Classifications

• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B33/00—Electroluminescent light sources
  • H05B33/12—Light sources with substantially two-dimensional radiating surfaces
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B33/00—Electroluminescent light sources
  • H05B33/12—Light sources with substantially two-dimensional radiating surfaces
  • H05B33/26—Light sources with substantially two-dimensional radiating surfaces characterised by the composition or arrangement of the conductive material used as an electrode

Definitions

• the present invention relates to the field of thin-film electroluminescent screens. It relates in particular to their application in motor vehicles where they are used for displaying information on their operation or their condition.
• An electroluminescent film is basically composed of a stack of several layers between two transparent protective films, a layer formed of one or more transparent electrodes before, a dielectric layer, a layer comprising the electroluminescent material, a dielectric layer, a layer comprising a or more rear electrodes.
• the transparent electrode (s) are for example based on indium tin oxide (ITO).
• the electroluminescent layer is made with a phosphor semiconductor material, the metal electrodes can be made of aluminum and the protective films are made of a transparent flexible material.
• the electroluminescent material becomes emitting and a visible image is formed whose outline corresponds to that of the rear electrodes.
• the color of the light emitted depends on the phosphor material used.
• An active element is thus created by electrode. It is possible to combine several individually controlled elements, to display information on a dashboard of a vehicle for example.
• thin-film luminescent screens have the advantage of offering a wider angle of view, a larger display surface, of not requiring auxiliary lighting, and of being thinner. This type of element is also used in background lighting of a dashboard of a motor vehicle.
• FIG. 3 shows an example of display which can be produced with this means.
• each digit is composed from a set of 7 electroluminescent elements. These elements are individually controlled as is known to those skilled in the art.
• Each element which is energized becomes luminous in relation to the background surface and is therefore visible when it is in this state.
• a display device of the thin-film electroluminescent screen type comprising a first layer comprising an electroluminescent material between a second layer forming a transparent front electrode and a third layer comprising at least a first rear electrode is characterized by the fact that said screen comprises, behind the third layer, a fourth layer comprising an electroluminescent material and a fifth layer with at least a second rear electrode masking an area not covered by the first electrode.
• the second overlaps the edge of the first.
• the first electrode covers a surface corresponding to a screen background and comprises at least one recessed area, the second electrode masking at least part of said recessed area.
• the first electrode comprising several recessed zones, the layer comprises second electrodes of shape complementary to said recessed zones so that the first and second electrodes together mask the entire screen background.
• the first and second electrodes are activated so as to display no information.
• the electroluminescent layers were formed from an electroluminescent ink and in particular, the electrodes were also obtained by depositing conductive particles in suspension in a liquid support.
• FIG. 1 is a schematic view of an electroluminescent screen according to the invention
• FIG. 2 represents the image formed by the first electrode of the third layer
• FIG. 3 represents the image formed by the second electrodes of the fourth layer
• FIG. 4 shows the superposition of the first and of the second electrodes
• Figure 5 shows an image formed by the screen.
• FIG. 1 represents a part of the electroluminescent screen according to the invention. It consists of a plurality of layers 1 to 10. In general, the different layers are applied by screen printing. The materials are suspended in a liquid support in the manner of an ink. The ink is applied to the surface using the stencil technique where the areas which should not be inked are masked. After the liquid support has been removed, a thin layer of a few microns, from 5 to 10, remains on the substrate with gaps corresponding to the masked areas.
• the transparent support 1 is of a quality which allows it to be printed by screen printing.
• the common conductive layer 2, forming the front transparent electrode, is obtained by depositing on the transparent support an indium tin oxide (ITO).
• ITO indium tin oxide
• the particles are suspended in a liquid support by means of which they are then deposited on their substrate.
• Layer 3 is formed by the deposition by screen printing of a phosphor material which is in the form of an electroluminescent ink.
• the masks correspond to the zones which do not comprise a phosphor.
• the image of FIG. 2 is reproduced in the present example.
• the luminescent ink is applied to the entire surface except in the recesses E ⁇ ... E n . These recesses have the form of digits and are grouped here in three positions of an odometer. The three groups aim to display a three-digit number.
• Layer 4 is made of a dielectric and transparent material. This material is applied in the form of a varnish.
• Layer 5 includes the first ELI rear electrode. This electrode continuously covers the surface of the screen, with the exception of the recesses E ⁇ ... E n , the shape of which is shown in FIG. 2, like the light-emitting layer therefore.
• This conductive layer is advantageously applied by screen printing and the conductive material is ITO.
• Layer 6 is a transparent dielectric produced like layer
• Layer 7 is formed by the deposition of a phosphor material in the form of an electroluminescent ink like layer 3.
• the pattern applied is that shown in FIG. 3. This pattern is the negative of the pattern in FIG. 2. preferably, however, the digits are slightly larger than the recesses in FIG. 2.
• FIG. 4 shows the way in which the two patterns overlap. Due to the larger dimension of the segments in Figure 3, the edges overlap.
• Layer 8 is a transparent dielectric produced in the same way as insulating layers 4 and 6.
• Layer 9 includes the second metal electrodes EL2j ... EL2 n . These are in the form of digits corresponding to those of the light-emitting layer 7. Their arrangement is that of FIG. 3. Each electrode is electrically controlled independently of the others. Referring to Figure 4 where we see the relative position they occupy with respect to the first electrode and its recesses, we observe that the electrodes EL2 ⁇ ... EL2 n completely hide the recesses E] ... E n . We chose the size of the digits so that the active digits mask the recesses while overlapping the borders. The outline of active digits is shown in dotted lines.
• Layer 10 is a transparent dielectric produced in the same way as the other insulating layers.
• FIG. 5 shows an example of an image formed by the screen. It is the number 128. The background being completely lit, this image is obtained by extinguishing the appropriate digits. The observer in front of the screen sees the unlit figures on an illuminated background.

Landscapes

• Electroluminescent Light Sources (AREA)
• Devices For Indicating Variable Information By Combining Individual Elements (AREA)
• Illuminated Signs And Luminous Advertising (AREA)

Applications Claiming Priority (3)

Publications (1)

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ID=28686197

Family Applications (1)

Country Status (6)

Families Citing this family (7)

Family Cites Families (4)

• 2002
  • 2002-04-19 FR FR0204929A patent/FR2838857B1/fr not_active Expired - Lifetime
• 2003
  • 2003-04-18 JP JP2003587141A patent/JP2005527947A/ja active Pending
  • 2003-04-18 WO PCT/FR2003/001259 patent/WO2003090500A1/fr active Application Filing
  • 2003-04-18 US US10/511,892 patent/US20050212417A1/en not_active Abandoned
  • 2003-04-18 EP EP03740644A patent/EP1500308A1/fr not_active Withdrawn
  • 2003-04-18 AU AU2003262392A patent/AU2003262392A1/en not_active Abandoned

Non-Patent Citations (1)

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