EP0361992B1 - Plasma display panel with a great addressability - Google Patents

Description

The present invention relates to a plasma panel according to the first part of claim 1, the electrodes of which are arranged in a new way, so as to make it possible in particular to increase the speed of obtaining the images displayed by this panel.

Plasma panels have flat screen display devices, now well known, which allow the display of alphanumeric, graphic or other images, in color or not. Generally plasma panels include two insulating tiles limiting a volume occupied by a gas (generally a mixture based on neon). These slabs support conductive electrodes arranged in columns called column electrodes, and electrodes arranged in lines called row electrodes. These column and row electrodes are crossed so as to define a matrix of cells each forming an elementary image or pixel point. The operating principle is the selective generation (at the intersection of row and column electrodes, i.e. at the level of selected pixels) of electrical discharges in the gas. The visualization of the information is ensured by an emission of light which accompanies these discharges.

Some plasma panels operate continuously, but it is more often preferred to use panels of the so-called "alternative" type, the operation of which is based on an excitation in alternating conditions of the electrodes. In this case, the electrodes are covered with a layer of dielectric material, and they are no longer in direct contact with the gas or with the discharge. One of the advantages of this type of “alternative” plasma panel is that it presents a memory effect which allows useful information to be addressed only to the pixels whose state one wishes to change (on or off); on the other elementary points of images or pixels, the state of these latter is simply maintained by repeating discharges alternating electrics, called maintenance discharges, which are obtained only for pixels which are in the on state, that is to say registered.

Under these conditions, the control of the pixels can consist of point-to-point addressing, that is to say pixel by pixel, so that the duration of addressing time which limits the rate of refreshment of the information, does not in general is not a problem.

It should be noted that among plasma panels of the so-called "alternative" type, some use only two electrodes to define a pixel: a cross column electrode with a row electrode. The operation of such a plasma panel is known in particular from a French patent No. 78 04 893 in the name of THOMSON-CSF, published under No. FR-B-2 417 848; this patent also describing a method of controlling such a panel.

Also known are so-called "alternative coplanar maintenance" plasma panels in which three or more electrodes are used to define a pixel. In this case, most often, each pixel of the matrix is formed by three electrodes, more precisely at the intersection between a column electrode with two parallel maintenance electrodes forming a pair of maintenance electrodes. With this type of screen, it is known that the maintenance of the discharges, that is to say the repetition of the alternating electrical discharges previously mentioned, is ensured between the two maintenance electrodes of the same pair, and that the addressing is by generation of discharge between two crossed electrodes. The column electrode in this case has only an addressing function, and among the two electrodes of the same pair of electrodes, one has only a maintenance function and the other provides a maintenance function and an addressing function.

A plasma panel of the alternative type with coplanar maintenance, with three electrodes per pixel, is known in particular from the European patent document EP-A-0135 382, which describes also a method for controlling this screen. The maintenance electrodes may include, at each pixel, a protrusion or protruding surface: in the same pair of maintenance electrodes, the protruding surfaces of one electrode are oriented towards those of the other electrode, the discharges between these protruding surfaces. On this technical point, we can also cite the article "Structure to reduce glow spreading in DC panel" published in IBM TECHNICAL DISCLOSURE BULLETIN, vol. 23, No. 10, March 1981, pages 4536-4537, New York, US; MO ABOELFOTOH: this article describes crossed electrodes whose surfaces are widened at the level of the crossings in order to reduce the priming voltages and locate the discharges.

Another panel structure of the alternative type with coplanar maintenance is described, with its control method, in an article by G.W DICK published in PROCEEDINGS OF THE SID, volume 27/3 1986, pages 183-187. It should be noted that in the structure described in this document, the maintenance electrodes have a constant width, that is to say that they do not have projecting surfaces facing each other in a pair of maintenance electrodes, but on the other hand have barriers made of insulating material, which serve to confine the maintenance discharges in the zone of intersection with the column electrode.

In all these types of plasma panels, the column electrodes are individualized so that it is possible to select only one of them, that is to say that they are each connected to a particular output of '' a control and addressing device. The same is true for the line electrodes in the case where a pixel is defined at the intersection of a column electrode and a single line electrode (both for plasma panels of the continuous type and of the alternative type); and with regard to the plasma panels with coplanar maintenance, among the maintenance electrodes, those which ensure the maintenance function of the discharges and the addressing function (addressing-maintenance electrodes) are also all individualized.

Regardless of the type of plasma panel, the information refresh rate is generally not a problem when the control method used is of the point-to-point addressing type. However, there are applications where it is desired to be able to carry out addressing in the most faster: these are particularly plasma panels for which compatibility with conventional video signals is required, and for which in particular it is desired to carry out control of an intermediate level of luminance ("shades of gray" or "halftone" ).

The time required to form an image depends on the number of pixels and on the overall time required for addressing operations (erasing addressing and / or writing addressing) and maintenance.

To reduce the time required to form an image, it is sought to reduce the overall addressing time, and for this purpose the known method consists in controlling the pixels by an addressing of semi-selective type (which is generally a command either of erasing, either of registration, of all the pixels of a given line), followed by a selective type addressing (in which one or more selected pixels of this line are controlled to be brought to the state opposite to that to which they were carried by semi-selective addressing). These two addressing phases constitute an addressing cycle whose duration seems currently difficult to reduce to less than 20 microseconds.

On the other hand, if we want to avoid visually annoying flickering, the renewal of images in the case of dynamic images or with gray tint must be ensured at least 50 times per second (frame time less than 20 milliseconds) , so that the number of lines entered per frame can hardly exceed a thousand.

If the image is formed of only 512 lines for example, and that the image is renewed 50 times per second, it is possible to obtain four shades of gray taking into account the method used for the control of these shades of gray. Or even with images of only 256 lines, these 256 lines can be written each four times per second, which leads to 16 levels of luminance or shades of gray for each image point, and an image limited to only 128 lines would achieve 64 levels of luminance; whereas however it would be desirable to obtain for example 128 levels of luminance or shades of gray for images of 512 lines.

The current state of the art does not allow a sufficient increase in the speed of addressing line by line, either in order to obtain a sufficient number of half tones as described above, or even in view of other results such as for example increasing the number of lines that make up an image.

The present invention relates to a plasma panel, both of the continuous type and of the alternative type with coplanar maintenance or not, whose new arrangement, particularly at the electrodes, makes it possible to reduce considerably compared to a plasma panel. the prior art, the time required for addressing all the lines which constitute an image, for the same number of pixels per line. This new arrangement of electrodes makes it possible in particular to carry out the simultaneous addressing of several lines of pixels both for the semi-selective addressing phase and for the selective addressing phase.

But this is obtained at the cost of an increase in the number of electrodes, compared to the number of electrodes necessary in the prior art for the same number of pixels, from which there results a difficulty which resides in the fact that the crosses between electrodes reach a number greater than the number of pixels desired.

The new arrangement proposed by the present invention makes it possible to overcome this latter difficulty in a simple manner, and it can be seen that the drawbacks brought by this new arrangement are more than offset by the advantages which it provides with regard to the speed d image.

According to the invention, a plasma panel comprising, pixels arranged in rows and columns, crossed column electrodes with row electrodes and defining a plurality of crossings, a column control and addressing device to which the column electrodes are connected, a line control and addressing device to which the line electrodes are connected, each crossing comprising a crossing surface formed by the surfaces in sight of the row electrode and the corresponding column electrode, characterized in that the crossings consist on the one hand of simple crossings, and on the other hand of widened crossings having a crossover surface larger than that of the simple crossings, each pixel being defined substantially at the level of a widened crossover in that at least two line electrodes are connected to the same output of the line control and addressing device the number M of column electrodes being greater than the number N of the pixels contained in a line formed using a line electrode belonging to a group of electrodes.

The authors of the invention have found that the voltages necessary between the electrodes to obtain the initiation and the maintenance of electrical discharges at the pixel level depend on the crossing surfaces: smaller crossing surfaces require higher voltages and vice versa . So that the voltage applied between the electrodes can be sufficient to cause electrical discharges at the crossings having a sufficient given crossing surface (enlarged crossing where the pixels are made up), and this voltage may be insufficient to cause discharges at the level other crosses with a smaller surface.

• la figure 1 montre schématiquement, à titre d'exemple non limitatif, un panneau à plasma selon une première version de l'invention dans laquelle des électrodes colonnes sont rectilignes et permettent d'obtenir des pixels ayant un premier type de distribution.
• la figure 2 montre schématiquement à titre d'exemple non limitatif un panneau à plasma dans une seconde version de l'invention, dans laquelle les électrodes colonnes sont munies de chicanes formant des changements de direction et permettant d'obtenir une seconde forme de distribution des pixels ;
• la figure 3 montre de manière schématique à titre d'exemple non limitatif, un panneau à plasma selon une version préférée de l'invention, dans laquelle les électrodes colonnes comportent un nombre plus faible de chicanes pour une même distribution des pixels que sur la figure 2 ;
• la figure 4 montre schématiquement à titre d'exemple non limitatif, un panneau à plasma du type à entretien coplanaire comportant un arrangement d 'électrodes conforme à l'invention ;
• la figure 5 montre schématiquement une forme de réalisation différente d'électrodes montrées aux figures 1 à 4.

The invention will be better understood with the aid of the following description, given by way of nonlimiting example, with reference to the appended figures among which:

• FIG. 1 schematically shows, by way of nonlimiting example, a plasma panel according to a first version of the invention in which column electrodes are rectilinear and make it possible to obtain pixels having a first type of distribution.
• FIG. 2 schematically shows by way of nonlimiting example a plasma panel in a second version of the invention, in which the column electrodes are provided with baffles forming changes of direction and making it possible to obtain a second form of distribution of the pixels;
• Figure 3 shows schematically by way of nonlimiting example, a plasma panel according to a preferred version of the invention, in which the column electrodes have a smaller number of baffles for the same pixel distribution as in the figure 2;
• FIG. 4 shows diagrammatically by way of nonlimiting example, a plasma panel of the coplanar maintenance type comprising an arrangement of electrodes according to the invention;
• FIG. 5 schematically shows a different embodiment of the electrodes shown in FIGS. 1 to 4.

FIG. 1 shows a plasma panel which is mainly represented by electrodes arranged in columns X1, X2, ..., X8 called column electrodes, and row electrodes Y1 to Y4 perpendicular to the column electrodes X1 to X8; the column electrodes X1 to X8 being shown in a plane deeper than the plane in which the line electrodes Y1 to Y4 are located.

The column electrodes X1 to X8 are each connected to a different output SX1 to SX8 of a first addressing device or control and addressing device column 2, and the row electrodes Y1 to Y4 are connected to a second device addressing or line 3 command and addressing device.

According to a characteristic of the invention, the line electrodes Y1 to Y4 are made up of groups G1, G2 each connected to a different output SG1, SG2 of the line 3 command and addressing device. In principle, at least one group d 'at least 2 lines Y1 to Y4 is thus formed, but in practice one might think that it is simpler to form a plurality of groups each comprising the same number N at least equal to 2 of line electrodes. With this in mind, in the nonlimiting example of the description where only 4 line electrodes Y1 to Y4 are shown to simplify FIG. 1, these line electrodes are formed in two groups G1, G2: the first group G1 comprising the first and second line electrodes Y1, Y2, and the second group G2 comprising the third and fourth line electrodes Y3, Y4; the two electrodes Y1, Y2 of the first group G1 are connected to the same output SG1 of the control and addressing device line 3, the second output SG2 of which is connected to the two electrodes Y3, Y4 of the second group G2.

Under these conditions the line electrodes Y1, Y2 of the first group G1 correspond to the same address and are therefore addressable simultaneously, and the line electrodes Y3, Y4 of the second group G2 are at a second same address and are therefore addressable simultaneously; so that in a way the first and the second line electrode Y1, Y2 of the first group G1 constitute a single line electrode G1 having at least two branches Y1 and Y2, and the second group G2 constitutes a second single line electrode having two branches Y3 and Y4.

We note that each of the column electrodes X1 to X8 form a crossing with each of the groups G1, G2 at as many points as there are branches or line electrodes Y1 to Y4 belonging to this group: thus for example, considering the first column electrode X1, the latter crosses the first group G1 at the level of the first line electrode Y1 and at the level of the second line electrode Y2; the first column electrode X1 then crosses the second group G2 at the third row electrode Y3 and then at the fourth row electrode Y4; and the same is true for the other column electrodes X2 to X8.

In such a configuration, it is clear that a pixel cannot be formed at each crossing between a column electrode X1 to X8 and a row electrode Y1 to Y4 (as in the prior art) because it is not possible with a traditional method of controlling and addressing pixels, as for example described in the documents which have been mentioned previously, to generate a selective discharge at crossing between a given column electrode and a given line electrode without also avoiding a discharge between this same column electrode and another line electrode belonging to the same group. Thus, for example, one cannot constitute a pixel at the intersection or crossing between the first column electrode X1 and the first row electrode Y1 and constitute another pixel at the crossing of the same first electrode X1 with the second row electrode Y2, these two row electrodes Y1, Y2 belonging to the same first group G1.

Also, with a view to producing only one pixel at the crossing of a given column electrode X1 to X8 with a given row electrode Y1 to Y4 without constituting pixels at the other crossings between this same column electrode and one or more row electrodes Y1 to Y4 belonging to the same group as the given electrode, according to a particularly important characteristic of the invention, the crossing or intersection intended to define a pixel is given a crossing surface Sc (represented in the figure by hatching) larger than the surface of crossing or intersection surface St (represented by hatching) of a simple crossing Cs, that is to say of a crossing not intended to define a pixel; the crossing surface and the intersection surfaces Sc, St are defined by a surface facing the row electrodes Y1 to Y4 and the column electrodes X1 to X8 which form these crossings.

• le long de la première électrode ligne Y1 du premier groupe G1 : un premier pixel Px1 formé par une surface de croisement Sc à l'intersection avec la première électrode colonne X1 ; puis on trouve un croisement simple Cs ayant une surface d'intersection St réduite, formée à l'intersection avec la seconde électrode colonne X2 ; puis on trouve un second pixel PX2 formé par une surface de croisement Sc à l'intersection avec la troisième électrode colonne X3 ; puis un second croisement simple Cs formé à l'intersection avec la quatrième électrode colonne X4 ; et ainsi de suite jusqu'à un quatrième croisement simple Cs formé à l'intersection St avec la huitième électrode colonne X8 ;
• on trouve le long de la seconde électrode ligne Y2 : un croisement simple Cs formé à l'intersection avec la première électrode colonne X1 ; puis un cinquième pixel PX5 formé par une surface de croisement Sc à l'intersection avec la seconde électrode colonne X2 ; puis un croisement simple Cs formé à l'intersection avec la troisième électrode colonne X3 ; puis un sixième pixel PX6 formé par une surface de croisement Sc à l'intersection avec la quatrième électrode colonne X4 ; et ainsi de suite jusqu'à un huitième pixel PX8 formé par une surface de croisement Sc à l'intersection avec la huitième électrode colonne X8.

In the nonlimiting example represented in FIG. 1, we find according to this concept:

• along the first row electrode Y1 of the first group G1: a first pixel Px1 formed by a crossing surface Sc at the intersection with the first column electrode X1; then there is a simple crossing Cs having a reduced intersection surface St, formed at the intersection with the second column electrode X2; then there is a second pixel PX2 formed by a crossing surface Sc at the intersection with the third column electrode X3; then a second cross simple Cs formed at the intersection with the fourth column electrode X4; and so on until a fourth simple crossing Cs formed at the intersection St with the eighth column electrode X8;
• along the second row electrode Y2, there is a simple crossing Cs formed at the intersection with the first column electrode X1; then a fifth pixel PX5 formed by a crossing surface Sc at the intersection with the second column electrode X2; then a simple crossing Cs formed at the intersection with the third column electrode X3; then a sixth pixel PX6 formed by a crossing surface Sc at the intersection with the fourth column electrode X4; and so on up to an eighth pixel PX8 formed by a crossing surface Sc at the intersection with the eighth column electrode X8.

According to a similar arrangement, the row electrodes Y3, Y4 of the second group G2 determine at their crossing with the column electrodes X1 to X8 pixels PX9 to PX12 for the third row electrode Y3 and pixels PX13 to PX16 for the fourth row electrode Y4.

The crossing surfaces Sc (at the pixels PX1 to PX16) can be made larger than the intersection surfaces St that the simple crossings Cs have, for example by widening either of the column electrodes X1 to X8 as shown in the figure 1, either by widening the line electrode Y1 to Y4 or even by widening these two electrodes. Taking for example the crossing surface Sc which defines the first pixel PX1 (this example also being valid for the other crossing surfaces), the first column electrode X1 has at this level a width l1 greater than the width l2 that it comprises at a simple crossing Cs where this column electrode constitutes only a conductor. It has been found, for example, that by giving the width l1 of a crossing surface Sc (forming a pixel) 0.1 mm more than per second width l2 (simple crossing), the resulting increase in surface area makes it possible to lower the voltage necessary to ensure priming (erasure or recording) or maintenance discharges by approximately 10 volts. Consequently, the potential differences developed between column electrodes X1 to X8 and row electrodes Y1 to Y4, during the conventional phases of semi-selective addressing, selective addressing and maintenance, can be adjusted so that , given the increase in the crossing surface Sc at the pixels PX1 to PX16, these potential differences are sufficient to generate the electrical discharges at the pixels, and insufficient to generate the discharges at the simple crossings Cs ; these potential differences being generated for example in a manner known per se, by voltage pulses (not shown), which are applied to these electrodes (X1 to X8 and Y1 to Y4) by the control and addressing devices row and column 3, 2, these having a common reference potential, mass for example; the amplitude of these pulses determining the values of the voltages VY applied to the row electrodes Y1 to Y4 and the values of the voltages VX applied to the column electrodes X1 to X8.

In this configuration, it becomes possible to carry out selective addressing simultaneously for the pixels belonging to rows of pixels L1 to L4 of the same group; the pixels PX1 to PX4 formed with the first row electrode Y1 constitute a first row of pixels L1 which belongs to the first group G1, as do the pixels PX5 to PX8 which are formed with the second row electrode Y2 and which constitute a second row of L2 pixels; the pixels PX9 to PX12 which are formed using the third line electrode Y3 form a third line of pixels L3 which belongs to the second group G2, as are the pixels PX13 to PX16 formed by the fourth line electrode Y3 and which constitute a fourth row of pixels L4.

Thus for example by addressing on the one hand, the first group G1, that is to say simultaneously the first and the second line electrodes Y1 and Y2, and by addressing on the other hand, simultaneously the first, second, sixth and eighth column electrodes X1, X2, X6 and X8, it is possible to selectively either erase or write simultaneously the first pixel PX1 which belongs to the first line L1 and the fifth, seventh and eighth pixels PX5, PX7 and PX8 which belong to the second row of pixels L2.

It should be noted that in the nonlimiting example described, each group G1, G2 comprises only 2 row electrodes Y1, Y2 and Y3, Y4, but of course each group G1, G2 could consist of a greater number n d 'lines electrodes Y1 to Y4; thus the number of line addresses (which corresponds to the number of groups G1, G2) would be smaller compared to the total number of line electrodes Y1 to Y4, so that the number of line electrodes can be addressed simultaneously and consequently the number of lines L1 to L4 of pixels whose pixels PX1 to PX16 can be selectively controlled simultaneously. However, this increase in the number of lines L1 to L4 addressable simultaneously requires an increase in the number of column electrodes X1 to X8. For example in the prior art, to obtain 16 pixels, 4 row electrodes and 4 column electrodes are sufficient: on the other hand with the present invention, if 4 row electrodes are divided into two groups G1, G2, each having a number n of two line electrodes connected to the same output of the line 3 command and addressing device, the number of line addresses is divided by the ratio of the total number of line electrodes to the number of groups (i.e. by 2 in the example), and the number of column electrodes must be increased in the same ratio; that is, if each group G1, G2 had 4 line electrodes, it would be necessary to use 16 column electrodes to form 16 pixels. In other words, assuming that all groups G1, G2 have the same number n of row electrodes, all the lines L1 to L4 can have the same number N of pixels PX1 to PX16, and in this case, the number M of column electrodes X1 to X4 must be equal to the product of the number N of pixels per line L1 to L4 by the number n of line electrodes Y1 to Y4 of each group G1, G2, ie M = Nxn (in the example M = 4x2).

In the nonlimiting example represented in FIG. 1, the column electrodes X1 to X8 are rectilinear, and for a given column electrode it is necessary that at one level or at another, a pixel is separated from a next pixel by a simple crossing Cs; thus for example, in the nonlimiting example described, the first pixel pX1 is separated from the next pixel PX9 by a simple crossing Cs formed with the second row electrode Y2, which constitutes a neighboring pixel PX5 with a neighboring column electrode X2, so that in this arrangement the pixels PX1 to PX16 appear placed in a staggered fashion. Indeed, a first column of pixels C1 is made up of the first and ninth pixels, a second column of pixels C2 is made up of the fifth and thirteenth pixels PX5, PX13, a third column C3 is made up of the second and tenth pixels PX2, PX10 and so on up to an eighth column of pixels C8 which includes the eighth and sixteenth pixels PX8, PX16; these columns of pixels being symbolized in the figure by dashed lines. These pixels are offset from a line electrode to a next line electrode by a distance which corresponds to the pitch P along which the column electrodes X1 to X8 are arranged. However, it is possible to give the column electrodes X1 to X8 a geometry such that all the intersections between a column of pixels and a row electrode Y1 to Y4 are constituted by a pixel.

It should be noted that this arrangement in group G1, G2 of the line electrodes Y1 to Y4 makes it possible to join together on the side of their two ends 5, 6 for example, electrodes lines Y1 to Y4 of the same group G1, G2, using connecting conductors 12.

This results in a particularly important advantage which resides in the fact that a cut 10 of a line electrode, the second line electrode Y2 for example, is self-repairing: indeed, in this case, the power supply of the pixels PX6, PX7, PX8 located on the section Y2 'arranged opposite the first end 5, Relative to the cut 10, is provided by the first line electrode Y1 and by connecting conductors 12 which connect these two line electrodes Y1, Y2.

FIG. 2 represents a matrix 1 according to the invention in which each crossing between a column of pixels and a row electrode Y1 to Y4 constitutes a pixel, so that the pixels PX1 to PX16 are no longer distributed in staggered rows as in example of figure 1.

In the nonlimiting example described, the plasma panel 1 comprises row electrodes Y1, Y2, Y3, Y4 arranged in the same manner as in the example in FIG. 1, and also comprises 8 column electrodes x1 to X8 allowing to make 16 pixels PX1 to PX16.

Contrary to the example of FIG. 1, the column electrodes X1 to X8 are not rectilinear but comprise a plurality of baffles 15 or turns so as to allow alignment on the same column of pixels Ca, Cb, Cc, Cd of pixels PX1 to PX16 formed by neighboring column electrodes X1 to X8 (in the nonlimiting example described, 2 neighboring column electrodes). In the nonlimiting example of the description, the baffles of the column electrodes X1 to X8 which are used to define the same column of pixels, have a complementary shape, but of course these baffles can have a shape different from that shown in FIG. 2 and different from each other.

In the example, the first column electrode X1 crosses the first row electrode Y1, so as to constitute the first pixel P1 which is substantially centered on the line representing the first column of pixels Ca; the first column electrode X1 then becomes parallel to the line electrodes so as to constitute a first spacer baffle 15 and release the intersection with the second line electrode Y2 and the first column of pixels Ca, intersection at which the fifth pixel PX5 is located formed by the passage of the second column electrode X2; which second column electrode X2 comprises a return baffle 16 which makes it possible to place it on the column Ca. The intersection between a straight section T of the first column electrode X1 and the second row electrode Y2 constitutes a simple crossing Cs located outside the column Ca, and after this simple crossing, the first column electrode X1 comprises a return baffle 16 which brings it back to the column Ca of pixels so that, when it collols with the third row electrode Y3, it forms the ninth pixel PX9; of course the second column electrode X2 has a spacer baffle 15 which allows it to move away from the column Ca of pixels to make room for the first column electrode X1. As shown in FIG. 2, a similar arrangement is made for crossing the other row electrodes, and likewise for the other column electrodes X3 to X8; so that the pixels Px1 to PX16 are aligned on four columns of pixels Ca, Cb, Cc, Cd, each comprising four pixels, while the rows of pixels L1 to L4 also have four pixels as in the example in FIG. 1 .

It should be noted that in the nonlimiting example described, the turns or baffles 15, 16 are formed by changes of direction of the column electrodes X1 to X8 which operate in directions perpendicular and / or parallel to the line electrodes Y1 to Y4 and columns Ca to Cd of pixels, but these turns could also be made by oblique directions, as illustrated for example by lines 17 in dotted lines at the level of the seventh pixel PX7 formed between the sixth column electrode X6 and the second row electrode Y2.

FIG. 3 shows a plasma panel according to the invention, and illustrates how to simplify the column electrodes so as to reduce the number of baffles 15, 16 or turns for the same arrangement of the pixels as in the example of FIG. 2. In the non-limiting example described, FIG. 3 shows three groups G1, G2, G3 connected to an output SG1, SG2, SG3 of the line 3 command and addressing device; each group comprising two line electrodes Y1 and Y2, Y3 and Y4, Y5 and Y6 respectively, according to an arrangement similar to that previously described; 6 column electrodes X1 to X6 are shown assembled two by two so that the pixels formed by two column electrodes are arranged in the same column of pixels. Also for each line electrode Y1 to Y6 three simple crosses Cs and three pixels are formed, that is to say in all 18 pixels PX1 to PX18 in the example, at the rate of three pixels per line L1 to L6 and six pixels by columns Ca, Cb, Cc.

Starting with the first column electrode X1, the latter is aligned on the line which represents the first column Ca of pixels: it crosses the first row electrode Y1 so as to constitute the first pixel PX1 then departs from the first column Ca with a spacer baffle 15 and then becomes perpendicular to the line electrodes in order to cross, according to simple crossings Cs, the second and third line electrodes Y2, Y3; then, a return baffle 16 brings it back on the axis of the first column Ca so that it successively crosses the fourth and fifth row electrodes Y4 and Y5 by forming the pixels PX10 and PX13; a baffle 15 separates it again from the first column Ca and it takes a direction perpendicular to the sixth row electrode Y6 which it crosses at a simple crossing Cs located outside the first column Ca. The second column electrode X2 to start, is parallel to the first column electrode X1 and crosses the first row electrode Y1 according to a simple crossing Cs, crossing after which it has a return baffle 16 which places it on the axis of the first column Ca so that it successively crosses the second and third row electrodes Y2, Y3 along the same straight line with which it constitutes the fourth and seventh pixels PX4, PX7; then it is offset from the axis of the first column Ca by a spacer baffle 15 and crosses the fourth and fifth row electrodes Y4 and Y5 by simple crossings Cs before being brought back to the axis of the first column Ca by a return baffle 16. It is then perpendicular to the sixth line electrode Y6 which it crosses constituting the sixteenth pixel PX16. The same shape is given to the third and fourth column electrodes X3, X4 which together make it possible to constitute a second column Cb of pixels formed by the pixels PX2, PX5, PX8, PX11, PX14 and PX17; the fifth and sixth column electrodes X5, X6 likewise constitute pixels PX3, PX6, PX9, PX12, PX15, PX18 aligned in the same column Cc.

In this arrangement, it is noted that each column electrode X1 to X6 has straight sections T between row electrodes Y1 to Y6 which are adjacent but belong to different groups G1, G2, G3, this as well between simple crossings Cs as crosses with enlarged surface Sc forming pixels; which results in a reduction in the number of baffles and a simplification of manufacturing.

FIG. 4 shows that the invention is also applicable to the case of a plasma panel 1 of the coplanar maintenance type. In the nonlimiting example of the description, the panel 1 comprises 8 pixels arranged in two columns: a first column of pixels Ca comprises four pixels PX1, PX3, PX5, PX7 and the second column Cb comprises the four pixels PX2, PX4, PX6, PX8.

The pixels PX1 to PX8 are defined at the crossing between only addressing electrodes forming, in the nonlimiting example described, four column electrodes, X1, X2, X3 and X4, with pairs of maintenance electrodes at number of four P1, P2, P3, P4 and which are perpendicular to the addressing only electrodes; the pairs P1 to P4 are therefore arranged in lines. In a conventional manner in itself, each pair P1 to P4 is constituted by a so-called maintenance only electrode E1 to E4, the function of which is only to allow maintenance discharges and which, at the same instants are brought to the same potentials; so that these maintenance-only electrodes do not have to be addressed and therefore do not have to be individualized, and can optionally be all connected to each other on the side of their first end 25, by a connecting conductor 20 and can be connected to the same output 22 of a pulse generator 21.

Each pair P1 to P4 further comprises a so-called addressing-maintenance electrode Y'1 to Y'4 which has the function on the one hand, with the maintenance only electrodes E1 to E4 of ensuring the maintenance discharges pixels PX1 to PX8, and which also provides an addressing function; the column electrodes X1 to X4 providing only an addressing function.

Also, the addressing-maintenance electrodes Y'1 to Y'4 must be individualized as was the case for the electrodes Y1 to Y4 of the previous examples. In accordance with the concept of the invention, the address-maintenance electrodes are assembled in groups G1, G2, each group comprising at least two address-maintenance electrodes linked together and with the control and addressing device line 3 d 'the same way as in the previous examples for the line electrodes Y1 to Y4. In the example shown in FIG. 4, the first and second addressing-maintenance electrodes Y'1, Y'2 are connected together on the side of their first end 5 and connected to the output SG1 of the control device and addressing 3 and they are also connected to each other on the side of their second end 6 by a link 12. In the nonlimiting example described, with respect to the plane of the figure, the electrodes of the pairs P1 to P4 are represented in a plane deeper than that of the column electrodes X1 to X4.

In this configuration, starting from the top of the figure, a first maintenance-only electrode E1 forms a pair P1 with a first addressing-maintenance electrode Y'1; then a second addressing-maintenance electrode Y'2 constitutes a second pair P2 with a second maintenance-only electrode E2; there is then a third maintenance-only electrode E3 which we note that it is connected by a link 26 to the second maintenance-only electrode E2, on the side of a second end 27 of these electrodes. The third maintenance only electrode E3 forms a third pair P3 with a third addressing-maintenance electrode Y'3; this third addressing-maintenance electrode Y'3 is followed by a fourth addressing-maintenance electrode Y'4 which constitutes, with a fourth maintenance-only electrode E4, a fourth pair P4 of maintenance electrodes.

As in the previous examples relating to the line electrodes Y1 to Y4, the addressing-maintenance electrodes Y'1 to Y'4 belonging to the same group G1, G2 are joined together on the side of their two ends 5, 6. So that the advantage cited above on the self-repair of cuts can also exist in this application of the invention, and this advantage also exists for the electrodes solely for maintenance E1 to E4 which also can be joined at their two ends 25 , 27, from the fact that these maintenance electrodes Y'1 to Y'4 and E1 to E4 are arranged in a succession of two solely maintenance electrodes E1 to E4 followed by two addressing-maintenance electrodes Y1 to Y4. It should be noted that this provision also makes it possible to reduce the capacities lateral (not shown) formed between pairs P1 to P4 of successive electrodes.

The first column electrode X1 crosses the first pair P1 above projecting parts 30, 31 with which the maintenance only electrodes E1 to E4 and the addressing-maintenance electrodes Y'1 to Y'4 are provided respectively. These protrusions 30, 31 constitute localized increases in the surface of these electrodes, and in the same pair P1 to P4 the protrusions 30, 31 are opposite and oriented towards one another. These projecting parts 30, 31 are arranged at the pixels PX1 to PX8, and one of the advantages of these projecting parts is to locate the maintenance discharges. Another advantage in the context of the present invention is that at least one of these projecting parts 30, 31, in particular that which belongs to the addressing-maintenance electrodes Y'1 to Y'4 makes it possible to obtain a crossing surface Sc at each pixel larger than the intersectlon surface St formed at the simple crossing Cs of a column electrode X1 to X4 with one of the maintenance electrodes, that is to say outside the one of these projecting parts; this latter crossing then constituting a simple crossing Cs, if the previously mentioned potential differences are small enough for electrical discharges to be generated between a pair P1 to P4 and a column electrode X1 to X4 only at the pixels PX1 to PX8.

As has already been explained, the widened crossing surfaces Sc, that is to say which make it possible to constitute a pixel, can also be obtained by playing on the shape of the line electrodes, which is the case elsewhere in the example described with reference to FIG. 4 where it must be admitted that the maintenance electrodes Y'1 to Y'4 or E1 to E4 are electrodes arranged in line. However, particularly in the case of plasma panels for which the maintenance discharges are not carried out between coplanar maintenance electrodes, the line electrodes Y1 to Y4 may have a geometry of the type shown for example in FIGS. 5 in order to produce crossing surfaces with an enlarged surface.

FIG. 5 shows row electrodes Y1, Y2 which are represented in a deeper plane than column electrodes X2, X3 relative to the plane of the figure; the example being limited to the representation of two row electrodes and two column electrodes Y1, Y2 and X1, X2 to simplify FIG. 5. The embodiment shown in FIG. 5 makes it possible to obtain crossing surfaces Sc with surface enlarged, that is to say capable of forming pixels by a modification of the geometry of the electrodes of the lines Y1, Y2 at the places provided for forming these pixels. In the nonlimiting example described, this embodiment is particularly applicable to a distribution of the pixels as shown in FIG. 1, and for example, particularly in the case of the crossings formed between the two line electrodes Y1 and Y2 and the two column electrodes X1 and X2; but of course the geometry which is given to the line electrodes Y1, Y2 could be used with another distribution of the pixels, as shown for example in FIGS. 2 and 3, and it should be noted in addition that the column electrodes could also have a similar geometry.

The line electrodes Y1, Y2 each consist of first and second parallel conductors 35, 36 each having for example a width l3 which was also the width of the line electrodes in the previous examples; the column electrodes X1, X2 having the second width l2 (the smallest).

At the intersection between column electrodes X1, X2 and row electrodes Y1, Y2 which are intended to constitute pixels, the two conductors 35, 36 of the same row electrode Y1, Y2 are connected by a bonding surface S1 which can be assimilated to an increase in the width 13 of one or the other or of the two conductors 35, 36. It follows that the crossings have a greater crossover area Sc at the crossovers intended to constitute pixels than for the other crossings: thus for example starting from the top of the figure, the first column electrode X1 crosses the first row electrode Y1 at a surface of connection S1 so that the crossing surface Sc is sufficient to constitute a pixel PX1, that is to say that the voltage applied between the column electrode X1 and the row electrode Y1 makes it possible to generate discharges at this level; then the first column electrode X1 crosses the second row electrode Y2 successively at the level of the first and of the second conductor 35, 36 with which it successively forms intersection surfaces St which do not make it possible to obtain discharges with voltage conditions also weak than those which allow discharges at the pixel PX1. For the second column electrode X2, its crossing with the first row electrode Y1 determines two intersection surfaces St of smaller surfaces, and then its crossing with the second row electrode Y2 at a level where the latter has a connecting surface S1 defines a crossing surface Sc sufficient to constitute a pixel PX5.

This description constitutes a nonlimiting example which shows on the one hand, that it is possible to form a number of crossings between row electrodes and column electrodes greater than the number of pixels desired, by producing larger crossing surfaces Sc at the level of the pixels than for the other crossings Cs and by adjusting the voltages VX and the voltages VY applied respectively to the column electrodes and to the row electrodes so that the potential differences VX-VY generated by these voltages between these column electrodes and row electrodes are sufficient for obtain electrical discharges at the pixel level and insufficient to produce electrical discharges at the level of the other simple crossings; of course, other embodiments are possible without departing from the scope of the invention, as regards for example the shape of the electrodes and their arrangement in rows or columns, or also the position of the column electrodes on the side of the visible part of the panel or vice versa. This description also shows how to arrange the different row and column electrodes in order to obtain, in combination with the above-mentioned production of pixels and an increase in the number of column electrodes, row electrodes assembled by group; the line electrodes of the same group being connected to the same output of the command and addressing register line 3, so that for the same number of lines of pixels (each line L1 to L4 of pixels corresponding to a line electrode Y1 at Y4) the number of addresses is reduced; and it is possible to simultaneously control the pixels which are formed using line electrodes situated at the same address, that is to say belonging to the same group G1, G2, the selection of the pixels belonging to the same group being obtained by addressing or choice of column electrodes whose number is increased.

It should be noted that the invention can be applied to all plasma panels of the alternative type, regardless of precisely their production technology and their control mode. The invention can also be applied to the case of plasma panels of the continuous type, for which the implementation of the invention offers additional advantages because in these panels of the continuous type, the number of lines to be controlled limits not not only the duration of the total addressing cycle, but also the amount of light that a pixel can emit. The application of the invention therefore makes it possible, in the case of the plasma panel of the continuous type, to improve each of these two parameters at the same time.

Claims (20)

1. Plasma panel including pixels (PX1 to PX16) arranged in lines (L1 to L4) and columns (C1 to C8, Ca to Cd), column electrodes (X1 to X8) crossed by line electrodes (Y1 to Y4) and defining a plurality of crossings (Cr, Cs), a column control and addressing device (2) to which the column electrodes (X1 to X8) are linked, a line control and addressing device (3) to which the line electrodes (Y1 to Y4) are linked, each crossing including a crossing surface (Sc, St) formed by the corresponding opposite surfaces of the line electrode (Y1 to Y4) and of the column electrode (X1 to X8), characterised in that the crossings consist, on the one hand, of simple crossings (Cs), and, on the other hand, of widened crossings having a larger crossing surface (Sc) than that of the simple crossings (Cs), each pixel (PX1 to PX16) being defined substantially in the region of a widened crossing, and in that at least two line electrodes (Y1, Y2) are linked to the same output (SY1) of the line control and addressing device (3), the number M of column electrodes (X1 to X4) being greater than the number N of pixels (P1 to PX 16) contained in a line (L1 to L4) formed with the aid of a line electrode (Y1 to Y4) belonging to a group of electrodes.
2. Plasma panel according to Claim 1, characterised in that the line conductors (Y1 to Y4) consist of a plurality of groups (G1, G2) each including at least two line electrodes linked together (Y1, Y2 and Y3, Y4), each group (G1, G2) being linked to a different output (SY1, SY2) of the line control and addressing device (3).
3. Plasma panel according to Claim 2, characterised in that all the groups (G1, G2) include the same number n of line electrodes (Y1 to Y4).
4. Plasma panel according to one of the preceding claims, characterised in that the column electrodes (X1 to X4) and/or the line electrodes (Y1 to Y4) have a width (l1, S1) greater in the region of the pixels (PX1 to PX16) than the width (12, 13) which they possess in the region of the simple crossings (Cs).
5. Plasma panel according to one of the preceding claims, characterised in that the number M of column electrodes (X1 to X4) corresponds to the product of the number n of line electrodes (Y1 to Y4) which constitute the same group (G1, G4) and the number N of pixels (PX1 to PX16) contained in a line (L1 to L4) of pixels, i.e. $\text{M = n x N}$

   

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6. Plasma panel according to one of the preceding claims, characterised in that the column electrodes (X1 to X4) are substantially in a straight line.
7. Plasma panel according to any one of Claims 1 to 5, characterised in that the column electrodes (X1 to X4) and/or the line electrodes (Y1 to Y4) include bends (15, 16).
8. Plasma panel according to Claim 7, characterised in that a column (C1 to C4) of pixels is constituted with the aid of at least two column electrodes (X1 to X4).
9. Plasma panel according to Claim 7, characterised in that the bends (15, 16) are constituted by successive changes in direction which are substantially perpendicular from one direction to another.
10. Plasma panel according to one of the preceding claims, characterised in that the column electrodes (X1 to X4) and/or the line electrodes (Y1 to Y4) are formed by at least two parallel conductors linked together by a linking surface (S1) in the region of the widened crossings (Sc) where pixels (PX1 to PX16) are constituted.
11. Plasma panel according to one of the preceding claims, characterised in that at least two line electrodes (Y1 to Y4) of the same group (G1, G2) are linked together at each of their ends (5, 6).
12. Plasma panel according to one of the preceding claims, characterised in that the line and column control and addressing devices (2, 3) deliver voltages (VY, VX) which are sufficient to generate electrical discharges in the region of the pixels (PX1 to PX16) and insufficient to generate these discharges in the region of the simple crossings (CS).
13. Plasma panel according to any one of the preceding claims, characterised in that it is of the alternating type with coplanar hold.
14. Plasma panel according to Claim 13, characterised in that it includes pairs (P1 to P4) of hold electrodes crossed by addressing-only electrodes (X1 to X4), each pair (P1 to P4) of electrodes being formed by an addressing/hold electrode (Y'1 to Y'4) and a hold-only electrode (E1 to E4), the addressing/hold electrodes (Y'1 to Y'4) and the hold-only electrodes (E1 to E4) including projecting surfaces (30, 31) which, between the two electrodes of the same pair (P1 to P4), are oriented towards one another and make it possible to define, at the crossing by an addressing-only electrode (X1 to X4), a widened surface at which a pixel (PX1 to PX16) is constituted.
15. Plasma panel according to Claim 14, including a first and a second addressing devices (2, 3) to which the addressing-only electrodes (X1 to X4) and the addressing/hold electrodes (Y'1 to Y'4) are respectively linked, characterised in that the addressing/hold electrodes (Y'1 to Y'4) are constituted into a plurality of groups (G1, G2) each including at least two addressing/hold electrodes (Y'1 to Y'4) linked together, each group (G1, G2) being linked to a different output (Sy1, Sy2) of the second addressing device (3).
16. Plasma panel according to Claim 14, characterised in that the arrangement of the hold-only (E1 to E4) and addressing/hold (Y'1 to Y'4) electrodes includes at least one succession of two hold-only electrodes (E1 to E4) followed by two addressing/hold electrodes (Y'1 to Y'4) of the same group (G1, G2).
17. Plasma panel according to Claim 16, characterised in that two successive addressing/hold electrodes (Y'1 to Y'4) of the same group (G1, G2) are linked together at their two ends (5, 6).
18. Plasma panel according to Claim 17, characterised in that two successive hold-only electrodes (E1 to E4) are linked together at their two ends (25, 26).
19. Plasma panel according to Claim 15, characterised in that, in addition to the widened crossings forming pixels (PX1 to PX16), the crossings between addressing-only electrodes (X1 to X4) and the pairs (P1 to P4) constitute simple crossings (Cs) having a crossing surface (St) smaller than the crossing surface (Sc) of the pixels (PX1 to PX16), and in that the addressing devices (2, 3) deliver voltages (VY, VX) which are sufficient to generate electrical discharges in the region of the pixels (PX1 to PX16), and insufficient to generate these discharges in the region of the simple crossings (Cs).
20. Plasma panel according to Claim 14, characterised in that the addressing-only electrodes (X1 to X4) constitute column electrodes and in that the pairs (P1 to P4) are arranged in lines.

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