Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J11/00—Gas-filled discharge tubes with alternating current induction of the discharge, e.g. alternating current plasma display panels [AC-PDP]; Gas-filled discharge tubes without any main electrode inside the vessel; Gas-filled discharge tubes with at least one main electrode outside the vessel
  • H01J11/10—AC-PDPs with at least one main electrode being out of contact with the plasma
  • H01J11/12—AC-PDPs with at least one main electrode being out of contact with the plasma with main electrodes provided on both sides of the discharge space
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J11/00—Gas-filled discharge tubes with alternating current induction of the discharge, e.g. alternating current plasma display panels [AC-PDP]; Gas-filled discharge tubes without any main electrode inside the vessel; Gas-filled discharge tubes with at least one main electrode outside the vessel
  • H01J11/20—Constructional details
  • H01J11/22—Electrodes, e.g. special shape, material or configuration
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J11/00—Gas-filled discharge tubes with alternating current induction of the discharge, e.g. alternating current plasma display panels [AC-PDP]; Gas-filled discharge tubes without any main electrode inside the vessel; Gas-filled discharge tubes with at least one main electrode outside the vessel
  • H01J11/20—Constructional details
  • H01J11/34—Vessels, containers or parts thereof, e.g. substrates
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J11/00—Gas-filled discharge tubes with alternating current induction of the discharge, e.g. alternating current plasma display panels [AC-PDP]; Gas-filled discharge tubes without any main electrode inside the vessel; Gas-filled discharge tubes with at least one main electrode outside the vessel
  • H01J11/20—Constructional details
  • H01J11/34—Vessels, containers or parts thereof, e.g. substrates
  • H01J11/36—Spacers, barriers, ribs, partitions or the like
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J2211/00—Plasma display panels with alternate current induction of the discharge, e.g. AC-PDPs
  • H01J2211/20—Constructional details
  • H01J2211/22—Electrodes
  • H01J2211/24—Sustain electrodes or scan electrodes
  • H01J2211/245—Shape, e.g. cross section or pattern
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J2211/00—Plasma display panels with alternate current induction of the discharge, e.g. AC-PDPs
  • H01J2211/20—Constructional details
  • H01J2211/22—Electrodes
  • H01J2211/32—Disposition of the electrodes
  • H01J2211/326—Disposition of electrodes with respect to cell parameters, e.g. electrodes within the ribs
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J2211/00—Plasma display panels with alternate current induction of the discharge, e.g. AC-PDPs
  • H01J2211/20—Constructional details
  • H01J2211/34—Vessels, containers or parts thereof, e.g. substrates
  • H01J2211/36—Spacers, barriers, ribs, partitions or the like
  • H01J2211/361—Spacers, barriers, ribs, partitions or the like characterized by the shape
  • H01J2211/365—Pattern of the spacers

Definitions

• the invention relates to a plasma display panel comprising a first panel 11 and a second panel 12 providing between them a space filled with partitioned discharge gas, in particular using a network of barriers, in a plurality of discharge cells 17 arranged in rows and columns.
• the first panel 11 comprises at least two arrays of so-called coplanar electrodes Y, Y ′ of maintenance, which are oriented in general directions parallel to each other and to the cell lines, and which are coated with a dielectric layer 13 and d 'a layer of protection and emission of secondary electrons 14 (dashed in the figure).
• the second panel 12 comprises at least one network of so-called addressing X electrodes, which are oriented in general directions parallel to each other and to the columns of cells, and which are coated with a dielectric layer 16.
• the electrodes Y, Y ′, X of the various networks are arranged so that each discharge cell is crossed by an electrode of each network.
• the network of insulating barriers comprises inter-cell separation elements 15 each separating two adjacent columns of cells.
• the invention also relates to an image display device comprising such a plasma panel and means for controlling and supplying the electrodes of this panel which are adapted:
• these control and supply means are suitable: - To apply, between the addressing electrode X and one of the maintenance electrodes Y or Y 'which pass through each cell 17, an addressing voltage signal suitable for depositing electrical activation charges on the layer dielectric covering said maintenance electrode, - to apply, between the maintenance electrodes Y, Y 'which cross each row of cells, a succession of maintenance voltage signals suitable for generating plasma discharges only in the cells of this line which have been previously activated, and to generate, just before or during each maintenance signal, between the addressing electrodes X and one or the other of the maintenance electrodes Y or Y ′ which pass through the cells from this line, a trigger voltage signal adapted to trigger said discharges.
• Trigger signals can be automatically induced or applied voluntarily using a suitable generator; these signals induce matrix discharges in the thickness of the gas space separating the slabs, in order to facilitate the start of maintenance discharges between the coplanar electrodes.
• An objective pursued by the invention is to improve the light output of this type of panel.
• the invention relates to a plasma display panel comprising a first panel and a second panel providing between them a space filled with partitioned discharge gas, in particular using a network of barriers, in a plurality of discharge cells arranged in rows and columns, said first slab comprising at least two arrays of so-called coplanar electrode electrodes which are oriented in general directions parallel to each other and to said lines, said second slab comprising at least one array of so-called addressing electrodes, which are oriented in general directions parallel to each other and to said columns, said electrodes being arranged so that, at each cell, an addressing electrode crosses an electrode of each maintenance network, said network of barriers comprising inter-column separating elements each separating two adjacent columns of cells, characterized in that, each cell subdividing into a triggering zone at each of the crossings of the addressing electrode with a maintenance electrode, and into at least one zone of coplanar discharge expansion s extending between the trigger zones, said network of barriers is adapted so that, at the level of each cell, that is to say
• each cell includes at least two trigger zones, each located at a crossing of the addressing electrode with a maintenance electrode.
• Each expansion zone forms a channel intended to contain the positive pseudocolumn of the coplanar plasma discharge.
• this channel has at least a narrower portion of constriction of the positive pseudo-column; this narrower part corresponds to said interval located between the trigger zones; the expansion zone can be narrow all along the channel, in which case said interval corresponds to the distance between the trigger zones.
• the plasma panel described in document WO03 / 060864 (not published on the priority date of this document, but a priori benefiting from an earlier priority date) has, at the level of each cell, one or more cavities ; when these cavities are curved or elliptical as in FIGS.
• these cavities provide zones of coplanar expansion whose width, measured along the lines, is not constant; nevertheless, nothing indicates in this document that there exist in each cell at least two triggering zones at the intersection of an addressing electrode carried by a slab and a coplanar electrode carried by another slab; nor, a fortiori, that there is an interval between these trigger zones; nor, a fortiori, that the width of the expansion zone measured along the lines in this interval is less than the width of the trigger zones also measured along the lines.
• the plasma panel described in document US2003 / 0080683 is provided with a network of addressing electrodes and with four (or even only three) networks of coplanar electrodes; as in the invention, at each cell, an addressing electrode crosses an electrode of each coplanar network; as indicated in ⁇ 30 of this document (and in more detail below), it is one of the coplanar electrodes X 'or Y' positioned in the center of each cell which is used to trigger each coplanar discharge, and not the addressing electrode as in the invention; at the level of the triggering zone of each cell, in this case here in the center of this cell, the barrier separating the columns only extends halfway up so that the cells seem wider at this point, at least on the side of the slab carrying the coplanar electrodes (see Figure 1 of the document); however:
• the coplanar expansion zone between the electrodes X and Y does not, unlike the invention, have an interval located between the zones of trigger;
• the width of the area expansion is, at no point in this interval, less than the width of one or the other trigger zone, unlike the invention; in fact, in this interval, as at each triggering zone, the barrier separating the columns extends only halfway up, so that the width is identical in all points.
• the network of barriers is adapted so that, at the level of each cell, the width of each zone of coplanar expansion measured in the direction of the lines between two adjacent dividing elements delimiting it is at least 15% less than the width of all the trigger zones measured in the direction of the lines between two adjacent dividing elements delimiting them.
• the first slab only comprises two networks of coplanar maintenance electrodes, unlike the panel described in document US2003 / 0080683; according to a variant, each maintenance electrode serves the cells of two consecutive rows of cells; this simplifies the manufacture of the panel.
• said inter-column separation elements extend continuously over approximately the entire height of said space between the slabs, unlike the barriers described in document US2003 / 0080683.
• the second slab comprises a single array of addressing electrodes, so that each cell is crossed only by a single addressing electrode; this simplifies the manufacture of the panel.
• the ignition voltage of a maintenance discharge between two coplanar maintenance electrodes obviously depends on the electrical charges previously stored on the dielectric layer covering these electrodes in the vicinity of the ignition zone; these charges may have been previously stored during a previous maintenance discharge or during an addressing operation; thus, before a maintenance discharge in a cell, positive charges are generally stored on the maintenance electrode which will serve as anode and negative charges on the maintenance electrode which will serve as cathode; these stored charges create what is called a voltage of memory ; the ignition voltage corresponds to the voltage of a maintenance signal applied between the electrodes, to which is added the memory voltage.
• the electronic avalanche which occurs in the discharge gas between the electrodes passing through this cell creates a positive space charge which concentrates towards the cathode to form what is called a cathode sheath;
• the plasma zone, known as the positive pseudo-column which is located between the cathode cladding and the anode end of the discharge, contains in equal proportion positive and negative charges; this area is therefore conductive of the current and the electric field is weak there; the electrons present in the positive pseudo-column zone have a relatively low energy, which promotes the excitation of the discharge gas and the production of ultraviolet photons with a high energy yield.
• the most significant part of the potential drop corresponds to the cathode cladding zone; the impact of the ions which are accelerated in the intense field of the cathode sheath and which are pulverized on the layer of protection and emission of secondary electrons, which covers the dielectric layer and the electrodes of maintenance, involves a significant emission secondary electrons in the vicinity of the cathode; under the effect of this intense electronic multiplication, the density of the conducting plasma then increases strongly between the electrodes, both in ions and in electrons, which causes a contraction of the cathode sheath in the vicinity of the cathode and the positioning of this sheath at the level where the plasma ions are deposited, on the portion of dielectric surface covering the coplanar electrode serving as cathode; on the anode or anodes side, the plasma electrons, which are much more mobile than the ions, are deposited on the portion of dielectric surface covering the coplanar electrode serving as ano
• the light output of the plasma panels is generally low because a large amount of the electrical power supply and maintenance of the panel is dissipated in the acceleration of the ions and in the heating of the walls under the effect of the spraying of the ions.
• the document US Pat. No. 6,184,848 describes a method for controlling the maintenance discharges which allows a first improvement in the luminous efficiency of the discharges. As illustrated in FIGS. 1A and 1B, the distance, or "gap", separating the maintenance electrodes Y, Y 'is substantially increased so that the discharges between these two electrodes are only possible by means of a discharge low intensity trigger. As illustrated in FIG.
• such a trigger discharge D M is obtained following a trigger signal, automatically induced or voluntarily applied, between a Y 'of the maintenance electrodes serving as cathode and the electrode of X addressing serving as an intermediate anode.
• a trigger signal automatically induced or voluntarily applied
• the electrons moving faster than the ions follow the lines of increasing potential up to the second maintenance electrode Y serving as anode, and, as illustrated in FIG. 2C, establish a current between the two maintenance electrodes, creating a long positive pseudo-column D E in which the excitation of the gas is very effective in generally UV light emission. This significantly improves the light output of plasma panels.
• the matrix discharge may be ineffective if the current density is too high there. , because, then, the electric field is important there.
• the luminous efficiency of the positive pseudo-column of the coplanar discharge is directly linked to the density of the current flowing through it. If the current density decreases, the efficiency increases.
• a further improvement in the light output of the plasma panels is thus obtained, by enlarging the cells at the point of ignition of the discharges, that is to say in the triggering zones, and in shrinking cells or subdividing them at the expansion zones.
• the section of one or the other of the trigger zones has a surface greater than the sections of each expansion zone.
• the invention thus proposes an optimization of the profile of the barriers of the panel so as to favor an ignition with low anodic capacity with a large cathode surface, while retaining a high efficiency of positive pseudo-column.
• the plasma panel according to the invention comprises two slabs separated by a gas space partitioned by separation elements forming a network of barriers, and networks of coplanar maintenance and addressing electrodes; each cell subdividing into a trigger zone at each of the crossings of an addressing electrode with a maintenance electrode, and at least one coplanar discharge expansion zone extending between the trigger zones, the barrier network is adapted so that, at the level of each cell, each coplanar expansion zone has a width which is less, preferably at least 15%, than the width of all the trigger zones.
• each cell comprises only a single expansion zone between two adjacent trigger zones.
• the separation elements which delimit trigger zones or expansion zones also delimit the cells: these are inter-cell separation elements, which are part of the network of barriers and which separate, each , two adjacent columns of cells.
• each cell then has a narrowing only at its expansion zone and a widening at each trigger zone.
• These narrowing and widening can in particular be obtained by adapting the network of barriers: the separation elements between the columns are widened at the location of the narrowing and narrowed at the location of the widening.
• the adaptation of the barrier network then leads overall to an increase in the overall surface area of the apexes of the barriers, which advantageously increases the surface area of the black contrast network which is generally applied at the top of the barriers, thereby increasing the contrast of viewing images in ambient light.
• the cells of any one column of the panel are offset in the general direction of the columns with respect to the cells of an adjacent column, so as to obtain a better nesting of the cells, which allows advantageously increase the density or the surface of the cells of the panel.
• each cell comprises a plurality of expansion zones between two adjacent trigger zones. These different expansion zones of the same cell are therefore arranged in parallel between two same trigger zones; this subdivision of the cells in the width direction, only between the trigger zones and not at the level of the trigger zones themselves, is another advantageous means of constricting the zones of expansion.
• the multiplication of the expansion zones brings a significant improvement in the light output of the panel.
• each cell is subdivided by at least one intra-cell separation element which extends in the direction of the columns in said interval located between the trigger zones and which delimits two adjacent expansion zones of this cell.
• These intra-cell separation elements are also part of the barrier network. Their dimensions are adapted to obtain the plurality of expansion zones operating in parallel. These intra-cell separation elements are generally not load-bearing, that is to say that their height is generally less than that of the inter-cell separation elements, also less than the distance between the slabs.
• the intra-cell barrier elements according to the invention are interrupted at the level of the triggering matrix discharge zones, generally say at the intersections of the address electrodes and the maintenance electrodes, so as to provide a larger space for the matrix trigger discharges.
• Each cell is preferably crossed only by a single addressing electrode; preferably, the intra-cell separation element is then positioned with regard to this addressing electrode, unlike the panel shown in FIG. 21 of US6376995.
• the coplanar electrodes are coated with a dielectric layer and with a protective and secondary electron emission layer.
• the dielectric layer thus ensures the memory effect which makes it possible to control the panel by a succession of addressing and maintenance operations; the protective and secondary electron emission layer in particular makes it possible to lower the operating voltages of the panel.
• the distance separating the electrodes from the different coplanar networks is greater than the distance separating the slabs.
• Such a panel structure is particularly advantageous in the case of the use of means for controlling and supplying the electrodes adapted so that each coplanar discharge is triggered by a matrix discharge.
• the distance separating two maintenance electrodes corresponds to the coplanar “gap”; the distance between the tiles corresponds to the thickness of the gas space between the tiles; the invention therefore preferably applies to so-called "large gap” panels which are particularly suitable for piloting by matrix triggering; in practice, a "gap" of the order of 500 ⁇ m is commonly used.
• the invention also relates to an image display device comprising a plasma panel according to the invention characterized in that it comprises means for controlling and supplying the electrodes of this panel capable of applying to these electrodes signals adapted to generate, at each cell, coplanar discharges between the different coplanar electrodes passing through it and so that these discharges are each triggered by a matrix discharge between the addressing electrode passing through it and one of said coplanar electrodes.
• the frames of the images to be displayed are generally subdivided into sub-frames capable of generating, by their succession, the gray levels necessary for viewing.
• the display of a subframe generally comprises an addressing step and a maintenance step;
• the addressing step which generally includes a single voltage pulse, aims to generate the surface charges necessary for triggering the first coplanar maintenance discharge of the next step, only and selectively in the cells of the panel which must be activated during the sub-frame considered;
• the following maintenance step comprises as many voltage pulses as coplanar discharges to be generated in the subframe; during this step and unlike the previous one, the same voltage pulses are applied between the coplanar electrodes of a set of cells, whether they have been previously activated or not; during this stage, the coplanar discharges will only take place in the cells previously activated; according to the invention, each of the coplanar discharges of this maintenance step is triggered by a matrix discharge between an addressing electrode carried by a slab and a coplanar electrode carried by the other slab.
• Each coplanar discharge that is to say a discharge between two electrodes carried by the same slab, is therefore triggered by a matrix discharge, that is to say a discharge between two electrodes carried by two different slabs; this trigger discharge is therefore different from an address discharge, which also takes place between two electrodes carried by two different slabs but only in preparation for a maintenance phase.
• the display device described in document US2003 / 0080683 describes a plasma panel provided with an array of electrodes addressing and four coplanar electrode networks; as indicated in ⁇ 30 of this document, the electrodes X ', Y' of the first two arrays of coplanar electrodes are close (small "gap") so as to facilitate the creation of coplanar discharges; these low-gap coplanar discharges serve to trigger high-gap “main” coplanar discharges between electrodes X, Y of the two other coplanar networks which are much more distant.
• FIG. 2A, 2B, and 2C already described, represent the different stages of development of a maintenance discharge triggered by a matrix discharge in the cell of Figure 1, shown schematically in section with, only, the electrodes and the dielectric layers covering them;
• FIG. 3 and 4 illustrate a first family of embodiments of the invention where each cell comprises only one expansion zone, and represent, in top view, a set of three cells of a panel according to l invention where the adjacent cells of the same line are offset with respect to each other, and where, for each cell, the width of the trigger zones is greater than the width of the single expansion zone:
• the maintenance electrodes are not straight, directly serve the cells, and are not provided with leads;
• the maintenance electrodes are rectilinear, and are provided with branches to serve the cells;
• FIG. 5 and 6 illustrate a second family of embodiments of the invention where each cell comprises two zones of expansion in parallel, and represent, in top view, a set of three cells of a panel according to invention where each cell is divided by an intra-cell separating element extending only between the maintenance electrodes: o Figure 5: each coplanar electrode serves only one row of cells; o Figure 6: each coplanar electrode serves two adjacent lines of cells;
• the plasma panel according to the invention differs mainly from the panel previously described with reference to FIGS. 1A and 1B in that the column separation elements 15 have a variable width, as illustrated in the FIG.
• the cell width L M measured in the zones Z M , Z ′ M of triggering matrix discharge is greater than or equal to the distribution pitch p of the electrodes X of the addressing network, while the cell width L E measured in the expansion zone Z E , that is to say between the maintenance electrodes Y, Y ', is less than the same pitch p.
• the avalanche gain in the triggering matrix discharge zone is increased, and the diffusion and the yield of the discharge in the expansion zone of the positive pseudo-column are increased.
• the cells of the panel are staggered with respect to each other, so as to best distribute the parts of cells which are the largest, that is to say the areas of matrix discharge; thus, as shown in FIG. 3, each matrix discharge zone of a cell belonging to a column (not bordering) of the panel is located, that is to say between the zones of expansion of cells of adjacent columns (case of Z " M on the figure), either between the zones separating two cells of different rows in these adjacent columns (case of Z M , Z ' M ); thus, the cells of any same column of the panel are shifted in the general direction of the columns by report to cells in an adjacent column.
• This family of embodiments also makes it possible to increase the possible area of a black network arranged for example at the top of the barriers and intended to improve the display contrast of the images, which makes it possible to limit the use of a neutral filter of low transmission, and further improves the final light output of the plasma panel.
• the staggered arrangement of the cells leads, as shown in FIG. 3, to maintenance electrodes which have a non-rectilinear sinuous profile.
• FIG. 4 illustrates a variant of the panel shown in FIG. 3, where the cells are also staggered but where the maintenance electrodes nevertheless have a straight path: the maintenance electrodes Y, Y 'are here provided with bypass 18 which extend towards the center of the matrix discharge zones Z M , Z ' M.
• These branches can be made of transparent conductive material such as TITO.
• the plasma panel according to the invention differs mainly from the panel previously described with reference to Figures 1A and 1B in that, as shown in Figure 5, each cell is provided an intra-cell separation element 19 which extends only between the maintenance electrodes Y, Y ′, so as to obtain two expansion zones Z E1 , Z E2 in parallel.
• This further improves the light output of the panel.
• the dimensions and the material of this separating element are adapted in a known manner in itself to obtain this separation in two of the positive pseudo-column, in order to strongly bring the plasma closer to the wall elements of the cell, namely the separation elements 15, 19.
• the intra separation elements cell 19 are integrated into the network of barriers and produced at the same time and in the same material as the intercell separation elements 15.
• the width of the intra-cell separation elements 19 is greater than or equal to 40 ⁇ m.
• This second family of embodiments of the invention is also advantageous compared to the first family because it makes it possible to increase the surface available for the phosphors in each cell, in particular on the slope of the inter- or intra-separation elements. -cellules. Note that the phosphor layer is not shown in the figures. This increase in the surface available for the phosphor contributes to the improvement of the light output.
• each maintenance electrode simultaneously serves two consecutive lines of cells.
• this electrode under the intra-cell separation elements 19 as shown in FIGS. 5 and 6, so as to increase the thickness of dielectric on these electrodes and thus greatly reduce the anodic capacity, which increases the speed of spreading of electrons and the formation of the positive column.
• the distance between the inter-cell separation elements delimiting these cells is reduced but not zero; this distance is less than the width of the expansion zones L E , L E1 , L E2 ; this distance is not zero to advantageously provide a notch which facilitates the deposit of phosphors in the columns, which makes it possible to limit the risks of deposit of phosphors on the tops of the barriers.
• plasma panels are advantageously integrated into display devices which include supply and control means which make it possible in particular to generate maintenance operations where each maintenance discharge is triggered by a matrix discharge; such supply and control means are known to those skilled in the art, have been briefly described previously, are described in more detail, for example in the document US6184848 already cited.

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