EP0436416A1 - Polychromatic display panel - Google Patents

Abstract

The invention relates to a display screen in particular of the plasma panel type. The object of the invention is to improve the purity of the primary colours. The display screen (21) includes a plurality of elementary image points (PX'1 to PX'12) each comprising three cells (C1, C2, C3) of different colours. According to a characteristic of the invention, the elementary image points or pixels (PX'1 to PX'12) comprise several types of pixels which differ from one another through the relative positions of the cells of different colours which they contain. A pixel of given type is adjacent to at least one pixel of another type, so that at least two adjacent cells of different pixels are of like colour. This arrangement prevents the excitation of a cell of a given colour leading to the emission of light of a different colour through a visual crosstalk effect between two neighbouring cells. <IMAGE>

Description

The invention relates to polychrome display screens, and its subject is a structure which makes it possible to improve the purity of the primary colors. The invention finds a particularly interesting application in display screens which are affected by a fairly pronounced defect in the crosstalk or optical intermodulation between neighboring pixels, as is particularly the case in plasma panels.

Taking plasma panels as an example, these panels are now well known flat screen display devices. They operate on the principle of light discharge in gases. They are used for viewing alphanumeric, graphic or other, monochrome or full color images. Plasma panels generally include two insulating tiles defining a space filled with gas (generally a neon-based mixture). These slabs support two or more networks of crossed electrodes, the electrodes of one network being for example arranged in columns and crossed with the electrodes of the other network which are arranged in lines, so as to define a matrix of cells elementary each formed substantially at the intersection of row and column electrodes.

The operating principle is the selective generation (that is to say at the level of selected cells) of electric discharges in the gas. Each discharge in the gas is accompanied by an emission of light localized at the level of each cell where this discharge known as elementary discharge occurs. Each cell can thus constitute an elementary light source whose state can be changed (on or off).

Given the matrix arrangement of the cells, their addressing is matrix, that is to say that for each cell this addressing is carried out by controlling two crossed electrodes at the level of the selected cell. Thus, for example, in plasma panels operating continuously, in which each cell is generally defined at the intersection between only a column electrode and only a row electrode, for a given cell, it is necessary to select the column electrode and the row electrode which define this cell and apply between these two electrodes a voltage called "ignition" as long as one wants to obtain an emission of light by this cell; the ignition voltage is a voltage whose value is equal to or greater than the cell's ignition voltage, the ignition voltage being the minimum voltage to be applied between the two electrodes of a cell to obtain ionization of the gas .

There are also plasma panels operating alternately. In these panels, the addressing of a given cell is also carried out by the control of two electrodes which are crossed at the level of this cell and which serve to define it. These so-called "alternative" plasma panels have certain advantages, one of which is a memory effect which makes it possible to send useful information only to the cell whose state one wishes to change, while the state of the other cells is simply maintained or maintained (in the case of the lit state) by repetition of alternating electrical discharges called maintenance discharges. In plasma panels of the alternative type, the electrodes are covered with a layer of dielectric material, and they are therefore no longer in contact with the gas or with the discharge.

Among the plasma panels of alternative type, some use only two crossed electrodes to define a cell, as described for example in a French patent in the name of THOMSON-CSF published under the number 2 417 848. Other alternative plasma panels are said "to interview coplanar ". In the latter type of plasma panel, three or more electrodes are used to form a cell. In this case most often each cell of the matrix is formed substantially at the intersection between a column electrode (the function of which is then only addressing) with two parallel and coplanar maintenance electrodes which form a pair of maintenance electrodes: the maintenance of the discharges of each cell, i.e. the repetition of the alternating electric discharges previously mentioned, is provided between the two maintenance electrodes of the same pair, and the addressing of a given cell is done by generation of discharges between two crossed electrodes at this cell.

Such an alternative plasma panel with coplanar maintenance is shown in FIGS. 1 and 2, in accordance with the teaching of European patent application EP-A-0135 382. This plasma panel comprises a glass slab 1, covered with first and second families of maintenance electrodes 2 and 3 arranged in line, parallel and coplanar and arranged in an alternation of an electrode 2 of the first family and an electrode 3 of the second family. A succession of an electrode 2 with an electrode 3 constitutes a pair of maintenance electrodes used to form the same row of cells. These electrodes are provided with a recess or protruding part 2a and 3a which, in the same pair of maintenance electrodes, are oriented towards each other so as to concentrate maintenance discharges between them. The assembly is covered with an insulating layer 4. The addressing only electrodes 5 or column electrodes are crossed with the maintenance electrodes 2 and 3; the latter are generally arranged in lines and the addressing electrodes 5 are generally arranged in columns. The assembly is covered with an insulating layer 6 and a protective layer 7 made of magnesium oxide (MgO). A second slab 8 completes the set. A gas is contained in a sealed space 9 formed between the slabs 1 and 8 held apart by shims of thickness (not shown).

FIG. 3 shows another embodiment of a plasma panel with coplanar maintenance of the type with 3 electrodes to form a cell. In the example shown in FIG. 3, the column electrodes are carried by a slab while the maintenance electrodes are carried by the other slab, as described in a French patent application published under No. 2,629,265. To simplify FIG. 3 and the description, there is shown only a cell formed substantially at the intersection of an only addressing electrode or column electrode X with two coplanar maintenance electrodes Yae and Ye which constitute a pair PE of electrodes d 'interview. The column electrode X is carried by a first plate 50, for example made of glass. The assembly is covered with a layer 51 of dielectric material, for example glass with low melting point (enamel).

The pair PE of maintenance electrodes is supported by a second slab 60, and it is covered with a layer of dielectric material 62. Conventionally, among the two electrodes which constitute the pair of maintenance electrodes PE: the first electrode YAE performs an addressing function in cooperation with the column electrode X, and a maintenance function in cooperation with the other maintenance electrode of the same pair PE; the second YE maintenance electrode only performs a maintenance function with the first YAE electrode of the same pair. Each of the electrodes of the pair of PE maintenance electrodes has a protruding part 66, 68 formed at the intersection (or in the vicinity) between the column electrode X and the electrodes of the pair of PE electrodes. These projecting surfaces 66, 68 define a zone of electrical discharges in the gas or maintenance discharges, zone whose contour is substantially defined by the line 70.

In the case of a color display, the first panel 50 can also carry, conventionally, phosphor pads such as for example the pad 56 shown in FIG. 3. In such a case, the elementary cell constituted at the intersection of the electrode X and the pair of PE electrodes, constitutes one of the cells (colored with the color of the phosphor with which the cell is provided) of different colors that each elementary point of images or pixels comprises.

During the electric discharges in the gas between the electrodes of a cell, both in the case where the cell consists only of two crossed electrodes as in the case of coplanar maintenance, ultra-violet rays generated during these discharges excite the phosphor pellets. The phosphors then emit visible light by photoluminescence, the color of which is determined by the nature of the phosphor.

Thus, each elementary image point of the plasma panel is constituted by the juxtaposition of small dimensions areas covered with phosphors of different colors, in a way which in itself is also found in other types of flat screen display or in color cathode ray tubes.

In plasma panels as in other types of display screen, two or three or even four cells of different colors are provided for each elementary image point or pixel: most often there are three colors per pixel, red, green and blue, and often a fourth color, white or one of the three colors indicated above.

In plasma panels (as in other color display screens) the different colors are restored by composition of the basic colors, the balancing of which allows the various desired shades to be obtained. This color balancing can be carried out for example according to the method described in French patent application No. 87 03456 published under No. 2,612,326, and in which is described the operation of a color plasma panel, the text of this patent application to be considered as part of this description.

FIG. 4 schematically shows one of the conventional arrangements (in a plasma panel), cells of different colors constitute an elementary image or pixel point. To simplify FIG. 4 and the description, only six pixels P1 to P6 are shown each comprising four cells c1 to c4 among which two cells are traditionally green in color. The cells c1 to c4 are made up of phosphors which are each substantially arranged opposite an electrode crossing where the discharge cell is made up, as has been explained above; and for the sake of simplicity, these discharge cells are formed at the intersection of only two electrodes, a column electrode and a row electrode, but they could just as easily be formed for example using a column electrode and a pair of line electrodes (coplanar maintenance).

Taking for example the cells of the first pixel P1: the first cell c1 (top left of the pixel) is formed using a green phosphor V arranged at the intersection of a first column electrode X1 with a first row electrode Y1; a second cell c2 of red color R is formed at the crossing of a second column electrode X2 with the first row electrode Y1; a third cell c3 of blue color B is formed at the intersection of the first column electrode X1 and a second row electrode Y2; the fourth cell c4 is green in color V, and it is formed at the intersection of the second column electrode X2 and the second electrode Y2. Similarly, each of the other pixels P2 to P6 comprises four cells c1 to c4 formed at the crossing of a column electrode X1 to X6, and in all these other pixels the relative position of the color cells red, green and blue R, G, B is the same as that described in the first pixel P1.

In this configuration, assuming that one wishes to display only a blue color at the level of the second pixel P2 for example, the blue color corresponding to the third cell c3. It suffices to switch on this cell, that is to say to apply the appropriate voltages between the third column electrode X3 and the second row electrode Y2. This results in an elementary electric discharge at the level of this third cell c3, and this electric discharge produces ultraviolet rays which bombard the nearest phosphor which in this case is the blue phosphor B. This blue phosphor emits a light of color blue which appears all the more sustained, saturated, as there are fewer cells in the "lit" state of different colors nearby.

Unfortunately, ultraviolet rays propagate easily and can create a phenomenon of crosstalk by the fact that they can bombard phosphors belonging to pixels close to the one in which they were emitted. Consequently, the neighboring elementary cells if they are for example normally extinct, can emit under the effect of these ultraviolet rays a parasitic light, of the color of the luminophore which it comprises, from which it results a deterioration of the color that we are trying to emit. Indeed, if instead of having only a blue color, there is a mixture of blue more red more green, this mixture generally results in a desaturation, that is to say by a drift towards the white of the color considered

In the example of Figure 4, the arrangement of cells of different colors in a pixel corresponds to a structure called "Quad structure", in which each pixel P1 to P9 has a square shape and where each side is formed by two cells of different colors (the square shape of a pixel of "Quad structure" or rectangular of a pixel of structure called "triad" supposes that the cells repeat themselves with the same pitch in both axes). The advantage of this structure is that it makes it possible to distribute the loss of resolution equally between the two horizontal and vertical axes, that is to say along the column electrodes and along the line electrodes: in each direction the the size of the pixels is double that of the elementary cells, the phosphors being distributed in small blocks.

Another classic arrangement is that of the so-called "triad" structure which is shown schematically in FIG. 5. In this "triad" structure, the blue, red and green phosphors are formed by bands which in this example are vertical, respectively bB, bR, bV, which follow one another with different colors. In this configuration, each elementary image point or pixel P′1 to P′6 comprises three elementary cells C′1, C′2, C′3 of different colors, which follow one another in a direction perpendicular to that of the bands, that is to say in the horizontal direction in the example described. Thus the pixels have the shape of a rectangle whose length is parallel to the line electrodes, and whose width parallel to the column electrodes (not shown) is that of a single elementary cell. It should be noted that in this arrangement, the above-mentioned phenomenon of crosstalk or intermodulation also exists: for example an elementary discharge produced in the third cell C'3 of blue color of the first pixel P′1, produces ultra- purple which not only can excite the phosphor of this cell, but can also excite the phosphors of green and red colors of the adjacent cells C′2 and C′1 which belong to the neighboring pixels P′2, P′3 and P′4.

In plasma panels, a known solution to this problem of color degradation by the effect of diaphotia, consists in dividing the various elementary cells by barriers, in order to avoid the propagation of ultraviolet rays from one cell to another. neighboring cell. This solution can be very effective, but it is not satisfactory in that it significantly complicates technology and industrialization.

The invention constitutes a relatively simple and easy to implement solution to this problem of the deterioration of colors due to the effects of crosstalk or optical intermodulation. It applies to display screens in which different colors are obtained by composition of at least two primary colors, and they apply particularly to plasma panels in which it makes it possible to reduce the emission of visible light other than that desired. , without intervening on the ultraviolet radiation itself.

According to the invention, a polychrome display screen, comprising a plurality of elementary image points or pixels, each pixel comprising at least two cells of different colors, is characterized in that the pixels consist of at least two types of pixels which differ from each other by the relative positions of the cells in these pixels, a pixel of a given type being adjacent to at least one pixel of a different type so that at least two adjacent cells belonging to pixels of different types are the same color.

• - les figures 1 et 2 déjà décrites montrent l'architecture classique d'un panneau à plasma du type connu;
• - la figure 3 déjà décrite illustre schématiquement les positions relatives d'une cellule élémentaire de décharges et d'une pastille de luminophores dans un panneau à plasma de type connu;
• - la figure 4 déjà décrite illustre une disposition classique des différentes cellules de couleurs différentes dans un pixel, dans le cas d'une structure à quatre cellules par pixel;
• - la figure 5 déjà décrite montre une disposition classique des cellules de différentes couleurs dans un pixel dans le cas d'une structure à trois cellules par pixel;
• - la figure 6 illustre schématiquement à titre d'exemple non limitatif, une application de l'invention à un écran de visualisation polychrome dans le cas d'une structure à quatre cellules par pixel;
• - la figure 7 illustre l'application de l'invention à un écran polychrome du type à trois cellules par pixel.

The invention will be better understood in the light of the description which follows, given by way of nonlimiting example with reference to the 7 appended figures, among which:

• - Figures 1 and 2 already described show the conventional architecture of a plasma panel of the known type;
• - Figure 3 already described schematically illustrates the relative positions of an elementary discharge cell and a phosphor patch in a plasma panel of known type;
• - Figure 4 already described illustrates a conventional arrangement of the different cells of different colors in a pixel, in the case of a structure with four cells per pixel;
• - Figure 5 already described shows a conventional arrangement of cells of different colors in a pixel in the case of a structure with three cells per pixel;
• - Figure 6 schematically illustrates by way of nonlimiting example, an application of the invention to a polychrome display screen in the case of a structure with four cells per pixel;
• - Figure 7 illustrates the application of the invention to a polychrome screen of the type with three cells per pixel.

FIG. 6 partially shows a display screen 20 which, in the nonlimiting example described, is a plasma panel. The screen 20 is of the type with three basic colors: red R, green V, blue B. It is represented using only 12 pixels PX1 to PX12, but of course it can include many more. The pixels PX1 to PX12 comprise cells C1 to C4 of different colors, according to a structure (Quad) with four elementary cells per pixel, also the pixels PX1 to PX12 have the general shape of a quadrilateral and more precisely that of a square . In the context of the invention, the plasma panel can be of the continuous as well as alternative type, with coplanar maintenance or not. Each cell C1 to C4 is formed at an intersection of electrodes in a manner which is in itself conventional, at the intersection of a column electrode and a row electrode as in the example of FIG. 4 for example, such column electrodes and row electrodes not having been shown in FIG. 6 to simplify the latter and the description; consequently cells C1 to C4 are represented by phosphor pellets of the color which they comprise, namely: green V for cells C1, red R for cells C2, blue B for cells C3 and green V for cells C4 cells.

According to a characteristic of the invention, the arrangement of the different cells C1 to C4 in a pixel is not not the same from one pixel to a neighboring pixel, so that each cell of a given color is surrounded by a maximum of neighboring cells having the same color.

In the nonlimiting example represented in FIG. 6, this leads to the formation of four types of pixels which differ from each other by the relative positions of the elementary cells, that is to say cells of different colors which they comprise: two adjacent pixels such as for example the first and second pixels PX1, PX2, are of different types. If we observe the relative positions of cells C1 to C4 in the second pixel PX2 for example: we find in the top left a cell C1 (green color) and in the top right a cell C2 (red color); under cell C1 is placed cell C3 (blue color), cell C4 (green color) being placed next to cell C3 and below cell C2; this provision is also valid for pixels PX4, PX10, PX12 which are of the same type as the pixel PX2. The pixels PX1, PX3, PX9, PX11 are of the same type and are of a different type from the second pixel PX2: we observe in fact that on the one hand, the position of the first and second cells C1, C2 one with respect to the other is inverted with respect to the position they occupy in the second pixel PX2, and on the other hand, the positions of cells C3 and C4 are also inverted with respect to the second pixel PX2; in fact observe, for two such neighboring pixels of a different type, for example the pixels PX1 and PX2, that the cells C1 to C4 in these two pixels occupy symmetrical positions with respect to the axis of separation of these two pixels .

The sixth pixel PX6 is located under the second pixel PX2 and, with the eighth pixel PX8 it constitutes a third type of pixel: in the eighth pixel PX8, the third and fourth cells C3 and C4 respectively blue and green are on the same horizontal line at the top of the pixel (they respectively occupy the same position as the first and second cells C1, C2 in the second pixel PX2); the first cell C1 (green color) is located at the bottom of the pixel PX8 under the third cell C3 (blue color), and the second cell C2 is positioned at the bottom of the pixel under the fourth cell C4 (green color).

A fourth type of pixel is represented by the fifth and seventh pixels PX5, PX7 located respectively under the first and third pixels PX1, PX3. In the fifth pixel PX5, the first cell C1 (green) is at the top left, and there is a third cell C3 (blue) at the top right; the second cell C2 (red color) of this fifth pixel is placed under the first cell C1 (green color), and the fourth cell (green color) is located under the third cell (blue color).

It results from such an arrangement that each cell C1 to C4 is surrounded by a maximum of neighboring cells of the same color.

Indeed, at the level of the sixth pixel PX6 for example, the second cell C2 of red color has for direct neighboring cells three other cells C2 of red color, one of which belongs to the seventh pixel PX7, another to the tenth pixel PX10, and finally the last one at the eleventh pixel PX11. A similar result is obtained for the other cells C1, C3, C4 which are each adjacent to three elementary cells of the same type, that is to say of the same color.

In operation, an elementary discharge which takes place at the level of a cell C1 to C4 of a given color of a given pixel PX1 to PX12, conventionally produces ultraviolet radiation to excite the photoluminescence of the luminophore which comprises this cell. With the invention, if this ultraviolet radiation extends to the cells of the neighboring pixels, the light mainly emitted by these neighboring pixels will be of the same color as that in which the elementary discharge took place. Consequently, without reducing the rate of crosstalk, the harmful effects are reduced.

Tests carried out according to an arrangement such as above have given particularly interesting results. These results have been reported conventionally in a color diagram (not shown) established in accordance with the standards defined by the international lighting commission for the case where the three colors red, green and blue are used in the same elementary point d image, and these results made it possible to draw, in itself known manner, a color triangle called "Maxwel triangle" (not shown) whose surface is almost double that of a triangle established with a panel at plasma where the phosphors of different colors are arranged according to the prior art. This means that with the arrangement according to the invention, the number of colors possible is increased in the same ratio as the increase in area of the triangle, which in practice leads to dividing in the same ratio the degree of crosstalk.

It should be noted that taking into account the fact that the pixels PX1 to PX12 are of different types (4 types in the example of FIG. 6), depending on the relative positions of cells C1 to C4 in these pixels, the electronics control of a plasma panel must take this additional complexity into account in the logical processing of information. In practice, however, this most often poses few problems, particularly in the (most numerous) cases where there is an image memory in which all the information is stored: it is then enough to modify the reading protocol of this image memory.

Another drawback brought by the arrangement of the invention lies in the fact that it destroys the regularity of the arrangement of colors compared to the prior art. It can be seen that cells C1 to C4 of the same color, of four pixels PX1 to PX12 adjacent, constitute the same group. Taking for example the case of the second cells C2 of red color R (this example also being valid for the cells of another color), it is observed that the four adjacent second second cells C2 belonging to pixels PX6, PX7, PX 10, PX11 can have phosphors formed from the same phosphor patch 30 (symbolized in FIG. 6 by a square in dotted lines); this example is also valid for cells of another color. Also considering the distance between cells of the same color in the vertical direction for example, (assuming that a whole column of pixels is lit in red), we see that cells C2 (red) of the fifth and ninth pixels PX5 , PX9 are at an average distance d1 from each other smaller than the average distance d2 which separates the cells C2 (red) from the first and from the fifth pixel PX1, PX5. This irregular distribution of cells of the same color may however not be a problem if the resolution of the screen is fine enough or, which amounts to the same thing, if the observer is far enough away.

This shows that the drawbacks attached to the invention, even if they may initially dissuade the specialist from using such a solution, are not unacceptable, and are largely offset by an improvement in colorimetric characteristics.

FIGS. 7 and 8 illustrate the application of the invention to a polychrome screen 21 of plasma panels, in which pixels PX′1 to PX′12 in three colors have a structure called "triad". In fact, apart from the arrangement of the colors inside each pixel PX′1 to PX′12, the screen 21 similar to that shown in FIG. 5.

Each pixel PX′1 to PX′12 comprises three cells C1, C2, C3 of different colors. FIG. 8 shows phosphors in the form of bands b1, b2, b3 which serve to constitute cells C1 to C3 of the screen 21, these bands b1 to b3 being respectively red R, green V and blue B. In the nonlimiting example described, the bands b1 to b3 are arranged vertically side by side so as to constitute a succession of bands of different colors.

Referring again to FIG. 7, it can be seen that the pixels PX′1 to PX′12 are of two different types which differ from one another by the relative positions of the cells C1 to C3 which they comprise. A first type of pixel is represented by the pixels PX′1, PX′5, PX′9 on the one hand, and PX′3, PX′7, PX′11 on the other hand, which are superimposed in the vertical direction ; a second type of pixel is represented on the one hand by the pixels PX′2, PX′6, PX′10, and by the pixels PX′4, PX′8, PX′12 on the other hand.

Taking for example the second pixel PX′2 (example valid for all pixels of the same type): it has in the central position, a cell C1 (green color), with to its left a cell C2 (red color) and with to on its right a C3 cell (blue color).

Taking for example the first PX′1 to represent the pixels of the other type: it includes in the central position a cell C1 (green color), with on the left a cell C3 (blue color) and on the right a cell C2 (color red).

In the nonlimiting example of the description, the difference between the two types of pixels resides in the positions of the second and third cells which are reversed from one type of pixel to another. It follows from this arrangement, as in the case of the previous example, that the cells of a given red or blue color belonging to a given pixel have for directly neighboring cells belonging to other pixels, cells of the same color; this can be checked in Figure 7 both horizontally and vertically.

Of course there is also an irregularity in the distance between cells of the same color, as illustrated in FIG. 7 in the horizontal direction by an average distance of 1 between two neighboring cells C2 and a distance of 2 which separates two C2 cells not neighboring but belonging to contiguous pixels.

It should be noted that the positioning according to the invention of the cells of different colors, that is to say phosphors of different colors with regard to the crossings (not shown) of electrodes, tends towards a simplification compared to the prior art in making the phosphors at the required positions. Indeed, in the case of the arrangement shown in FIG. 7 where the pixels PX′1 to PX′12 extend in the horizontal direction, and are formed in the vertical direction only by a phosphor of a given color, the realization of the phosphors in the form of bands remains valid. The grouping of cells of the same color simply leads to placing phosphor strips of the same color side by side or, as shown in FIG. 8, to successively give them a simple width L1 and a double width L2. The double width L2 makes it possible to constitute the end cells (ie cells C2 and C3 in the nonlimiting example described) of two adjacent pixels situated on the same axis (that is to say a horizontal line in the non-limiting example described); the central cells (C1) having the same color for all the pixels. As regards the previous example, shown in FIG. 6 and which relates to a so-called "QUAD" structure, the arrangement of the invention may even lead to a simplification, since in this case the phosphors may be in the form of pastilles or paving stones whose surface is sufficient to be divided into four parts each assigned to a cell C1 to C4 of the same color.

The positions of colored cells in a pixel, shown in Figures 6 and 7 are given by way of non-limiting example, and other arrangements fall within the scope of the invention as soon as they lead to surrounding a cell of a color given by a maximum of cells of the same color.

Claims (9)

Full color display screen, comprising a plurality of elementary image points or pixels (PX1 to PX12), each pixel comprising at least two cells (C1, C2, C3) of different colors, characterized in that the pixels (PX1 to PX12 ) comprise at least two types of pixels which differ from one another by the relative positions of the cells (C1, C2, C3) in these pixels, a pixel (PX2) of a given type being adjacent to at least one pixel (PX6) d 'a different type, so that at least two adjacent cells (C1, C2, C3) belonging to pixels of different types are of the same color. Display screen according to claim 1, characterized in that it is of the plasma panel type. Display screen according to one of the preceding claims, characterized in that the pixels (PX1 to PX12) comprise three cells (C1, C2, C3) of different colors. Display screen according to claim 3, characterized in that the three cells (C1, C2, C3) of different colors of the same pixel are arranged on the same axis, the central cell (C1) having the same color for all pixels. Display screen according to one of claims 3 or 4, characterized in that the cells (C1 to C3) of different colors are formed using three bands of phosphors (b1, b2, b3), the bands (b1 , b3) which serve to constitute end cells (C2, C3) having a width (L2) twice the width of the strips (b2) which serve to constitute the central cells (C1). Display screen according to one of claims 1 or 2, characterized in that each pixel comprises four cells (C1 to C4) arranged substantially to form a quadrilateral. Display screen according to claim 6, characterized in that two cells (C1, C4) of the same pixel (PX1 to PX12) are of the same color. Display screen according to either of Claims 6 and 7, characterized in that four adjacent cells (C2) of different pixels (PX1 to PX12) have the same color. Display screen according to one of Claims 6 or 7 or 8, comprising phosphor pads of given colors, characterized in that a phosphor pad is common to four adjacent cells (C2) of different pixels.

Images