JPH04100085A - Multicolor display screen - Google Patents

Abstract

PURPOSE: To obtain various colors by the mixing of two primary colors on a display screen by including two cells having respectively different colors in each pixel and mutually changing the positions of cells in two adjacent pixels. CONSTITUTION: The screen 20 has three primary colors of red R, verdure V, and blue B. Cells C1 to C4 having respectively different colors are included in pixels PX1 to PX12 so as to be formed on respective intersections between column electrodes and row electrodes and the colors of the cells C1 to C4 are respectively expressed by the light emitting element dots of verdure V, red R, blue B, and verdure V. As the result of prescribed arrangement, each of the cells C1 to C4 is surrounded by the maximum number of adjacent cells having the same colors. In operation, reference discharge generated in the cell of applied color out of the cells C1 to C4 in an applied pixel out of the pixels PX1 to PX12 generates ultraviolet radiation for exciting the photoluminescence of the light emitting body included in the cell by a standard method. When the ultraviolet radiation is expanded to adjacent pixels, beams radiated from these adjacent pixels have the same colors as that of reference discharge. Consequently inconvenient influence can be removed without reducing the rate of unclearness.

Description

[Detailed description of the invention]

[0001]

[Industrial application field]

The invention relates to a multicolor display screen, the purpose of which is a structure that improves the purity of primary colors. The invention is particularly useful for display screens where blurring is quite severe, ie optical intermodulation between adjacent pixels occurs, as is the case with plasma panels. [0002]

[Conventional technology]

Taking plasma panels (or gas plasma displays) as an example, these panels are currently well-known flat screen display devices. These panels operate on the principle of light discharge in a gas. These panels are used to display monochromatic or multicolored images, such as alphanumeric characters or graphics. Plasma panels generally use gas (neon-based mixtures are common)
There are two insulating plates separating the space filled with. These plates support two or more arrays of intersecting electrodes to form a matrix of elementary cells, for example the electrodes of one array are arranged in columns and the electrodes of another array are arranged in rows. The arrays are intersecting, with each array substantially organized at the intersection of row and column electrodes. [0003] The operating principle is based on the selective generation of electrical discharges in the gas (ie, generation in selected cells). Each discharge in the gas is caused by the emission of light in each cell at each location where the discharge occurs, called an elementary discharge. In this way, each cell constitutes an elementary source of light, and their state (on or off) changes. [0004] Looking at the matrix arrangement of cells, their addressing is done in the form of a matrix, ie for each cell this addressing is done by controlling two electrodes that intersect at the selected cell. . Thus, for example, each cell is generally defined by the intersection between only one column electrode and only one row electrode, and for a given cell the row and column electrodes that define this cell are selected. A voltage needs to be applied between these two electrodes only if it is necessary to obtain the emission of light by this cell. The emission voltage must be higher than the spark voltage of the cell. voltage, the spark voltage of which is the minimum voltage that can be applied between two electrodes of a cell to ionize the gas. [0005] Additionally, there are plasma panels that operate in alternating current mode. , the addressing of a given cell is done by controlling the two electrodes that intersect at the level of this cell and are used for its determination.These so-called "alternating current" plasma panels have certain advantages. There is,
One of its advantages is the memory effect, which allows useful information to be specified only to cells whose state has changed, but the state of other cells can be easily changed by repeating an alternating current discharge called a sustain discharge. held or maintained (in case of luminous state). In the case of AC plasma panels, the electrodes are covered with a layer of dielectric material and are therefore no longer in contact with the gas or discharge. [0006] Certain AC plasma panels include, for example, Patent No. 241, represented by THOMSON-C3F.
As described in the French patent No. 7848, only two alternating current electrodes are used to define the cell. Other alternating current plasma panels are so-called "coplanar" panels. In the case of the latter plasma panel,
Three or more electrodes are used to construct the cell. In this case, it is also common for each cell of the matrix to be constituted by two parallel coplanar sustain electrodes forming a pair of sustain electrodes at the intersection of the column electrodes (whose function is only an addressing function). ing. Sustaining the discharge of each cell, which is a repetition of the above-mentioned alternating current discharge, is carried out between two sustaining electrodes of the same combination, and the designation of a given cell is between the two electrodes that the cell intersects. This is done by the generation of electrical discharge between. [0007] This type of AC plasma panel with coplanar maintenance is disclosed in European Patent Application No. EP-A-0135382
1 and 2 as taught in No. A glass plate 1 in this plasma panel is covered with a first class and a second class of sustain electrodes 2 and 3, which are arranged parallel to the row direction and on the same plane. They are arranged to alternate with the electrodes 3 of the second group. The continuity of electrode 2 with electrode 3 constitutes a set of sustain electrodes used to form one and the same row of cells. These electrodes have shoulders or lobes 2a, 3a. In one and the same set of sustain electrodes, these two shoulders or lobes 2
a and 3a are mutually pointed so as to mutually concentrate the sustaining discharge. All units are covered with an insulating layer 4. Only address electrodes 5 or column electrodes intersect sustain electrodes 2 and 3. These sustain electrodes 2 and 3 are generally arranged in the column direction. All units have an insulating layer 6 and a protective layer 7 made of oxidizing gnesium (MgO).
covered with. A second plate 8 covers the unit. The gas enters a tamping sealing space 9 formed between plates 1 and 8 and separated and protected by thick shims (not shown). [0008] FIG. 3 shows another embodiment of a coplanar sustaining plasma panel with three electrodes to form one cell. In the example shown in FIG. 3, the column electrodes are supported by one plate while the sustain electrodes are supported by the other plate, as described in French Patent Application No. 2,629,265. To simplify the description in FIG. 3, only one cell is formed at the intersection of one address electrode or column electrode It shows. The column electrodes X are supported by a first plate 5o made of glass, for example. All units are covered by a layer 52 made of dielectric material, for example low melting point (enamel) glass. [0009] The sustain electrode set PE is supported by a second plate 60 and covered by a layer of dielectric material 62. In the standard method, between the two electrodes forming a set of sustain electrodes PE, ``the first electrode Yae performs the addressing function in cooperation with the column electrode X, and also with the other sustain electrodes of the same set PE. The second sustain electrode Ye functions independently with the first electrode Yae of the same group. Each electrode of the sustain electrode combination PE has an electrode at (or near) the intersection between the column electrode
The formed ledges 66,68 are included (XJ). The surfaces 66,68 of these lobes define the discharge area within the gas or sustaining discharge. The outline of this area is line 70
It is determined by [00101 In the case of a color display, the first plate 50 produces luminescent dots, such as the dotted lines 56 shown in FIG. 3, in a standard manner. In such a case, the basic cell formed at the intersection of the electrode one cell is configured. [0011] When a discharge occurs between the electrodes of one cell in a gas, the cell is formed singly by two crossed electrodes, and in the case of coplanar maintenance, the ultraviolet rays generated during these discharges are excites the luminescent dot. The illuminant then emits visible light through photoluminescence. [0012] In this way, each pixel of the plasma panel is itself distinguished from other types of flat displays or color cathode ray tubes. , are constructed by juxtaposing small areas covered with light emitters of different colors. [0013] In plasma panels, two or three of different colors, as in the case of other types of display screens, Furthermore, four cells are provided for each pixel (XJ). Most commonly, there are three colors per pixel: red, green, and blue, and often a fourth color, either white or a dot of one of the three colors listed above. [0014] In a plasma panel (as in the case of color displays of other colors), various colors are restored as a composition of basic colors, and by balancing them, various necessary hues can be obtained. This color balance can be achieved, for example, by the method described in French Patent Application No. 8,703,456 published under French Patent Application No. 2,612,326, which describes research on color plasma panels. At this time, it is necessary to consider the patent application as a component of this invention. [0015] FIG. 4 shows a schematic diagram of one standard arrangement (in a plasma panel) for cells of various colors that make up a pixel. To simplify the explanation in FIG.
There are four cells, two of which are green as before. The cells C1 to 04 are each constituted by a light emitting body substantially arranged so as to face the intersection of the electrodes forming the discharge cell, as described above. For simplicity, these discharge cells are formed at the intersection of only two electrodes, one column electrode and one row electrode, but they can be formed, for example, by a column electrode or by a set of row electrodes. (coplanar maintenance). [0016] For example, if we take the cell of the first pixel P1, the first cell C1 (
The upper left side of the pixel is formed by a green emitter V at the intersection of the first column electrode with the first row electrode Y1. The second cell C2 of red R is formed at the intersection of the second column electrode X2 with the first row electrode Y1; the third cell C2 of blue B
3 is formed at the intersection of the first column electrode X1 with the second electrode Y2; the fourth cell C4 is colored green V;
Further, a second electrode Y2 is formed at the intersection of the second column electrode X2. Similarly, each of the other pixels from P2 to Pl6 has row electrodes from Xl to X6 with row electrodes from Yl to Y6.
contains four cells C1 to C4 formed at the intersections of the column electrodes, and among all these other pixels are cells colored red, green, blue, R, V, B. is the first pixel P1
in the same relative position as described for . [0017] In this arrangement, the second pixel P2, for example, the third cell C3
When it is desired to display the blue color independently in response to the cell, it is sufficient to generate the cell, that is, to apply an appropriate voltage between the third column electrode X3 and the first column electrode X1. As a result, the third cell C3 becomes a basic discharge, and this discharge also generates ultraviolet radiation which irradiates the light emitter, in this case the blue light emitter B. The blue light emitted by this blue light emitter causes −
All that remain layer-preserving and saturated appear to have very few cells of other colors nearby in a luminescent state. [0018] Unfortunately, ultraviolet light propagates easily and causes blurring phenomena, which is based on the ultraviolet light irradiating light emitters included in pixels adjacent to those from which the ultraviolet light is emitted. Thus, for example, if neighboring elementary cells are normally off and then receive these ultraviolet rays, these neighboring elementary cells will emit stray light having the color of the included emitters. The result is a degradation of the emitted color. If instead of using only one color, blue, we use a mixture of blue, red, and green, this mixture will typically be unsaturated, i.e., the color under consideration will be represented by a drift towards white. be. [0019] In the example of FIG. 4, arranging cells of various colors within a pixel corresponds to a structure called a "rectangular structure", in which each pixel from Pl to P9 has a rectangular shape. Each side of the screen is formed by two different color cells (a rectangular structure of pixels, or a so-called "triad" structure). ).The advantage of this structure is that it distributes the loss of sharpness equally between the two axes, horizontal and vertical, i.e. it distributes the loss of sharpness equally along the column and row electrodes. It is possible to distribute: for each direction the pixel size is twice the size of the basic cell, and the light emitters are distributed in small pads. [0020] Other standards Figure 5 shows an overview of the so-called ``triad'' structure, which is a typical arrangement.In this ``triad'' structure, the bands (b a n
d) are vertical in this example, B, bR, bV, respectively.
The colors are different from each other. In this arrangement, three basic cells C'l, C'2 . The C'3 have different colors, which follow each other in the direction perpendicular to the band, ie horizontal in the example described. Thus, the shape of the pixel is rectangular, and its length direction is parallel to the row electrodes, and its width direction is parallel to the column electrodes (not shown), which constitutes a single basic cell. It should be noted that the blurring or intermodulation phenomenon described above is also caused by this arrangement; for example, the ultraviolet radiation that causes the basic discharge in the first pixel P'l and in the blue third cell C'3 is , which not only excites the emitter of this cell, but also the neighboring P'2. P'3.
The green and blue light emitters of adjacent cells C'2 and C'11 included in P'4 are also excited. [0021] In plasma panels, a known approach to this type of problem of color degradation due to blurring effects 1 is due to the division of the various elementary cells by barriers, which can cause problems from one cell to the next This is to prevent the propagation of ultraviolet rays to the cell. Although this approach is very effective, it is unsatisfactory because of the considerable complexity of the technology and its application on an industrial scale. [0022]

[Summary of the invention]

The approach provided by this invention is relatively simple and easy to implement for problems of this type where color is degraded by optical intermodulation or blurring effects. In display screens to which this invention is applicable, the various colors are obtained by mixing at least two primary colors, and in plasma panels, to which it is particularly applicable, the emission of visible light other than the desired light is reduced without emitting ultraviolet light itself. be able to. [0023] According to the invention, a multicolored display screen is provided having a large number of pixels, each pixel including at least two cells having different colors, and each pixel including at least two cells forming a pixel. Different types of pixels have different cell positions within the pixel, and a given type of pixel is adjacent to at least one pixel of a different type, and this means that at least two adjacent cells belonging to different types of pixels are adjacent to each other. This is so that they have the same color. [0024]

【Example】

FIG. 6 shows a partial view of a display screen 20 within a plasma panel in the non-limiting example described above. The screen 20 is of a type having three primary colors: red R1, green V, and blue B. The screen is 1 from PXl to PXl2
Although represented by only two pixels, it is of course possible to have more pixels. PXl to PXl
Pixels up to 2 had 4 elementary cells per pixel (
Based on the rectangular structure, there are cells C1 to C4 with different colors. Therefore, the shape of the pixels from PXl to PXl2 is generally a trapezoid, and more specifically a quadrilateral. Within the scope of the present invention, plasma panels are of the DC as well as AC type, with or without coplanar maintenance. For example, each cell from C1 to 04 is shown in Figure 4.
They are formed at the intersections of column electrodes and row electrodes, as in the example below: Such column electrodes and row electrodes are not shown in FIG. 6 to simplify the drawing, as in the description. Therefore, C1 to 0
Cell 4 is illuminated by the color it contains, i.e. green v1 for cell CI, red R for cell C2, blue B for cell C3, and green ■ for cell C4. expressed. [0025] According to one feature of the invention, the arrangement of the different cells C1 to 04 within a pixel is not the same from one pixel to the next, so that each cell of a given color has the same color. Surrounded by the maximum number of adjacent cells. [0026] In the non-limiting example shown in FIG. 6, four types of pixels are formed, which differ from each other by the relative positions of the basic cells, ie cells with different internal colors: for example, first and second Two adjacent cells, such as pixels PXI and PX2, are of different types. For example, if you know the relative cells of cells C1 to 04 in the second pixel PXZ, cell C1 (green) is on the upper left, and cell C2 (green) is on the upper right.
You can see that there is a red). Below cell CI is cell C3 (blue)
are arranged, and cell C4 (green) is placed near cell C3 and below cell C2. This arrangement is valid for pixel PX2 and pixels PX4 and PXIO of the same type.
, PXl2. Pixel PXI, PX3, PX
9. PXll has the same type and is different from the second pixel PX2. In reality, the positions of the first and second cells C1 and C2 are first exchanged with the positions occupying the second pixel, and then the positions of the cells c3 and C4 are also changed to the second pixel PX2.
replaced with. In fact, for two adjacent pixels of different types, such as pixels PXI and PX2, these two
It can be seen that the cell CL04 within one pixel occupies symmetrical positions with respect to the axes of two separate pixels. [0027] The sixth pixel PX6 is below the second pixel PX2 and is the same as the eighth pixel PX8, forming a third type of pixel: within the eighth pixel PXS, each blue and the third and fourth cells C3 and 04 in green are in one and the same horizontal row above the pixel (they are in the second
The first cell C1 (green) is located below the third cell C3 (blue) in the pixel PX
8, and the second cell C2 is below the fourth cell C.
4 (green) and below the pixel. [0028] The fourth type of pixels are the fifth and seventh pixels PX5 below the first and third pixels PXI and PX3, respectively.
, PX7. In the fifth pixel PX5, the first cell CI (green) is located on the upper left side, and the third cell (blue) is located on the upper right side. The second cell C2 (red) of this fifth pixel is located below the first cell C1 (green), and the fourth cell (green) is located below the third cell (blue). . [0029] As a result of this arrangement, each cell C1 to C4 is surrounded by the maximum number of adjacent cells of the same color. [0030] In fact, for example in the sixth pixel PX6, the second red cell C2 has three other red cells C2 immediately adjacent to it. Among these three other red cells, the first belongs to the 7th pixel PX7 and the second belongs to the 10th pixel PXIO
Furthermore, the third pixel belongs to the 11th pixel PXII. Other cells c1, C3, and C4 that yield similar results are each adjacent to three basic cells of the same type, that is, the same color. [00311 In operation, the elementary discharge that occurs in cells 01 to 04 of a given color of a given pixel of PXI to PX12 excites the photoluminescence of the emitter in which this cell is contained by standard methods. This produces ultraviolet radiation. In this invention, if this ultraviolet radiation is spread in adjacent directions, the light emitted by these adjacent pixels will be of the same color as the elementary discharge occurs. As a result, undesirable effects are removed without reducing the blurring rate. [0032] Particularly beneficial results are obtained from tests conducted with arrangements such as those described above. These results are recorded in the usual manner on a color chart (not shown) prepared according to standards set by the International Commission on Illumination. and these results allow us, in a manner known per se, to plot a colored triangle known as a Maxwell's triangle (not shown), whose surface area can be divided into various colors. of light emitters is approximately twice the surface area of a triangle made with a plasma panel arranged according to conventional techniques. This shows that with the arrangement according to the invention the number of possible colors increases in the same proportion as it increases within the area of the triangle: this actually divides the blurring ratio by the same proportion. [0033] It should be noted that the types of pixels from PXI to PXI2 (four types in the example of FIG. 6) are 01 to 04 within the pixel.
It is necessary to take into account that the electronic control circuit of the plasma panel has a complicated upper logic processing. In practice, however, most commonly this poses few problems, especially if there is an image memory in which all the information is stored (which is the most frequent case); therefore, this image memory The readout protocol can be sufficiently modified. [0034] Another drawback presented by the arrangement of the present invention is that it disrupts the even distribution of colors as compared to the prior art. In reality, it can be seen that cells C1 to C4 of the same color belonging to four adjacent pixels PXI to PXI2 form one and the same group. For example, if we take the case of the second cell C2 of red R (this example is also valid for cells of other colors), pixels PX6, PI3, PXIOlPXll
The light emitters in the four adjacent second cells C2 belonging to
It can be seen that it may be formed by a single and identical luminous dot 30, marked with a square dash in FIG. This example is also valid for cells of other colors. In this way, for example, if we consider the distance between cells of the same color in the vertical direction, we assume that all columns of page pixels emit red light) 5th and 9th pixels PX5, cell C2 of PI3 (
It turns out that the average distance between cells (red) is dl, and this distance is the cell C2 (red) of Lth and 5th PXI, PI3.
is smaller than the average distance d2. However, if the screen sharpness is fairly good, or equivalently the observer is at a considerable distance, the uneven distribution of cells of the same color becomes troublesome. [0035] This means that even if these techniques are not initially incorporated into such an approach due to the disadvantages of this invention, these techniques do not preclude that approach; 7 and 8 illustrate the application of the present invention to a polychromatic screen 21 of a plasma panel, in which a P with three colors is shown.
The pixels from X'1 to PX'12 have a so-called "triad" structure. In fact, except for the position of the colors within each pixel from PX'1 to PX'12, the screen 21 is the same as the screen shown in FIG. [0037] Each cell from PX'l to PX'12 has three cells of different colors, C1, C2, and C3. FIG. 8 shows the light emitters in the form of bands bl, b2, b3 used to constitute cells 01 to 03 of the screen 21, and these bands bl to 53 are red R1 green V, respectively. , colored blue B. In the non-limiting example given above,
The bands bl to b3 are arranged vertically and in parallel to form continuous bands of different colors. [00381] Referring again to FIG. 7, it can be seen that the pixels PX'l to PX'12 are of two different types, which differ from each other in the relative positions of the cells C1 to C3 inside. The first type of pixels is pixels PX'l and PX'5 on one side.
, PX'9, and the other is PX'3, px'7, PX
'll, and they are stacked vertically. The second type of pixel is first pixel PX'2, PX
represented by '6, PX'lO, then pixel PX'4, PX'
8, represented by PX'12. [0039] For example, if we take the second pixel PX'2 (this example is valid for all pixels of the same type), cell C1 (green) is in the center position and cell C2 (red is ), but on the right is cell C3 (blue). [0040] For example, to represent another type of pixel, the first pixel PX'
Taking l, there is cell CI (green) in the center position, cell C3 (blue) on the left, and cell C2 (red) on the right. [0041] In an example non-limiting description, the difference between the two types of pixels is 1
One type of pixel is replaced with another type of pixel 2
in the positions of the 3rd and 3rd cells. With this arrangement, as in the previous example, a cell of a given color, red or blue, belonging to a given pixel will have cells of the same color in the immediate vicinity of cells belonging to other pixels. This can be confirmed in the horizontal direction as well as the vertical direction in FIG. [0042] Of course, the non-uniformity of the distance between cells of the same color can also be seen here, which is the average distance d'l between two adjacent cells C2 in FIG. This is horizontally illustrated by the distance d'2 between two cells C2 included in the pixel. [0043] Based on the present invention, the positioning of different colored cells, i.e., different colored light emitters with respect to electrode intersections (not shown), is simplified compared to conventional techniques of creating light emitters at the required locations. We need to focus on what is useful. In fact, in the case of the arrangement shown in Fig. 7, the pixels from PX'l to PX'12 are spread out horizontally, and where the pixels are vertically composed of only the light emitters of a given color, the light emitters are located within the horizontal band. It is effective to create Groups of cells of the same color facilitate the juxtaposition of bands of light emitters of the same color, or to provide a single width L1 and a double width L2 in succession, as shown in FIG. Double width L2 creates the terminal cells (i.e., cells C2 and C3 in the non-limiting example above) of two adjacent cells in one and the same axis (e.g., horizontal parallel in the non-limiting example above). The central cell (C1) has the same color for all pixels. Regarding the above-mentioned example shown in FIG. 6 and related to a so-called "rectangular" structure, the arrangement of the invention is facilitated in this case by the fact that the emitter is in the form of a dot or pad, the area of which is 4. This is because it is sufficient to divide it into two parts, and each part is assigned to cells C1 to C4 of the same color. [0044] The positioning of colored cells within the pixels shown in FIGS. 6 and 7 is given as a non-limiting example;
Other arrangements are also within the scope of the present invention surrounding cells of a given color with a maximum number of cells of the same color.

[Brief explanation of drawings]

FIG. 1, as already mentioned, shows the standard construction of a known type of plasma panel.

FIG. 2, as already mentioned, shows the standard construction of a known type of plasma panel.

Figure 3 gives a schematic diagram of the basic discharge and emitter dots of a known type of plasma panel.

FIG. 4 illustrates a standard arrangement of different cells of different colors within a pixel in a structure with four cells per pixel;

FIG. 5 shows a standard arrangement of cells of various colors within a pixel in a structure with three cells per pixel.

FIG. 6 illustrates, as a non-limiting example, the application of the invention to a multicolored display screen in a structure with four cells per pixel;

FIG. 7 illustrates the application of the invention to a multicolor screen of the type with three cells per pixel;

[Explanation of symbols]

1・・・・・・・・・・・・Glass plate
2.3...Sustaining electrodes 2a, 3a...Shoulders (or protrusions) 4...Insulating layer 5...
・・・・・・Address electrode 6...
...... Insulating layer 7 ...... Protective layer 8 ... Second plate 9 ...... Stop Seal space 20...
...Display screen 21...
. . . Multicolored screen 50 . . . First plate 52 . . . Layer 56 made of dielectric material.・Dot
60... Second plate 62...
...layers 66, 68 made of dielectric material...
Projecting portion 70... Lines bl, b
2. b3... Band C1,..., C4, C'l,..., C'3...
・Cell di, d2. d′1. d'2...
・・・・・・・・・・・・Average distance LL, L2・・・・
Width PI,..., P6. P'l,...P'12...
... Pixel PE ...... Sustaining electrode set X1.
... X6 ... Column electrode Yl, ..., Y6 ... Row electrode Yac, Ye ... ... Coplanar sustain electrode B.
・・・・・・Blue R・・・・・・Red ■・
・・・・・・Green bB, bR, bV...
,band

【Document name】

[Figure 1] drawing

[Figure 2]

[Figure 4]

[Figure 5]

[Figure 6]

[Figure 7]

[Figure 8]

Claims (9)

[Claims] Claim 1: Consisting of a large number of pixels, each pixel includes at least two cells of different colors, and at least two types of pixels forming the pixel are the cells of these pixels. Pixels of a given type are adjacent to at least one pixel of a different type such that at least two adjacent cells belonging to different types of pixels have the same color. Colored display screen. 2. A display screen according to claim 1, wherein the multicolored display screen is of the plasma panel type. 3. A display screen according to claim 1, wherein the pixel includes three cells of different colors. 4. A display screen according to claim 3, wherein the three colored cells within one and the same pixel are on the same axis, and the central cell is of the same color for all pixels. 5. Cells of different colors are composed of three bands of light emitters, and the width of the band used for the configuration of the terminal cell is equal to the width of the band used for the configuration of the central cell. 4. A display screen according to claim 3, which is twice as large. 6. A display screen according to claim 1, wherein each pixel includes four cells arranged substantially in the form of a trapezoid. 7. A display screen according to claim 6, wherein the two cells of the same pixel have the same color. 8. A display screen as claimed in claim 6, in which four adjacent cells within the various pixels are of equal color. 9. Consisting of luminescent dots having a given color, one luminescent dot being common to four adjacent cells of the various pixels. display screen.