EP1349816A1

EP1349816A1 - Glass substrate provided with embossed glass elements

Info

Publication number: EP1349816A1
Application number: EP01271827A
Authority: EP
Inventors: Didier Jousse
Original assignee: Saint Gobain Glass France SAS; Compagnie de Saint Gobain SA
Current assignee: Saint Gobain Glass France SAS; Compagnie de Saint Gobain SA
Priority date: 2000-12-22
Filing date: 2001-11-28
Publication date: 2003-10-08
Also published as: RU2276113C2; KR20030062428A; HK1063774A1; FR2818634B1; CN1483006A; CN1243676C; WO2002051760A1; JP2004523453A; US7419415B2; FR2818634A1; US20040045321A1; PL362057A1; KR100873931B1; PL198101B1; CZ20031629A3

Abstract

The invention concerns a glass substrate comprising embossed glass elements (20) on part of its surface, characterised in that the glass elements (20) are intrinsically incorporated to the substrate. Said substrate is advantageously used in a plasma display screen whereof the front surface includes a first array of electrodes (13a, 13b) and the rear surface, which is constituted by said structured substrate, comprises a second array of electrodes (12) substantially perpendicular to the first array (13a, 13b) and arranged on the outer surface (23) of the structured substrate, opposite the gap (21) between the embossed elements (20), while the luminophores (16) occupy the surface of the gap (21) between the embossed elements.

Description

GLASS SUBSTRATE HAVING GLASS AND RELIEF ELEMENTS.

The invention relates to a glass substrate provided with glass elements arranged in relief over a part of its surface.

Although it is not limited to such an application, the invention will be more particularly described for glass substrates with reference to the production of an emissive flat screen and more precisely of a plasma screen. Other uses, such as for FED screens or flat lamps, can also be considered. The expression flat lamp should be understood to include lamps intended for the manufacture of portable computers, and lamps of larger dimensions for architectural applications such as the production of advertising panels or partitions, for example of offices, whatever moreover the technology of these lamps. A plasma screen essentially consists of two flat glass substrates. On at least one of the substrates are deposited one or more networks of electrodes, a layer of dielectric material and layers made of phosphor materials corresponding for example to the colors green, red and blue. Before being joined together, the glass substrates also receive barriers whose functions consist in forming a multitude of cells which isolate the phosphors therefrom, and in maintaining a distance between the two glass substrates.

The barriers also qualified as "ribs" are produced independently of the glass substrates and attached to the substrate. The "ribs" are obtained by depositing a glass frit associated with one of the substrates by a process which however presents slow stages such as screen printing, sandblasting, as well as complex and costly stages requiring in particular recycling dust generated during the sanding step which is not without creating some pollution problems. Furthermore, we have noticed a functional degradation of the phosphors which would be due to the deposition of impurities on the ribs generated during the process for obtaining the ribs.

In addition, to ensure proper operation with regard to the ignition voltages of the electrodes, it is necessary to cover the electrodes with a dielectric, the deposition of which constitutes an additional step going in the opposite direction to the always desired improvement in production costs.

The object of the invention is therefore to propose a glass substrate provided with glass elements arranged in relief in order to constitute in particular “ribs” which do not generate the drawbacks of the prior art and allow cost savings on the manufacture of products using such a substrate.

According to the invention, the glass substrate comprising glass elements arranged in relief over a part of its surface, is characterized in that said glass elements are incorporated intrinsically into the substrate. Preferably, the body of the substrate has two opposite parallel faces, the elements being integrated into at least one of the two faces.

According to one characteristic, the glass elements extend along at least one line substantially parallel to one side of the substrate; they can form at least one continuous low wall or form isolated studs. Preferably, they constitute regularly spaced parallel lines, with a pitch p which can vary from 0.2 to

30 mm, from the proximity of one edge of the substrate to the opposite edge.

According to another characteristic of the invention, the section of the elements can take various forms. Thus, the section is for example of triangular shape, the base of the triangle being integrated into the substrate. It can also have a concave curved geometry at the level of the body of the substrate, and a substantially straight neck at the top. As a variant, the section is in the form of an arch such that the volume constitutes a half-cylinder.

According to other characteristics, the height of these elements can vary from 0.15 to 12 mm, the top of these elements can form a flat whose width is less than 500 μm while their base can have a width of 50 vm to 50 mm.

One mode of use of the structured substrate of the invention is in particular that of a plasma screen which comprises said structured substrate constituting the rear face of the screen, and a flat substrate constituting the front face of the screen and provided on its internal face opposite the internal face of the substrate structured with a first network of electrodes, the plasma screen being characterized in that a second network of electrodes substantially perpendicular to the first network is disposed on the internal face of the substrate structured in the space existing between the elements in relief while a dielectric covers said second array of electrodes and phosphors are housed in said space above the dielectric.

According to a variant plasma screen, the second network of rear face electrodes substantially perpendicular to the first network of front face is arranged on the external face of the structured substrate and opposite the space existing between the elements in relief while that luminophores occupy in surface the space existing between the elements in relief.

In this variant of plasma screen, the rear face electrodes are advantageously placed on the external face of the substrate, that is to say outside the screen and not inside the screen. The advantages are manifold:

- There is no longer any need for a dielectric for this network of electrodes because the thickness of the substrate provides the dielectric function;

- once the screen is assembled, it is always possible to carry out a repair on the electrodes; - one removes one of the sources of internal pollution of the screens linked to the evaporation and incomplete combustion of the organic compounds constituting the screen printing binders of the electrodes, and also the risks of pollution of the phosphors by the materials of the Ag type electrodes Finally, according to this last variant of the screen, and in particular when the elements in relief have a flat at their top, a third network of electrodes may be provided parallel to the second network, arranged on the external face of the substrate and at 'opposite vertices of the elements in relief, while luminiphores occupy in surface the space existing between the elements in relief.

The structured substrate of the invention, in particular in its use for a plasma screen, comprises a multitude of walls, constituting the "ribs", parallel to each other and extending from one edge of the substrate to the opposite edge, the two lateral walls of the two respective edges of the substrate being of greater width than the intermediate walls in order to ensure a sufficient rest and contact surface in this peripheral zone for sealing the two substrates of the screen.

The structured substrate of the invention can of course be used in other embodiments, the elements in relief being able to constitute simple spacers between two walls, for example between two faces of an FED screen for example, or between a bottom and a cover of a flat lamp.

According to the invention, the process for manufacturing the structured substrate is characterized in that the substrate is obtained by extrusion by introducing flat glass under high pressure into a heated die so that the glass reaches a temperature close to that of softening.

Preferably, glass is extruded by means of a die to form an intermediate substrate incorporating elements in relief, substrate having a cross section of shape substantially identical to that which is to be obtained to the nearest homothetic ratio, then the intermediate substrate is stretched to form the final substrate of desired section.

More precisely, flat glass is introduced into the die which is heated so that the glass reaches a temperature close to that of softening, the bottom of the die being machined so as to present the section of the intermediate substrate to be delivered by extrusion in exit from the die, then the drawing of the intermediate substrate is carried out by drawing means according to a drawing factor (f), at the temperature close to that of softening of the glass.

In a process variant, it is possible that the stretching takes place in the die. This extrusion forming process allows very precise dimensional control of a few per-thousand of the objects formed, which, combined with a homogeneous and flawless glass composition, ensures precise control of the electrical capacity constituted by the electrode and the dielectric.

This results in greater pixel-to-pixel uniformity of the ignition discharge ignition voltages, this uniformity being in fact dependent on the exact height of the "rib", on the centering of the electrode relative to the phosphor and on the thickness. of the dielectric.

Other characteristics and advantages of the invention will appear on reading the following description with reference to the appended drawings in which: - Figure 1 is a partial schematic sectional view of a plasma screen of the prior art;

- Figure 2 is a partial schematic sectional view of a plasma screen according to the invention;

- Figures 3 and 4 are alternative embodiments of Figure 2; - Figure 5 schematically illustrates a device for implementing the process for obtaining a structured substrate according to the invention;

- Figure 6 is a sectional view from above of the bottom of the die illustrated in the device of Figure 5; - Figures 7a to 7d illustrate in section and partially several variants of geometry of the relief elements incorporated in a substrate of the invention;

- Figure 8 is a partial schematic sectional view of a plasma screen according to the invention from the geometry of the substrate illustrated in Figure 7b;

- Figure 9 is an additional variant of geometry of the elements in relief.

A conventional known plasma screen as illustrated in FIG. 1 consists of a first glass substrate 10 and a second substrate 11 which are parallel and arranged one opposite the other to constitute the rear face and the front of the screen. The substrates are flat, that is to say having no particular element integrated into their surface.

On the respective internal faces 22, 23 of the substrates 10, 11, facing each other of the substrates are arranged layers constituting networks of electrodes 12 and respectively 13 which are arranged perpendicularly to each other constituting what 'the columns and lines of the screen delimiting the pixels are called respectively.

The electrodes 12 on the rear face, for example in silver, are covered with a dielectric 14 based on elements with a low melting point such as PbO, and the electrodes 13a and 13b, an ITO layer for example, are covered with a dielectric 15, also based on PbO.

The front face electrodes 13a and 13b generally form double electrode tracks, that is to say that they are pairs of two lines of electrodes spaced about 70 to 80 μ and connected to each other. . The electrodes 12 on the rear face of the screen are also covered with a layer 16 of a phosphor. Each phosphor, red, green or blue, is separated by glass-based elements 20 of the "ribs" type extending in the form of continuous walls over almost the entire length of the substrate.

10 along a multitude of lines parallel to the longitudinal edges of the substrate and positioned regularly at a step p of 0.3 mm, for example, which depends on the size of the screen and its resolution. The walls of the ribs are also partially covered with phosphors, that is to say up to the thickness of the electrodes. The volume 17 created between the two substrates 10 and 11 and in the channels 21 delimited by the "ribs" 20 is filled with a gas, for example a mixture of neon and xenon. During the operation of the screen, the gas mixture is excited by applying suitable voltages to the electrodes 12, 13a and 13b, which generates Xe ⁺ and Ne ⁺ ions emitting UN photons. UN photons. then excite the phosphors which convert the excitation energy into visible red, green or blue light.

Three variants of plasma screens using the structured substrate of the invention are respectively illustrated in Figures 2 to 4; the elements common to the prior art are identified by identical references. FIG. 2 reproduces the same arrangement of the electrodes as that of FIG. 1 on the front and rear faces of the screen, the phosphors being isolated by the ribs which, not reported as in the prior art, form an integral part of the substrate 11. The ribs extend along several parallel lines spaced regularly by the pitch p. The electrodes 12 on the rear face of the screen are arranged in the channels 21 delimited by the ribs 20, a layer of dielectric 14 covering them and on top of them the phosphors 16.

The variant of FIG. 3 takes advantage of the new configuration of the structured substrate of the invention, generating a different arrangement of the rear electrodes 12. These electrodes are arranged opposite the channels 21 delimited by the "ribs" 20, and at the exterior of the glass substrate 10 on the external face 24. No dielectric layer of the layer 14 type of the prior art for these electrodes is then necessary because the glass thickness of the substrate 10 very advantageously plays the role of dielectric.

If in the variants of Figures 2 and 3, the integration of the glass elements is carried out on only one of the faces 22 of the substrate; in another embodiment of the substrate in particular, for a plasma screen, it may be advantageous to establish elements 20 on the two opposite faces 22, 24 of the substrate as illustrated in FIG. 4. The raised elements 20 of the face 24 are at least opposite the walls of the walls of the face 22 so that grooves 25 are created opposite the basins of the face 22 so as to accommodate the electrodes 12 from the rear face in Ag paste. This configuration advantageously provides an imprint that can directly accommodate conductive paste deposited with the squeegee, which allows savings on the supply of screen printing screens and electrode material.

The process for obtaining a substrate in accordance with the invention intrinsically incorporating the glass elements 20 of the "ribs" type will now be described. The method of manufacturing a plasma screen will be explained below so as to show the facilities for its implementation, which are provided by a substrate thus structured.

The process for obtaining the substrate according to one embodiment is explained with reference to the device 30 illustrated diagrammatically in FIG. 5 which is a sectional view along a plane perpendicular to the plane of the glass ribbon. The device 30 comprises an oven 31, a piston 32 for driving the glass, a die 33 capable of extruding an intermediate glass ribbon 41, a thermal regulation system 34 which makes it possible to give the intermediate ribbon the appropriate temperature for its drawing, a ribbon stretching system 35 to provide a final ribbon of the desired dimensions and cooling means not visible in the figure.

A strip of flat glass 40 such as float glass free of bubbles and solid defects is introduced under pressure by means of the piston 32 into the furnace 31 and the die 33. The thickness of the glass can vary from 5 to 20 mm depending on the availability of the base material used and according to the final destination of the structured substrate. The die is heated so that the temperature of the glass can reach that of softening. The bottom 36 of the die is made of graphite for reasons of resistance to abrasion by glass.

The die bottom 36, illustrated in FIG. 6, is provided with a cutout 36a, the pattern of which is similar to the section of the final substrate to be obtained, except for a homothetic ratio. It is advantageously removable from the body of the die so that it can be easily changed in order to adapt the type of pattern to the desired profile of the substrate. Several variants of patterns obtained for the glass elements 20 are proposed in FIGS. 7a to 7d by way of nonlimiting examples.

FIG. 7a illustrates a form of prismatic “ribs” with a triangular section, the base of the triangle being integrated into the substrate. The top of the triangle is preferably truncated to avoid the peak effect during the operation of the electrodes.

The section of the “ribs” of FIG. 7b presents, on the one hand, a concave curved geometry at the level of the body of the substrate, such as consisting of two curves of the exponential type symmetrical with respect to an axis perpendicular to the plane of the substrate, and on the other hand, a substantially straight neck at the top. The radius of curvature of the concave part can vary from 5 to 100 μm.

The “ribs” in FIG. 7c have an arch-shaped section such that the volume of the ribs constitutes a half-cylinder.

It can be envisaged on the same substrate to combine "ribs" 20 of different sections.

In the variant of FIG. 7d, elements in relief exist on the two faces of the substrate symmetrically to the plane of the body of said substrate. Such a configuration allows symmetrical cooling during the process for forming said substrate and will increase the heat dissipation capacity of the screen in operation thanks to the fin effect provided by the elements in relief.

At the outlet of the die, the intermediate substrate ribbon 41 extruded has the section of the ribbon 42 of final substrate to the nearest homothetic ratio. It is then stretched thanks to the stretching means 35 by crossing immediately downstream of the die the thermal regulation system 34 which aims to control and adapt the temperature over the total width of the ribbon which has its asymmetrical profile variable temperature points. The temperature of the tape to be that of softening must be perfectly uniform over the entire width of said tape to guarantee a constant stretching factor f over the entire width of the tape. The stretch factor f can vary from 1 to 20 depending on the final application.

Finally, the cooling system through which the strip of final substrate 42 passes makes it possible to freeze the final shape of the substrate. Means for traditional cutting of the flat glass not illustrated, or any other suitable means such as a laser, are provided for cutting the strip 42 along its width in order to provide structured substrates 10 to the desired lengths.

The substrates thus delivered will constitute the rear faces of plasma screens, the body of the substrate having for example a thickness of 1 mm and the glass elements being 150 μm in height.

The plasma screen of the invention as illustrated in Figure 3 is manufactured in the following manner.

The structured substrate 10 is held by suction, by appropriate means, in a horizontal position, its external face 24 devoid of the "ribs" being turned upwards. A uniform layer of silver in the form of paste is deposited by screen printing on this external face.

The silver paste is advantageously photosensitive so as to fix it by exposure of the substrate to a UN beam. Also, when the layer has undergone the drying step, the substrate is turned over, internal face 22 provided with “ribs” facing upwards, to receive the bundle UN. intended to sensitize UN activators. photosensitive silver paste.

The relief geometry of the substrate, defined uniformly by the

“Ribs” 20 which successively establish the color isolation walls and the channels 21 forming flat-bottomed bowls and intended to receive the phosphors, makes it possible to focus the UN all the better. at the bottom of the bowl, so that the Ag 12 electrodes are after development, positioned precisely along lines opposite to the cups. No photomask is then necessary as in the prior art, which represents an additional pecuniary saving in the manufacturing process. In addition, the wall-bowl structure integrated into the substrate and the method of depositing the paste ensure, whatever the linearity of the ribs, a self-alignment of the electrodes in

Ag, essential characteristic to guarantee a great uniformity of the ignition voltages during the operation of the screen. The development of the electrodes 12 is carried out in a known manner by the wet method and is followed by high-temperature cooking of the order of 550 ° C.

The substrate with symmetrical reliefs as illustrated in FIG. 7d very advantageously makes it possible to produce silver electrodes self-aligned with the "ribs" inside the screen, from a photosensitive silver paste, without require photomask. For this, it suffices to deposit the photosensitive silver layer on the inside of the screen and to expose it to ultraviolet light by the opposite structured face, on the outside.

In order to obtain a sealing zone for the two glass substrates, as will be explained below, the “ribs” of the lateral ends of the substrate are not used for the deposition of the electrodes and phosphors, their section can moreover be separate from that of the intermediate ribs.

Immediately next to these "ribs" of lateral ends can be reserved "ribs" to accommodate elements involved in the operation of the product such as getters well known to those skilled in the art, these elements placed on the periphery of the image should not be in contact with the phosphors, the plasma, or the sealing frit.

In the variant geometry of the “ribs” with reference to FIG. 7b, the flatness of the vertices of the “ribs” leads to the production, on the external face 24 of the substrate and opposite to said vertices, to a second network of electrodes 12a parallel to the network of electrodes 12 disposed opposite the cuvettes (Figure 8). The external face 24 is here flat but could just as well be structured as in FIG. 4, grooves would then be arranged not only opposite the bowls but also opposite the vertices. This second network of electrodes allows, by connection to the electrodes 12, rapid repair of the latter if they are possibly damaged.

The step following the deposition of the electrodes on the rear face of the screen consists in depositing the phosphors by electrophoresis by polarizing the electrodes. This technique is well known in the manufacture of televisions, the deposit of phosphors being carried out on the front face of the cathode-ray tubes. By polarizing the electrodes of the face 24 of the substrate, the phosphors can thus be deposited on the bottom of the bowls of the channels 21.

The voltage values applied to the electrodes are adjusted according to the particular geometry of the "ribs". The geometry of the “ribs” in FIG. 7b, which makes it possible to obtain two networks of electrodes adjacent to each other, facilitates the deposition of the luminiphores not only in the bottom of the bowls but also on the walls of the walls.

After the phosphors have dried, a sealing frit is put in place with a view to securing the two glass substrates of the screen. The structured substrate 10 is placed on a metal support equipped with suction and uniform heating means. A sealing frit is applied to the periphery of the structured substrate 10, that is to say in the cuvettes of the two "ribs" of lateral ends and along the two adjacent sides in the ends of the cuvettes of the intermediate "ribs" .

Finally, the front face substrate 11 which has the electrodes 13 previously screen-printed is positioned on the structured substrate 10 resting on the top of the "ribs", the electrodes 13 of the substrate 11 extending perpendicular to the electrodes 12 of the substrate 10. L The entire screen is housed in a closed enclosure in which the vacuum is created to create the vacuum between the substrates. Gas is then introduced inside the screen via the gap existing between the two uncompressed substrates. The joining of the two substrates via the sealing frit is then done by compression and heating of the assembly in the enclosure operating under a controlled atmosphere to guarantee high temperature uniformity.

In order to take advantage of the structure of the substrate with integrated "ribs", a variant in the stages of securing the substrates and filling the gas is possible.

Thus, regarding the sealing frit, it is deposited only on the two sides of the structured substrate 10 which will be arranged vertically in the mounted position of the screen, that is to say along the sides parallel to the "ribs" , which allows the channels 21 formed by the "ribs" to open freely. After placing the substrate 11 on the front face on the structured substrate 10 on the rear face, the channels 21 of the "ribs" are connected by means of a suction cup system to a device for evacuating, purging and filling. The device successively performs the steps of vacuuming the channels, purging under a neutral gas such as argon and filling with the discharge gas. The free circulation of fluids from one channel to another and the direct connection with said device improves the time for carrying out these steps. The resulting efficiency is not negligible since we go from 24 hours for the conventional solution of gas introduction to a few hours by this embodiment, bringing a significant saving on the cost of assembly of the screen . Once the gas is filled, the channels are closed by local heating and mechanical stamping of the edges of the two substrates having no sealing frit. The joining of the other edges associated with the sealing frit is obtained by compression and heating of said edges. Similar implementation steps as regards the use of the structured substrate of the invention can be applied to other embodiments, such as the manufacture of flat lamps.

In known manner, a flat lamp comprises two facing substrates which are kept apart by means of spacers to form a space containing a discharge gas.

For a flat lamp according to the invention, one of the two substrates is flat while the other is structured, the elements 20 in glass and in relief constituting the spacers. In a variant of spacers, the glass elements are in the form of isolated studs obtained by sawing and grinding of the extruded continuous "ribs". Of course, the structured substrate of the invention can be used for any application which either requires maintaining a space between two glass walls, the glass elements 20 acting as spacers, or gives the substrate a new technical property.

For example, for the spacer function, FED screens and building applications are targeted where it is necessary to maintain a constant distance between two substrates. Mention may be made, for example, of double glazing under vacuum or else double glazing inside which it is desired to circulate a functional liquid.

Also, the dimensions of the bases, vertices and heights of the elements in relief 20 and the pitch between the elements as well as the thickness of the body of the substrate vary according to the envisaged application of the structured substrate. The table below summarizes some values for the applications: plasma screen, flat lamp, screen

EDF, building.

Regarding the technical novelty that a substrate of the invention can provide, it can target the production of microlenticular panels which are attached to flat display screens in order to obtain a three-dimensional perception of the image. A microlenticular panel thus consists of a substrate according to the invention, flat on one of its faces intended to be placed on the screen, and structured on its opposite face with semi-cylindrical raised elements forming the lenses and as illustrated in FIG. 9. The thickness of the body of the substrate can be between 2 and 5 mm, the base of an element in relief 0 or the pitch of the lenses can vary from 0.15 to 2 mm, and the radius of curvature of the half-cylinders can be between 1 and 3 mm.

Claims

1. Glass substrate comprising glass elements (20) arranged in relief over a part of its surface, characterized in that the glass elements (20) are intrinsically incorporated into the substrate.

2. Substrate according to claim 1, characterized in that the body of the substrate has two opposite parallel faces, the elements (20) being integrated into at least one of the two faces.

3. Glass substrate according to claim 1 or 2, characterized in that the elements (20) extend along at least one line substantially parallel to one side of the substrate.

4. Substrate according to claim 3, characterized in that the elements (20) form at least one continuous wall.

5. Substrate according to claim 3, characterized in that the elements (20) form isolated studs.

6. Substrate according to any one of the preceding claims, characterized in that the elements (20) extend along several parallel lines spaced regularly from the proximity of one edge of the substrate to the opposite edge.

7. Substrate according to claim 6, characterized in that the parallel lines are spaced from each other by a pitch (p) varying from 0.2 to 50 mm.

8. Substrate according to any one of the preceding claims, characterized in that the elements (20) have a section of triangular shape, the base of the triangle being integrated into the substrate.

9. Substrate according to any one of claims 1 to 7, characterized in that the elements (20) have a concave curved geometry at the level of the body of the substrate, and a neck that is substantially straight at the top.

10. Substrate according to any one of claims 1 to 7, characterized in that the elements (20) have an arch-shaped section.

11. Substrate according to any one of the preceding claims, characterized in that the elements (20) have a height of between

0.15 and 12 mm.

12. Substrate according to any one of the preceding claims, characterized in that the top of the elements (20) forms a flat whose width is less than 500 μ.

13. Substrate according to any one of the preceding claims, characterized in that the elements (20) have a base with a width varying from 50 μm to 50 mm.

14. Substrate according to claim 3, characterized in that it comprises a multitude of walls parallel to each other and extending from one edge of the substrate to the opposite edge, the two lateral walls of the respective two edges of the substrate being of wider than the intermediate walls.

15. Use of a substrate according to any one of the preceding claims in the production of a display type screen, such as a plasma screen.

16. Use of a substrate according to any one of claims 1 to 14 in the production of a flat lamp.

17. Plasma screen comprising a structured substrate (10) according to any one of claims 1 to 14 constituting the rear face of the screen, and a flat substrate (11) constituting the front face of the screen, the flat substrate being provided on its internal face (22) facing the internal face of the structured substrate with a first network of electrodes (13a, 13b), characterized in that a second network of electrodes (12) substantially perpendicular to the first network (13a, 13b) is arranged on the internal face (22) of the substrate structured in the space (21) existing between the elements in relief (20) while a dielectric (14) covers said second network of electrodes (12 ) and that phosphors (16) are housed in said space (21) over the dielectric (14).

18. Plasma screen comprising a structured substrate (10) according to any one of claims 1 to 14 constituting the rear face of the screen and a flat substrate (11) constituting the front face of the screen, the flat substrate being provided on its internal face (22) facing the internal face of the structured substrate of a first network of electrodes (13a, 13b), characterized in that a second network of electrodes (12) substantially perpendicular to the first network ( 13a, 13b) is arranged on the external face (23) of the structured substrate and opposite the space (21) existing between the elements in relief (20) while luminophores (16) occupy the surface area (21) existing between the elements in relief.

19. Plasma screen comprising a structured substrate (10) according to any one of claims 1 to 14 constituting the rear face of the screen and a flat substrate (11) constituting the front face of the screen, the flat substrate being provided on its internal face (22) facing the internal face of the structured substrate of a first network of electrodes (13a, 13b), characterized in that a second network of electrodes (12) substantially perpendicular to the first network ( 13a, 13b) is arranged on the external face (23) of the structured substrate and opposite the space (21) existing between the elements in relief (20), and in that a third network of electrodes ( 12a) parallel to the second network (12) is arranged on the external face (23) of the substrate and opposite the vertices of the elements in relief (20), while luminiphores (16) occupy the space (21 ) existing between the elements in relief.

20. Planar lamp comprising a structured substrate according to any one of claims 1 to 14, and another substrate arranged facing the structured substrate, the two substrates being kept spaced apart by means of the elements in relief (20).

21. A method of manufacturing a substrate according to any one of claims 1 to 14, characterized in that the substrate is obtained by extrusion by introducing flat glass under high pressure into a die (33) heated so that the glass reaches a temperature close to that of softening.

22. A method of manufacturing a substrate according to claim 21, characterized in that glass is extruded by means of the die (33) to form an intermediate substrate (41) incorporating elements in relief, substrate having a shaped section substantially identical to that which is to be obtained to the nearest homothetic ratio, then the intermediate substrate is stretched to constitute the final substrate (42) of desired section.

23. The method of claim 22, characterized in that flat glass is introduced into the die (33) heated so that the glass reaches a temperature close to that of softening, the bottom of the die being machined so as to present the section of the intermediate substrate to be delivered by extrusion at the outlet of the die, then the drawing of the intermediate substrate is carried out by drawing means (35) according to a drawing factor (f), at the temperature close to that of softening of the glass.

24. The method of claim 22, characterized in that the drawing takes place in the die.