DE2304944C3 - - Google Patents

Description

45

The invention relates to a method for operating a plasma display panel with gas discharge cells arranged between two groups of coordinate electrodes at their intersection points. _S o

A plasma display panel typically consists of a stack of three thin, flat, clear ones Sheets of glass or other dielectric. The center plate has a multitude of holes in it predetermined arrangement. The edge of the stack is hermetically sealed, and its interior becomes evacuated and with inert gas, e.g. B. neon or a corresponding gas mixture filled. The coordinate electrodes are attached to the outside of the outer plates, usually in the form of Matrix electrodes, d. H. row and column electrodes running perpendicular to one another, with crossing points at the holes. But the invention is also at other arrangements of the coordinate electrodes applicable, e.g. B. in the form of segments for display tion of digits. Furthermore, the invention is applicable to plasma display panels without and with a center plate dielectric coating on the inside of the outside

plates.

The gas discharge in the cell at the intersection of two coordinate electrodes is ignited by Applying a voltage to these electrodes that is higher than the ignition voltage of the cell (if the Voltage drop across the dielectric plates is neglected). If the discharge is ignited, then wander charged particles to the outer plates and create a counter-voltage as wall charge, which is in the cell effective electric field decreases The discharge disappears when the sum of the applied Voltage and the counter voltage is less than that required to maintain the discharge Tension. If the polarity of the applied external voltage is reversed, so that it is the opposite voltage is rectified, the result is an overlay voltage which is again greater than the ignition voltage. The discharge starts again until it disappears again

By repeating this process, namely applying a voltage with alternating polarity between selected electrodes, an intermittent discharge can be maintained at all times. By choosing an optimal frequency of the alternating voltage, a display with sufficient Brightness can be generated.

To control the gas discharge cells in such a way that only the cells selected in each case burn at the desired times, there are basically two Procedure known. In the case of one method known as inherent memory type A holding voltage is constantly applied to all electrodes and thus all cells, d. H. an alternating pulse voltage whose amplitude is smaller than that The ignition voltage of the cell is high enough to maintain a gas discharge once it has ignited. If the gas discharge is to be ignited or terminated in certain cells, the associated Electrodes are supplied with short-term write or erase signals. Such a method is e.g. B. from CH-PS 5 08 247 known, wherein each write signal consists of a short pulse which is superimposed adding to one of the holding voltage pulses, while the Clear signals are single pulses applied in pauses in the hold signal.

In contrast, the present invention is based on a control method that does not require a holding voltage, namely works according to the time selection mode. In this case, control signals are of a given duty cycle and repetition frequency of the coordinate electrodes of the one group in succession corresponding to one Query sequence and those of the other group with such a selection and time shift that they come to a gas discharge igniting and only during the Superimpose control voltage maintaining the duty cycle. Each control signal in turn consists of a group of pulses, so that the control voltage resulting from their superposition at the each selected cell consists of a pulse alternating voltage of alternating polarity Write and erase pulses worked, but the gas discharge in the cell goes out by itself at the end of the scanning interval when the control voltage ceases and must, if a continued display on this Cell is desired each time the

assigned sampling interval can be re-ignited.

A control method of this type according to the time selection mode is z. B. from US-PS 36 14 769 known, wherein within the drive signals assigned to the row electrodes, the pulses in the pulse gaps of the Drive signals applied to column electrodes fall. This is referred to below as the control method first type. From the publication "Densi Zairyo" (Electronics Materials), July 1971, page 89 it is but also known to carry out the process so that the pulses coincide in time in the control signals supplied to the two electrode groups. A Such a method is referred to below as a method of the second type and has advantages in terms of avoiding unwanted ignition of neighboring cells.

A problem that arises with such control signals working with time selection is that when commissioning the plasma display panel z. B. the first after a break of several days Ignition of the controlled cells can be significantly delayed. This delay depends on the number of free electrons and ions present in the cell after a long period of inactivity. Their number can e.g. B. can be increased by strong ambient light, but even with an illumination of 100 lux the Discharge delay can be up to 10 s. Attempts have also been made by attaching radioactive Substances in the cells for the constant presence of free electrons and ions too care for. However, this is because of the hazards associated with radioactive material, particularly regarding the treatment and accommodation of disused or destroyed display boards, and because of the Considerable manufacturing costs are not a viable option.

The ignition delay is also dependent on the Amplitude of the control voltage. However, it is not possible to determine the amplitude of the control voltage Choosing to reduce the ignition delay as large as desired, since then there may also be an ignition would occur in unauthorized cells.

The invention is based on the object of a method for controlling a plasma display panel with external electrodes according to the time selection method, with which the delay of the Initial ignition can be reduced after breaks in operation without having to do this with radioactive Material or must be worked with undesirably large control voltages.

This object is achieved according to the invention with a method according to the preamble of claim 1 solved in that to reduce the initial ignition delay the control signals that all or at least some coordinate electrodes of the one group are fed to a base DC voltage is superimposed.

The superimposed base DC voltage only has an effect when a cell is activated for the first time additional ignition voltage, which reduces the delay in the initial discharge. In later continuous operation on the other hand, it has no effect and therefore the ignition cannot spread to either effect controlled cells. It has been shown that the delay in the initial discharge also occurs when weak ambient light of about 5 lux could be reliably reduced to less than 0.5 seconds.

It is known from GB-PS 12 39 779 in a control method for a plasma display panel that works with holding voltage to temporarily supply signals to the electrodes which consist of a base DC voltage and pulses superimposed on it. However, these are the write signals that are only fed to selected electrodes instead of the holding signals, the base DC voltage only having the duration of a few pulse periods of the holding voltage. There is no control voltage of alternating polarity on the cell, but only a brief write pulse which, once the discharge has been ignited, is then replaced by the normal hold signal on which no base DC voltage is superimposed. In the method according to the invention, the base DC voltage, although constantly applied, only has an effect on the initial ignition, while in later continuous operation only the superimposed control signal ensures the cyclically repeated ignition of the cell.
In the method according to the invention, the amplitude of the alternating control voltage resulting from the superimposition of the control signals over a cell is preferably between two and four times the ignition voltage of the cell.
A circuit arrangement for carrying out the method according to the invention with a pulse generator which feeds the control signals, each consisting of pulse groups, to the coordinate electrodes of one group cyclically and to those of the other group in a timed manner and is connected to the coordinate electrodes via control lines, in each of which a capacitor is arranged according to the invention characterized in that all or at least some coordinate electrodes of one or the other group are connected to a direct voltage potential via a diode each.

The invention is explained in more detail and exemplary embodiments are described with reference to the drawings. It demonstrate

Fig. 1 and 2 waveforms according to the prior art Technique for two types of control of a plasma display panel using the time selection method,

F i g. 3 shows a diagram in which the ignition voltage against the pulse width in this control method 4S are applied in both ways,

4A shows the discharge on an enlarged scale generating signal form when activating the first type,

F i g. 4B shows a diagram of the ignition voltage as a function of the repetition frequency of the pulses for different pulse duty factors for the signal form according to FIG. 4A,

F i g. 5 is a diagram in which the delay time of the initial discharge as a function of that at the cell applied voltage is entered,

F i g. 6 shows a representation of a typical voltage curve as it occurs in the control method according to FIG Invention is used,

7 is a schematic representation of the in the signal forms used in the method according to the invention,

8 shows an important circuit part for an anti-ejection control circuit and FIG

9 to 12 circuits for different execution (15 Forms of the invention.

Before describing the preferred exemplary embodiments of the invention, FIG. 1 to 5 that common methods for controlling a plasma display

panel examined in time selection fashion to facilitate understanding of the principle on which the invention is based.

First of all , reference is made to FIG. 1 referred to. A not shown drive control circuit or drive circuit of the so-called here the first type, as described in the aforementioned US-PS 36 14 769 comprises means for the supply of the first or time selection pulse voltages as at (a), (b), (c) are shown for the first, second, third line electrode ι ο trode. Similar pulse voltages are applied to the further row electrodes (not shown), each of the pulse voltages consists of pulse groups with a predetermined duration, and each group in turn consists of pulses with a pulse height V which is sufficiently higher than the ignition voltage Vf, a pulse width Wp and a repetition frequency f . the pulse voltages for the consecutive row electrodes are shifted by the duration of each pulse of a group and repeated this time with a period of / j times, where π, the number of row electrodes in a group, eg. B. for a single letter is. The drive circuit further includes means for selectively applying second or address pulse voltages as depicted at (d) to at least a selected one of the column electrodes, such as the m-th column electrode (not shown). If a discharge is to be generated in cells arranged along a specific column electrode, then the relevant column electrode is supplied with an address pulse voltage of magnitude V with such a time offset in relation to the time selection pulses on the row electrodes which cross the specific column electrode on the desired cells, that these address pulses i> occur within the duration of the time selection pulse groups fed to these row electrodes, specifically in the pulse gaps of these time selection pulses. In this way, the drive circuit supplies the resulting ν pulse voltages shown at (e) and (f) to the cells of the first row, / n-th column, and the second row, m-th column. In Fig. 1 (e) , the discharge occurs in the cell in the first row, mth column, in response to a first pulse 21, and disappears as the reverse voltage increases as 4 ^ a result of the charged particles generated by the discharge. In response to a second pulse 22 applied to the cell of the same polarity as the voltage generated by the discharge, a discharge reoccurs in the cell until it disappears. Similar processes follow up to the eighth pulse 28. In so far as the interior of the cell is made of insulating material, the reverse voltage caused by the discharge caused by the eighth pulse 28 persists for a considerable period of time, so that the pulses of the polarity of the reverse voltage, such as about a ninth pulse 29, cannot cause a discharge. It follows from the foregoing that the discharge occurs only in the cells which are determined by the waveform of the pulse voltages applied to the fio column electrodes. The fact is, however, that the discharge also occurs, for example, in the cell of the second row, m-th column, as a result of the resulting voltage applied to it, as is shown in FIG. 1 (7?) More precisely, a pulse 31 leads the discharge A second pulse 32 and the following pulses with a polarity opposite to the voltage resulting from the charges does not produce a discharge, but a fifth pulse 35 with the same polarity has the opposite polarity to the voltage resulting from the charges and produces one again momentary discharge. A sixth pulse 36 and the following pulses of the same polarity do not cause a discharge, but a ninth pulse 39 again causes a temporary discharge each pulse group is small. On the other hand, a high pulse count would be a require high switching speed of the drive circuit and is undesirable from an economic and technical point of view.

Reference is made to FIG. 2 below. A drive circuit of the so-called second type here has means for supplying at (a), (b), (c, shown first pulse voltages to the first, second, third row electrode or similar pulse voltages to further row electrodes (not shown) Pulse voltages have the same waveform as the pulse voltages in the drive circuit of the first type and are repeated in the same manner. The drive circuit further comprises means for selectively applying second pulse voltages, as depicted at (d) , to at least one selected column electrode, such as the m-th column electrode (not shown) In the event that a discharge is to take place in cells arranged along a specific column electrode, the pulse voltage applied to the special column electrode has negative pulses with a pulse height V ₁ which coincide with the first pulse voltages, which the row electrodes, which have the specific Sp cross the old electrode on the selected cells. The drive circuit thus supplies the resulting voltages shown in (e) and (f) to the cells in the first row, / η-th column, and the second row, m-th column. Referring to Fig. 2 (e) , a positive pulse 41 causes a discharge in the cell of the first row, mth column, and the following inverse voltage resulting from the charges. A negative pulse 42 follows, which is added to the reversed voltage in order to generate a discharge again. In this way, the intermittent discharge is supported as long as the polarity of the pulse voltages alternately changes up to the fourth negative pulse 44. During the duration of this pulse 44, the discharge ceases al; Consequence of the positive voltage resulting from the charges. The subsequent occurrence of a positive rising pulse 46 therefore does not contribute to the discharge. A subsequent negative pulse 4Ϊ does not have a sufficient height to generate a discharge zi. In the cell determined by the second row and m-th column, only a first pulse 49, which originates from the negative pulse of the second pulse voltage supplied to the m-th column electrode, triggers a temporary discharge. The following impulses of both polarities cannot carry the intermittent discharge. It is known that the voltage V should be greater than the ignition voltage Vf and less than da: twice the ignition voltage.

In the following, reference is made to FIG. 3 referred to, in dei the abscissa shows the pulses applied to the cell of a plasma display panel, and the ordinate shows the voltage

(Ignition voltage) at which the pulses trigger the gas discharge in the cell. It can be seen that the ignition voltages for the drive circuit of the second type at the same repetition frequency the impulses are considerably lower than in the drive circuit of the first type.

The waveform of the pulse voltage used in the drive circuit of the first type shown in FIG. 4A has a repetition frequency f and an interpulse period Wp. In FIG. 4B, the repetition frequency f is plotted on the abscissa and the ignition voltage VV is plotted on the ordinate. The ignition voltage hardly varies as a function of the repetition frequency, but as a function of the pulse duty factor P of the pulse voltage.

For a better understanding of the results shown in Fig. 4B, the process of increasing the avalanche in the discharge will now be considered. It can be considered that the electrons and ions generated during the duration Wp of the pulse disappear during the time Wo when the pulses are absent due to diffusion, neutralization and the like. The frequency of the occurrence of avalanches during the segment IVr in which a pulse is present is Wp · v / d, where v, the speed of the ions and d the distance between the cell walls in the direction of the electric field. The number of ions increases during the period according to the pulse width Wp

- 1 S] Wpvjd ■ exp (-

> 1

+ 1

(2)

whereby the ions and / or electrons that were present in the cell before the first pulse hit are to be gradually boosted current. From this it is now concluded that the ignition voltage is reduced can be achieved through increased current amplification and that this can be carried out through a continuous Applying a voltage to the cells.

With regard to the constant application of voltage to the cells, the drive circuit is of the second type preferable because the pulses such as 41 and 42 are always present, so that the time of the pulse pause Wu while there is no pulse, is in principle zero. Under these circumstances, equation (2)

where λ and γ represent the first and second Townsend coefficients of ionization. It can be assumed that the ions disappear as a result of the diffusion and the 3s neutralization during each interval Wo between the pulses approximately according to exp (-W ₀ Zt) , where f represents the time. Under these circumstances, the number of ions varies accordingly

40

during a series of intervals W _P + Wq. When the value of equation (1) is at least one, the avalanche for discharge increases. The condition for the avalanche to grow into a discharge is then

Since γ (second Townsend coefficient) and d (distance between the cell walls) are constants for a plasma display panel, equation (2) shows that the ignition voltage Vt, which is implicitly contained in <k (V) and v (V) , is a function of the duty cycle P and does not depend on the repetition frequency /. From Fig. 4B it can be seen that the assumptions made above are acceptable and that the ignition voltage assumes its minimum when the duty cycle is zero. This also explains the reduction in the ignition voltage obtained with the drive circuit of the second type, as shown in F i G. 3 is shown

With this consideration, it is shown that the discharge occurs when the < _.5 condition given in equation (2) is satisfied. In other words, no discharge occurs at the single first pulse but as a result of the application of different pulses.

exp (, W)> I / -, - · I I

and further

A ■ pdexp [-B {pd / Vf ^l2 ~ \> In (I /; - + 1), (3)

where A and B are constants and ρ is the pressure in the cell. Equation (3) is identical to the relationship between the coefficient γ and the ignition voltage of a discharge tube with internal electrodes. In other words, the mechanism of the initial discharge, which is initiated in a discharge display panel with external electrodes by pulses of alternating polarities of the same pulse height when there is no discharge (voltage resulting from the charges) in the cells, is the same as the mechanism of the discharge in a discharge tube with internal electrodes. This explains the delay in the initial discharge in cells that do not contain radioactive material.

In the following, reference is made to FIG. 5 referred to. The average time delay required for starting the discharge - after applying a voltage V to a cell of a plasma discharge panel - is shown for different illuminance levels of the cells by ambient light, with the voltage V on the abscissa being represented by the ratio of the difference ΔV the voltage V and the ignition voltage Vf to the ignition voltage. From Fig. 5 it follows that this ratio must be greater than 1.5, ie V> 2.5 · Vf, in order for the delay to be shorter than a practically acceptable value of 0.5 seconds (average) for the darkest ambient light of 5 lux. On the other hand, in connection with a drive circuit of the first or second type, it becomes clear that the ratio must be less than 1.0, because the application of a voltage V is greater than twice the ignition voltage V / (the change in voltage levels is greater than twice the Ignition voltage V ₁ ) on the row and column electrodes causes the discharge to occur in all cells arranged along the electrode and it becomes impossible to select one or more of the cells. In view of the fluctuation in the source voltage, it is customary to set the voltage to about three halves of the ignition voltage V ₁ , that is to say the ratio to about 0.5. As a result, the delay is inevitably up to 20 seconds with an ambient lighting level of 5 lux. In this regard, the drive circuit of the second type is unsatisfactory.

It is referred to below on FIG. 6 referred to. It has also been demonstrated that a DC voltage V ₀ higher than the ignition voltage causes a pulse discharge (a current pulse with a width of less than

microsecond) in a plasma display panel with external electrodes. The charged particles generated by the discharge give a wall voltage Vw in the opposite sense to the DC voltage. As a result, the ^{voltage applied to the cell s is} reduced to Vo- Vw. In particular, it is assumed that a pulse voltage 50 with pulses at a pulse height V and alternating positive and negative directions, which are superimposed on a base DC voltage Vo, is applied to a cell of a ι ο Plasma display panel is applied across the selected row and column electrodes. In response to the base of the pulse 51, a pulse discharge occurs. The charged particles thereby create a wall tension, as shown at 52. The voltage applied to the cell is now determined by the difference between the pulse voltage 50 and the wall voltage Vw. In so far as the resulting wall voltage curve according to the dashed line 52 is superimposed on the wall voltage generated by applying the pulse voltage shown in Fig. 4A to the cell the DC voltage V _{0 is established} , the effects of the DC voltage component Vo on the effective voltage applied to the cell disappear after the start of the intermittent discharge. The direct voltage Vo is therefore only effective at the beginning of the discharge on the cell. In this way, when the pulse voltage 50 is used, the delay is markedly reduced.

In the following, reference is made to FIG. 7 referred to. A drive circuit includes conventional means for applying first or timing section pulse voltages as shown at (a), (b), (c) and other corresponding pulse voltages to the first, second, third, etc. row electrodes. The first pulse voltages correspond to those in connection with FIGS. 1 (a), (b), (c) and F i g. 2 (a), (b) and (c) are shown. The drive circuit further includes second means for selectively applying second or address pulse voltages, as shown at (d) , to selected column electrodes, such as the n-th column electrode. The second pulse voltages are similar to those in FIG. 2 (d) , but are superimposed on a base DC voltage V _0. If no wall voltage were present, then the pulse voltage shown at (e) would be applied to the line at the intersection of the first line, mth column, so that a negative voltage at the beginning with the absolute value V + Vo is applied to the cell. That in connection with F i g. 5 is consequently (Vq + AV) Vf, which means an unexpected reduction in the delay. The at the cell of the second row, m-th column according to FIG. 7 (f) applied voltage is not much different from that in connection with FIG. Voltage shown in Figure 2 (f).

In Fig. 8 shows a circuit for superimposing a DC voltage component with the value Vo via a pulse voltage generated by a driver circuit. The circuit may include a capacitor 61 between the drive circuit and each coordinate electrode and a rectifying diode 62 for fixing of the potential of the electrode to the DC voltage Vo.

In the following, Fi g. 9 referred to. One The first embodiment is provided by a DC voltage source 71 and a control signal generator 72 powered and controls a plasma display panel with it opposed electrodes 73 and 74. The DC voltage source 71 supplies a positive DC voltage Vo to a first conductor 75 with respect to a second conductor 76 which is grounded. The control signal generator 72 supplies a continuous sequence φ of negative high-frequency pulses to a third conductor 77, furthermore time selection pulse sequences T with positive pulses Tl, 7 * 2 ... cyclically to a plurality of fourth conductors 78 and a cell address pulse sequence t of positive pulses selectively to at least one selected one fifth conductor 79. The embodiment comprises a plurality of pnp switching transistors 81, 82, etc. connected to the respective row electrodes 73, and an equal number of npn switching transistors 91, 92, etc. connected to the respective column electrodes 74, each of the Switching transistors 81, 82, 91, 92, etc. is designed so that it can switch a relatively high DC voltage. The emitters of the pnp transistors 81, 82... Are connected directly to the first conductor 75, and the collectors are connected to the corresponding row electrodes 73 directly and to the second conductor 76 via resistors 101. The emitters of the npn transistors 91, 92 are connected directly to the third conductor 77 and the collectors to the first conductor 75 via resistors 102. Between each of the npn transistor collectors and the associated column electrodes 74 there is a circuit 105 superimposing a direct current component, as shown in FIG. 8 is described, interposed. The bases of these npn transistors are connected to the second conductor 76 via resistors 106 and to the corresponding fifth conductor 79 via resistors 107. The embodiment further comprises a plurality of npn-Kilfstransistors 111, 112, etc., the emitter directly to the third conductor 77 is connected and the collector voltage V _x of which is applied via resistors 121. The bases of these auxiliary transistors are connected to the second conductor 76 via resistors 122 and to the corresponding fourth conductors 78 via resistors 123. The bases of the pnp switching transistors 81, 82,... Are connected to the first conductor 75 via resistors 126 and to the collectors of the corresponding auxiliary transistors 111, 112,... Via capacitors 127.

During operation, the auxiliary transistors 111, 112 ... serve as AND circuits, which are put into operation in response to the negative high-frequency pulse sequence φ and the positive time selection pulse sequence 7 * 1, T2, etc. If the base and the emitter of one of these auxiliary transistors 111, 112 ... are acted upon by the negative high-frequency pulses and the positive pulses of the time selection pulse sequence Ti , then the auxiliary transistor in question becomes conductive, the high-frequency pulses are amplified and the high-frequency pulses are amplified and the polarity-inverted pulses are amplified the base of the associated pnp switching transistor 81 via the capacitor 127 for temporarily switching on the transistor 81 during the positive periods of the time pulse sequence 7 * In response to the temporary switching on of the pnp switching transistor 81, the voltage of the relevant row electrode 73 varies essentially between the positive voltage V ₉ and the positive voltage applied to the associated resistor 101. The npn switching transistors 91, 92 ... serve as AND circuits, which respond to the negative high-frequency pulses and the positive pulses of the address pulse trains f 1, f 2, etc. To be more precise, they reduce

negative high-frequency pulses temporarily reduce the emitter potential of these npn switching transistors essentially to ground potential. On the other hand, the positive address pulses of the address pulse trains fl, 12 ... raise the base potentials for supplying bias voltages to the base-emitter connections of these npn switching transistors. For example, during the positive periods of the address pulse sequence 1 1 of the respective npn-switching transistor 91 is temporarily conductive, decreases in response to the negative pulses, ι so η the voltage of the associated column electrode 74 to the ground potential, which otherwise substantially at the level of the DC voltage Vo lies. In this way, the process shown in FIG. 7 (d) is applied to the cell or cells between the row and column electrodes coupled to the switching transistors 81 and 91.

As further from FIG. 9, the output impedance of the control circuit for the pulses superimposed on the selected cells is very low because the relevant switching transistors, such as 81 and 91, are switched on when these pulses occur. It is also clear that the time constant determined by the resistor 126 and the capacitor 127 is sufficiently greater than the width of the high-frequency pulses and that the resistance of the collector resistor 101 or 102 is chosen such that the resistance caused by this resistance and the stray capacitance between the respectively controlled electrodes 73 and 74 and the remaining electrodes 73 and 74 exists, certain time constant is smaller than the interval between the high-frequency pulses. On the other hand, the resistance value of the collector resistor 101 or 102 should be so large that the power consumption in these resistors when the associated switching transistors are switched on is low. For example, the capacitance between the respectively activated electrodes 73 and 74 and the other electrodes can be 30 pF, and the frequency and the pulse width of the high-frequency pulses can be 50 kHz or 5 microseconds. Under these circumstances, the resistance of each of the collector resistors can be 100 kilo ohms.

In an example of a flash display panel with external electrodes, the ignition voltage Vr = 130 V, and the individual electrode _{ignition voltage V / ft,} namely the ignition voltage for the case where voltage is only applied to either the row or column electrodes, was 220 V. The delay in the initial discharge was measured with the display panel placed in a dark room and with a DC voltage of 160 V from the DC voltage source 71 applied to the drive control circuit according to the first embodiment. The delay was less than 0.5 seconds. For comparison, the delay was measured under the same circumstances with a similar drive control circuit, but without the DC voltage superimposition circuit 105. The delays were up to 80 seconds. In addition, the DC voltage Won of the ignition voltage V / was increased to the ignition voltage Vk of the single electrode with a drive control circuit according to the first embodiment. No malfunction was found

In Fig. 10 shows a second exemplary embodiment which is similar to the first exemplary embodiment, but in which the circuits 105 superimposed on the DC voltage component of the circuit shown in FIG. 8 are now connected to the corresponding row electrodes 73 and to _{the row drive control circuits for superimposing a DC voltage component - V 0} via the drive signals supplied to the row electrodes. The results of the measurements of the initial discharge were the same as in the previous case.

It should be noted that the invention can also be used when driving the above-mentioned second type (Fig. 2). The above-described embodiments are based on a plasma display panel drive control circuit, as has been proposed in DT-OS 22 56 528.2. This circuit is advantageous by using a control signal generator 72 with a relatively high output impedance for the Time selection and address pulse trains and is preferred in view of the low output impedance for the cell firing pulses and the resulting high brightness of the display compared to a conventional drive control circuit of the second type.

A third embodiment of the invention is described in FIG. 11, which is based on the circuit proposed in the above-mentioned patent application. The same components are provided with the same reference numerals as in the first and second embodiments. Instead of a single continuous sequence of negative high-frequency pulses, the control signal generator 72 now supplies a pair of continuous sequences φ and φ of negative and positive pulses to a third pair of conductors 77 and 77 '. The emitters of the npn auxiliary transistors, for example 111, are connected directly to the second conductor 76, but not to the third conductor 77 or 77 '. Instead, these auxiliary transistors are acted upon by the corresponding positive time selection pulse sequences T1 , T2, ... Via the positive logical AND circuits, for example 131 . Instead of the npn switching transistors, for example 91, serving as AND circuits, a plurality of pnp auxiliary transistors 132 are provided in the third embodiment, which are connected to the corresponding npn switching transistors and from the negative high-frequency pulse train φ and the corresponding negative address pulse trains, for example fl, are applied via the negative logical AND circuits 133. In this context, the positive high-frequency pulses and the time selection pulses starting from the ground potential up to the collector voltage V _n ; range and the negative high frequency pulses and address pulses drop from the collector voltage to the earth voltage.

In operation, the positive logic AND circuit 131 shown in FIG. 11 briefly allows the positive high frequency pulses to pass through only when the positive timing selection pulses of the sequence Ti occur. The associated npn auxiliary transistor 111 causes a current amplification of the gated high-frequency pulses with the opposite polarity. The negative logical AND circuit 133 in a similar manner only lets the negative high-frequency pulses through when the negative address pulses of the sequence f 1 occur. The associated pnp auxiliary transistor 132 causes a current amplification of the sensed high-frequency pulses and reverses their polarity.

A fourth embodiment of the invention is described in FIG. Same components are with

the same reference numerals as in the previous one
Embodiment described. The bases of the pnp transistors 81 are with the negative high frequency pulse train φ and the negative address pulse train 1 1
via the negative logical AND circuits 136 s
applied to the bases of the npn transistors 91
turn with the positive high frequency pulse sequence ψ
and the positive time pulse sequence Ti, T2 ... over
positive logical AND circuits 137 applied
This embodiment is particularly advantageous when ι ο
the output impedance of the control signal generator 72
is small enough

It should be remembered once again that the
once in a row of a plasma display board

ignited discharge generates charged particles. This discharge also generates photons. This loaded Particles and photons migrate to neighboring cells. The delay in the neighboring cells diminished when the tension on these cells was taking effect charged particles is applied. It is therefore sufficient that the DC voltage superimposed on the pulse voltage is only applied to the cells where discharge is likely to begin. It is also clear that the plasma display panel need not necessarily have row and column electrodes, but segment electrodes or other, similarly effective electrodes.

For this 6 sheets of Zciclinunccii

Claims (3)

Patent claims: 1. Method of operating a plasma display panel with between two groups of 'coordinate Electrodes at their crossing points arranged gas discharge cells, their control according to the time selection method is carried out by control signals of a predetermined duty cycle and repetition frequency that the coordinate electrodes of the one group one after the other according to a query sequence and those of the other group with such selection and time shift are supplied that they are at the respectively controlled Crossing point to ignite the gas discharge ι s superimpose the control voltage that is maintained only during the keying period, each Ans; euersignal from a pulse group and the control voltage resulting from their superposition from an alternating pulse voltage age- changing polarity, characterized in that to reduce the initial ignition delay the control signals, all or at least some coordinate electrodes of the one group are supplied, a base DC voltage is superimposed. 2. The method according to claim 1, characterized in that the control voltage resulting from the superposition of the control signals between two and four times the ignition voltage. 3. Circuit arrangement for carrying out the method according to claim 1, the control signals consisting of pulse groups for the coordinate electrodes of the one group and cyclically for the of the other group is generated in a temporally selected manner and is connected to each coordinate electrode by a control line in which a capacitance is arranged, characterized in that all or some of the coordinate electrodes (74) of the one or the other group are each connected to a DC voltage potential via a diode (62). (Fig. 8 and 9 to 12).