Classifications

• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C17/00—Surface treatment of glass, not in the form of fibres or filaments, by coating
  • C03C17/02—Surface treatment of glass, not in the form of fibres or filaments, by coating with glass
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C10/00—Devitrified glass ceramics, i.e. glass ceramics having a crystalline phase dispersed in a glassy phase and constituting at least 50% by weight of the total composition
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C4/00—Compositions for glass with special properties
  • C03C4/12—Compositions for glass with special properties for luminescent glass; for fluorescent glass
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K11/00—Luminescent, e.g. electroluminescent, chemiluminescent materials
  • C09K11/08—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials
  • C09K11/77—Luminescent, e.g. electroluminescent, chemiluminescent materials containing inorganic luminescent materials containing rare earth metals
  • C09K11/7701—Chalogenides
  • C09K11/7703—Chalogenides with alkaline earth metals
• • 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
  • H01J29/20—Luminescent screens characterised by the luminescent material
• • 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

Definitions

• a radiation converter screen often also called a fluorescent screen, fluorescent screen or phosphorescent screen, comprises a layer made of a luminescent material, which is also referred to as a phosphor layer.
• a high-energy photon radiation is converted into a less energetic photon radiation.
• UV, X-ray and gamma radiation are converted into visible light.
• the energy-rich radiation is absorbed in the phosphor layer of the radiation converter screen and the emission of visible light is excited (luminescence).
• Radiation converter screens are used, among other things, in cathode ray tubes, such as those used for. B. be used as a television picture tube, as well as in X-ray image intensifiers as input and output screen and as X-ray detection systems in medical diagnostics. A two-dimensional or one-dimensional pattern of radiation which is not visible to the eye or cannot be detected by a detector used is converted into a visible or detectable image.
• such a radiation converter screen In addition to the degree of conversion and the luminosity, such a radiation converter screen also depends on its resolution. With many phosphor layers, the light generated in the phosphor layer spreads isotropically. By spreading the light to the side, so-called transverse conduction, the original image becomes blurred because each point illuminated by the X-rays is represented as a circle of visible light. This worsens the resolution.
• Various possibilities are known from the literature for preventing the cross line or for ensuring that the cross line is only of short range. In this way, the light propagation is preferably directed perpendicular to the layer plane.
• the phosphor layer consists of mutually adhering crystal needles that are perpendicular are oriented to the layer level. This orientation of the phosphor crystals results in an optical light-guiding effect in the direction of the crystal longitudinal axis. This effect is reinforced by cracks or gaps between the crystal needles. The formation of such cracks and gaps is favored when using carrier substrates with a mosaic or network structure (see DE 28 10 920). In this way, screens made of doped alkali halides such.
• the crack and column structure is statistical, so that the resolving power cannot be strictly regulated. A complete separation of all crystal needles is not possible in these structures.
• a radiation converter screen by epitaxially growing a luminescent layer on a self-supporting, single-crystalline body.
• the luminescent layer contains one
• the layer is produced, for. B. by liquid phase epitaxy.
• the activator is e.g. B. introduced by diffusing.
• the radiation converter screen is z. B. formed from shells of Y, Gd, Ga and AI and activated with Tb, Tm, Eu, Ce and Nd. This production process is very complex because of the need for a single-crystalline support and is limited to small areas and layer thicknesses. The resolution of the radiation converter screen is also limited because of the optically isotropic permeability of the single crystal body.
• the invention is based on the problem of a radiation Specify converter screen and a method for its production, which has a high resolution, the size, thickness and shape can be designed as arbitrarily as possible and which is easy and inexpensive to manufacture and controllable in its structure.
• a glass ceramic which contains at least one luminescence activator is used as the phosphor layer.
• the glass ceramic can be self-supporting or, for example, on an optically transparent support.
• B. be made of glass. Glass ceramic materials are created by the controlled crystallization of glasses.
• glass ceramics In glass ceramics, crystalline areas are embedded in a glass matrix. This structure is achieved by special temperature treatments of glasses made of a glass ceramic material system.
• a glass melt In the production process, a glass melt is converted into a glass body using typical glass-technical procedures such as B. pour, press, pull, molded.
• the glass body is at least partially converted from its amorphous structural state into a crystalline state by tempering.
• appropriate activators such as. B. rare earths or transition elements, the finished glass ceramic has luminescent properties.
• Luminescent glass ceramics are e.g. B. from J. Andrews, H. Beall, A. Le picki, 3. Lumin. 36 (1986), 65-74 and G. Boulon, Mat. Che. Phys. 16 (1987), 301-347. They are examined with regard to laser applications.
• the radiation converter screen according to the invention can be produced using simple glass technology.
• the radiation converter screen is optically transparent and stable. He is tall- flat, thin and structurally producible.
• the physical and technological properties of glass ceramics are combined with the luminescence ability of crystalline and amorphous solids. Radiation converter screens according to the invention can therefore be produced with great economy.
• the phosphor layer by appropriate temperature treatment so that it consists of crystallites oriented perpendicular to the layer plane, which are separated by a remaining glass phase.
• the phosphor layer is arranged on a support and structured so that it consists of individual phosphor blocks arranged periodically in the layer plane.
• this embodiment can advantageously be produced by exposing, annealing and selectively etching out the exposed parts.
• the side surfaces of the phosphor blocks can be provided with reflective material.
• a further improvement in the resolution is achieved by filling the gaps between adjacent fluorescent blocks with reflective material.
• the cavities can additionally be filled with a collimator material which has a high absorption compared to the incident radiation, such as, for example, B. Pb or W.
• Fig. 1 shows a section of a radiation converter screen, in which the phosphor layer consists of crystallites oriented perpendicular to the layer plane.
• Fig. 2 shows a section of a radiation converter screen, in which the phosphor layer consists of polycrystalline glass ceramic blocks.
• FIG 3 shows a section of a radiation converter screen in which the phosphor layer consists of amorphous glass ceramic blocks.
• a phosphor layer 12 made of glass ceramic is arranged on a carrier 11 (see FIG. 1).
• the carrier 11 is, for. B. made of glass.
• the phosphor layer 12 consists of a glass ceramic from the material system Sr0-Ba0-Ti0 2 -Ln 2 0-, where Ln at least one element from the group Y, Gd, Eu, Ce, Tb, Sm, Nd, Pr, La, Dy, Tm, Lu, Ho, Er, Yb is.
• Ln acts as a luminescence activator.
• the phosphor layer 12 is formed such that crystallites 13 oriented perpendicular to the layer plane are separated by a remaining glass phase 14.
• the phosphor layer 12 is thus anisotropic.
• the phosphor layer 12 is produced in particular by directional crystallization of a glass layer of the appropriate composition in a temperature gradient.
• the crystallites 13 and the glass phase portions 14 are chemically and structurally different in the phosphor layer 12. Accordingly, they show different refractive indices for the emitted luminescent light. This causes light to be guided in the direction of the longitudinal axis of the crystallites 13 or the glass phase 14, the greater the difference in the refractive indices, the more effective the light is. This minimizes the optical cross-conduction in the phosphor layer 12. In this way, a high resolution is achieved.
• the phosphor layer 22 On a carrier 21 from z. B. Glass is a fluorescent layer 22 arranged (see Fig. 2).
• the phosphor layer 22 is structured. It consists of fluorescent blocks 221 and filler layers 222 arranged between adjacent fluorescent blocks 221.
• the filler layers 222 are formed from a material such that they act as reflector layers or radiation collimator layers.
• the phosphor blocks 221 are completely separated from one another.
• the phosphor blocks 221 consist of many individual crystallites 23 which are cross-linked by a glass phase 24.
• the crystallites 23 and the glass phase 24 together form a pore-free, completely closed block of material.
• the filling layers 222 are used for optical encapsulation of the phosphor blocks 221 or for beam collimation. In this way, the resolving power of the radiation converter screen is improved.
• As filler layer z. B. a metal layer of Al or Au or an oxide layer of Ti0 2 , MgO or 1 2 0, used.
• the filling layer 222 then acts as a reflector layer. Depending on the application, it may be sufficient to provide only the surfaces of the side walls of the phosphor blocks 221 with a mirror coating. In this case, the filling layers 222 filling the cavities are omitted.
• the filling layer 222 can also be made of an absorbing collimator material, e.g. B. made of Pb or W.
• the phosphor layer 22 consists, for. B. from the material system Si0 2 -R 2 0-Ln 2 0 , where Ln at least one element from the group Y, Gd, Eu, Ce, Tb, Sm, Nd, Pr, La, Dy, Tm, Lu, Ho , Er, Yb and R is at least one element of the alkali group. It is particularly advantageous to add a small amount of a photosensitive compound to at least one of the elements Ag, Ce, Cu, Sn or Au to the phosphor layer. In this case, the phosphor layer can be structured very easily.
• the phosphor layer 22 made of photosensitive glass ceramic is produced by applying a photosensitive glass layer made of a glass ceramic material system to the carrier 21.
• the photosensitive glass layer is selectively exposed and then annealed.
• the exposed areas crystallize out.
• These crystal phases, which arise at the exposed areas, are more soluble than the glass phases, which remain at the unexposed areas. Because of this greater solubility, the crystal phases are selectively etched out.
• a layer is created that consists of individual glass blocks.
• the glass blocks are crystallized into a glass ceramic by renewed exposure and tempering.
• the crystallites 23 form in the
• a phosphor layer 32 On a carrier 31 from z. B. glass, a phosphor layer 32 is arranged (see FIG. 3).
• the phosphor layer 32 is structured. It consists of phosphor blocks 321 arranged periodically on the carrier 31. The phosphor blocks 321 are completely separated from one another.
• the phosphor blocks 321 consist of glass of a glass ceramic which has not crystallized out.
• the phosphor blocks 321 are therefore amorphous. They consist of the material system Si0 2 -R 2 0 -Ln 2 0_, where Ln and R have the same meaning as in the exemplary embodiment described with reference to FIG. 2.
• a photo-sensitive compound of at least one of the elements Ag, Ce, Cu, Sn or Au is additionally added to the glass-ceramic material system from which the phosphor blocks 321 are made.
• Filling layers 322 can be arranged between the phosphor blocks 321.
• the filler layers 322 are formed from such a material that they act as reflector layers or as radiation collision layers.
• the filling layers 322 are formed from such a material that they act as reflector layers or as radiation collision layers.
• filler layer 322 thus serve for the optical encapsulation of the fluorescent blocks 321 or for radiation collimation. That way improves the resolving power of the radiation converter screen.
• filler layer 322 z. B. a metal layer made of Al or Au or an oxide layer made of Ti0 2 , MgO or A1 2 0 used.
• the fill layer 322 then acts as a reflector layer. Depending on the application, it may be sufficient to provide only the surfaces of the side walls of the phosphor blocks 321 with a mirror. In this case, the filling layers 322 filling the cavities are omitted.
• the filling layer 322 can also be made of absorbent collimator material, eg. B. consist of Pb or W.
• the phosphor layer 32 is produced by applying a glass layer of the stated composition to the carrier 31.
• the exposed areas are crystallized out by selective exposure and subsequent tempering.
• these crystal phases are selectively removed from the remaining glass phase. This results in the amorphous phosphor blocks 321.
• An improvement in the resolution can be achieved by optically coating the side surfaces of the phosphor blocks 321, as also described with reference to FIG. 2. A trouble-free and loss-free propagation of the emitted luminescent light is ensured in the interior of the phosphor blocks 321, since neither grain boundaries nor secondary phases are present in the interior of the phosphor blocks 321.
• the method for structuring photosensitive glasses which is used in the examples described with reference to FIGS. 2 and 3, is known for structuring glass or glass ceramic.
• Methods for the production of glass or glass ceramics are e.g. B. in U.S. Patent 2,628,160, S.D. Stookey, Ind. Engineer. Chem. Vol. 45, pp. 115-118 (1953) and G.P. Smith, Glass Techn. Vol. 20, pp. 149-157 (1979).

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Organic Chemistry (AREA)
• Materials Engineering (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Life Sciences & Earth Sciences (AREA)
• General Chemical & Material Sciences (AREA)
• Geochemistry & Mineralogy (AREA)
• Dispersion Chemistry (AREA)
• Crystallography & Structural Chemistry (AREA)
• Ceramic Engineering (AREA)
• Inorganic Chemistry (AREA)
• Manufacturing & Machinery (AREA)
• Luminescent Compositions (AREA)

Applications Claiming Priority (3)

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• 1991
  • 1991-07-26 DE DE19914124875 patent/DE4124875A1/de active Granted
• 1992
  • 1992-06-30 WO PCT/DE1992/000537 patent/WO1993002978A1/de not_active Application Discontinuation
  • 1992-06-30 EP EP92913718A patent/EP0597874A1/de not_active Withdrawn

Non-Patent Citations (1)

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