu'il atteigne l'épaisseur de la couche de laque. Les murs de laque sont ainsi bien réguliers: c'est une croissance guidée.
  • - On enlève la laque non polymérisée restante à l'aide d'acétone ou d'alcool, et on obtient ainsi une configuration d'alvéoles possédant des bords et un fond métalliques.
  • - Le support muni de sa configuration d'alvéoles est alors disposé dans un appareillage, qui par centrifugation d'une poudre en milieu liquide, permet de déposer le produit luminescent dans la configuration d'alvéoles. Ce produit luminescent a typiquement une granulométrie centrée sur 3 um avec des diamètres de grains allant de 1 à 6 pm. A l'issue de cette dernière étape du procédé, l'écran est prêt à être monté dans le tube lui-même.
In FIG. 5, the support 40 and the cooling liquid circulation system already shown in FIG. 4 appear. It is on the convex face 61 of the support 40 that the screen is made. The material of this support has a high thermal conductivity, so that the evacuation of the heat developed in the screen by the bombardment of electrons is ensured. The fact that according to one of the variants of the method illustrated below in the case of an operation in reflection, the face 61 must be electrically conductive, if the support chosen is not metallic, for example a glass or a ceramic , deposition is then carried out by vacuum evaporation of a thin metallic layer, for example nickel-chromium. During a first step, the method consists in producing, above 61 and concentrically with this surface, a high resolution mask without distortion with opaque and transparent parts, the geometry of which in configuration of cells corresponds to that of the face. 48 of the screen shown in FIG. 4. To make this mask, the method comprises the following steps:
  • - The support is coated with a layer 41 of 5 to 6 μm of a first lacquer photosensitive to UV rays, such as the lacquer Shipley 8 AZ 1350 of the positive type. This lacquer is deposited by centrifugation.
  • - The surface of this first lacquer is covered with a thin layer of approximately 0.5 μm of a second lacquer 62 sensitive to visible light.
  • - With the optics of the tube, the reduced image of the desired configuration of cells is projected onto the second layer of lacquer 62 and exposure is carried out.
  • - Development of the exposed lacquer layer 62 is carried out. Obtaining, reproducing the configuration of cells, a mask which perfectly matches the shape, for example the convex shape of the support 40. In FIG. 6, the opaque and transparent parts of this mask are the parts respectively on the one hand 71, 72, 73, 74 and 75 and on the other hand 76, 77, 78, 79.
  • - The support is then placed in a second exposure device emitting UV radiation produced for example by a short arc. The support is placed in such a way that the UV radiation produced by the short arc comes from point A which will subsequently be the deflection point of the electron beam. In the case of the tube described this point A is 130 mm from the screen. We obtain zones where the lacquer is polymerized, and which have their axes concurring at point A. In FIG. 6, the beams of ultraviolet rays of sunshine are respectively 81, 82, 83, 84. The parts of lacquer exposed and the parts of unexposed lacquer are respectively on the one hand 85, 86, 87, 88 and on the other hand 89, 90, 91, 92, 93.
  • - The areas thus polymerized are removed using a UV developer such as the developer Shipley "microposit developper". The negative of the desired cell configuration is thus obtained.
  • - Using the metallic layer initially deposited as an electrode, or the metallic support itself, a metallic deposit of Cu or Au or Ag or Ni is carried out by electrolytic growth in the hollow parts of the thick layer of 5 pm approximately formed by the first lacquer (such as 85 to 88 in FIG. 6). The metallic deposit is made until it reaches the thickness of the lacquer layer. The lacquer walls are thus very regular: it is a guided growth.
  • - The remaining unpolymerized lacquer is removed using acetone or alcohol, thus obtaining a configuration of cells with metal edges and bottom.
  • - The support provided with its configuration of cells is then placed in an apparatus, which by centrifuging a powder in a liquid medium, makes it possible to deposit the luminescent product in the configuration of cells. This luminescent product typically has a particle size centered on 3 μm with grain diameters ranging from 1 to 6 μm. At the end of this last step of the process, the screen is ready to be mounted in the tube itself.

Si le matériau luminescent doit présenter une structure massive, son dépôt peut être réalisé par croissance épitaxiale en phase de vapeur, ou encore au moyen d'une pulvérisation cathodique ou par plasma ou encore par pulvérisation de liquide.If the luminescent material must have a massive structure, its deposition can be carried out by epitaxial growth in the vapor phase, or even by means of a cathodic or plasma spraying or even by spraying of liquid.

Dans le cas d'un écran utilisé en transmission, le substrat doit être transparent, par exemple en verre ou en cristaux. La première des étapes précédentes est alors modifiée, le dépôt métallique étant alors un dépôt d'oxyde conducteur électriquement et transparent optiquement. Des dépôts de SnO2 ou In203 de 300 Angtrôms environ d'épaisseur et de résistivité de 400 ohms/ carré environ répondent à cet usage.In the case of a screen used in transmission, the substrate must be transparent, for example made of glass or crystals. The first of the preceding steps is then modified, the metal deposit then being an electrically conductive and optically transparent oxide deposit. Deposits of SnO 2 or In 2 0 3 of around 300 Angtroms of thickness and resistivity of around 400 ohms / square correspond to this use.

Les autre étapes se succèdent de manière identique au cas d'un fonctionnement par réflexion.The other steps follow one another in an identical manner in the case of an operation by reflection.

Une étape nouvelle se présente alors: sur la face où le produit luminescent apparait on dépose, en milieu liquide, une mince pellicule de nitrocellulose sur laquelle, par évaporation sous vide, on dépose une mince couche métallique de 1000 À par exemple de l'aluminium. On opère un traitement thermique à l'air, vers 350°C, afin de brûler la mince pellicule de nitrocellulose de sorte que la mince couche métallique reste seule ce qui permet d'obtenir une configuration d'alvéoles operculées remplies de produit luminescent. Cette mince couche métallique est transparent aux électrons du faisceau d'électrons mais réfléchit la lumière issue du produit luminescent lorsque celui-ci émet sa lumière de luminescence.A new stage then presents itself: on the face where the luminescent product appears, a thin film of nitrocellulose is deposited, in liquid medium, on which, by vacuum evaporation, a thin metallic layer of 1000 A is deposited, for example aluminum . Heat treatment is carried out with air, at around 350 ° C., in order to burn the thin nitrocellulose film so that the thin metal layer remains alone, which makes it possible to obtain a configuration of sealed cells filled with luminescent product. This thin metallic layer is transparent to the electrons in the electron beam but reflects the light from the luminescent product when the latter emits its luminescence light.

Selon une seconde variante, après obtension des parties en creux 84 à 88 de la figure 6, celles-ci sont remplies par cathaphorèse ou anaphorèse d'un matériau isolant à l'aide des forces électrostatiques résultant d'un champ électrique appliqué entre le support d'écran 40 et une électrode parallèle à 48 et située entre 48 et le point A. Pour augmenter la solidité mécanique des murs obtenus, la croissance de ces derniers est suivie d'un frittage à haute température, le procédé se déroule alors comme selon la première variante. Le matériau utilisé, constitutif de ces murs, est par exemple Si02, AlpO3, MgO ou, encore mieux, pour améliorer la conductibilité thermique, BeO.According to a second variant, after obtaining the hollow parts 84 to 88 of FIG. 6, these are filled by cathaphoresis or anaphoresis of an insulating material using the electrostatic forces resulting from an electric field applied between the support screen 40 and an electrode parallel to 48 and located between 48 and point A. To increase the mechanical strength of the walls obtained, the growth of the latter is followed by sintering at high temperature, the process then proceeds as follows the first variant. The material used, constituting these walls, is for example Si0 2 , AlpO 3 , MgO or, even better, to improve the thermal conductivity, BeO.

Selon une autre variante, le support d'écran 40 n'est pas nécessairement conducteur électriquement. Il est plus épais que sur la figure 6. Il a par exemple l'épaisseur de 41 et, de plus, il est constitué par un matériau lui-même photosensible aux rayons ultraviolets, de sorte qu'il n'est pas nécessaire de le recouvrir d'une couche de laque sensible au rayonnement ultraviolet. Ce matériau est par exemple un verre photosensible. Après formation d'un masque sur la surface du verre, dont les parties transparentes aux rayons ultraviolets correspondent aux ouvertures des alvéoles désirées, celui-ci est insolé à l'aide d'une source ponctuelle de rayonnement ultraviolet qui, tout comme précédemment, est placé au point A, le procédé se déroulant d'une façon analogue sauf que les alvéoles se trouvent formées de façon directe dans le support sans besoin de croissance par électrolyse ou autres des parois de ces alvéoles.According to another variant, the screen support 40 is not necessarily electrically conductive. It is thicker than in FIG. 6. It has for example the thickness of 41 and, moreover, it is made up of a material itself photosensitive to ultraviolet rays, so that it is not necessary to cover with a layer of lacquer sensitive to ultraviolet radiation. This material is for example a photosensitive glass. After forming a mask on the surface of the glass, the parts of which transparent to ultraviolet rays correspond to the openings of the desired alveoli, the latter is exposed using a point source of ultraviolet radiation which, just as before, is placed at point A, the process taking place in a similar manner except that the cells are formed directly in the support without the need for growth by electrolysis or other of the walls of these cells.

Claims (15)

1. A cathode-ray tube having a luminescent screen comprising a support with luminescent material, which support has a pattern of cells filled with the luminescent material, said cells being in the form of juxtaposed tubes extending in the support and the walls of which are reflective, characterized in that the axes of the cells converge substantially towards the deflection centre of the electron beam.
2. A cathode-ray tube as claimed in Claim 1, characterized in that the support comprises two glass plates which are transparent to light and which are both plane parallel and mutually parallel and form a double wall integrated in the envelope of the tube, the cells of the screen terminating on the inner wall of the carrier in the tube and being provided with a metal film, which is transparent at this termination to the electrons and reflects light, the double wall having inlet and outlet means for a coolant circulating between the two glass plates of the double wall.
3. A cathode-ray tube as claimed in Claim 1, characterized in that the support is opaque, whilst the cells of the screen emit light only on the side where the electron beam impinges on the screen, said tube comprising means for projecting the image, the support comprising means to cool the said screen.
4. A cathode-ray tube as claimed in Claim 2, characterized in that the screen and the support are flat.
5. A cathode-ray tube as claimed in Claim 2, characterized in that the screen and the support are concave.
6. A cathode-ray tube as claimed in Claim 3, characterized in that the screen and the support are flat.
7. A cathode-ray tube as claimed in Claim 3, characterized in that the screen and the support are convex.
8. A cathode-ray tube as claimed in any of the Claims 6 and 7, characterized in that the optical means for projecting the image from the screen behind the tube and which are centred on the axis of the tube comprising a concave mirror which is directed towards the screen and a correction plate for the aberrations of said mirror which is placed behind the screen.
9. A cathode-ray tube as claimed in Claim 8, characterized in that the concave mirror is provided within the tube on the envelope thereof.
10. Use of one of the cathode-ray tubes as claimed in any of the Claims 1 to 9 for projection television display.
11. A method of manufacturing a luminescent screen which is deposited on a support, which screen comprises a pattern of cells in the form of tubes which are filled with luminescent material and the axes of which converge substantially to the same point on the axis of the screen, characterized in that it comprises the following steps:
- depositing a first layer of a lacquer which is photo-sensitive to ultraviolet radiation on one of the sides of the support which is electrically conductive by itself or is covered with a conductive layer, the thickness of said layer being equal to the depth of the desired cells of the screen;
- drying and polymerizing said first layer;
- depositing on said first layer a second layer which is photosensitive to white light or to monochromatic light;
- projection by means of an optical enlargement system smaller than 1 of the white or monochromatic light on said second layer of the picture of a pattern of cells which is manufactured on a mask of large dimensions, the pattern of cells being homothetic in the enlargement ratio of the optical system of the pattern of cells which consists of the apertures of the cells on the screen surface;
- developing the said second layer thus exposed;
- exposure via the resulting mask of the first lacquer layer by means of a punctiform ultraviolet radiation source which is placed opposite to the said layer on the axis of the support and in the deflection centre of the beam;
- developing the said first layer thus exposed, drying and heating;
- growing walls of metal or an insulating material in the empty lacquer parts of the said first layer, the electric field which ensures the metal transport being applied between the conductive surface of the support and an electrode which is parallel to the free surface of the said first layer;
- dissolving the remaining resin;
- optionally providing a reflecting layer on the inner side walls and the walls which are common to the screen support;
- filling the formed cells with luminescent material;
- optionally depositing on the surface of the cells an electrically conductive and optically reflective layer.
12. A method as claimed in Claim 11, characterized in that metal walls are formed by electrolytic growth in the empty lacquer parts of the said first layer, the electric field which ensures the metal transport being applied between the conductive surface of the support and an electrode which is parallel to the free surface of the said first layer.
13. A method as claimed in Claim 11, characterized in that walls of insulating material are grown in the empty lacquer parts of the said first layer by cataphoresis or anaphoresis, the transport of the grains of the said insulating material being effected by means of electrostatic forces from the electric field which is applied between the screen support and an electrode parallel to the free surface of the said first layer, the growth being succeeded by sintering at high temperature.
14. A method as claimed in Claim 13, characterized in that the said electrically insulating material is Si02, AI203, MgO, BeO.
15. A method as claimed in Claim 11, characterized in that the screen support is of glass which is sensitive to ultraviolet radiation and that the cells of the screen are formed directly in the photosensitive glass by exposure to a substantially punctiform ultraviolet source of radiation which is placed on the axis of the support, the exposure being carried out via a mask deposited previously on the support.
EP19830201591 1982-11-10 1983-11-08 Cathode ray tube with a luminescent screen, process for manufacturing a screen for such a tube and television picture projection tube with such a screen Expired EP0110458B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8218919 1982-11-10
FR8218919A FR2535896A1 (en) 1982-11-10 1982-11-10 IMPROVEMENT TO THE LUMINOPHORE SCREENS OF AN ELECTRONIC TUBE OF THE CATHODE TUBE GENUINE, METHOD FOR MANUFACTURING SUCH A PERFECTED SCREEN AND TUBE IN PARTICULAR FOR PROJECTING TELEVISION IMAGES PROVIDED WITH SUCH SCREEN

Publications (2)

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EP0110458A1 EP0110458A1 (en) 1984-06-13
EP0110458B1 true EP0110458B1 (en) 1987-04-01

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EP19830201591 Expired EP0110458B1 (en) 1982-11-10 1983-11-08 Cathode ray tube with a luminescent screen, process for manufacturing a screen for such a tube and television picture projection tube with such a screen

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EP (1) EP0110458B1 (en)
JP (1) JPS5999647A (en)
DE (1) DE3370718D1 (en)
FR (1) FR2535896A1 (en)

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US4626739A (en) * 1984-05-10 1986-12-02 At&T Bell Laboratories Electron beam pumped mosaic array of light emitters

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3089956A (en) * 1953-07-10 1963-05-14 Westinghouse Electric Corp X-ray fluorescent screen
US2996634A (en) * 1958-08-20 1961-08-15 American Optical Corp Cathode ray tubes
DE1414684B2 (en) * 1961-02-27 1972-04-13 American Optical Corp., Southbridge, Mass. (V.StA.) TUBE WITH LIGHT SCREEN
JPS493295B1 (en) * 1970-03-23 1974-01-25

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EP0110458A1 (en) 1984-06-13
DE3370718D1 (en) 1987-05-07
FR2535896B1 (en) 1985-01-18
FR2535896A1 (en) 1984-05-11
JPS5999647A (en) 1984-06-08

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