JP2004240430A - Plasma display panel provided with drive means suitable for carrying out rapid charge-equalization operation - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten reset operations in a discharge region without reducing efficiency, that is, while maintaining the equalization level in various discharge regions. <P>SOLUTION: The invention relates to division of the reset operations into two successive steps: a metastable space charge-generation step P1; an accelerated charge-generation end step P2 during which the system operates in the mode with weak discharges between the electrodes E1, E2, serving at least for addressing. Thanks to this division, the reset operations may be shortened and the luminous performance of the panel and/or the manufacturing yields of plasma panels may be improved. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to an apparatus comprising an AC-type plasma panel having a memory effect serving at least for addressing, comprising a coplanar electrode serving at least to maintain the charge and a charge equivalent value in a discharge region of the plasma panel. And means for driving a panel suitable for performing a reset (or reset) operation, an address operation and a sustain operation.

  An AC plasma display panel (PDP) having a memory effect is generally composed of two parallel substrates having a space containing a discharge gas between them. Such panels typically have an array of several electrodes between and on the inside surfaces of the substrates, as follows.

A general function provided for addressing the discharge at the intersections of the electrodes, which are each provided on a different substrate and therefore in a non-coplanar manner, the space between the substrates, where the discharge region with light is defined. An array of two intersecting electrodes; and at least two parallel coplanar electrodes provided on the same substrate and serving to sustain the discharge, these arrays providing in particular a memory effect A coplanar electrode, which is generally a protective layer based on magnesium oxide and is covered by a second electron emitting layer.

  Each sustaining array electrode, together with the other sustaining array electrodes, forms a pair of electrodes defining a series of photodischarge areas that are generally distributed along the rows of the discharge area of the panel.

  The photodischarge areas form a two-dimensional matrix in the panel, each area capable of discharging light, so that the matrix displays the image to be displayed.

  Generally, one of the arrays of coplanar electrodes plays a role for both addressing and maintenance. In this particular case, the electrode array is hereafter referred to as Y, the second array of child plays as X, and the array of address electrodes positioned orthogonal to Y and X and located on the other substrate is referred to as A. The array of electrodes X and Y therefore supplies the rows of the discharge area, and the electrode array A, which serves only for addressing, provides the columns of the discharge area.

  In at least adjacent discharge regions that emit different colors, the adjacent discharge regions are generally bounded by barrier ribs, which generally act as spacers between the substrates.

  The walls of the photodischarge area are generally partially covered with a phosphor that is sensitive to ultraviolet radiation from the photodischarge. Adjacent discharge areas comprise phosphor layers that emit three different primary colors, such that a combination of three adjacent areas forms an image element or pixel.

  In practice, these phosphors generally cover the inclined walls of the substrate supporting these ribs and the barrier ribs, which are the substrates supporting the electrode array serving only for addressing, and the address electrodes Therefore, it is covered with the phosphor.

  When the plasma panel is in operation, a series of displays or a series of operations are performed using a matrix of discharge regions to display an image, and generally each sub-display operation comprises the following steps.

  The first is a selective addressing phase, the purpose of which is to apply electrical at least one voltage pulse between the address electrodes of interest in the discharge area, so that the electrical in the dielectric layer in each discharge area becomes active. Correcting the discharge.

  The second is a non-selective sustaining step in which a series of voltage pulses is applied between the pair of sustaining electrodes to produce a series of photodischarges only in the previously active discharge region.

  After the sub-display operation, the discharge region may be at a very different internal voltage state, depending, in particular, on whether or not the discharge region is activated during the sub-display operation; This leads to such variations in internal voltage conditions, such as the nature of the phosphors corresponding to, unavoidable variations in the dimensional characteristics of these discharge areas and the surface composition of the walls in these areas related to the panel manufacturing process.

  Most of the addressing phase is preceded by a step of making these areas identical, so that the internal voltage state is the same for all discharge areas to be addressed, the purpose of which is, inter alia, of the preceding sub-display operation. Resetting all discharge areas to be addressed to the same internal voltage state, during which the discharge areas are activated or not. This reset stage conventionally consists of a charge forming or pre-maging operation followed by a charge adjustment operation, after which, ideally, the internal voltage in each discharge region substantially equals the ignition threshold between the address electrodes and between the sustain electrodes. That is.

  For each pair of addressing or sustaining electrodes in the discharge region, it is possible to correlate the internal voltage in the gas space separating the material covering these electrodes with the external voltage applied between these electrodes. In general, the internal voltage differs from the external voltage due to the surface charge on the surface of the insulator material covering the electrodes at the interface between the gas in the discharge region and these dielectric materials.

  On the other hand, these surface charges result from capacitive effects due to the dielectric properties of the material defining the discharge area, and, on the other hand, the accumulation of what is called the "memory" charge generated by a previous discharge in the gas in these discharge areas. Brought from.

  The ignition threshold inside the discharge region in a given direction corresponds to the internal voltage limit along this direction, above which the gas is ionized in this region. This value depends on the properties of the gas in this area, the properties of the material in contact with the gas in this area, and the geometry of the electrodes outside this area and across this area.

In the special case of the three electrode arrays X, Y, A described above, generally six internal thresholds are associated with each discharge region, as follows.
● Internal threshold V _{IT_XY} for firing between anode X and cathode Y
● Internal threshold V _{IT_YX} for firing between cathode X and anode Y
● Internal threshold V _{IT_XA} for firing between anode X and cathode A
● Internal threshold V _{IT_AX} for ignition between cathode X and anode Y
● Internal threshold V _{IT_YA} for firing between cathode Y and anode A
● Internal threshold V _{IT_AY} for firing between cathode Y and anode A
The terms "anode" and "cathode" relate to the internal potential in the gas in the discharge region near the electrode across this region. If the potential in the gas near the electrode is large compared to the potential near the other electrode, the electrode is said to be a cathode in relation to another electrode, and thus the other electrode is an anode.

The next two internal thresholds have the same value to characterize the discharge in coplanar mode, produced by electrodes supported by the same substrate and comprising one electrode generally symmetrically with respect to the other.
V _{IT_XY} = V _{IT_YX} and is represented as V _{IT_S} .
However, characterizing the discharge in matrix mode, the next two internal thresholds between the two different substrates depend on whether the electrode of interest functions as a cathode or an anode, and Become like
V _{IT_XA} = V _{IT_YA} and V _{IT_A_ca}
V _{IT_AX} = V _{IT_AY} and V _{IT_A_ac}
This is because when the column address electrode A functions as a cathode, the secondary emission from the phosphor supporting it is smaller than the secondary emission from magnesium oxide on the surface of the dielectric covering the electrode X or Y, so that discharge occurs. Is by generating a larger voltage when it functions as an anode.

Generally, it is as follows.
Each electrode Y, which serves for both addressing and maintenance during a charge forming or priming operation, is an anode with respect to the other two electrodes X and A;
Each electrode Y, which serves for both addressing and maintenance during a charge conditioning or erasing operation, is a cathode with respect to the other two electrodes X and A;

  These operations generally apply a slowly increasing potential difference between, on the one hand, between the two coplanar electrodes and, on the other hand, between the two matrix electrodes for addressing all of the discharge areas of the group to be addressed. It is performed by References, French Patent No. 2,417,848 (THOMSON-1978) (Patent Document 1) and US Pat. No. 5,745,086 (PLASMACO-1998) (Patent Document 2), Thus, the application of a ramp voltage signal to an electrode that serves both addressing or sustaining while applying a constant voltage signal only to other addressing or sustaining electrodes has been described.

  US Pat. No. 5,745,086 discloses that when the slope of the applied ramp signal does not exceed 20 V / μs, it involves a series of so-called “weak” but not strong discharges between the electrodes, A reset operation for the discharge area of the panel is advantageously performed in each area. These "weak" discharges compensate for the increase in external voltage applied to the electrodes by surface discharges made on the walls of the area provided by these electrodes, and because of the absence of "strong" discharges, The internal voltage in the region gas is kept equal to or less than the internal firing threshold defined above.

  A known advantage of a reset due to a weak discharge, also called a "positive resistance" reset, is that it allows a precise adjustment of the internal voltage in the discharge region by generating a weak light emission. Accurate coordination is important for the performance and efficiency of the next address operation. This limitation of light emission is essential to the contrast performance of the display.

The maximum slope of the ramp signal that produces a weak discharge in the discharge region depends, inter alia, on the properties of the material covering the cathode in this area, the secondary electron emission coefficients of these materials and the properties of the gas metastable component and space charge in this area. Depends on. Commonly used gradient values are no greater than 5 V / μs for priming operations where the Y electrode functions as the anode with respect to the X and A electrodes. Generally, the total amplitude of the lamp voltage reaches 200 V, so that the period of the priming operation reaches several tens of μs. This period means wasted time with respect to other operations to be performed during the operation or sub-operation, namely addressing and sustaining operations, and thereby the performance of the display device, in particular its emission Restrict on the maximum value of In addition, certain panels may be rejected at the end of the production line as they malfunction due to the strong discharges that appear during priming lamps using standard lamp voltage values. Yes, further increasing the manufacturing cost of the panel.
French Patent No. 2,417,848 U.S. Pat. No. 5,745,086

  An object of the present invention is to reduce the above problems. It is also an object of the present invention to shorten the duration of the reset operation of the discharge region without reducing the efficiency, i.e. while maintaining the level of equalization of the various discharge regions.

To this end, the subject of the present invention is:
An AC plasma with a memory effect, two substrates, two substrates separated by a space containing a discharge gas, and a point of intersection at which a photodischarge area is defined in the space between the two substrates. An AC plasma, comprising at least an intersecting electrode (E2, E1) which serves for addressing at; and performing an operation intended to reset the discharge region or equalize the charge. Driving means suitable for applying a voltage signal to the electrode that is suitable for:
A display device comprising:
The driving unit, during a specific operation of resetting a group of discharge areas,
If each discharge region of the panel has an external matrix firing threshold voltage (V _{ET — E2E1} ) between the electrodes that at least serves to address and cross said region, and Min [V _{ET — E2E1} ] and Max [V _{ET — E2E1} ] _Where each is the minimum and maximum value of the matrix firing voltage (V _{ET — E2E1} ) in the group area,
By what V _E2E1 called the end of the operation the gradient is greater slope than the maximum slope of increase of _{V E2E1} during the instants is between _{Max [V ET_E2E1]} and _{Min [V ET_E2E1],} during the reset operation As _{soon as} V _E2E1 is greater than the value 1.1 × Max [V _{ET — E2E1} ], the potential difference V _E2E1 applied between the electrodes which at least crosses and serves to address the area of this group increases.
The present invention is to provide a display device designed as such.

  The invention therefore corresponds to Case 1 or the first embodiment, which is described in more detail below.

The subject of the invention also follows the same principle,
An AC plasma having a memory effect, wherein two substrates are separated from each other by a space containing a discharge gas, and at an intersection where a photodischarge region is defined in the space between the two substrates. Intersecting electrodes serving at least for addressing, and an array of at least two electrodes serving at least for maintenance and having one of each electrode of these arrays traversing each discharge region An AC plasma, comprising: an array of at least two electrodes; and a voltage signal suitable for performing a reset operation intended to reset the discharge region or equalize the charge. Drive means suitable for applying to said electrodes (EA2, EA1, ES2, ES1);
A display device comprising:
The driving unit, during a specific operation of resetting a group of discharge areas,
If each discharge region of the panel has an external matrix firing threshold voltage (V _{ET — EA2EA1} ) between the electrodes (EA 2, EA 1) that serves at least to address and cross the regions, Min [V _{ET —EA 2EA1} ] and Max [ V _{ET — EA2EA1} ] electrodes (ES2, ES1) where each discharge region of the panel traverses the region and at least serves to maintain it, if each is the minimum and maximum value of the matrix firing voltage of the group region , And when Min [V _{ET_ES2ES1} ] and Max [V _{ET_ES2ES1} ] are the minimum and maximum values of the coplanar firing voltage (V _{ET_ES2ES1} ) in the region of the group, respectively. ,
The potential difference V _ES2ES1 applied between the electrodes (ES2, ES1) which at least serves to traverse and maintain the regions of this group is not greater than the value Max [V _{ET_ES2ES1} ] and at least plays a role of maintenance As _soon as the potential difference V _ES2ES1 applied between the electrodes (ES2, ES1) is greater than the value Max [V _{ET_ES2ES1} ], it is increased by what is called the end of the operating gradient, while at least crossing and addressing said area of this group. The potential difference V _EA2EA1 applied between the electrodes (EA2, EA1), which _fulfills the following function, does not become greater than the value Min [V _{ET_EA2EA1} ] or
By what V _ES2ES1 called end of positive operating slope is greater slope than the maximum slope of increase of _{V EA2EA1} between instant lying between _{Max [V ET_ES2ES1]} and _{Min [V ET_ES2ES1],} the region As _soon as the potential difference V _ES2ES1 applied between the electrodes (ES2, ES1) which at least crosses and maintains becomes greater than the value Max [V _{ET_ES2ES1} ], the electrodes which at least cross and address this region of this group The potential difference V _ES2ES1 applied during (EA2, EA1) is either increased,
The present invention is to provide a display device designed as such.

  The invention therefore corresponds to either Case 2 or the second embodiment or Case 3 or the third embodiment, which will be described in greater detail below.

In general, the driving means is further suitable for performing the following operations.
A selective addressing operation for selectively activating or deactivating the discharge region, said operations being performed by applying a voltage pulse between electrodes which at least serve for addressing. motion;
A non-selective sustaining operation for initiating a discharge only in a preactivated discharge region of the panel, said operations being performed by applying a voltage pulse between the electrodes which at least serves to sustain; Non-Selected Sustained Operation Such a panel is said to have a "memory effect" because during the sustain period, a discharge is generated only in pre-activated areas. To this end, in each discharge region, at least one electrode serving at least for sustaining is coated with a dielectric layer, which is a protective layer and is itself covered by a second electron-emitting layer. .

  The dielectric layer provides a memory effect that allows a discharge to be initiated only in the activated areas during the sustain operation. The protective layer is generally based on magnesium oxide, has a high secondary electron emission coefficient, and in each discharge area the secondary electrons of the material coated with at least one of the electrodes which serves for addressing. It has a secondary electron emission coefficient greater than the emission coefficient and this material is generally a phosphor.

  Preferably, the driving means is designed such that, during the specific charge equalization operation or the reset operation, in each of the discharge areas of the group, the electrode covered by the protective layer acts as an anode. You. The specific reset operation is then a charge forming operation or a priming operation. In this case, therefore, there is no charge conditioning or erasing operation, in contrast, this electrode covered with a protective layer functions as a cathode.

  Each reset operation is generally associated with a group or all of the rows in the discharge area of the panel. These operations are generally started before the selective address operation.

  The term “matrix firing” is understood to mean the initiation of a discharge between the electrodes, which at least serves for addressing, and the term “coplanar firing” at least, between the electrodes serving for maintenance. Is understood to mean the start of

  If the panel consists of an array of coplanar electrodes supported by the same substrate, these electrodes at least play a role in maintenance. Other substrates, therefore, generally support an array of electrodes, which may serve to initiate the sustain discharge, but serve primarily for addressing. In this case, at least one of the arrays of electrodes serving for addressing is preferably integrated with one of the arrays of electrodes serving for at least maintaining. It is therefore this array of electrodes that acts as the anode during the priming operation. Conventional coplanar plasma substrates from the prior art are therefore used.

  If the panel does not have coplanar electrodes, the sustaining operation is generally performed by applying a voltage pulse between the electrodes, which also serves for addressing. Thus, in general, a panel has two electrode arrays, each electrode array being on a respective substrate. As a variant, the sustaining operation is performed by applying a high frequency to the discharge area, in which case the electrode array plays a role only for addressing.

  In accordance with the present invention, it is possible to reduce the period required for the reset operation and to spend additional time on the sustain operation, thus improving the luminance performance of the panel.

  Preferably, the end of the operating gradient for increasing the potential difference between the electrodes, which at least serves for addressing, is greater than 5 V / μs.

  Thus, as soon as the matrix firing threshold in case 1 is greater, and as soon as all of the coplanar firing thresholds in case 2 and case 3 are greater, all of these operations are not compromised and the contrast is compromised. The reset operation can be performed significantly faster than in the prior art without any risk of a strong discharge. Therefore, more time can be devoted to other driving operations, especially to sustaining operations, which can improve display performance, especially in video image display.

  Preferably, the end of the operating gradient for increasing the potential difference between the electrodes, which at least serves for addressing, is greater than 10 V / μs. The advantages and device performance of the present invention are further improved.

Preferably, in case 2 or case 3, during the reset operation V _ES2ES1 is between Min [V _{ET_ES2ES1} ] and Max [V _{ET_ES2ES1} ] and the potential difference applied between the electrodes which at least serves to maintain V _ES2ES1 is increased by what is referred to as the onset of an operating gradient of greater than 5 V / μs, preferably greater than 10 V / μs. The invention's superiority and device performance are further improved.

Preferably, during each said specific reset operation, the potential difference (V _E2E1 ; V _EA2EA1 ) applied at least between the electrodes serving for addressing is Min [V _{ET_E2E1} ] <V _E2E1 <Max [ _{VET_E2E1} ], or Min [ _{VET_EA2EA1} ] < _VEA2EA1 <Max [ _{VET_EA2EA1} ], and increases uniformly and strictly. The expression “uniform and strictly increasing” is understood to mean a non-zero increase. Preferably, this increase increases linearly with time. Therefore, this is achieved with a linear voltage ramp applied to one of the arrays of electrodes, which is relatively easy to implement.

Preferably, in case 2 or 3, during each said particular reset operation, the potential difference applied between the electrodes which at least serves for maintenance is Min [V _{ET_EA2EA1} ] <V _EA2EA1 <Max [V _{ET_EA2EA1} ] uniformly and strictly.

  The expression “uniform and strictly increasing” is understood to mean a non-zero increase. Preferably, this increase increases linearly with time. Therefore, this is achieved with a linear voltage ramp applied to one of the arrays of electrodes, which is relatively easy to implement.

A summary of the principles on which the present invention is applied to the priming operation is as follows.
● To obtain a discharge mode in which the two electrodes which play a role for addressing, the weakest discharge mode with the largest possible slope value between E1 and E2 or EA1 and EA2, wherein E1 or EA1 functions as a cathode In turn, the starting level for conditioning the discharge area rises before a large gradient signal is applied between these electrodes.
The present invention therefore relates to two successive steps, one in the same reset operation, which are as follows:
○ Step P1 of generating a metastable space charge obtained by discharging
O The system operates in a mode where there is a weakest discharge between the electrodes, E1 and E2 or EA1 and EA2, with the largest possible gradient, typically a gradient greater than 10 V / μs, that serves at least for addressing. During the termination phase P2 of accelerated charge generation corresponding to making all these discharges the same
The present invention can be applied to a plasma panel having various cell or discharge region structures, for example, having an “ACM”, “ACC” or “ACC3E” type structure.
• In case 1 applicable to either an "ACM" matrix panel with two electrodes E1, E2 per cell or an ACC panel with three or more electrodes per cell, step P1 Will be slow, whatever the previous stage of the cell, for a long enough time to generate a discharge between the two electrodes E1 and E2 (or, alternatively, EA1 and EA2) Is to apply a ramp ramp. This gentle slope value actually corresponds to the slope normally used in the prior art, ie a value less than 10 V / μs. The E1-E2 (or alternatively EA1-EA2) discharge thus generated is a part of the internal voltage for the cell between the electrodes E1 and E2 (or alternatively between EA1 and EA2). Plays a role in both equalization and cell conditioning.
● In cases 2 and 3 applicable to an “ACC” type coplanar panel consisting of at least three electrodes EA1, EA2 = ES2, ES1 per cell, stage P1 is the coplanar electrode of the cell, EA2 (In the case of standard "ACC": EA1 column, EA2 = ES2 = "scan / maintain" row, ES1 = "common" row) ES2 and secondary electron emission larger than the material covering EA1 The application of a higher gradient lamp in the prior art, generally greater than 10 V / μs, between the ES1 functioning as a cathode covered with a material having a modulus. The ES1-ES2 planar discharge thus generated plays a part for both part of the equalization of the internal voltage between ES1 and ES2 and conditioning of the cell. Cases 2 and 3 are distinguished as follows.
Case 2: During phase P1, no discharge occurs between EA1 and EA2, and the ignition voltage does not rise internally between these electrodes. This can be performed with various signals (constant, ramp or other signals) between EA1 and EA2 provided without exceeding the firing threshold. During this phase P1, a weak coplanar discharge is initiated and a weak matrix discharge is prevented from occurring, and the amplitude of the ramp signal applied like a matrix does not exceed the matrix threshold voltage at any instant. .
Case 3: During phase P1, a matrix discharge is formed between EA1 and EA2 simultaneously with a coplanar discharge between ES1 and ES2. In this case, the signal gradient between EA1 and EA2 needs to be small to allow operation in the weak discharge mode until a sufficiently large level of cell conditioning is reached. In this case, the slope of the signal between EA1 and EA2 is smaller than that between ES1 and ES2.
• Stage P2 is characterized by the application of a ramp signal between EA1 and EA2, which is a higher slope in the prior art, generally greater than 10 V / μs. At this stage, what happens between the other electrodes is of little importance.
• Stages P1 and P2 can be arbitrarily separated by a period without any discharge in the cell (for example, if the applied voltage stops temporarily increasing). This period need not be greater than 20 μs for the conditioning effect generated during P1 to be still active at P2.
● The described embodiments are derived from the situation in which a discharge is generated between the electrodes specific to each cell of the panel and from these general principles, as they relate to:
○ The firing threshold value that changes depending on the cell ○ The state of the surface memory charge depending on the process of the cell (whether it was discharged or not in advance)
The present invention will be more clearly understood on reading the following detailed description, which is provided by way of non-limiting embodiment with reference to the accompanying drawings.

  Various general embodiments of the present invention are described below. The first embodiment is a matrix type having only two electrode arrays E1 and E2 formed on each substrate and having both an electrode array and a discharge addressing and maintaining discharge. Applies to plasma panels. Another embodiment applies to a coplanar plasma panel having an EA2 on a coplanar substrate and two arrays of sustain electrodes ES1, ES2 on the same substrate, called an address substrate facing the coplanar substrate. These other embodiments apply to conventional coplanar panels where the array of coplanar electrodes plays a role for both addressing and maintenance, meaning that EA2 is combined with ES2.

  The sustaining electrodes, E2 or ES1 and ES2, are made of a material such as magnesium oxide which has a large secondary electron emission coefficient, which in all cases is higher than the material covering the electrode E1 or EA1 of the address substrate. It is covered by a covered dielectric layer. The material covering the electrode E1 or EA1 is generally a phosphor, and when its meaning is expanded, it is a substrate supporting these electrodes, and the magnesium oxide layer is a sustaining substrate or a coplanar substrate in the case of a coplanar panel Called.

A matrix panel is composed of a large number of discharge areas. After scanning or sub-scanning of the image, each region of the panel has an external firing threshold voltage _{VET_E2E1} in case of a charge generation operation where E2 functions as an anode on the sustain substrate. The minimum value of the firing voltage in all regions of the panel is represented by Min [V _{ET_E2E1} ], and the maximum value of the firing voltage in all regions of the panel is represented by Max [V _{ET_E2E1} ].

Coplanar panels are composed of a large number of discharge areas. After scanning or sub-scanning of the image, each area of the panel has an external maximum firing threshold voltage V _{ET_EA2EA1} and an external coplanar firing threshold repression V _{ET_ES2 ES1} , and the charge generation EA2 and ES2 in the coplanar substrate function as anodes. This is the case in operation. The minimum voltages of the matrix firing voltage and the coplanar firing voltage of all areas of the panel are represented by Min [V _{ET_EA2EA1} ] and Min [V _{ET_ES2ES1} ], respectively, and the matrix firing voltage and coplanar firing voltage of all areas of the panel are provided. The maximum voltage is represented by Max [V _{ET_EA2EA1} ] and Max [V _{ET_ES2ES1} ], respectively.

  All embodiments of the invention described below relate to charge generation or priming operations. In accordance with an essential feature of the invention, each of these operations consists of a phase P1 called the charge generation and conditioning start phase of period τ1, followed by a phase P2 called the end of accelerated charge generation of period τ2, If it is desired to derive sufficient benefit from conditioning of the discharge region in the two-stage P2, the time separating the end of the first stage and the start of the second stage need not necessarily be greater than 20 μs.

In FIG. 1, which shows the charge generation or priming operation of the matrix panel, the external voltage between the electrodes E2 (anode) and E1 (cathode) can be distinguished continuously as follows.
_{-VE2E1_P1_ST at} the start of phase P1
_{-VE2E1_P1_ND at} the end of phase P1
_{-VE2E1_P2_ST at} the start of phase P2
_{-VE2E1_P2_ND at} the end of phase P1
2 and 3 showing the charge generation or priming operation of the coplanar panel, on the one hand the external voltage between the address electrodes EA "(anode) and EA1 (cathode) and on the other hand the sustain electrodes ES2 (anode) and ES1 (cathode) Can be continuously distinguished as follows.
- _V at the start of the stage P1 _{EA2EA1_P1_ST} and _{V ES2ES1_P1_ST}
- _V at the end of stage P1 _{EA2EA1_P1_ND} and _{V ES2ES1_P1_ND}
- _V at the start of step P2 _{EA2EA1_P2_ST} and _{V ES2ES1_P2_ST}
- _V at the end of stage P1 _{EA2EA1_P2_ND} and _{V ES2ES1_P2_ND}
For simplicity, the same reference numerals have been used in various embodiments for elements that perform the same function.

First Embodiment: In the case of a matrix panel or a coplanar panel Referring to FIG. 1, two stages P1 and P2 are defined as follows.
_{−VE2E1_P1_ST} <Min [ _{VET_E2E1} ]. Therefore, at the beginning of phase P1, no cell state of the panel will be greater than the discharge firing threshold in any cell of the panel, regardless of the charge state resulting from the operation during the previous scan or sub-scan. Preferably, V _{E2E1 —} P1 — _ST ≧ 0.9 _× Min [V _{ET — E2E1} ], so that a weak discharge starts to occur in the area of the panel from the beginning of the conditioning phase P1.
_{-VE2E1_P1_ND} <Max [ _{VET_E2E1} ]. Therefore, after the conditioning phase P1, it is greater than the discharge firing threshold in each cell of the panel, regardless of the charge state resulting from the previous operation, to generate the initial conditioning state. Preferably, _{VE2E1_P1_ND} ≤ 1.1 _x Min [ _{VET_E2E1} ] so as not to unnecessarily exceed the slow potential increase period P1 and to execute the fast potential increase period P2 as quickly as possible. .
_{-VE2E1_P2_ST} = _{VE2E1_P1_ND} , so the two stages P1 and P2 are linked to each other without transition. And _{-VE2E1_P2_ND} is _defined in the same way as in the prior art, i.e. at the end of stage P2, to obtain the desired priming level in all the discharge areas of the panel.

During phase P1, the rate of increase of the potential V _E2E1 between the electrodes or the instantaneous value of the slope dV _E2E1 / μτ is in accordance with the prior art, ie, less than 5 V / μs throughout the duration τ1 of this phase. In contrast, according to the present invention, during the phase P2, the rate of increase of the potential V _E2E1 between the electrodes or the instantaneous value of the gradient dV _E2E1 / μτ is substantially greater than in the prior art throughout the duration τ2 of this phase. Large, preferably greater than 10 V / μs.

  Generally, according to the invention, the interelectrode potential therefore increases much more rapidly at the end of the charge generation period during phase P2 than at the beginning of this period during phase P1. The time for the priming operation is therefore greatly reduced without compromising the quality of any of these operations.

Second Embodiment: Coplanar Panel Referring to FIG. 2, the two stages P1 and P2 are defined as follows.
_{−VE2E1_P1_ST} <Min [ _{VET_E2E1} ]. Therefore, at the beginning of phase P1, no cell state of the panel will be greater than the discharge firing threshold, whatever the charge state from the previous operation. Preferably, _{VE2E1_P1_ST} <0.9xMin [ _{VET_E2E1} ], so that a weak discharge starts to occur in the area of the panel from the beginning of phase P1.
_{-VE2E1_P1_ND} <Max [ _{VET_E2E1} ]. Therefore, after the conditioning phase P1, it is greater than the discharge firing threshold in each cell of the panel, regardless of the charge state resulting from the previous operation, to generate the initial conditioning state. Preferably, _{VE2E1_P1_ND} <1.1xMin [ _{VET_E2E1} ] so as not to unnecessarily exceed period P1 and to execute period P2 as fast as possible.
_{VE2E1_P1} <Min [ _{VET_EA2EA1} ], which means that at each instant τ of the conditioning phase P1, the potential difference _{VE2E1_P1} between the address electrodes is kept smaller than Min [ _{VET_EA2EA1} ] and therefore the matrix discharge is Not generated in the panel during the phase. _Note that this inequality is satisfied at every instant of P1 by varying _{VET_EA2EA1} during P1 depending on the charge generated near the electrode.
-V _{EA2EA1_P1} <Min [V _{ET_EA2EA1} ]. Therefore, at the start of phase P2,
No matter what charge state results from the previous operation, the matrix discharge firing threshold will not be greater in any cell of the panel. Preferably, V _{EA2EA1_P2_ST} <0.9 _× Min [V _{ET_EA2EA1} ], so that a weak matrix discharge starts to occur in the area of the panel from the beginning of phase P2.
_{VEA2EA1_P2_ND} is _defined in the same way as in the prior art, ie to obtain the desired priming level in all the discharge areas of the panel.

During phase P1, the rate of increase of the potential V _EA2EA1 between the sustaining electrodes or the instantaneous value of the slope dV _E2E1 / μτ is substantially greater than in the prior art, preferably greater than 10 V / μs. During phase P1, the rate of increase of potential V _EA2EA1 can be 0, less than 0, or greater than 0 if this potential is kept less than Min [V _{ET_EA2EA1} ].

During the phase P2, the rate of increase of the potential V _EA2EA1 between the sustain electrodes or the instantaneous value of the slope dV _E2E1 / μτ is substantially greater than in the prior art, preferably greater than 10 V / μs. During phase P1, the rate of increase of potential V _ES2ES1 can be less than or less than zero, zero, or zero.

  Generally, in accordance with the present invention, in such a way that the gas is regulated before the matrix discharge is initiated, the charge generation operation should be greater than all coplanar discharge thresholds before it begins to be greater than the first matrix discharge threshold. Is executed by This is advantageous because a coplanar discharge occurs in the material with a high secondary emission coefficient coated on the electrodes of the coplanar substrate, whereby a weak child planar discharge ES1-ES2 with a steep gradient during phase P1. Can be generated. Therefore, in general, the material that is the phosphor coated on the electrodes of the address substrate, the individual material here being the phase P1 despite the very general secondary electron emission characteristics of the material used as cathode The conditioning achieved during then makes it possible, during the stage P2, to generate a weaker matrix discharge EA1-EA2 with a larger gradient in the prior art. In accordance with the present invention, the time for the priming operation can therefore be reduced very significantly, and the correcting operation can reduce the weak secondary electron emission properties of the phosphor without ever compromising the quality of these operations. Can be achieved using a panel having

Third Embodiment: In the case of a coplanar panel This embodiment differs from the above embodiments in that a limited matrix discharge is allowed during the period of coplanar conditioning.

Referring to FIG. 3, the two stages P1 and P2 are defined as follows.
_{-VES2ES1_P1_ST} <Min [ _{VET_ES2ES1} ] and _{VEA2EA1_P1_ST} <Min [ _{VET_EA2EA1} ]. Therefore, at the beginning of phase P1, no cell state of the panel will be greater than the coplanar or matrix firing threshold in any cell of the panel, regardless of the charge state from the previous operation. Preferably, _{VES2ES1_P1_ST} ≧ Min [ _{VET_ES2ES1} ] and _{VEA2EA1_P1_ST} ≧ Min [ _{VET_EA2EA1} ]. Therefore, at the end of phase P1, to generate an initial conditioning state, whatever the charge state from the previous operation, will be greater than the coplanar discharge firing threshold in each panel cell. Also, in all or some of these cells the matrix discharge firing threshold will be greater.
_{VEA2EA1_P2_ND} is _defined in the same way as in the prior art, ie to obtain the desired priming level in all the discharge areas of the panel.

During phase P1, the rate of increase of the potential V _ES2ES1 between the sustain electrodes or the instantaneous value of the slope dV _E2E1 / μτ is substantially greater than in the prior art, preferably greater than 10 V / μs. During the phase P1, the rate of increase of the potential _VES2ES1 is in accordance with the prior art, ie less than 5 V / μs.

During the phase P2, the rate of increase of the potential V _EA2EA1 between the sustain electrodes or the instantaneous value of the slope dV _E2E1 / μτ is substantially greater than in the prior art, preferably greater than 10 V / μs. During phase P1, the rate of increase of potential V _ES2ES1 can be less than or less than zero, zero, or zero.

  In accordance with the present invention, the time for the priming operation can therefore be reduced very significantly, and the correcting operation can reduce the weak secondary electron emission properties of the phosphor without ever compromising the quality of these operations. Can be achieved using a panel having

Fourth Embodiment: In the case of a coplanar or matrix panel This embodiment provides the conditioning generated in all or some of the cells by a strong discharge and during P1 to be performed in other cells by a weak discharge. . This is not a preferred embodiment if the strong discharge is a sustain discharge.

Fifth Embodiment: In the case of a coplanar or matrix panel The fifth embodiment is different from the above four embodiments in that the conditioning effect of P1 is not longer than 20 μs, so that it is still active at the start of the discharge during P2. The possibility is added to include between the phases P1 and P2 a period of time without any discharge in all or part of the cells. The actual use of periods without discharge is well known in the prior art and will not be described in detail here. The internal voltage needs to be kept below the ignition threshold.

The various embodiments described above using non-limiting figures of the present invention allow the rate of increase of the potential applied between the electrodes during the reset operation of the panel to be increased compared to the prior art To Therefore, the invention allows any of the following:
Reducing the time allotted to the priming operation and using it for addressing or switching, thereby allowing the peak brightness or fidelity of the panel to be improved.
● Or to increase the efficiency of panel manufacturing by not rejecting panels with strong discharges during priming with standard slopes.

  Ultimately, it will be apparent to those skilled in the art that the present invention can be applied to other cases using a ramp signal to drive a plasma panel without departing from the scope of the concurrently filed claims. Will be understood.

Examples and Comparative Examples of the Present Invention Using the same coplanar plasma panel having three electrode arrays composed of two coplanar electrodes X and Y on the front panel and electrodes A on the rear panel for addressing, A type of charge equalization or reset signal is applied and their impact on the discharge during the application of these signals is evaluated.

  Such coplanar panels are known from the prior art and are described in the introduction to this specification using the same reference signs X, Y and A for the electrodes.

FIG. 4 is a timing diagram for voltage signals applied to the various electrodes X, Y and A of the panel during the priming operation. A linear voltage ramp, characterized by a ramp peak level V _pY , here at 400 V, is applied to a sustain and address electrode Y (corresponding to electrode EA2 here, which is consistent with ES2 of the general embodiment described above). After this, the constant signal _VpX is applied to the X electrode which functions only for maintenance, and the constant signal VA = 0 is applied to the address electrode A provided on another substrate. These signals are used to indicate the panel's response to excessively steep ramps with and without the present invention.

During each priming operation, the intensity of the strong discharge D _S impaired in coincidence may occur in normal use, it is recorded using a sensitive sensor to light provided before the group of screen discharge area .

The records obtained correspond to FIGS. All of these recordings are obtained under the same priming operating conditions, except for the value of the constant bias signal _VpX of the coplanar electrode X, especially under the application of a linear ramp signal.

Referring to FIG. V _pX = + 100V. The internal firing threshold between the electrodes Y and X, which serves at least for maintenance, is reached later than the internal firing threshold between the address electrodes. Matrix discharges therefore have priority over matrix discharges. If there is no pre-conditioning of the cells, many strong discharge D _S for the excessively steep gradient value is observed.

Referring to FIG. A V _pX = -120V. The internal firing threshold between address electrodes Y and A is at least slower than the internal firing threshold between electrodes Y and X, which serves for maintenance. Therefore, the start of the coplanar discharge is given priority. FIG. 8 shows that weak coplanar discharge does not cause strong discharge DS due to pre-conditioning of the cell. Such a setting describes the invention.

  Figures 6 and 7 correspond to the intermediate state, where VpX is 0V and -80V, respectively, and an unacceptable residue of strong discharge DS is observed.

  During each priming operation, the potential difference between the electrodes Y and X, which function at least for maintenance, and the potential difference between the address electrodes Y and A therefore increase with the same linear slope, and 2 and a situation similar to one of the cases shown in FIG. 2 results. Therefore, according to the embodiment of the present invention as shown by FIG. 8, by priming the coplanar electrode X sufficiently negative with respect to the address electrode A, the priming operation starts from the first stage P1 where the coplanar discharge is sufficiently prioritized. . Above a certain voltage level between the address electrodes Y and A, the matrix discharge will be greater than the matrix firing threshold without producing a strong discharge at this time, since the discharge area is pre-conditioned by the coplanar discharge. Inevitably generated for. Therefore, the respective bias voltages at X and A determine a stage P1 characterized by only the child planar discharge that produces the initial conditioning state of each cell. The intermediate states shown in FIGS. 6 and 7 correspond to coplanar discharge and matrix discharge in a particular cell being simultaneously active. Since the gradient applied between Y and A is the same as the gradient applied between Y and X, poor conditioning results in a strong discharge. To avoid a strong discharge DS, the solution according to the invention applies a gradual initial gradient between the electrodes Y and A, as in the third general embodiment of the invention described above.

FIG. 4 is a timing diagram for applying a potential difference between electrodes of a matrix panel during a charge generation operation according to the first embodiment of the present invention. FIG. 7 is a timing diagram for applying a potential difference between sustain electrodes and between address electrodes of a coplanar panel during a charge generation operation according to a second embodiment of the present invention. FIG. 11 is a timing diagram for applying a potential difference between sustain electrodes and between address electrodes of a coplanar panel during a charge generation operation according to a third embodiment of the present invention. According to the detailed embodiment shown in the above description, a voltage is applied to a three-electrode array of a conventional coplanar panel during a charge generation operation to demonstrate the advantages of the present invention compared to prior art timing diagrams. Is a general timing diagram for FIG. 4 shows a strong discharge which unfortunately appears when applying a voltage to the three-electrode array according to the fast timing diagram and which is outside the range defined by the present invention. FIG. 4 shows a strong discharge which unfortunately appears when applying a voltage to the three-electrode array according to the fast timing diagram and which is outside the range defined by the present invention. FIG. 4 shows a strong discharge which unfortunately appears when applying a voltage to the three-electrode array according to the fast timing diagram and which is outside the range defined by the present invention. FIG. 3 illustrates the advantage provided by the present invention, i.e., without strong discharge when applying voltages to three electrode arrays according to a fast timing diagram.

Claims (11)

An AC plasma having a memory effect, wherein two substrates are separated from each other by a space containing a discharge gas, and at an intersection where a photodischarge region is defined in the space between the two substrates. An AC plasma comprising at least an intersecting electrode (E2, E1) serving for addressing; and for performing an operation intended to reset the discharge region or to equalize the charge. Driving means suitable for applying a voltage signal to said electrode that is suitable for:
A display device comprising:
The driving unit, during a specific operation of resetting a group of discharge areas,
If each discharge region of the panel has an external matrix firing threshold voltage (V _{ET — E2E1} ) between the electrodes that at least serves to address and cross said region, and Min [V _{ET — E2E1} ] and Max [V _{ET — E2E1} ] _Where each is the minimum and maximum value of the matrix firing voltage (V _{ET — E2E1} ) in the group area,
By what V _E2E1 called the end of the operation the gradient is greater slope than the maximum slope of increase of _{V E2E1} during the instants is between _{Max [V ET_E2E1]} and _{Min [V ET_E2E1],} during the reset operation As _{soon as} V _E2E1 is greater than the value 1.1 × Max [V _{ET — E2E1} ], the potential difference V _E2E1 applied between the electrodes which at least crosses and serves to address the area of this group increases.
A display device characterized by being designed as follows.   2. The display device according to claim 1, wherein the end of the operating gradient for increasing the potential difference between the electrodes serving at least for addressing is greater than 5 V / [mu] s.   3. The display device according to claim 2, wherein the end of the operating gradient for increasing the potential difference between the electrodes serving at least for addressing is greater than 10 V / [mu] s. 2. The display device according to claim 1, wherein the potential difference (V _E2E1 ) applied between the electrodes serving at least for addressing during each of the specific reset operations is Min [V _{ET_E2E1} ]. The display device, which increases uniformly and strictly when <V _E2E1 <Max [V _{ET_E2E1} ]. An AC plasma having a memory effect, wherein two substrates are separated from each other by a space containing a discharge gas, and at an intersection where a photodischarge region is defined in the space between the two substrates. An array of intersecting electrodes (E2, E1) serving at least for addressing and at least two electrodes (EA2, EA1) serving at least for maintenance and each electrode (ES2 , ES1) comprising an array of at least two electrodes (ES2, ES1) arranged across each discharge area; and an AC plasma; and resetting the charge area or charging the charge, etc. The voltage signals (EA2, EA1, ES2, ES1) that are suitable for performing a reset operation intended to be Driving means that are suitable for adding to
A display device comprising:
The driving unit, during a specific operation of resetting a group of discharge areas,
If each discharge region of the panel has an external matrix firing threshold voltage (V _{ET — EA2EA1} ) between the electrodes (EA 2, EA 1) that serves at least to address and cross the regions, Min [V _{ET —EA 2EA1} ] and Max [ V _{ET — EA2EA1} ] electrodes (ES2, ES1) where each discharge region of the panel traverses the region and at least serves to maintain it, if each is the minimum and maximum value of the matrix firing voltage of the group region , And when Min [V _{ET_ES2ES1} ] and Max [V _{ET_ES2ES1} ] are the minimum and maximum values of the coplanar firing voltage (V _{ET_ES2ES1} ) in the region of the group, respectively. ,
The potential difference V _ES2ES1 applied between the electrodes (ES2, ES1) which at least serves to traverse and maintain the regions of this group is not greater than the value Max [V _{ET_ES2ES1} ] and at least plays a role of maintenance As _soon as the potential difference V _ES2ES1 applied between the electrodes (ES2, ES1) is greater than the value Max [V _{ET_ES2ES1} ], it is increased by what is called the end of the operating gradient, while at least crossing and addressing said area of this group. The potential difference V _EA2EA1 applied between the electrodes (EA2, EA1), which _fulfills the following function, does not become greater than the value Min [V _{ET_EA2EA1} ] or
By what V _ES2ES1 called end of positive operating slope is greater slope than the maximum slope of increase of _{V EA2EA1} between instant lying between _{Max [V ET_ES2ES1]} and _{Min [V ET_ES2ES1],} the region As _soon as the potential difference V _ES2ES1 applied between the electrodes (ES2, ES1) which at least crosses and maintains becomes greater than the value Max [V _{ET_ES2ES1} ], the electrodes which at least cross and address this region of this group The potential difference V _ES2ES1 applied during (EA2, EA1) is either increased,
A display device characterized by being designed as follows.   6. The display device according to claim 5, wherein the end of the operating gradient for increasing the potential difference between the electrodes serving at least for addressing is greater than 5 V / [mu] s.   7. The display device according to claim 6, wherein the end of the operating gradient for increasing the potential difference between the electrodes serving at least for addressing is greater than 10 V / μs. _{6. The} display device according to claim 5, _wherein when _VES2ES1 is between Min [ _{VET_ES2ES1} ] and Max [ _{VET_ES2ES1} ], a potential difference _VES2ES1 applied between electrodes that at least serves for maintenance. Is increased by what is referred to as the onset of an operating gradient greater than 5 V / μs.   9. The display device according to claim 8, wherein the onset of the operating gradient for increasing the potential difference between the electrodes serving at least for addressing is greater than 10 V / [mu] s. 6. The display device according to claim 5, wherein during each of the specific reset operations, the potential difference (V _EA2EA1 ) applied at least between the electrodes serving for addressing is Min [V _{ET_EA2EA1} ] <. A display device strictly increasing when V _EA2EA1 <Max [V _{ET_EA2EA1} ]. 6. The display device according to claim 5, wherein during each of the specific charge equalization operations or reset operations, the potential difference (V _ES2ES1 ) applied between the electrodes serving at least for maintenance is: A display device, which strictly increases when Min [V _{ET_ES2ES1} ] <V _ES2ES1 <Max [V _{ET_ES2ES1} ].

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