EP1516348B1 - Dalle de decharges coplanaires pour panneau de visualisation a plasma apportant une distribution de potentiel de surface adaptee. - Google Patents

Dalle de decharges coplanaires pour panneau de visualisation a plasma apportant une distribution de potentiel de surface adaptee. Download PDF

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Publication number
EP1516348B1
EP1516348B1 EP03760707A EP03760707A EP1516348B1 EP 1516348 B1 EP1516348 B1 EP 1516348B1 EP 03760707 A EP03760707 A EP 03760707A EP 03760707 A EP03760707 A EP 03760707A EP 1516348 B1 EP1516348 B1 EP 1516348B1
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Prior art keywords
zone
discharge
axis
electrode
ignition
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EP03760707A
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German (de)
English (en)
French (fr)
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EP1516348A2 (fr
Inventor
Laurent Tessier
Ana Lacoste
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Thomson Plasma SAS
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Thomson Plasma SAS
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    • 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
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/22—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources
    • G09G3/28—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using luminous gas-discharge panels, e.g. plasma panels
    • G09G3/288—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using luminous gas-discharge panels, e.g. plasma panels using AC panels
    • G09G3/291—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using luminous gas-discharge panels, e.g. plasma panels using AC panels controlling the gas discharge to control a cell condition, e.g. by means of specific pulse shapes
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/22—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources
    • G09G3/28—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using luminous gas-discharge panels, e.g. plasma panels
    • G09G3/288—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters using controlled light sources using luminous gas-discharge panels, e.g. plasma panels using AC panels
    • G09G3/296—Driving circuits for producing the waveforms applied to the driving electrodes
    • 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
    • H01J11/24—Sustain electrodes or scan electrodes
    • 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
    • H01J11/38—Dielectric or insulating layers
    • 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

Definitions

  • the invention relates to the delimitation of zones of ignition, expansion and stabilization of discharges in the different cells or discharge zones of a plasma display panel.
  • slabs are used for the manufacture of conventional plasma panels of the type comprising a slab 11 of coplanar discharges of the aforementioned type and another slab 12 provided with an array of addressing electrodes, forming between them a two-dimensional assembly gathering said zones. discharged filled with a discharge gas.
  • Each discharge zone is positioned at the intersection of an address electrode X and a pair of electrodes of the coplanar discharge slab Y, Y '; each set of discharge areas served by the same pair of electrodes generally corresponds to a horizontal line of discharge zones or subpixels of the panel; each set of discharge zones served by one and the same addressing electrode generally corresponds to a vertical column of discharge zones or subpixels.
  • the electrode arrays of the coplanar discharge slab are coated with a dielectric layer 13 to provide a memory effect, itself coated with a layer 14 for protecting and emitting secondary electrons, generally based on magnesia. .
  • Adjacent discharge areas at least those that emit different colors, are generally delimited by horizontal and / or vertical barriers 16; these barriers generally serve as spacers between the slabs.
  • the cell shown in Figures 1A and 1B is rectangular in shape; other cell geometries are disclosed by the prior art; the largest dimension of this cell extends parallel to the addressing electrodes X; let Ox be the longitudinal axis of symmetry of this cell; at each discharge zone served by a pair of electrodes which forms a discharge cell, the portions or electrode elements Y, Y 'delimited by the barriers 15, 16 here have a constant width measured in the direction perpendicular to the Ox axis.
  • the walls of the light discharge zones are generally partially coated with phosphors sensitive to ultraviolet radiation from the light discharges; adjacent discharge areas are provided with phosphors emitting different primary colors, so that the association of three adjacent areas forms a picture element or pixel.
  • FIG. 15 of the document EP0782167 - PIONEER, the figure 3 of the document EP0933017 (see element 412), the figure 3 of the document EP1032015 (see items 122a and 122b), the figure 11 for example, from the document US2002 / 008473 (see element 56) and FIG. 3A below show a coplanar discharge slab of the above-mentioned type where, at each discharge zone served by a pair of electrodes, each electrode of this pair comprises a shaped element. T comprising a transverse bar 31 facing the other electrode and a central leg of constant width 32; each electrode element is electrically connected by a conductive bus 33 by the foot of its central leg.
  • Each cross bar 31 of an electrode element forms a discharge firing zone Z a
  • each central leg 32 forms a discharge expansion zone Z b
  • each transverse bar 33 can form a discharge stabilization zone.
  • Z c in fact, during operation, during the maintenance phases, each discharge starts at one of the said ignition edges of the transverse bar 31, then extends along the corresponding leg 32 to the bus 33 to which it is connected.
  • FIG. figure 14 A variant of the T-shape is shown in FIG. figure 14 from the same document EP0782167 -PIONEER : it is the inverted U shape which has two side jambs (instead of a central) perpendicular to the same crossbar ignition that previously, each connected to one end of this bar; after ignition, the discharge is subdivided and then extends along two parallel expansion lateral paths each corresponding to a leg of the inverted U, the two paths meeting at the conductive bus of the electrode.
  • each lateral leg of U 42a, 42b is shared between two adjacent cells and the transverse bars of the elements of the same electrode form a continuous conductor, so that each coplanar electrode has a shape of scale, with an initial amount serves Z ignition zone, the bars are positioned at the boundary of the discharge zone and serve as zones of expansion of discharges Z b , and a second amount of which serves as stabilization zone Z c .
  • Such a spreading process of discharges along an expansion zone forming an electrode portion is favorable to the ultraviolet radiation production efficiency of the discharges and to a wider distribution of the excited phosphor surfaces.
  • the object of the invention is to define a new type of coplanar discharge plasma panel cell which further improves the light output of the discharges and the service life of a plasma panel.
  • the electrode element plays the role of cathode, the surface of the dielectric layer which covers it is positively charged.
  • the two opposite electrode elements and the underlying dielectric layer are identical and symmetrical with respect to the center of the inter-electrode space.
  • each of the two electrode elements serves alternately to anode and cathode.
  • each coplanar maintenance discharge in this panel then comprises successively an ignition phase, an expansion phase, and an end of discharge or stabilization phase during which the cathodic sheath of the discharge respectively does not does not move, moves, disappears or stabilizes.
  • Such electrode elements and the underlying dielectric layer allow maintenance discharges to spread rapidly from the firing area to the end discharge or stabilization zone, with a minimum of dissipation. energy in the ignition zone, and a maximum of energy dissipation in the high efficiency discharge end zone, while using conventional maintenance generators delivering, between the electrodes of the different pairs, conventional series of maintenance voltage pulses, where each pulse comprises a constant voltage step, without pronounced increase of the applied electrical potential.
  • the invention relates to a coplanar discharge slab for a plasma display panel which comprises, for each discharge zone, at least two electrode elements which have an axis of symmetry Ox and which are adapted so that the potential of surface V (x) evaluated at the surface of the dielectric layer covering these elements increases, away from the discharge edge of the elements, in a continuous or discontinuous manner, without decreasing part, when applying a difference of constant potential between the two electrodes serving said discharge zone.
  • Such a coplanar slab makes it possible to obtain plasma panels with improved light output and lifespan.
  • the stable operating point of the discharge can not be the ignition zone once the discharge is initiated, and once initiated, the discharge inevitably spreads into the expansion zone along the surface of the dielectric layer towards the end discharge edge.
  • the width W e (x) or w a (x) of the electrode element delimiting said straight elementary bar may be discontinuous, for example when said element is subdivided into two lateral conductive elements; we then take the sum of the width of each lateral conductive element.
  • the stable operating point of the discharge can not be the ignition zone once the discharge is initiated, and once initiated, the discharge inevitably spreads into the expansion zone along the surface of the dielectric layer towards the end discharge edge.
  • the width W e (x) of said electrode element is constant in said range of values of x.
  • R bc > R ab , R ab > 0.9, and (R bc -R ab ) ⁇ 0.1. These characteristics make it possible to limit the voltages necessary for the ignition.
  • the values of R (x) for any x such that x bc ⁇ x ⁇ x cd . are strictly greater than the values of R (x) for any x such that 0 ⁇ x ⁇ x ab .
  • the values of R (x) for any x such that x bc ⁇ x ⁇ x cd . are strictly greater than the values of R (x) for any x such that 0 ⁇ x ⁇ x ab .
  • the width W e (x) of the electrode element may be discontinuous, for example when said element is subdivided into two lateral conductive elements; we then take the sum of the width of each lateral conductive element.
  • said electrode element is subdivided into two lateral conductive elements which are symmetrical with respect to the axis Ox and disjoint at least in the zone where x is in the interval [x ab , x b3 ], where X b3- X ab > 0.7 (x bc -x ab ).
  • x b3 x bc .
  • Oy is an axis transverse to the axis Ox which extends along the ignition edge
  • d ep (x) the distance, measured parallel to the axis Oy at any position x included between x ab and x bc , between the edges facing each other of these two lateral conductive elements
  • the electrode element then has a lug in the center of the transverse ignition bar positioned between the two lateral conductive elements.
  • the invention also relates to a plasma panel having a coplanar slab where the profile of all the electrode elements is in accordance with the invention.
  • the electrostatic influence of a lateral conductive element on the other is sufficiently strong here to allow, according to the invention, a variation of the normalized potential at the surface of the dielectric between V n -ab preferably greater than 0.9 and V n-bc preferably close to 1, while maintaining constant the width of each lateral conductive element.
  • said electrode member comprises a transverse bar which connects said ignition said side conductive elements, one edge of which corresponds to said ignition edge and whose the length, measured along the axis Ox, is greater than a value ⁇ L a for
  • these geometric characteristics make it possible to reduce the ignition voltage without significantly increasing the energy dissipation in the cathodic sheath at the onset of the discharges, in particular because the displacement of this sheath at the time of expansion must be offset laterally, outside the zone of the pin, at each of the lateral conductive elements; the increase in the memory load in the center of the transverse ignition bar at this slang will not adversely affect the energy of the cathode sheath.
  • the capacity of the dielectric layer located at the end of discharge zone is greater than the specific capacity of the dielectric layer located at the ignition zone of the discharge, so as to establish a positive potential difference between the ignition zone and the end of discharge zone.
  • one edge of the intermediate transverse bar being spaced from one of said discharge stabilizing bar and the other edge being spaced from d 2 of said ignition bar was ad 2/2 ⁇ d 1 ⁇ d 2 .
  • This characteristic advantageously keeps a surface potential of the dielectric layer in the ignition zone identical to the surface potential at the beginning of the expansion zone.
  • this panel comprises a network of parallel barriers disposed between said slabs at a distance W c from each other perpendicularly to the general direction of said coplanar electrodes, where, if Oy is an axis transverse to the Ox axis which extends along the ignition edge and if W a is the width of said transverse ignition bar measured along the axis Oy, we have: W c -60 ⁇ m ⁇ W a ⁇ W c -100 ⁇ m.
  • the reduction of the gap separating the two electrode elements at the lateral zones Z a-p1 , Z a-p2 close to the barriers makes it possible to increase the electric field in this zone and to compensate for the reduction of primary particles resulting from the wall effect by locally adapting the conditions of Pashen. This results in a reduction of the ignition potential with a constant ignition area area, or a reduction of the ignition zone area at constant ignition potential.
  • one or the other of the plasma panels according to the invention comprises supply means adapted to generate between the coplanar electrodes of the different pairs of sets of voltage pulses called constant level maintenance.
  • the invention advantageously makes it possible to substantially increase the luminous efficiency and the service life of the plasma panels by using this conventional and economical type of maintenance generator.
  • FIG. 2A shows a schematic longitudinal section of a coplanar discharge zone type cell as described in FIG. 1A
  • FIG. 2B represents the evolution of the electric current. between the coplanar electrodes of this cell during a maintenance discharge.
  • the ignition voltage of a discharge obviously depends on the electrical charges previously stored on the anode and the cathode in the vicinity of the ignition zone, in particular during the previous discharge where the cathode was an anode and vice versa; before the discharge, positive charges are stored on the anode and negative charges on the cathode; these stored charges create what is called a memory voltage; the ignition voltage corresponds to the voltage applied between the electrodes, or maintenance voltage, plus the memory voltage.
  • the electronic avalanche in the discharge gas between the electrodes then creates a positive space charge which is concentrated towards the cathode to form the so-called cathode sheath;
  • the so-called positive pseudo-column plasma zone situated between the cathode cladding and the anode end of the discharge contains, in an identical proportion, positive and negative charges; this zone is therefore current conducting and the electric field is weak; the zone of positive pseudo-column therefore has a weak electron energy distribution and, in fact, favors the production of ultraviolet photons by privileging the excitation of the discharge gas.
  • the most important part of the electric field in the gas between the anode and the cathode therefore corresponds to the field within the cathode sheath; along the field lines between the anode and the cathode, the largest portion of potential drop corresponds to the cathode cladding zone; the impact of the ions, accelerated in the intense field of the cathodic sheath, on the magnesium-based layer which covers the dielectric layer, causes a large emission of secondary electrons in the vicinity of the cathode; under the effect of this intense electronic multiplication, the density of the conductive plasma then strongly increases between the electrodes, both in ions and in electrons, which causes a contraction of the cathodic sheath in the vicinity of the cathode and the positioning of this sheath at the level where the positive charges of the plasma are deposited on the portion of dielectric surface covering the cathode; on the side of the anode, the plasma electrons, which are much more mobile than the ions, are deposited on the portion of dielectric surface
  • the potential distribution along the longitudinal axis of symmetry Ox at the surface of the dielectric layer overlying the cathode is uniform, as explained later in more detail with reference to curve A of FIG. figure 5 . Since, before the beginning of each discharge, the potential is thus contant along the Ox axis of expansion of the discharge, there is therefore no transverse electric field allowing the displacement of the cathodic sheath. The positive charge from the discharge is therefore deposited and therefore accumulates gradually at the ignition zone Z a without sheath displacement.
  • the ignition zone Z a thus corresponds to the zone of accumulation of ions at the start of the discharge during the entire period during which the cathodic sheath of this discharge does not move.
  • the ion bombardment is then concentrated on a small surface of the magnesia layer and causes a strong local sputtering of said layer.
  • a so-called "transverse" field is created between these positive charges just deposited on the one hand and the negative charges previously deposited.
  • this transverse field causes the cathode sheath to move further and further from the ignition zone as the ionic charges accumulate on the dielectric surface that covers the cathode; it is this displacement which causes the expansion of the plasma discharge; the cathodic sheath is positioned at the level where the ions of the plasma are deposited, at the limit of expansion zone; during discharges, the displacement of the cathode sheath follows the pattern of the electrode elements in each cell.
  • the expansion zone Z b corresponds to the area swept by the displacement of the cathode sheath of the discharge.
  • each electrode element includes an end discharge edge.
  • the discharge is generally not yet extinguished because the surface potential of the dielectric layer at the end of this displacement still has, with respect to the surface potential of the dielectric layer covering the anode, a sufficiently important difference for the maintenance of this discharge; in other words, because the global deposition of ions on the dielectric layer covering the cathode has not yet sufficiently compensated for the potential applied to this cathode; the discharge then continues without displacement of the cathode sheath on a surface area of the cathode corresponding to what is called the stabilization zone or the discharge end zone Z c .
  • This "end of discharge zone” becomes strictly speaking “stabilization zone” only when, before starting a discharge, the surface potential of the dielectric layer in this zone is greater than that of the remainder of the dielectric layer in the expansion and ignition zone. If this is not the case, the end of discharge zone is only the end of the expansion zone, without being strictly speaking a stabilization zone.
  • a time T1 of end of ignition or start of expansion, and a time T2 of end of expansion or start of stabilization are defined.
  • the plasma expansion on the the surface of the dielectric layer, between the instant T1 and the instant T2 makes it possible to extend the zone of positive pseudo-column of the discharge, thus of increasing the part of electrical energy of this discharge which is dissipated for the excitation of the gas in the cell, and thus improve the production yield of ultraviolet photons of the discharge.
  • Expansion of the discharge also distributes the ion-bombardment spray of the magnesia layer over a larger area and locally reduces degradation, increasing the lifetime of said layer and, therefore, the screen life. with plasma.
  • the quantity of energy dissipated at the instant T2 which corresponds to the electric current I2 at this instant, remains low.
  • the total energy dissipated during the discharge only a small portion is dissipated during the times when this discharge is sufficiently wide to have a high output of ultraviolet photons and a low sputtering of the magnesia layer.
  • One way to improve the light output and the lifetime is therefore to reverse the distribution of the energy dissipated during the course of landfills, or to aim at a ratio I1 to I2 minimum value. It is in particular to dissipate the maximum energy in the discharge when it is at its optimal point of expansion, that is to say at the time T2 when the discharge leaves the expansion zone Z b and enters the stabilization zone Z c .
  • the rate of formation of the transverse field allowing the spreading of the discharge on the surface of the dielectric layer covering the cathode depends on the local capacitance of the dielectric layer located under the cathodic sheath, in the ignition zone as in any point of the expansion zone. The higher this local capacitance, the greater the quantity of charges deposited, and the greater the growth of the transverse field of displacement of the cladding requires time.
  • This local capacitance determines the surface potential seen by the discharge; if the local capacitance is uniform, there is no transverse electric field and the formation of this transverse electric field depends entirely on the potential difference generated by the charge previously stored on the surface of the dielectric layer from the previous discharge and the charge filed by the discharge in Classes. In other words, there can be a transverse field, and therefore a discharge spread, only if a sufficient quantity of electrical energy is provided to completely locally charge the surface of the dielectric layer.
  • the discharge zone Z b extends along an electrode member having a uniform width over the entire half cell length, so that the local capacitance of the dielectric layer portion 13 between this electrode element and the cathode jacket has a constant value at any point in the firing zone and the expansion zone, whatever or the position of the cathode sheath during its expansion period, that is to say whatever the state of the discharge.
  • this local capacitance is always maximum since the electrode element corresponds to the totality of the discharge zone.
  • the distribution of the potential at the surface of the dielectric layer covering the electrode element of the discharge zone is represented on the curve A of the figure 5 at a time T which immediately precedes the beginning of the discharge and as a function of the distance x at the ignition edge, measured on the axis Ox of the figure 1-A which is here a longitudinal axis of symmetry of the electrode element of the considered cell.
  • This distribution is obtained using the 2D modeling software called SIPDP2D version 3.04 from Kinema Software, the operation of which is described later.
  • this surface potential is uniform and constant over the entire length of the electrode element, since the local capacitance of the dielectric layer is constant at all points on the surface of this layer, and there is no transverse electric field favorable to the displacement of the discharge on the surface of the dielectric layer after the ignition phase.
  • the discharge current shown in FIG. 2B then has the characteristics described above, according to which a large part of the electrical energy is dissipated before the transverse field of discharge spreading is sufficiently formed to cause displacement of the sheath, and a small portion of electrical energy is dissipated during the displacement and at the end of displacement of the sheath, while the discharge reaches the maximum of light output.
  • the ratio I1 to I2 is then high.
  • each electrode element Y or Y ' has, perpendicular to the axis Ox, a width which is not uniform as one moves along the mean direction of displacement of the cathodic sheath of the discharge, ie along the Ox axis.
  • Specific longitudinal capacitance of the dielectric layer covering an element of a coplanar electrode the capacity of an area of this layer extending along a very small length dx positioned in x on the axis Ox corresponding to a length slice and extending in a width W e (x) corresponding to that of the electrode element at the same position x on the Ox axis.
  • FIG. 3A is strong in the ignition zone Z a where the electrode element is constituted by the first transverse bar 31 , then weak in the expansion zone Z b where the electrode element is constituted by the central leg 32, and finally again strong in the discharge end zone Z c where the electrode element is formed of the second transverse bar 33.
  • the evolution of the intensity I of the electric current of the discharge as a function of the instant T of this discharge is represented in FIG. 3B for the cell structure of FIG. 3A.
  • the distribution of the potential V at the surface of the dielectric layer covering the electrode element Y is represented on the curve C in dotted lines of the figure 5 at a time before the start of a discharge.
  • this distribution has a "hollow" in the expansion zone, which forms a potential barrier between the ignition zone and the stabilization zone.
  • the discharge is initiated above the dielectric surface covering the ignition zone Z a . It has been found that the expansion zone formed by the jamb 32 between the two transverse bars 31, 33 having in any position x a capacity longitudinal specific low, the surface potential of the dielectric layer covering this leg was less than or equal to that of the dielectric layer covering the crossbar 31 of the ignition zone, depending on whether the width of this leg 32 is respectively less or greater than the length of the cross bar 31 in the ignition zone in the cell.
  • the longitudinal capacitance of the electrode element being low in the zone of the jamb 32 of the expansion zone Z b , the deposition of charges in this zone is rapid, so the transverse field necessary for the displacement of the sheath is rapidly created at any point in this area, which promotes rapid displacement of the cathode sheath along the leg 32 to the second crossbar or bus 33.
  • the electrons do not spread any more immediately on the whole of the anode as in the structure of the figure 1 , But only on the part of the anode element which is located upstream of the potential barrier, namely on the part situated at the level of the first transverse bar then, as soon as the charge accumulated on the anode makes it possible to pass the potential barrier, the electrons spread over the rest of the anode rapidly and the potential difference, between the surface of the dielectric layer located above the anode and the surface of the dielectric layer located above the cathode at the position of the sheath, decreases rapidly.
  • the electric field within this sheath decreases rapidly as the deposit charges at the anode, which causes an expansion of this cladding, a decrease in the energy of the ions striking the magnesia layer, and a decrease in the rate of charge generation on this layer; as a result of this expansion, the speed of displacement of the cathodic sheath decreases in turn, and the discharge is extinguished before reaching the second crossbar.
  • the second crossbar 33 forming the discharge end zone Zc having a strong specific longitudinal capacity, the elongated discharge is immobilized on this bar as the charge deposition on the dielectric surface covering the second crossbar 33 is not completely compensated for the potential applied between the electrodes.
  • the electric energy portion of the discharge which is dissipated at the end of the expansion period is then increased, and the intensity of the electric current I2 increases.
  • the ratio I1 to I2 then decreases by increasing I2; nevertheless a large part of the electrical energy of the discharge remains lost in the ignition zone to deposit charges on the dielectric surface and create a transverse field sufficiently strong to allow the passage of the cathode sheath of the first bar 31 to the second crossbar 33, and cross the potential barrier generated by the jamb 32.
  • Figure 4A shows a structure similar to that described in Figure 3A. Instead of a single leg centered on the axis Ox to connect the same two transverse bars, there are two jambs 42a, 42b reported at the cell limit and positioned here on the top of the barriers 15. Using the same software SIPDP-2D cited above, the distribution of the potential, before the start of a discharge, to the surface of the dielectric layer covering the electrode element constituted by these two transverse bars and these two legs; this distribution is presented on curve B1 of the figure 5 .
  • the Ox axis corresponds globally to the axis of symmetry of the zone of displacement of the cathode sheath.
  • This potential distribution here has a higher potential barrier between the two transverse bars, resulting from the absence of a leg in the center of the discharge zone between said bars.
  • the potential drop between the two bars is nevertheless limited by the presence of the legs 42a, 42b positioned along the walls of the cell.
  • the intensity of the electric current I generated by the discharge is presented in FIG. 4B as a function of time T.
  • the discharge starts on the surface of the dielectric layer covering the first transverse bar (ignition zone Za) as before, and then collides here with the potential barrier caused by the absence of central leg. As the electron spreading at the anode is not possible, the discharge goes out quickly.
  • the transverse electric field is here opposed to the direction of expansion of the discharge from the front to the back of the conductive element. To reverse this transverse field, it is necessary to deposit sufficient loads on the first crossbar so as to compensate for the potential barrier.
  • the first part of the discharge is therefore carried out at a voltage much greater than the normal operating voltage, with consequent significant contraction of the cathode cladding on the first transverse bar and significant sputtering of the magnesia surface by ion bombardment and an intensity of electric current I1 greater than the intensity I2 of the second discharge.
  • the ratio I1 to I2 for this type of discharge is further improved by forming a second discharge on the cross bar constituting the end of the expansion zone.
  • the invention aims to maintain and control the transverse electric field of displacement of the cathode sheath at a sufficiently high level to rapidly extend the discharge while dissipating the minimum of electrical energy, then to stabilize the discharge once elongated and then dissipate the maximum electrical energy.
  • the figure 6 schematically represents a discharge zone 3 of rectangular shape delimited between its larger faces by a coplanar slab 1 carrying a pair of symmetrical electrode elements 4, 4 'disposed on either side of an inter-electrode gap or gap 5 and by an addressing plate 2 carrying, but not necessarily, an X address electrode of general direction perpendicular to the electrode elements 4, 4 'and coated with a dielectric layer 7; the ends of the gap-opposing electrode elements are electrically connected to a conductive bus Y c not shown, which serves to supply voltage; the coplanar electrodes 4, 4 'are coated with a dielectric layer 6.
  • the discharge zone 3 is delimited not only by the slabs, but also by barriers disposed perpendicularly to the slabs (not shown), and thus forms a discharge cell.
  • L e is the length of each electrode element along this dimension, between its ignition edge and its end-of-discharge edge;
  • the distance H c thus corresponds to the thickness of gas between the two slabs 1 and 2;
  • the electrode elements 4, 4 'described in the figure are T-shaped as in the prior art.
  • Ox is an axis located on the surface of the coplanar slab in the longitudinal plane of symmetry of the cell, which extends toward the end edge of discharge.
  • Oy is an axis, also located on the surface of the coplanar slab, generally transverse to the axis Ox, which extends along the ignition edge towards a side wall of the cell
  • Oz is an axis perpendicular to the surface of the coplanar slab that extends towards the opposite slab of the plasma panel.
  • the main purpose of the invention is to adjust the specific longitudinal capacitance of the dielectric layer covering the coplanar electrode elements of each cell so as to create, before the beginning of each discharge, a positive or zero transverse electric field at any point in the an expansion zone allowing the discharge to spread rapidly from the ignition zone to the end-of-discharge or stabilization zone, with a minimum of energy dissipation in the ignition zone, and a maximum of energy dissipation in the high efficiency discharge end zone Z c , while using conventional maintenance generators delivering, in between electrodes of the different pairs, conventional series of maintenance voltage pulses, wherein each pulse comprises a constant voltage step, without pronounced increase of the applied electrical potential.
  • no point has a negative potential gradient; this potential gradient is measured along the Ox axis of symmetry of the zone of displacement of the cathode sheath of the discharge in the direction of displacement of this discharge opposite the ignition edge; at this potential gradient corresponds an electric field; according to the invention, this growth of the potential can be continuous as explained hereinafter with reference to the curve C of the figure 7 or discontinuous in potential jumps, with at least one, preferably two, potential stages between the beginning and the end of the expansion zone.
  • the dotted curve C of the figure 7 gives an example of continuous growth of the potential corresponding to such a strictly positive field over the entire dielectric surface of the slab 1 corresponding to the expansion zone Z c ; this example will be developed later with reference to the figure 8 if ⁇ V is the potential difference of the surface of the dielectric layer between the beginning x ab and the end x bc of the expansion zone, this difference is distributed according to the invention along this interval so as to generate any point of this interval, and for the same potential applied at any point of the electrode element 4 under the surface of the dielectric layer, a positive electric field oriented in the direction Ox towards the end x bc of the zone d expansion located opposite the ignition edge.
  • the end of the ignition zone x ab is less than L e / 3 and the beginning of the discharge end zone x bc is greater than L e / 2; furthermore, the length of the expansion zone (x bc- x ab ) represents more than a quarter of the total length Lc of the electrode element, preferably more than half that length.
  • the normalized surface potential V norm is defined as the ratio between the surface potential V at a level x of the dielectric layer for the electrode element under consideration and the potential maximum possible along the axis Ox for an electrode element of infinite width, that is greater than the width W c of the cell.
  • the software thus presents a grid of 48 steps x 48 steps on which one enters, according to a cross-section of the cell to study the influence of the electrode width, at any point the shape of the dielectric layer covering the electrodes and its local dielectric constant.
  • Variable width bars are then positioned on this grid, representing on the one hand the coplanar electrode element on the front coplanar slab of the panel and on the other hand the addressing electrode on the other rear slab.
  • a coplanar electrode of variable width centered on the Ox axis was chosen.
  • the distribution according to the invention of the potential at the surface of the dielectric layer can be obtained by modifying the relative thickness or permittivity of the dielectric layer covering the constant width electrode elements.
  • E1 (x) the thickness expressed in microns and P1 (x) the relative permittivity of the dielectric layer above each electrode element 4, 4 'at the position x along the axis Ox of expansion of the discharge
  • E2 (x) the thickness expressed in microns and P2 (x) the relative permittivity of the dielectric layer above the address electrode X or the slab 2 in the absence of an addressing electrode, at the position x along the axis Ox expansion of the discharge.
  • the ratio 1- [E 1 (x) / P 1 (x) ] / [E 1 (x) / P 1 (x) + H (x) + E 2 (x) / P 2 (x) ] is, for 0 ⁇ x ⁇ x bc , increasing continuously or discontinuously as a function of x; the evolution of this ratio in this interval does not include any point of negative growth; in case of discontinuous growth by jump, the evolution of this ratio preferably comprises at least two stages in this interval; in the case of continuous growth, this ratio preferably increases linearly as a function of x (according to a law of the type ax + b).
  • a second general embodiment specific to the invention consists in varying the width W e (x) of the electrode element in the discharge expansion zone Z b , so as to increase the surface potential of the dielectric layer according to the basic law of the invention defined above; then, for simplicity, a dielectric layer of uniform thickness and composition is kept in the expansion zone.
  • the figure 9 graphically presents the general law connecting the electrode element width W e-ua (logarithmic scale in arbitrary unit "ua") and the normed potential V norm obtained at the surface of the dielectric layer covering this electrode element before a discharge, where V norm has been previously defined.
  • the parameter "a” of the relation (1) depends mainly on the specific surface capacitance of the dielectric layer 6 of the slab 1.
  • E1 (x) the thickness expressed in microns
  • W e-ab at the entrance to the expansion zone depends directly on the choice of V n-ab .
  • V n-ab 0.9
  • V (x) (xx ab ) x (V n-bc -V n-ab ) / (x bc -x ab ) + V n-ab .
  • This relation (2) defines the preferred ideal profile of the invention W e-id-0 , which makes it possible to achieve a linear distribution of the surface potential in the expansion zone.
  • any electrode element profile which was between this lower limit profile W e-id-inf and this upper limit profile W e -id-sup allowed to achieve a continuous or discontinuous increasing distribution of potential between the beginning and the end of the expansion zone Z a , according to the essential general characteristic of the invention.
  • the conventional embodiments of dielectric layers limit the ratio P1 / E1 so that, generally, we have: 0.2 ⁇ P1 / E1 ⁇ 0.8 and so it is preferable, to limit the amount of energy dissipated at the beginning of the discharges, to choose a width W e-ab of conductive element less than or equal to 50 ⁇ m at the beginning x ab of zone expansion Z b and a width W e-bc , end x bc expansion zone, strictly greater than this value.
  • W e-ab of conductive element less than or equal to 50 ⁇ m at the beginning x ab of zone expansion Z b and a width W e-bc , end x bc expansion zone, strictly greater than this value.
  • W e-ab d conductive element slightly greater than this value.
  • the realization of the electrode conducting elements uses manufacturing technologies which obviously have limitations in precision.
  • the precision of realization of the electrodes does not call into question the application of the invention, insofar as the electrode width W e (x) in the expansion zone Z b along the axis Ox does not vary from plus or minus 15% with respect to the values defined in the invention.
  • the specific longitudinal capacity of the dielectric layer in the zone Z c should be greater than to the specific longitudinal capacity of the dielectric layer at any other point in the discharge zone. If W s is the width of the electrode member in the stabilizing zone preferably is chosen W s as high as possible, so relatively close to W c (cell width) and W is selected e-ga less than or equal to W s .
  • the cell walls play an important role in the ultraviolet radiation production behavior and efficiency of the discharge, particularly at regions of the electrode element which are located in the vicinity of these walls, in the areas where this element has a width W e close to the width W c of the cell.
  • this zone of influence of the walls typically extends to a wall distance of between 30 and 50 ⁇ m, depending, in particular, on the composition and the pressure discharge gas.
  • the example of figure 10B is similar to that of the figure 10A already described, but in the discharge stabilization zone, the electrode element here has a width less than the width W c of the cell, and is separated from the conductive bus 101 by an insulating thickness 151 of the horizontal wall 15 the cell, except in an area 102 of electrical contact, so as not to allow the discharge to enter the area of influence of low light output wall; the width of the electrical contact zone 102 is generally between 50 microns and 150 microns so as not to increase the contact resistance between the conductive bus Y c and the discharge stabilization zone Z c .
  • the luminous efficiency and the lifetime of the phosphors are thus further improved by using the structure of the figure 10B .
  • the total capacitance of the dielectric layer in said area is also partially reduced, so that the luminance of the discharge can be reduced.
  • the example of Figure 10C takes up the general structure of the figure 10B , the conductive bus being this time integrated in the discharge stabilization zone Zc and remote from the zone of influence of the wall, so that the least thickness of the dielectric layer covering the conductive bus increases the specific surface capacitance along the bus driver and here increases the capacity of the discharge stabilization zone. This increases the time and luminance of the discharge.
  • the example of figure 10D is a variant of the example of the Figure 10C , to reduce the opacity of the conductive bus in the visible light emission region of the phosphor.
  • the alignment method for the assembly of the slab 1 with the slab 2 does not always align with non-parallel patterns or perpendicular to each other. It may therefore be preferable not to use an electrode whose contours would be curved as previously described.
  • the object of the invention can be achieved by generating a discontinuous increase in potential jumps at the surface of the dielectric layer, using successive portions of conductive element of increasing width.
  • the figure 11A illustrates an example identical to that of the Figure 10C with the difference that, under the expansion zone, the electrode element is formed of a central conductor of narrow width W r electrically connecting a succession of conductive segments of constant width W e1 , W e2 , W e3 s extending transversely to the central conductor in order of increasing width according to average positions of these segments marked x1, x2, x3 on the Ox axis; according to the invention, it is verified that the width values W e1 , W e2 , W e3 , related to the positions x1, x2, x3 on the axis Ox are well between the lower limit profile W e-id-inf and the upper limit profile W e-id-sup previously described, which respectively deviate by -15% and + 15% from the linear ideal profile W e-id-0 previously defined for the second general embodiment specific to the invention; to evaluate this conformity to the definition of the invention, the outline drawn in discontinuous lines connecting the ends
  • the manufacturing method of the conductive elements may not allow to achieve sufficiently fine segments, especially in the part of the expansion zone closest to the discharge start zone. It is then possible to use the same and only weak segment width W e1 on a first part of the expansion zone Z b between x ab and a value x b1 , provided that the length x b1 -x ab of the expansion zone part corresponding to this first segment is less than at half the length of the expansion zone x bc -x ab .
  • the Figure 11B illustrates an example identical to that of the figure 11A with the difference that the segments here extend in the same direction as the Ox axis; as at the figure 11A , their ends define in dotted lines an outline within 15% of the ideal linear contour of electrode element W e-id-0
  • the figure 11C illustrates an example identical to that of the Figure 10C with the difference that, under the expansion zone, the electrode element comprises a first rectilinear zone of width equal to W e -ab or to the minimum width allowed by the manufacturing method and preferably less than 50 ⁇ m, and a second trapezoidal zone whose smallest base is equal to the width of the rectilinear zone.
  • the dimensions of the first and second areas are chosen so that the contour of the electrode element is globally inscribed between the lower limit profile W e-id-inf and the upper limit profile W e-id -sup previously described, which respectively deviate from -15% and + 15% of the linear ideal profile W e-id-0 previously defined for the second specific general embodiment of the invention.
  • the electrode element according to this variant makes it possible to obtain an effect substantially identical to that of an ideal contour, while advantageously eliminating certain manufacturing constraints.
  • a first rectilinear zone of length less than or equal to 100 ⁇ m will be used.
  • the figure 11D illustrates a variant of the figure 11A where the distance between the electrode segments is zero.
  • the contour of the electrode element is then in the form of a staircase along the axis Ox of spreading of the discharge in the expansion zone Z b .
  • V a As far as ignition is concerned, Paschen's well-known laws make it possible to define the electrical voltage V a to be applied between the electrodes of the same maintenance pair in order to trigger an electronic avalanche in the discharge gas filling the discharge zones. between the slabs of a plasma panel, and thereby to generate a plasma discharge; these laws establish the relations of this voltage with, in particular, the nature and the pressure of the discharge gas, the distance or "gap" separating the discharge edges of the two electrodes.
  • an electrode element whose ignition edge would be very narrow as described above in the examples of the second general embodiment of the invention, for example an electrode element having only a zone of FIG. expansion and whose width, at the edge of ignition, would be of the order of W e-ab , would change the uniformity of the electric field and the avalanche gain of the discharge, with the consequence of an increase of the voltages of functioning and an increase in the delay the discharge for a given voltage, with consequences on the cost of the power electronics and the addressing speed of the plasma display screen.
  • the width of the ignition front is W a
  • the "length" of the ignition zone measured along the axis Ox defined above, is equal to L a and corresponds to the level at which the expansion zone (not shown) begins and where the width of the expansion zone is minimal W e-ab .
  • width W a of the ignition zone the lower the ignition potential.
  • W a-min a minimum width W a-min above which the ignition voltage V a is not slightly modified by the width W a of the ignition front. This value of W a-min corresponds to the critical width beyond which the walls cause significant losses on primary particles created in the space between W a-min and W c .
  • the width W has of the zone ignition of the electrode element must be relatively high to maintain a low ignition voltage, it is preferable that the ignition surface is low enough not to generate an ignition current I is too high. Any increase in ignition zone width beyond W a-min provides little additional primary particle and no or little electrostatic increase in surface potential.
  • the wall influence zone, between W a-min and W c extends to at most 50 microns of each side wall.
  • an ignition front width W a greater than or equal to W c - 100 microns to obtain the lowest ignition potential; preferably, in the case of cells with a width greater than 400 .mu.m, W a does not exceed 300 .mu.m.
  • the width of the ignition zone will be close to W c -100 microns so as to limit the surface and therefore the capacity of the dielectric layer in the ignition zone. To maintain a low capacity in the ignition zone, this means, as explained below, the dimension L of the ignition area is relatively small.
  • the length L a of the ignition front only changes the value of the surface potential of the dielectric layer along the ignition zone.
  • the variation of the surface potential along this length L a is similar to the variation given for the electrode width W e in the expansion zone.
  • the length L a of the electrode element equal to W e-ab .
  • W a > W a-min by preferably adopting the following provisions.
  • W a-min corresponds to the width beyond which the walls cause a significant reduction of surface potential of the dielectric layer and significant losses of primary particles created in the space between W a-min and W c .
  • the ignition zone Z a it is then possible to distinguish a central zone Z ac for which, at any point, y ⁇ W a-min / 2 and two lateral zones Z a-p1 , Z a-p2 of the part and of other of the central zone for which, at any point, y> W a-min / 2.
  • the inter-electrode gap In the lateral zones Z a-p1 , Z a-p2 , it is then preferable for the inter-electrode gap to be strictly smaller than the value it has at the central zone Z ac .
  • Such an ignition zone profile is described in FIG. figure 14 . This type of profile advantageously makes it possible to achieve an even smaller electrode element surface in the ignition zone, and thus to more easily obtain a low capacitance of the dielectric layer in this zone.
  • the reduction of the gap separating the two electrode elements at the side zones Z a-p1 , Z a-p2 close to walls makes it possible to increase the electric field in this zone and to compensate for the reduction of primary particles resulting from the wall effect by locally adapting the conditions of Pashen. This results in a reduction of the ignition potential with a constant ignition area area, or a reduction of the ignition zone area at constant ignition potential.
  • Examples of ignition zones of Figures 13, 14 can be combined with any other expansion zone Z b and stabilization zone Z c described in the examples of the figures 10 and 11 as shown by Figures 15A and 15B resuming the general structure of Figure 10C supplemented with ignition zones of the respective figures 13 and 14.
  • the capacity formed by these walls between the two slabs of the panel weakly but gradually decreases the surface potential on the dielectric layer along the axis Oy, so that the discharge remains centered on the central axis Ox of the cell, on the surface of the dielectric layer covering the coplanar electrode elements of the slab 1, and so that the discharge, ie the source of ultraviolet photons, is at a maximum distance from each wall covered with phosphor (barriers 15, 16 generally supported by the slab 2).
  • the expansion zone is preferably subdivided into two expansion paths rather than one, as in the U-shaped electrodes previously described with reference to the documents EP0782167 and EP0802556 ; the expansion zone of the electrode element according to the invention is then subdivided into two lateral zones Zb-p1 , Zb-p2 that are symmetrical with respect to the axis Ox; the electrode element according to the invention is then subdivided into two lateral conductive elements, and the sum W e -p1 (x) + W e-p2 (x) of the width of each lateral element fulfills the conditions specific to the second general embodiment of the invention defined above, so as to be between the lower limit profile W e-id-inf and the upper limit profile W e-id-sup previously described, which deviate respectively of 15% and 15% of the linear ideal profile W e-id-0 previously defined.
  • the figure 16 represents an electrode element according to this preferred embodiment of the invention, wherein the two lateral conductive elements give rise to two expansion zones Z b-p1 and Z b-p2 arranged symmetrically with respect to the longitudinal axis Ox of symmetry of the cell.
  • the greater part of each lateral expansion zone of the lateral conductive element is more than 30 ⁇ m distant from the side wall of the cell, to avoid the harmful wall influences described above.
  • Figures 18A, 18B, 18C, 18D repeat the general pattern of electrode element presented in Figure 10C , with the difference that the electrode element is here subdivided into two lateral conductive elements symmetrical with respect to the central axis Ox of the cell, both at the level of the expansion zone Z b and the zone of ignition Z a ; the total width W e of the lateral conducting elements satisfies, in the expansion zone Z b , the general law defined above with reference to the second general embodiment of the invention; thus, the discharge spreads along two parallel general directions both at the ignition zone Z a than at the expansion zone Z b .
  • each firing area of a conductive element has an electrode width W a1 and W a2 less than W e-ab .
  • the example of figure 18B illustrates this preferred embodiment: this example is similar to that of the figure 18A , with the difference that the distance between the edges of the two lateral conductive elements is between 100 and 200 ⁇ m.
  • the ignition properties of the discharge are substantially improved.
  • the electrostatic influence of a lateral conductive element on the other increases and disturbs the evolution of the surface potential on the dielectric layer above each lateral conductive element, to the point that it deviates from the general objective of increasing potential pursued by the invention even if the total width W e of the conductive elements satisfies, in the expansion zone Z b , the general law defined above with reference to FIG. second general embodiment of the invention.
  • ignition Z a-p2 the distance, measured parallel to the axis Oy at any position x between x ab and x bc , is called d ep (x) between the edges facing each other of a portion of the first lateral zone d Z b-p1 expansion positioned at x and a portion of the second expansion zone Z b-p2 also positioned at x.
  • the figure 18C illustrates an example of an electrode element subdivided into two lateral conductive elements which exhibit these characteristics.
  • Each lateral conductive element is curved at the start towards the walls, so that the distance between the two lateral conductive element is low at startup, in a range between 100 and 200 microns, and then increases steadily with x until each Lateral conductive element has approached a wall of the cell to the point that the disadvantageous wall effect begins to manifest itself; to avoid this wall effect, the distance separating the nearest lateral edge of a wall from each lateral conductive element remains at any point in the zone of expansion greater than or equal to 30 ⁇ m.
  • the tangent in x at the mean line of this element makes with the Ox axis an angle less than 60 °, preferably between 30 ° and 45 °.
  • the mutual electrostatic influence of two axio-symmetrical lateral conducting elements is used.
  • This third general embodiment therefore relates to electrode elements each subdivided, at least at the level of the zone of expansion, into two axiosymmetric lateral conducting elements which present this time a constant width but a mutual spacing of ep (x) which decreases continuously or discontinuously as a function of x for any x between x ab and x bc so as to obtain, in accordance with the invention, a continuous or discontinuous growth of the surface potential of the dielectric layer, along the Ox axis; a dielectric layer of uniform thickness and composition is then kept in the expansion zone.
  • the dielectric surface potential variation covering each electrode portion would saturate with a distance of ep (x ab ) greater than 350 ⁇ m between the two lateral electrode elements, or the rate of increase of the potential as a function of position x would be less than the preferential limit level of 1% for a variation of x of 100 ⁇ m, which would be insufficient to obtain rapid spreading of the discharge in the expansion zone.
  • each conductive element of the coplanar electrodes comprises, in addition to a transverse bar in the ignition zone and a transverse bar in the stabilization zone connected by axi-symmetrical lateral conductor elements of constant width as in FIG. prior art, at least one additional transverse bar positioned at the expansion zone; in addition, the dimensions and the positions of the transverse bars fulfill other conditions explained below.
  • the figure 20A describes a coplanar electrode element type structure quite similar to that of FIG. 4A, already described with reference to FIG. figure 9 of the document EP0802556 - MATSUSHITA .
  • Each conductive element Y is divided into three zones, an ignition zone Z a , an expansion zone Z b and a stabilization zone or end of discharge Z c .
  • the ignition zone Z a corresponds here to the transverse bar 31.
  • the stabilization zone Z c here corresponds to a transverse bar 33 'which extends here, unlike FIG. 4A, over a greater length L s than the length L a of the transverse bar 31 of the ignition zone Z a , these lengths corresponding, as before, to the dimension of these bars along the longitudinal axis Ox of the cell.
  • transverse bars 31, 33 ' are connected, at the level of the expansion zone Z b , by lateral axiosymmetric conducting elements or side jambs 42a, 42b, which are far apart from each other since they are deported at the levels of the walls of the cell, and which each have a width W e-p1 and W e-p2 constant.
  • the figure 21 describes the distribution of the surface potential of the dielectric layer according to the sections A - curve A - and B - curve B - of the cell of the figure 20A . This distribution is obtained using the aforementioned SIPDP-2D software.
  • the capacity of the dielectric layer located at the end of discharge zone is greater than the specific capacity of the dielectric layer located at the ignition zone of the discharge, so as to establish a positive potential difference between the ignition zone and the end of discharge zone.
  • the length Le of a conductive element modifies the potential at the surface of the dielectric layer according to the same laws.
  • the length Le did not play any role because Le is always greater than W e , so that the variation of potential at the surface of the dielectric layer is only influenced by the width of the conductive element.
  • the dielectric surface potential on the curve A decreases substantially at the exit of the ignition zone, due to the absence of an electrode in the expansion zone between the two side walls. In this part of the expansion zone, the surface potential depends on the potential created by both perpendicular bars located at the side walls.
  • At least one third transverse bar 205 is added.
  • the length L b of this bar measured along the axis of longitudinal symmetry Ox of the cell, is such that L b ⁇ L a ⁇ L s .
  • this bar is positioned this time at the level of the expansion zone as follows: if d1 is the distance between the edges which merges with the ignition zone Z a and the zone of Z b expansion, if d2 is the distance between the edges which face the bottom of the stabilizing zone Z c and Z expansion zone b, we have d 2/2 ⁇ d 1 ⁇ d 2.
  • each electrode element comprises at least three transverse bars 31, 205, 33 'which extend in a general direction perpendicular to the expansion direction Ox of the discharges, which are interconnected by axial lateral conducting elements. symmetric perpendicular to the transverse bars and positioned at the side walls of the slab 2.
  • the invention finds its application particularly in the case where these electrodes Y, Y 'of the co-planar slab of the plasma panel are powered by voltage pulses having constant voltage steps (pulses in the form of a slot) to conventional frequencies generally between 50 and 500 kHz.

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EP03760707A 2002-06-24 2003-06-19 Dalle de decharges coplanaires pour panneau de visualisation a plasma apportant une distribution de potentiel de surface adaptee. Expired - Fee Related EP1516348B1 (fr)

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FR0208094A FR2841378A1 (fr) 2002-06-24 2002-06-24 Dalle de decharges coplanaires pour panneau de visualisation a plasma apportant une distribution de potentiel de surface adaptee
FR0208094 2002-06-24
PCT/EP2003/050243 WO2004001786A2 (fr) 2002-06-24 2003-06-19 Dalle de decharges coplanaires pour panneau de visualisation a plasma apportant une distribution de potentiel de surface adaptee.

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CN1663008A (zh) 2005-08-31
AU2003255512A8 (en) 2004-01-06
FR2841378A1 (fr) 2003-12-26
WO2004001786A3 (fr) 2004-02-19
WO2004001786A2 (fr) 2003-12-31
JP2005531110A (ja) 2005-10-13
US7586465B2 (en) 2009-09-08
US20060043891A1 (en) 2006-03-02
AU2003255512A1 (en) 2004-01-06
KR20050008850A (ko) 2005-01-21
JP4637576B2 (ja) 2011-02-23
CN100377281C (zh) 2008-03-26
EP1516348A2 (fr) 2005-03-23
KR100985491B1 (ko) 2010-10-08

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