Abstract: A problem associated with field emission displays is that of `smearing` where an otherwise sharp image appears to be surrounded by a diffuse halo of light. Our investigations have suggested that this is due to spurious reflections from the surface of the gate electrode layer. To eliminate these we have deposited an anti-reflection coating on the top surface of the gate electrode layer. This prevents the reflection of light rays travelling away from the phosphor layer towards the cathode. Such rays, if their reflection were allowed, would emerge at a different spot in the display from what was intended, resulting in a false image. A method for manufacturing a field emission display based on this approach is also described.

Abstract: A composite electrode in a channel substrate for a PALC display panel comprises a core that includes a metal and a surface layer of a resistive anodic oxide of the core metal.

Abstract: A process for making a cesiated diamond film comprises (a) depositing a quantity of cesium iodide on the diamond film in a vacuum of between about 10.sup.-4 Torr and about 10.sup.-7 Torr, (b) increasing the vacuum to at least about 10.sup.-8 Torr, and (c) imposing an electron beam upon the diamond film, said electron beam having an energy sufficient to dissociate said cesium iodide and to incorporate cesium into interstices of the diamond film. The cesiated diamond film prepared according to the process has an operating voltage that is reduced by a factor of at least approximately 2.5 relative to conventional, non-cesiated diamond film field emitters.

Abstract: The object of the present invention is to provide an organic thin film EL device that has an improved close adherence of a hole injection electrode to an organic thin film layer and a long life, maintaining uniform luminance and minimized performance deterioration over the lapse of time. The organic thin film EL device, which includes an electron injection electrode and a hole injection electrode with an organic thin film layer placed therebetween, has a part or the whole of the hole injection electrode formed of a carbon film. In addition, the carbon film is formed by a sputtering method.

Abstract: An anode of a flat panel display besides having a glass substrate, a patterned black grille on the substrate, a conductive layer covering the grille and the substrate, and a phosphor layer covering, also has one or more additional transparent layers that reduce the reflectance of the flat panel display from 14% down to 1%-4%. These additional layers are placed between the black matrix grille and the substrate, and between the conductive layer and phosphor layer. The two additional layers are selected and designed to reduce the reflectance that occurs at these respective interfaces.

Abstract: A cathode is formed on a glass substrate by depositing nickel thereon, and silicon dioxide is allowed to accumulate on the cathode by sputtering to form an insulator film. Then, a gate electrode is provided on the insulator film by depositing nickel thereon. A hole is formed on the glass substrate by lithography to carry out patterning, and the gate electrode and the insulator film are selectively etched to create a hole for the formation of an emitter emitting electrons. Furthermore, nickel is stacked into the hole by deposition to form the emitter, and subsequently the emitter is covered with sulfur as a high vapor-pressure substance to form a high vapor-pressure substance layer.

Abstract: The present invention relates to a method for manufacturing a metallized luminescent screen for a CRT. At least one phosphor layer is deposited (10) on an inner surface of a faceplate panel to form the luminescent screen. The panel containing the screen is then preheated (12) to a temperature equal to, or in excess of, a minimum film-forming temperature and prewetted (14) by applying water to the screen. An aqueous filming emulsion containing a copolymer of acrylates and methacrylates with an average molecular weight of from 250,000 to 500,000 is applied (16) to the prewetted screen and dried (18) to form a film layer. Next, a layer of aluminum is deposited (20) onto the film layer, and the panel, bearing the metallized screen, is sealed to a funnel by heating the panel and the funnel through a sealing cycle. The sealing cycle(22) has a first rate of temperature increase to a first temperature and a second rate of temperature increase, less than the first rate, to a second temperature.

Abstract: A method for fabrication of a display device is provided which comprises the steps of: forming an aluminum electrode having a predetermined configuration on a substrate; and treating the aluminum electrode with a solution containing an oxidizing agent to form on a surface of the aluminum electrode a compound film containing as a principal component a substance derived from the solution containing the oxidizing agent.

Abstract: In a field-emission cold cathode forming an emitter by the vacuum deposition method, contamination at the side surface of the insulating layer due to deposition of an emitter material during formation of the emitter is prevented. Thereby, deterioration of insulating resistance and dielectric strength between gate and emitter can also be prevented. With an oblique vacuum deposition, a sacrificing layer 5 is formed onto the entire area of the side surface within the cavity 4, an emitter is then vacuum deposited, and thereafter emitter material particles are removed together with the protecting film.

Abstract: A refractory compound coating (188) for electrodes is sputter resistant, has a low work function so that it is a good emitter of secondary electrons, is very resistant to oxidation, and is easy to apply by way of electrophoresis. More specifically, cathode electrodes (162) are used in a plasma addressing structure (10). The coating is preferably formed by electrophoretic deposition of particles (184) of at least one refractory compound along with a frit. The coating is subsequently baked to fuse the frit and bond the electrophoretically deposited particles to the electrodes.

Abstract: According to the invention, a flat panel device includes a spacer for providing internal support. In one embodiment, the spacer is made of ceramic, glass-ceramic, ceramic reinforced glass, devitrified glass, metal with electrically insulative coating or high-temperature vacuum-compatible polyimide, and can be a spacer wall, a spacer structure including a plurality of holes, or some combination of a spacer wall, spacer walls, and spacer structure. Spacer surfaces are treated to reduce secondary emissions and prevent charging of the spacer surfaces. The flat panel device can include a thermionic cathode or a field emitter cathode, and the faceplate and backplate can both be straight or both be curved. The flat panel device can include an addressing grid. In a method according to the invention for assembling a flat panel device, spacer walls are held in proper alignment during assembly by being inserted into a notch formed in the addressing grid and/or a top or bottom wall of the enclosure.

Abstract: The invention relates to a controllable thermionic electron emitter for vacuum tubes, which comprises an emitter layer (3, 27) and a control layer (5) which is separated from the emitter layer by an insulating layer (4), with the insulating layer and the control layer being manufactured by a deposition process. Also when its dimensions are small, such an electron emitter can be dimensionally accurately manufactured. All functional elements of the controllable thermionic electron emitter, more particularly control layer(s) (5, 7, 22, 24), emitter layer (3, 27) and separating insulating layers (2, 4, 6, 21, 23, 25) are successively deposited on a substrate (1, 20) in the direction of growth, in such a manner that the layers adhere to each other via solid boundary layers. In operation and, in particular, when the temperature varies, the dimensional accuracy of the electron emitter is preserved within narrow limits, and said electron emitter has a long service life.

Abstract: A cold cathode vacuum discharge tube, and method for making same, with an interior surface of the trigger probe coated with carbon deposited by carbon vapor deposition (CVD) or diamond-like carbon (DLC) deposition. Preferably a solid graphite insert is employed in the probe-cathode structure in place of an aluminum bushing employed in the prior art. The CVD or DLC probe face is laser scribed to allow resistance trimming to match available trigger voltage signals and to reduce electrical aging.

Abstract: A light-scattering coating comprising light-scattering particles, such as alumina, dispersed in a silica matrix is formed by applying to the filter a silicone solution in which is dispersed colloidal silica and the light-scattering particles to a suitable substrate and then pyrolyzing the dispersion at high temperature to drive off the organic components and form the silica matrix. This coating is hard and abrasion resistant and is useful for reflectors, lamps and lenses.

Abstract: A method of manufacturing EL lamp systems is available which incorporates some of the processes used in manufacturing flexible, printed circuit boards with surface mounted components along with those used to form multilayered EL lamps. The EL lamp system produced by this method is suitable for a variety of graphics and low-cost consumer applications.

Abstract: The electric lamp (1) has a lamp vessel (2), wherein an electric element (3) is accommodated. This element is connected to current conductors (4). Molybdenum end portions (5) of the current conductors extend outside the lamp vessel and have a skin of molybdenum nitride as a protection against oxidation.

Abstract: A photocathode which is responsive to ultraviolet light to release photoelectrons includes a supportive window layer of sapphire and a single-crystal active layer of AlGaN. Interposed between the window layer and the active layer is an interface layer which insures a low population density of crystalline defects at the interface of the interface layer with the active layer and in the active layer itself. Consequently, the photocathode is an effective emitter of photoelectrons in the transmission mode.

Abstract: An interference filter or coating is provided in a predetermined pattern on a lamp envelope. The coating is comprised of alternating layers of high and low index of refraction materials applied to a vitreous outer surface of a lamp envelope. The coating may be geometrically symmetric or asymmetric, continuous or discontinuous with respect to the coating itself or the envelope to which it has been applied. The envelope can be masked prior to deposition of the coating so that removal of the mask leaves the filter in the desired pattern. The preferred process for forming the coating includes forming a boric oxide mask on a portion of the envelope, applying the coating over the mask and removing the coating from masked areas of the envelope by dissolving the mask in an aqueous solution.

Abstract: A method for manufacturing low-cost electroluminescent (EL) lamps is disclosed. The method of the present invention includes the first step of die cutting, embossing or chemically etching a metal foil to form one or more rear capacitive electrodes. Next, the capacitive electrodes are bonded to a paper core stock which is coupled to a precisely positioned indexing system. In the third step, a layer of EL phosphor ink is applied to the capacitive electrodes to precisely form the areas of illumination. In step four, a layer of conductive ITO ink is applied to cover the layer of EL phosphor ink. Next, in step five a transparent polyester film or ultraviolet activated dielectric coating is applied to the entire surface of the lamp. Finally, in step six electrical terminations are provided to the rear capacitive electrode and the layer of conductive ITO ink.

Abstract: A low-pressure mercury vapor discharge lamp with a tubular discharge vessel (1) with an internal diameter D. The discharge vessel (1) encloses a discharge space (3), which comprises mercury and a rare gas, in a gastight manner. Electrodes (5A, 5B) are arranged in end portions (4A, 4B) of this discharge space. The discharge vessel (1) has a luminescent layer (10) which supports a protective layer (11) comprising a metal oxide at an inner surface (9). In the lamp according to the invention, at least 75% by weight of the metal oxide is present in total in the end portions (4A, 4B), said end portions (4A, 4B) each extending up to a distance beyond the electrodes (5A, 5B) which is three times the internal diameter of the discharge vessel (1). The lamp has a comparatively low luminous decrement and can be manufactured comparatively efficiently.

Abstract: A metal halide lamp includes a cast ceramic reflector almost completely comprised of alumina. A conventional metal halide bulb is positioned within the reflector. A glaze and then a dielectric coating are applied to the inside surface of the reflector, such that appreciable amounts of infrared radiation from the bulb are absorbed into the glaze and ceramic and not reflected into the beam.

Abstract: An improved electroluminescent display of the type having a substrate on which are applied ITO electrodes having dielectric, phosphor and dielectric stacks positioned thereon is formed with cavities between the stacks which expose a portion of each ITO electrode. The structure is annealed before or after the cavities are cut. Then a metal assist structure applied over the exposed portion of each ITO electrode. A planarization layer is applied over each metal assist structure and metal electrodes are placed to complete the display.

Abstract: In a method for manufacturing a glow cathode for an electron tube, a layer of an alloy, such as iridium-lanthanum (Ir.sub.2 La), is produced on a substrate by coating the substrate, such as in a number of layers, with the components of the alloy by deposition from the vapor phase, such that the components of the alloy are present in the stoichiometrically correct ratio on the substrate, and in that the substrate is heated for a time duration adequate for alloy formation to a temperature that is lower than the melting temperature of the phase of the alloy having the lowest melting point.

Abstract: The outer surface of the glass display panel of a cathode ray tube (CRT) is first coated with an antistatic conductive metal salt solution. A water or organic solvent soluble antireflective coating is then applied by conventional means such as spinning, spraying or dipping to the glass display panel over the first coating. The antireflective coating is comprised of either an organic or an inorganic salt, or a polymer. The coated display panel is then baked, followed by thorough washing with either water in the case of an organic or inorganic salt or water soluble polymer antireflective coating, or toluene in the case of a non-water soluble polymer antireflective coating. Washing the display panel partially dissolves the salt or polymer in the antireflective coating more on the outer surface of the coating than on the inner portion of the coat adjacent the glass facelate.

Abstract: An electric lamp has a tubular discharge vessel or a lamp envelope with an optically active layer of a material at an inner surface. The optically active layer has window in which the layer is absent. The material of the optically active layer adjacent both to the window and to the wall of the discharge vessel has a form different from that of portions of the optically active layer not adjoining the window as a result of fusion. The lamp may be readily manufactured by a method according to the invention whereby the material situated within the window to be formed is removed by intensive electromagnetic radiation which is directed through the wall of the discharge vessel at the material to be removed.

Abstract: An electroluminescent device is described, as well as a method of making same, wherein the device is characterized by a semiconductor nanocrystal electron transport layer capable of emitting visible light in response to a voltage applied to the device. The wavelength of the light emitted by the device may be changed by changing either the size or the type of semiconductor nanocrystals used in forming the electron transport layer. In a preferred embodiment the device is further characterized by the capability of emitting visible light of varying wavelengths in response to changes in the voltage applied to the device.

Abstract: The display screen (3) of a cathode ray tube (1) is provided with a light-absorbing coating (8) comprising a hybrid inorganic-organic material consisting of an inorganic network of at least silicon oxide and a polymeric component. By means of a sol-gel process the coating can be provided in a relatively large thickness without causing crackles. Consequently, the layer can contain large quantities of dyestuff, so that said layer can very suitably be used as a chrominance or transmission coating to improve the picture contrast. Even if the display screen is not highly polished, the coating can be obtained with a high-polish and it complies with the customary mechanical, chemical and optical requirements.

Abstract: A method for manufacturing a thin-film EL device utilizes a Zn-Mn target that contains less Mn than the optimum Mn concentration on the basis of the finding that the light-emitting layer grown by the sputtering method contains more Mn than in the target. Manganese concentration on the target surface layer is controlled by changing the area ratio between ZnS and Mn exposed on the surface of the target. Manganese concentration on the target surface is controlled at preferably from 0.3 to 0.4 wt % when the target surface is sulfurized during sputtering and less than 0.1 wt % when the target surface is not sulfurized.

Abstract: A method of manufacture for a lamp involves making up, separate from an envelope, a sub-assembly comprising a lead structure and a vitreous body that surrounds it. In one form of this method, particles of vitreous material are pressed into a mold cavity that surrounds the lead structure, thus forming a compact surrounding the lead structure. This compact is sintered in an inert atmosphere, thereby forming the sub-assembly. Thereafter, the sub-assembly is placed in an opening in the envelope, and a hermetic seal is made between the envelope and the vitreous body in the interface region between the envelope and the vitreous body.

Abstract: An improved low power pulsed anode magnetron is provided having a cylindrical cathode centrally disposed within a plurality of radial anode vanes. An interaction region is provided between the surface of the cathode and the anode vane tips. A ratio of the anode-to-cathode space over the center-to-center distance between adjacent vane tips is within a range between 0.95 and 1.05. The cathode is joined to a magnetic polepiece assembly which channels magnetic flux to the interaction region. Both the cathode and the polepiece are mechanically adjustable from external to the magnetron to reposition the cathode and polepiece with respect to the anode vanes. The cathode surface is formed from an active nickel alloy which is cleaned by a chemical process followed by a high temperature and vacuum firing. An emissive surface is applied over the cleaned cathode surface.

Abstract: The invention relates to display screens of the plasma panel type. Its subject is more particularly electrically insulating elements such as spacers (12, 15) and/or dielectric layers (4, 6).According to the invention, the spacers (12, 15) and/or the dielectric layers (4, 6) are produced from a polymerizable organic compound.It results therefrom that the highest temperature imposed on the plasma panel during its manufacture can remain lower than a temperature of the sealing of this panel.

Abstract: The magnetic performance of a color CRT is optimized by firing ferromagnetic components thereof in an exothermic atmosphere to anneal the components and form a stable black iron oxide layer on a surface thereof. The components are introduced into a furnace having such an atmosphere and the components are heated to a temperature sufficient to initiate pre-oxidation of the surface thereof. The temperature is then increased to optimize the magnetic characteristics of the components and at least partially relieve stress therein. The components are next cooled to a temperature at which the thickness of the stable black oxide layer on the surface of the components is optimized. A CRT is manufactured according to the process described above.

Abstract: A holding fixture is used to hold single-ended or double-ended lamps within a chemical vapor deposition chamber. The holding fixture includes first and second wire mesh screens for holding lamps that are to be coated within the deposition chamber. A screen support is provided to secure and support each screen within the fixture. Spacers to secure the screens and supports together and provide spacing between such screens and supports. Holes may be cut in the screen to allow portions of the lamps to pass through screen. In addition, a housing may be provided for the holding fixture.

Abstract: A fluorescent lamp including a lamp bulb which has been coated with phosphor powder which has been ground in an attritor to reduce the powder weight without loss in light output and light maintenance. A process to produce such a fluorescent lamp utilizes a particular sequence of steps including firing, milling, attritor milling, and washing to produce an improved stir-in alkaline earth halophosphate.

Abstract: A cathode structure for an electron tube that includes a cathode sleeve, an upper heat radiation part blackened by the oxidation of the Cr contained therein in order to increase the rate of the heat radiation, a lower supporting part covered by a nickel layer for preventing the oxidation of Cr, and a cathode sleeve holder that is connected to the lower supporting part by resistance welding.

Abstract: Method of vapor-depositing an interference filter layer on the inside of a display window, a display window, a projection cathode ray tube and a projection television apparatus.A method of manufacturing a projection cathode ray tube comprising an interference filter on an inwardly directed surface of a display window, the method comprising as a process step the vapor deposition of at least one layer of the interference filter. It has been found that the edges of a display window during the vapor deposition of an interference filter layer detrimentally influence the thickness of the vapor deposited layer, the thickness increases more towards the edges than follows from geometrical computations. In the method according to the invention vapor deposition is performed on a display window for which the height of the edge is less than 1/5 of the minor axis. The display screen preferably comprises a recessive edge.

Abstract: A field emitter device comprising a conductive metal and a diamond emission tip with negative electron affinity in ohmic contact with and protruding above the metal. The device is fabricated by coating a substrate with an insulating diamond film having negative electron affinity and a top surface with spikes and valleys, depositing a conductive metal on the diamond film, and applying an etch to expose the spikes without exposing the valleys, thereby forming diamond emission tips which protrude a height above the conductive metal less than the mean free path of electrons in the diamond film.

Abstract: A panel of a metal backed color cathode ray tube and a manufacturing method thereof are disclosed which are characterized in that the height of the graphite remaining on the skirt is higher than or same as the metal deposition height of the deposited metal layer, and that a shielding plate having a height higher than or same as the cutting height of the graphite is used on a deposition dolly for forming the deposited metal layer. According to the present invention, the deposited metal layer is neither floated nor detached due to the combustion of the organic materials used in forming the luminescent layer or the intermediate layers such as the filming layer, and therefore, the defect rate due to the blocking of the holes of the shadow mask is markedly reduced, thereby making it possible to save labor and materials in producing the product, and concomitantly upgrading the quality of the metal backed color cathode ray tube.

Abstract: In the production of micron-size pyramid emitters for field emission devices, a first layer of electrically-conductive material, such as single crystal silicon or metal, is etched to form column-like structures each of which tapers from each end of the column towards an intermediate portion along its length. A second conductive layer is formed in contact with the free ends of the columns, and etching of the columns is then resumed until the intermediate portion of each column is etched through, leaving a pair of pyramid emitters pointing towards one another and supported by the respective conductive layer.

Abstract: A field emission electron device employing an electron emitter comprised of a coating of diamond material disposed on a surface of a selectively formed conductive/semiconductive electrode and a method of forming the device including a step wherein carbon ions are implanted at a surface of a conductive/semiconductive electrode to function as nucleation sites for the diamond formation.

Abstract: A method of encasing a luminous translucent tubing (12,32) of a non-linear complex geometrical configuration in a transparent outer member (14,34) and forming a passage (25,35) of annular radial cross section therebetween, which method comprises coating the exterior of the tubing (12,32) with a viscous temporary material (17,47) which solidifies to provide a coating with smooth exterior surface, coating the temporary substance (17,47) with a permanent forming material in a viscous liquid state which hardens to form a rigid transparent outer member (14,34) in coextensive surrounding relation to the tubing (12,32) and its coating of temporary material (17,47), applying heat to said coating of temporary material at a temperature above the melting point of the temporary material and below the softening temperature of the outer member, and removing the temporary material from between the translucent tubing (12,32) and the transparent outer member (14,34) while supporting the translucent tubing in fixed relation to

Abstract: A method of manufacturing a display tube comprising an envelope having an envelope portion and a display window. The quantity of X-rays released from the envelope portion is determined, after which discrete X-ray absorbing means are provided in those places of the envelope where the quantity of X-rays released exceeds a limiting value. In a display tube manufactured according to such a method and comprising, in particular, a substantially rectangular display screen and a cylindrical neck portion having an electron gun the diagonals of the envelope of which are provided with discrete X-ray absorbing means, the desirable quantity of X-rays is absorbed in a simple and cost-effective manner.

Abstract: An insulating layer, a luminescent layer, a transparent electrode, base sheet with a transparent electrode formed thereon and a desiccant film are laminated in that order on the upper surface of a pointer body which also serves as a rear electrode. The upper surface of the dessiccant film is sealed with a moistureproof film. In producing a luminous pointer, these layers are laminated at a plurality of portions on the upper surface of a sheet which is to constitute pointer bodies, the pointer bodies are blanked along the outlines thereof by press working, and then the outside of the disiccant film is sealed with a moistureproof film. Alternatively, the outside of the desiccant film may be sealed with a moistureproof film before blanking the pointer bodies by press working.

Abstract: Disclosed is an electrode for electrical discharge used for diesinking, comprising an electrode member produced by subjecting a base and binder of gypsum hemihydrate powder and a filler of conductive metal powder to modeling and/or molding and setting into a desired form of electrode, and followed by plating the electrode member with a conductive metal; and a process for manufacturing the same, wherein a gypsum hemihydrate powder, a gypsum dihydrate powder in an amount of 1% by weight of the gypsum hemihydrate powder and a conductive metal powder are kneaded in vacuo, and water is added thereto to continue further kneading in vacuo, followed by casting into a mold having a predetermined shape transferred thereon to carry out hydration, molding and setting to provide an electrode member; after the electrode member is dried, it is plated with a conductive metal to enhance mutual continuity in the conductivity of the former conductive metal powder and also to form a thin metal layer on the surface of the electro

Abstract: An accelerator vacuum pipe for a charged-particle acceleration and storage system having a vacuum zone defined therein is provided with a layer of getter material which can capture residual or generated gas molecules in the pipe-member. The layer of getter material is disposed over the entire inner wall of the vacuum pipe in at least a deflection zone where the charged-particles are deflected.

Abstract: A method for applying a protective coating to the inner surface of the arc tube of a high-intensity metal halide discharge lamp involves dosing the arc tube with an inert gas that is doped with a metal hydride gas. Preferably, the metal hydride gas comprises silane. The arc tube is heated to a sufficiently high temperature to decompose the silane gas. As a result, silicon is deposited as a protective coating on the inner surface of the arc tube wall. The hydrogen gas that is generated by the silane decomposition is removed from the system either by pumping it out before dosing the arc tube with the final arc tube fill, or by diffusion through the arc tube wall during operation of the lamp.

Abstract: A method of producing a lamp having a coated layer and of a type in which linear tubes in parallel are interconnected, comprises the steps of forming a connected glass tube by making an airtight connection via connecting portions between side walls of a plural number of glass tubes having openings at both ends and main portions that are linear and arranged parallel to each other; of forming a coated layer on the inner wall surface of the connected tube including the connecting portions by introducing a coated substance from opening end portions of the connected glass tube; and of forming an airtight path as a discharge path in the connected tube including the main and connecting portions by sealing the opening end portions on a side of the connecting portions of the connected tube after the formation of the coated layer.

Abstract: Flush and pump flush processes yielding light sources for incandescent and metal vapor discharge lamps are disclosed. The flush and pump flush processes also yield lamps that are particularly suitable for deposition of a reflective coating on its outer surface. For such reflective coated light sources, the associated lamp leads are encased in glass and therefore are protected against any deleterious reactions that may otherwise result from the deposition of the reflective coating process. The light source yielded by the flush and pump flush processes of the present invention are advantageous in reducing the mounting arrangement of the lamps in which the light sources are housed.

Abstract: A fluorescent lamp including a lamp bulb which has been coated with phosphor powder which has been ground in an attritor to reduce the powder weight without loss in light output and light maintenance. A process to produce such a fluorescent lamp is also provided.

Abstract: A shadow mask sheet manufactured from an iron-nickel alloy is drape-drawn by means of a drawing process to form a shodow mask 15. Prior to the actual drawing process the shadow mask sheet is subjected to an annealing treatment. After the drawing process the shadow mask is successively subjected to a complementary annealing treatment in a non-oxidizing gas atmosphere at a temperature between 700.degree. C. and 1200.degree. C. to improve the magnetic screening properties of the shadow mask 15, and to an annealing treatment in an oxidizing gas atmosphere. After oxidation the shadow mask 15 is connected on a supporting frame 17 which may be subjected to an annealing treatment in a non-oxidizing gas atmosphere and then to an oxidizing annealing treatment.