EP0968512B1 - Bi-substrate plasma panel - Google Patents

Description

The present invention relates to display panels with color plasma, alternative bi-substrate type, with light output improved.

Plasma panels suffer from lack of performance electrooptical compared to cathode ray tubes and this what whatever the production technique used.

Dual-substrate alternative color plasma panels operate on the principle of an electrical discharge in gases and they use only two crossed electrodes, located on substrates different, to define and order a discharge.

Figure 1 shows such a plasma panel of the known art. he has two substrates or slabs 2, 3 of which one, called front slab 2 is located on the side of an observer (not shown). This slab 2 before door a first network of electrodes called line electrodes, two of which only Y1, Y2 are shown. The line electrodes Y1, Y2 are substantially parallel and spaced apart by a py step. Y1 line electrodes, Y2 are covered with a layer 5 of a dielectric material.

The second slab 3 or so-called back slab is opposite the observer; it carries a second network of electrodes called electrodes columns of which only five X1 to X5 are represented. The electrodes columns X1 to X5 are substantially parallel and spaced one step px apart. The no px is worth about a third of the py step and can be understood for example between 100 µm and 500 µm depending on the definition of the image.

The two tiles 2, 3 are generally made of glass. They are intended to be assembled together so that the electrodes lines Y1 to Y2 are substantially perpendicular to the electrodes columns X1 to X5. The two slabs 2, 3 once assembled delimit a space 13 which is intended to be filled with gas. The gas used is usually based on neon.

The thickness H0 of the space 13 between the front slab 2 and the slab rear 3 must be as precise as possible to obtain discharges homogeneous.

On the rear panel 3, the column electrodes X1 to X5 are also covered with a layer 6 of dielectric material. The dielectric layer 6 is itself covered with several groups of three bands B1, B2, B3 corresponding luminophore, for example respectively to the colors green, red, blue. The phosphor bands B1, B2, B3 are substantially parallel to the column electrodes X1 to X5. They have much the same not px than the column electrodes X1 to X5. A column electrode, X1 by example, is then under a strip of phosphor B1 substantially in the middle.

The rear panel 3 generally also comprises a network of barriers 11 substantially parallel to the column electrodes X1 to X5 and separated by the px step. They separate two bands of phosphor B1, B2 adjacent. Their height H1 is generally less than the thickness H0 of the space 13 between the front panel 2 and the rear panel 3.

Two electrodes X1, Y1 located on different slabs 2, 3 can induce a gas discharge if brought to appropriate potentials. The discharge area has a section which corresponds substantially to the facing surface of the two electrodes X1, Y1 opposite.

In order to reduce the voltages to be applied to the electrodes for get a discharge, we were led to dig holes or Ep1 spares, Ep2, Ep3, ... in the phosphor bands B1, B2, B3, at the facing surface between a row electrode Y1 and a column electrode X1. These savings Ep1, Ep2 confine the discharge.

Conventionally in color panels, three are used neighboring savings Ep1, Ep2, Ep3, located at the same electrode line Y1 but in three adjacent phosphor bands B1, B2, B3 for form a trichromatic pixel P which can take a large number of colors.

The savings Ep1, Ep2, Ep3 of the same pixel P are therefore aligned along the same line electrode Y1 and they are separated by distance equal to the px step.

To improve the contrast, the front panel 2 is often fitted of a black network 4 in the form of black bands extending between two row electrodes Y1, Y2. These black bands 4 generally occupy a surface area worth approximately half the surface of the front slab 2.

The light output of such bi-substrate alternative panels varies in the same direction as the thickness H0 of the space 13 filled with gas. Remember that the light output is the ratio of the luminance emitted by the panel on the electric power it consumes. Next the panel structure, this yield can currently vary between 0.5 and 1 lumen / Watt for a value of the thickness H0 close to 100 micrometers.

However, the thickness H0 of space 13 cannot be increased thoughtlessly with respect to the px step without risking disturbing the panel operation. A landfill ordered at a savings can trigger accidental discharges at the level neighboring savings that must remain at rest, especially in the panels whose barriers are not full height.

In the so-called coplanar panels in which the discharges are established between two electrodes carried by the same slab, the efficiency light is not sensitive to the thickness of the gas-filled space.

It has already been proposed to reduce the occurrence of these landfills inadvertent to use full height barriers. These barriers have more of their role of separation between bands of colored phosphor different, a role of confinement of the discharge occurring at the level a savings so that it does not induce a discharge at the level of a neighboring savings not to be activated. These full height barriers also serve as a spacer between the two tiles. These barriers allow a thickness of the space filled with gas greater than that required with half height barriers. However, it has been observed that these full height barriers can interfere with the proper functioning of the panel, especially when high pixel firing rates are required. These speeds are required in television applications. Total containment between savings located on phosphor strips adjacent, belonging to the same pixel, leads to a lack of circulation of charges in plasma and / or ultraviolet photons likely to help initiate discharges.

Another disadvantage of these full height barriers is related to their difficulty in achieving with great precision. They are often performed by successive screen printing operations and it is difficult to obtain a uniform thickness.

The object of the present invention is to provide a panel for alternating plasma display, dual color substrate which has identical resolution, improved light output, this improved light output resulting in neither degradation of the operation of the panel, nor degradation of its intrinsic contrast. improvements proposed does not make the manufacturing of the different elements more complex plasma panel and can even make it easier to manufacture some of these.

To achieve this the present invention is a panel of alternative plasma display, bi-susbtrat type, in color, comprising two tiles assembled facing each other delimiting a space intended to be filled with gas, one of the slabs having column electrodes substantially parallel, separated by a px step, each covered with at least at least one phosphor zone, the other panel comprising at least one line electrode. The phosphor zones are provided with at least one savings disposed at the crossroads of a column electrode and an electrode line, this savings locating landfills likely to occur between two electrodes. A colored pixel is formed by neighboring savings located at the same line electrode, in areas of adjacent phosphor. According to the invention, to obtain a better light output, the distance between two neighboring savings, located in adjacent phosphor areas of the same pixel is greater than the pitch, so as to allow a thickness of the space greater than that required when the two savings are separated noticeably not. A plasma panel according to the preamble of claim 1 is described in document FR-A-2699717.

Savings of the same pixel can be arranged in triangle, which leads to the largest spacing between savings at identical resolution.

If the savings of the same pixel are aligned, savings located in separate phosphor zones corresponding to the same color but on different column electrodes are also aligned this which allows a line in this color formed by these savings to be very straight.

So that the line electrode follows the savings of the same pixel, it can be multiplied into several sub-electrodes.

It is possible that the sub-electrodes are connected to each other by at least two short-circuits in order to allow self-repair in breakage of one of them.

A variant is that the line electrode has at least one change of direction to follow the savings of the same pixel. She can be in particular in zig-zag.

The panel may also have barriers which separate two adjacent phosphor zones of different colors, these barriers having a height less than the thickness of the space, which allows improve the colorimetry of the panel.

To increase the emission area around savings, successive barriers may be further apart from each other at the level of savings only on both sides of this savings. This leads by example of a broken line or curved line barrier pattern.

It is possible to predict that the savings will be sufficient deep to confine the landfills so as to avoid the use of barriers. Their removal is advantageous because they are difficult and time-consuming and represent around half the cost of realization of the slab fitted with barriers.

To save phosphor it is possible that the savings are formed from wells in a sublayer of material additional, these wells being lined with phosphor without being plugged.

To further reduce the amount of phosphor, it is advantageous a phosphor zone ends in a rim which follows the mouth of a well.

The panel can also have a black network on the slab carrying the line electrode, in order to improve the intrinsic contrast, the black network can cover the slab with the exception of openings facing savings and wedged on the savings, these openings having an area significantly higher than that of savings.

In this configuration a phosphor zone can be set on a black network opening, its surface area being substantially greater than that of the opening.

To further gain in light output it is possible to cover the line electrode with phosphor zones with savings.

• la figure 1 déjà décrite, une vue en éclaté d'un panneau de visualisation à plasma de l'art antérieur ;
• les figures 2a, 2b respectivement une vue en éclaté et de face d'un exemple d'un panneau de visualisation à plasma selon l'invention ;
• la figure 3 une vue de face d'une variante d'un panneau de visualisation à plasma selon l'invention ;
• la figure 4 une vue de face d'une autre variante d'un panneau de visualisation à plasma selon l'invention avec des électrodes lignes en zig-zag ;
• les figures 5a, 5b deux autres variantes d'un panneau de visualisation à plasma avec différents motifs de barrières,
• les figures 6a, 6b deux coupes respectivement selon une électrode colonne et selon une électrode ligne d'un panneau de visualisation à plasma selon l'invention sans barrière,
• les figures 7a, 7b deux coupes respectivement selon une électrode colonne et selon une électrode ligne d'un panneau de visualisation à plasma selon l'invention avec puits dans une sous-couche en matériau additionnel,
• les figures 8a, 8 b deux coupes respectivement selon une électrode colonne et selon une électrode ligne d'un panneau de visualisation à plasma selon l'invention avec zones de luminophore qui se terminent en formant un rebord autour des puits.

Other characteristics and advantages of the invention will appear on reading the following description illustrated by the appended figures which represent:

• Figure 1 already described, an exploded view of a plasma display panel of the prior art;
• Figures 2a, 2b respectively an exploded and front view of an example of a plasma display panel according to the invention;
• Figure 3 a front view of a variant of a plasma display panel according to the invention;
• Figure 4 a front view of another variant of a plasma display panel according to the invention with zigzag line electrodes;
• FIGS. 5a, 5b two other variants of a plasma display panel with different barrier patterns,
• FIGS. 6a, 6b two sections respectively along a column electrode and along a line electrode of a plasma display panel according to the invention without barrier,
• FIGS. 7a, 7b two sections respectively according to a column electrode and according to a line electrode of a plasma display panel according to the invention with well in a sub-layer of additional material,
• FIGS. 8a, 8b two sections respectively along a column electrode and along a line electrode of a plasma display panel according to the invention with phosphor zones which terminate by forming a rim around the wells.

In these figures the scales are not respected for the sake of of clarity.

We refer to Figures 2a, 2b. Compared to Figure 1, we found on the rear slab 3, the column electrodes X1 to X5 covered dielectric layer 6, itself covered with zones B1, B2, B3 of phosphor. The phosphor zones B1, B2, B3, here in the form of bands, are arranged substantially parallel to the column electrodes X1 to X5. The rear panel 3 further comprises barriers 11 for separating the phosphor zones B1, B2, B3.

The phosphor zones B1, B2, B3 are equipped with savings Ep1, Ep2, Ep3 and a pixel P has at least two savings neighbors located at the same line electrode Y1, Y2 in adjacent areas of B1, B2, B3 phosphor. In the example treated, a pixel P is trichrome and has three savings but we can consider that it only has two or more than three. Savings are represented circular but it is understood that other shapes are possible.

Instead of two neighboring savings Ep1, Ep2 being part of a same pixel P and located in adjacent areas B1, B2 of phosphor are separated by the pitch px of the column electrodes X1, X2, according to the invention, these two neighboring savings Ep1, Ep2 are separated by a distance L which is now greater than the step px.

In FIGS. 2a, 2b the savings Ep1, Ep2, Ep3 of the same pixel P are arranged in a triangle. If the panel retains the same steps py and px as in FIG. 1, the distance L is for example such that:
L = 1.8 px

By increasing the distance L between neighboring savings Ep1, Ep2 of the same pixel P, located in adjacent phosphor zones, we can increase the thickness H0 of the space 13 between the two slabs, by compared to that required when savings are significantly distant from not px. In the example described, a factor of 1.8 exists between the px step and the distance L and the increase in thickness H0 can be done with roughly the same factor.

This increase in the distance L and that of the thickness H0 which results greatly improve the light output of the panel without degrade its contrast. The new distribution of savings Ep1, Ep2, Ep3, .... does not lead to an increase in the difficulties of achieving the rear panel 3.

Regarding the front panel 2, the same line electrode Y1 follows the savings Ep1, Ep2, Ep3 belonging to the same pixel P. A configuration which allows it is to use line electrodes Y1, Y2 multiplied. In figure 2, the line electrode Y1 is split in two sub-electrodes Y1a, Y1b so as to pass at the level of the three savings Ep1, Ep2, Ep3 in triangle of pixel P. With such line electrodes, multiplied, the line resistance is reduced, hence a better passage of discharge current.

The next pixel P 'traversed by the same line electrode Y1 is formed of savings Ep4, Ep5, Ep6 in a triangle and the triangle of pixel P is head to tail with respect to the triangle of pixel P '.

The two sub-electrodes Y1a and Y1b are interconnected by at least two short circuits 12. With such short circuits, a break 14 in a sub-electrode between these two short circuits 12 has no repercussion on the network. In Figure 2b, there are three short circuits 12 represented between the sub-electrodes Y1a and Y1b, one upstream of the pixel P, one between the two pixels P, P 'and one downstream of the pixel P'. A cut 14 on the sub-electrode Y1b is represented between the savings Ep4 and the savings Ep6, this cut 14 is self-repairing and discharges may occur at level of savings Ep6. The power supply of the Y1b sub-electrode at the level of savings Ep6 is ensured by the sub-electrode Y1a and the short circuit 12 located downstream of pixel P '. Plus number of short circuits 12 the greater the capacity for self-repair. This self-repair is advantageous because in high resolution panels the electrodes lines are very fine and fragile, cuts often appear. With this possibility of self-repair, the manufacturing yield of panels is greatly increased as the disposal rate decreases. Or well, at the same scrap rate, the width of the electrode can be significantly reduced, hence a gain in the light emitted at the level of a savings because there is less screening.

This split Y1 line electrode inevitably crosses column electrodes X1, X2, X3 outside the savings Ep1, Ep2, Ep3, but this crossing does not give rise to discharges because on the one hand the presence of the phosphor which covers the column electrodes X1, X2, X3 and on the other hand the voltage level to be applied to obtain a discharge at savings level.

In the variant shown in Figure 3, the savings Ep1, Ep2, Ep3 of the same pixel P are aligned instead of being in a triangle. If the panel always keeps the same steps py and px, the distance L between two neighboring savings Ep1, Ep2 of the same pixel P then becomes equal to:
L = 1.4 px

This distance L is smaller than in the case of FIGS. 2 and the performance of the panel will not be quite as good. In this variant, the line electrodes are also multiplied but now it is a tripling. Each of the savings Ep1, Ep2, Ep3 of a pixel P is traversed by a sub-electrode respectively Y1a, Y1b, Y1c. The three sub-electrodes are interconnected by at least two short circuits 12. However, this structure has an advantage which is that the savings Ep1, Ep4 located at the same line sub-electrode Y1a correspond to successive phosphor zones B1 of a same colour. Three savings are then aligned. This alignment leads to a better image in certain types of application, for example for computer images using horizontal lines of a color of based.

Instead of the line electrodes Y1, Y2 being multiplied and each have sub-electrodes so as to pass opposite of all the savings of a pixel P, we can consider that they include at least one change of direction. Figure 4 illustrates this variant with a pixel P whose savings Ep1, Ep2, Ep3 are in a triangle and a Y1 line electrode is in a zig-zag pattern to come across from all saves Ep1, Ep2, Ep3 from pixel P. Configurations other than the zig-zag are entirely possible.

In FIGS. 2a, 2b of the barriers 11 for confining the savings-level discharges were represented. These barriers 11 whose height H1 is less than the thickness H0 of the space 13 filled with gases to promote circulation and therefore ionization, separate two zones B1, B2 of adjacent phosphors relating to the same pixel. In this example the zones B1, B2 of phosphor are rectilinear and the barriers 11 are parallel, distant substantially from the px step.

We can consider, to increase the emission surface of the discharge around the savings Ep1, Ep2 that the two barriers 11 which pass on either side of an Ep2 savings are more distant level of this savings Ep2 that between this savings Ep2 and its neighbor Ep8 located on the same B2 phosphor strip. Two neighboring barriers move away from each other at the level of a savings and approach one on the other between two savings.

In this variant shown in FIG. 5a, in which the line electrodes are not shown for clarity, the barriers 11 change direction around the savings Ep1, Ep2 and are in form of broken lines. Changes of direction can be done with an angle substantially equal to 45 °. In FIG. 5b, the barriers 11 are in form of curved lines and notably substantially sinusoidal.

One advantage of such barriers is that the surface emissive of the discharge being enlarged, the constraints on the pairing of barriers and savings are released. Positioning accuracy barriers to savings can be lowered due to the offset which leaves some possible play in the positioning of masks.

The spacing d1 between two neighboring barriers 11, at the level of a savings Ep8 is then greater than the pitch px between column electrodes X1, X2. The spacing d2 between the two barriers 11 on either side of the savings Ep8 is then less than the pitch px between column electrodes X1, X2. The relation which links the spacings d1 and d2 can be such that:
d1 = d2 + 2c with c equal to the thickness of the barriers 11.

The width c of the barriers 11 can be of the order of 19.5 micrometers if the px pitch between column electrodes is 127 micrometers.

It is advisable to keep a sufficient dimension to the spacing d2 so as not to prevent the circulation of gas.

In this variant, the barriers 11 are not straight and the phosphor zones B1, B2, B3 are adapted to the pattern of the barriers 11 since the barriers 11 separate two zones B1, B2, B3 of phosphor adjacent.

The fact of having removed two neighboring savings Ep1, Ep2 by one same pixel P, located in adjacent areas B1, B2 of phosphor eliminates containment barriers without degrading quality discharges if the savings Ep1, Ep2 have a sufficient depth for confine the landfills thus created. This depth can represent about half the thickness H0 of space 13. For example this depth can reach 60 micrometers if H0 is worth approximately 110 to 120 micrometers.

A plasma display panel according to the invention without barrier is shown in Figures 6a, 6b. The phosphor of the different zones B1, B2, B3 has been thickened and the savings have a depth which corresponds to the thickness of the phosphor.

This thickness makes it possible to form real wells of containment of landfills, these wells prevent the spread of landfills to neighboring savings where a landfill shouldn't happen. They then avoid a crosstalk effect between neighboring savings.

These wells also prevent the ultraviolet radiation created by a discharge in a given savings excites the material luminophore from neighboring areas and does not cause a lack of saturation of the colors. This phenomenon is known as a crosstalk effect. A good location of landfills is possible.

Another way to save Ep1, Ep2, Ep3 deep, illustrated in Figures 7a, 7b is to deposit beforehand, on the dielectric material 6, a sublayer 13 of an additional material there arrange wells 16 and cover this sublayer 13 with phosphor in a thinner layer so as to form the different zones B1, B2, B3. The phosphor lines the sides 15 of the wells 16 and does not block them. he can possibly overflow on the bottom 17 of the wells 16. We then obtain savings Ep1, Ep2, Ep3 of required depth by limiting the amount of phosphor used.

The section of the wells 16 is preferably greater than that of the savings to account for the phosphor. The additional material of the underlay 13 is preferably chosen reflective and colored white.

The additional material may contain alumina and / or titanium oxide and / or yttrium oxide. This sublayer 13 can be deposited for example by screen printing, photolithography.

Removing barriers brings significant cost savings of manufacturing since the realization of the barriers represents approximately the half the cost of manufacturing the slab. A gain in cycle time is thus realized. The structure obtained, open, favors the ionization of the gas at low luminance level and therefore improves the operation of the panel.

In FIG. 2a, the zones B1, B2, 83 of the phosphor occupy the entire surface of the slab 3 on which they are deposited. They form contiguous bands which follow the column electrodes X1, X2, X3 and each have multiple savings. Landfills are only likely to happen only at the savings level as described previously. With the use of sublayer 13 under the phosphor, it is possible to reduce the surface of areas B1, B2, B3 of phosphor compared to that of slab 3. The saving in material cost is appreciable because phosphors are expensive materials.

Figures 8a, 8b illustrate this configuration. A zone B1, B2, B3 phosphor lines the sides 15 of a well 16 in the underlay 13 and ends by forming a rim 18 which follows the mouth of the well 16. Top view, the phosphor zones B1, B2, 83 are configured in disk. A phosphor zone has only savings. The underlay 13 is in contact, in certain places with the gas. The underlay 13 then provides protection to prevent discharges can take place at the intersection of a line electrode and an electrode column but excluding savings. In Figure 8b, we notice that there is no phosphor zone at the cross of the column electrode X2 and the electrode line Y1a. The underlayer 13 prevents a discharge from taking place at this place.

With savings Ep1, Ep2, Ep3 more distant than in the state of art, for example arranged as shown in Figure 2b, it is possible to increase the surface of the black network 40 relative to the surface total of the front panel 2.

According to the invention, as illustrated in FIGS. 2a, 2b, the network black 40 now covers substantially all of the front panel 2 except openings Z1, Z2, ...... which are arranged opposite the savings Ep1, Ep2 and which are wedged on these. Each opening Z1, Z2 is associated with savings Ep1, Ep2 and has an area slightly greater than that of the savings Ep1, Ep2 with which it is associated.

For example, for a plasma panel, called high definition, with a step px between column electrodes of 127 micrometers and in which the distance L between neighboring savings Ep1, Ep2 located in adjacent phosphor areas is 229 micrometers, if the openings Z1, Z2 of the black network 40 have a diameter of 180 micrometers, the rate of black network coverage 40 is worth around 60% whereas with openings Z1, Z2 with a diameter of approximately 150 micrometers, the rate of 40 black network coverage is worth about 80%. Such a coverage rate equivalent to an actual diffuse reflection rate of the front panel 2 of the panel to plasma about 10%. This black network 40 more extensive than in art therefore allows an advantageous increase in contrast intrinsic of the panel.

In the configuration with reflective underlay 13 in contact with the gas, it is possible that a zone B1, B2, B3 of phosphor is circumscribed at an opening Z1, Z2 of the black network 40. This variant is visible in Figure 8a. A zone B1, B2, B3 of phosphor while being set on an opening Z1, Z2 will preferably have an area slightly greater than that of the opening Z1, Z2 so as to avoid any problem if a possible mismatch exists between the two tiles or their elements.

This type of display panel with alternating plasma and bi-substrate can also accommodate on its front side zones B'1, B'2, B'3 of phosphor.

A thin layer of phosphor transmits as much than in reflection. It is then easy to deposit the different zones B'1, B'2, B'3 phosphor with savings Ep'1, Ep'2, Ep'3 ...., on the front 2 by setting them on the savings Ep1, Ep2, Ep3 on the rear panel 3.

The phosphor zones according to their color can be either deposited one after the other by screen printing followed by a single operation sunstroke, skinning, either in a uniform layer over the entire surface followed by an exposure operation, counting by color. The yield luminous is then multiplied by at least 1.5.

Claims (21)

1. Colour AC plasma display panel of the two-substrate type, comprising two facing plates (2, 3) joined together that define a space (13) intended to be filled with gas, one of the plates (3) having approximately parallel column electrodes (X1, X2) spaced apart with a pitch (px), covered with at least one phosphor region (B1, B2, B3), the other plate (2) having at least one row electrode (Y1, Y2), the phosphor regions (B1, B2, B3) being provided with at least one recess (Ep1, Ep2, Ep3) placed at the intersection of a row electrode (Y1, Y2) with a column [lacuna] (X1, X2), in order to localize discharges liable to occur in the gas between the two electrodes, a colour pixel (P) being formed by neighbouring recesses (Ep1, Ep2, Ep3) located in adjacent phosphor regions (B1, B2, B3) at the row electrode (Y1), characterized in that, to obtain a better luminous efficiency, the distance (L) separating two neighbouring recesses (Ep1, Ep2) of the same pixel (P) is greater than the pitch (px) of the column electrodes (X1, X2) so as to allow a greater thickness (H0) of the space (13) than that required when the two adjacent recesses (Ep1, Ep2) are separated by a distance approximately equal to the pitch (px).
2. Panel according to Claim 1, characterized in that the recesses (Ep1, Ep2, Ep3) of the same pixel (P) are arranged in the form of a triangle.
3. Panel according to Claim 1, characterized in that the recesses (Ep1, Ep2, Ep3) of the same pixel (P) are aligned.
4. Panel according to one of Claims 1 to 3, characterized in that the row electrode (Y1) is divided into several subelectrodes (Y1a, Y1b).
5. Panel according to Claim 4, characterized in that the subelectrodes (Y1a, Y1b) are connected together by at least two short circuits (12) for the purpose of allowing self-repair in the event of a break (14) in one of them.
6. Panel according to one of Claims 1 to 3, characterized in that the row electrode (Y1) has at least one change of direction.
7. Panel according to Claim 6, characterized in that the row electrode (Y1) is zig-zagged.
8. Panel according to one of Claims 1 to 7, characterized in that it includes ribs (11) which separate two adjacent phosphor regions (B1, B2), these ribs (11) having a height (H1) less than the thickness (H0) of the space (13).
9. Panel according to Claim 8, characterized in that two successive ribs (11) are further apart from each other at a recess (Ep2) than they are on either side of this recess (Ep2).
10. Panel according to Claim 9, characterized in that at least one rib (11) is in the form of a broken line.
11. Panel according to Claim 9, characterized in that at least one rib (11) is in the form of a curved line.
12. Panel according to one of Claims 1 to 7, characterized in that the recesses (Ep1, Ep2) are deep enough to confine the discharges so as to avoid the use of ribs separating two adjacent phosphor regions (B1, B2).
13. Panel according to Claim 12, characterized in that the depth of the recesses (Ep1) is approximately half the thickness (H0) of the space (13).
14. Panel according to either of Claims 12 and 13, characterized in that the recesses (Ep1, Ep2, Ep3) are formed from wells (16) in a sublayer (13) of an additional material, these wells (16) being coated with phosphor without being plugged.
15. Panel according to Claim 14, characterized in that the additional material is reflective.
16. Panel according to either of Claims 14 and 15, characterized in that the additional material is white.
17. Panel according to one of Claims 14 to 16, characterized in that the additional material contains alumina and/or titanium oxide and/or yttrium oxide.
18. Panel according to one of Claims 14 to 17, characterized in that a phosphor region (B1, B2, B3) terminates in the formation of a rim (18) which follows the mouth of a well (16).
19. Panel according to any one of Claims 1 to 18, which includes a black matrix (40) on the plate (2) with the row electrode (Y1, Y2), characterized in that the black matrix (40) covers the plate (2) with the exception of apertures (Z1, Z2) that face the recesses (Ep1, Ep2) and are aligned with respect to the recesses, these apertures (Z1, Z2) having an area substantially greater than that of the recesses (Ep1, Ep2).
20. Panel according to Claim 19, characterized in that a phosphor region (B1, B2, B3) is aligned with respect to an aperture (Z1, Z2) of the black matrix (40), its area being substantially greater than that of the aperture.
21. Panel according to one of Claims 1 to 20, characterized in that the row electrode (Y1, Y2) is covered with phosphor regions (B'1, B'2, B'3) having recesses.

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