Plasma display

Abstract

Two arrays of main X and Y electrodes are juxtaposed with two arrays of auxiliary electrodes in two parallel plane respectively. Two half illumination or extinction pulses less in magnitude than a discharge voltage across the opposite arrays and opposite in polarity are applied to selected ones of the X and Y electrodes to initiate or terminate an electric discharge or discharges across them. A pulse train including positive pulses alternating negative pulses is applied across the arrays of auxiliary electrodes to be discharged across those auxiliary electrodes juxtaposed with the selected X and Y electrodes upon each inversion of the pulses polarity after the first discharge.

Description

BACKGROUND OF THE INVENTION

This invention relates to improvements in panel display devices utilizing a gaseous discharge and known as plasma display panels.

The conventional type of panel display devices have comprised a pair of electrically insulating layers disposed in spaced parallel relationship to form a discharge gap therebetween and an array of parallel strip-shaped electrodes disposed at predetermined equal intervals on the inner surface of one of the insulating layers to be perpendicular to an array of similar electrodes similarly disposed on the inner surface of the other insulating layer. Both arrays of electrodes have a pair of sustaining voltages applied thereto respectively so that a sustaining voltage in the form of a pulse train including positive pulses alternating negative pulses is developed across the discharge gap. A half illumination pulse is applied to a selected one or ones of the electrodes of one of both arrays while at the same time another half illumination or extinction pulse opposite in polarity to the firstmentioned half illumination pulse is supplied to a selected one or ones of the electrodes of the other array to cause an electric discharge or discharges across the discharge gap at a point or points where the selected electrodes apparently intersect each other. Then each time the sustaining voltage is inverted in polarity, an electric discharge or discharges occurs or occur at that or those points across the gap. A pair of half extinction pulses similar to the half illumination pulses are simultaneously supplied to the selected electrodes of both array to inhibit further electric discharges.

In the conventional panel display devices, it has been required to provide one adder circuit for adding each pair of the sustaining, half illumination and half extinction pulses to each other and further an increase in the number of the electrodes has led to the necessity of using more circuit elements and therefore to a complicated circuit configuration.

SUMMARY OF THE INVENTION

Accordingly it is an object of the present invention to provide a new and improved plasma display device very simplified in circuit configuration and substantially free from any malfunction.

The present invention accomplishes this object by the provision of a plasma display device comprising, in combination, a first plane, an array of first main electrodes in the form of longitudinally elongated strips disposed in substantially parallel relationship in the first plane, an array of first auxiliary electrodes disposed in the first plane so that each of the first auxiliary electrodes runs in substantially parallel relationship with and adjacent to a different one of the first main electrodes, a second plane disposed in spaced parallel relationship with the first plane to form a discharge gap therebetween, an array of second main electrodes in the form of longitudinally elongated strips disposed in substantially parallel relationship in the second plane to be at a predetermined angle to the array of first main electrodes, an array of second auxiliary electrodes disposed in the second plane so that each of the second auxiliary electrode runs in substantially parallel relationship with and adjacent to a different one of the second main electrodes, first circuit means for selectively applying a first voltage pulse across the first and second main electrodes to initiate or terminate an electric discharge or discharges across the selected first and second main electrodes having applied thereto the first voltage pulses, and second circuit means for successively applying second voltage pulses to both arrays of first and second auxiliary electrodes so as to develope a pulse train including pulses of one polarity alternating pulses of opposite polarity thereacross whereby the electric discharge or discharges is or are followed by electric discharges intermittently caused across those first and second auxiliary electrodes disposed adjacent to the first and second main electrodes applied with the first voltage pulses.

Preferably, the first voltage pulses may be less in magnitude than a discharge voltage for the discharge gap and simultaneously applied in opposite porality relationship to selected ones of the first and second main electrodes to initiate and terminate the electric discharge or discharges thereacross with the sum of the first voltage pulses.

Advantageously, the first main and auxiliary electrodes in the first plane run perpendicularly to the second main and auxiliary electrodes in the second plane.

If desired, only one of the arrays of first and second auxiliary electrodes may be disposed in the associated plane while a train of bipolar pulses is applied across the one array of auxiliary electrodes and that array of main electrodes opposite thereto.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more readily apparent from the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a partly exploded perspective view of one portion of a plasma display device constructed in accordance with the principles of the prior art;

FIG. 2 is a wiring diagram of a circuitry for operating the device shown in FIG. 1;

FIG. 3 is a graph illustrating waveforms developed at various points in the arrangement shown in FIG. 2;

FIG. 4 is a partly exploded perspective view of one portion of a panel display device constructed in accordance with the principles of the present invention;

FIG. 5 is a fragmental wiring diagram of a circuitry for operating the display device shown in FIG. 4;

FIG. 6 is a graph illustrating waveforms developed at various points in the arrangement shown in FIG. 5;

FIG. 7 is a view similar to FIG. 4 but illustrating a modification of the present invention;

FIG. 8 is a graph illustrating a waveform used with the arrangement shown in FIG. 7; and

FIG. 9 is a fragmental wiring diagram of a circuitry for operating the device shown in FIG. 7.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings and FIG. 1 in particular, there is illustrated a panel display device constructed in accordance with the principles of the prior art. The arrangement illustrated comprises a base plate 10 of transparent or translucent glass, an array of fine strips 12 of any suitable electrically conductive material disposed in predetermined equal intervals on one of the opposite main surfaces of the glass plate 10 and in a predetermined direction, in this case, in the longitudinal direction as viewed in FIG. 1, and a thin electrically insulating layer 14 disposed on the one surface of the glass plate 10 to sandwich and hold the array of conductive strips 12 between the same and the glass plate 10. The insulating layer 14 is formed of a transparent or translucent, electrically insulating material, for example, a glass high in electric resistance.

The arrangement further comprises an assembly of a glass base plate 16, an array of fine, electrically conductive strips 18 and a thin, electrically insulating layer 20 identical to the components 10, 12 and 14 respectively. Then the insulating layer 18 is arranged to oppose in parallel relationship to the insulating layer 14 to form therebetween a gap whose distance is determined by a frame member 22 hermetically interposed between the outer peripheries of both layers 14 and 18 while at the same time, the conductive strips 18 run in a direction orthogonal to the predetermined direction, in this case, the transverse direction as viewed in FIG. 1. Thus the insulating layers 14 and 20 cooperate with the frame member 22 to define a hermetically enclosed space 24. The enclosed space 24 is filled with a gas consisting essentially of neon having added thereto a small amount of argon or nitrogen gas.

The gas filled space 24 has the two arrays of conductive strips 12 and 18 running orthogonally to each other on the opposite sides thereof. The conductive strip 12 forms a Y pole discharge electrode and is called hereinafter a Y electrode while the conductive strip 18 forms an X pole discharge electrode and is called hereinafter an X electrode for the gas filled space 24 or a discharge gap.

FIG. 2 shows a circuitry for operating the arrangement as illustrated in FIG. 1. It is seen that a pulse generator circuit 26 is operatively coupled to the array of Y electrodes 12 and another pulse generator circuit 28 is operatively coupled to the array of X electrodes 18. More specifically, the pulse generator circuit 26 includes a plurality of generator portions connected to different ones of the Y electrodes 12 through respective resistors 30 for discharge adjustment and the pulse generator circuit 28 similarly include a plurality of generator portions connected to different ones of the X electrodes 18 through respective resistors 32 for discharge adjustment. The resistors 30 are also connected to respective capacitors 34 subsequently connected together to a source 36 of sustaining voltage. Similarly, the resistors 32 are connected to respective capacitors 38 which are, in turn, connected together to another source 40 of sustaining voltage.

Each of the generator portions of the circuit 26 produces a half illumination pulse P.sub.y tending to cause an electric discharge at that Y electrode 12 connected to the same or a half extriction pulse Q.sub.y tending to extinguish the electric discharge at the same Y electrode as the case may be. Similarly, each of the generator portions of the circuit 28 produces a half illumination pulse P.sub.x tending to cause an electric discharge at that X electrode 18 connected to the same or a half extinguishment pulse Q.sub.x tending to extinguish the electric discharge at the same X electrode 18 as the case may be. The source 36 applies a half illumination pulse P.sub.y to the Y electrodes 12 to produce a voltage for sustaining an electric discharge thereon. Similarly, the source 40 applies a half illumination pulse P.sub.x to the x electrodes 18 to produce a voltage for sustaining an electric discharge thereon.

In FIG. 2 the reference numeral 42 designates a luminous point lying in a plane midway between the opposite surfaces of both insulating layers 14 and 30 and at a point where one of the X electrodes 18 intersects one of the Y electrodes 12 and strictly the projections of both electrodes in the said plane intersect each other.

As shown at waveforms A and B in FIG. 3, the source 36 supplies the sustaining voltage in the form of a train of rectangular pulses to the array of Y electrodes 12 while the source 40 supplies the sustaining voltage in the form of a train of similar rectangular pulses to the array of X electrodes 18 with the pulses of each train temporally alternating those of the other train. Both sources 36 and 40 continue to supply also the sustaining voltages to the respective arrays of electrodes to develope the resultant voltage in the form of a train of bipolar rectangular pulses at each of the cross points 42 for the X and Y electrodes (as viewed in FIG. 2) as shown at waveform C. The cross points are called luminous points hereinafter. It is noted that, under these circumstances, none of the luminous points 42 emits light. It is now assumed that the sources 26 and 28 simultaneously apply individual half illumination pulses P.sub.y and P.sub.x to the particular Y and X electrodes 12 and 18 forming one luminous point 42 where light is desired to be emitted (see waveforms A and B shown in FIG. 3). Under the assumed condition, both half illumination pulses P.sub.y and P.sub.x alone do not reach a discharge initiation voltage V.sub.f as shown in FIG. 3, waveform C but if both pulses are added to each other then an illumination pulse P (see FIG. 3, waveform C) formed of the sum of both pulses exceeds the voltage V.sub.f. The illumination pulse P appears between a pair of positive and negative sustaining pulse as shown in FIG. 3, waveform C. This causes an electric discharge at the desired luminous point 42 formed of a point of intersection as viewed in FIG. 2 of those Y and X electrodes 12 and 18 respectively having applied thereto the half illumination pulses P.sub.y and P.sub.x respectively (see FIG. 3, waveform E). Then electrons and ions generated through this electric discharge reach those portions of the insulating layers 14 and 24 adjacent to the luminous point 42 resulting in the formation of a wall charge about that luminous point 42 where the electric discharge has been caused (see FIG. 3, waveform D). The wall charge D tends to decrease the sustaining voltage applied across the discharge gap 24. As a result, the discharge is extinguished. However with the insulating layers 14 and 20 high in insulation resistance, the wall charge D is sustained for a short time so that, upon inverting the polarity of the next sustaining voltage, the inverted sustaining voltage C is added to the wall charge D until the discharge initiation voltage V.sub.f is exceeded. This results in an electric discharge at the same luminous point 42. This electric discharge is followed by the inversion of the polarity of the wall charge D. Therefore the discharge is extinguished for the same reason as the preceding discharge. However when the next succeeding pulse of the sustaining voltage D applied across the discharge gap 24 is inverted in polarity, another electric discharge takes place at the same luminous point 42. The process as above described, is repeated to intermittently cause electric discharges at the luminous point (see FIG. 3, waveform E). In other words, the luminous point 42 emits light each time the sustaining voltage across the Y and X electrodes is inverted in polarity.

It is now assumed that those Y and X electrodes forming a luminous point 42 where light is intermittently emitted has a pair of half extinction pulses Q.sub.y and Q.sub.x simultaneously applied thereto from the associated driving portions of the circuit 26 and 28 respectively (see waveforms A and B shown in FIG. 3). Under the assumed condition, an extinction pulse Q formed of the sum of both half extinction pulses Q.sub.y and Q.sub.x is developed between a pair of adjacent sustaining voltage pulses as shown in FIG. 3, waveform C, causing an electric discharge. Each of the half extinction pulses Q.sub.y or Q.sub.x has a magnitude, a pulsewidth and a phase predetermined such that the electric discharge caused by the extinction pulse Q formed of the sum thereof inverts the polarity of the just preceding wall charge to return it to a null level. In other words, the extinction pulse Q erases the wall charge. Thus even if the sustaining voltage is repeatedly inverted in polarity after the erasion of the wall charge, no electric discharge occurs. In this way any luminous point 42 that has been alternately put in its luminous and non-luminous modes of operation up to that time is now maintained in its non-luminous mode.

Conventional panel display devices such as above described in conjunction with FIGS. 1 through 3 have practically encountered great difficulties. For example, as will be apparent from the foregoing, each of the Y and X electrodes involved have been necessary to be applied with half cycles of the sustaining voltage through respective capacitors connected thereto and also with the half illumination pulses and the half extinction pulses through respective resistors connected thereto. This measure has, as a matter of course, led to the necessity of using adder circuits for adding the sustaining voltage pulses to each other, adding the half illumination pulses to each other and adding the half extinction pulses to each other. Further an increase in the number of electrodes of each electrode array has inevitably caused an increase in the number of elements involved and therefore the complication of the resulting circuit configuration.

The present invention contemplates to avoid the difficulties as above described by the provision of panel display devices very simplified in circuit configuration as compared with the prior art type devices and free from a fear that malfunction may occur.

According to the principles of the present invention, one auxiliary electrode in the form of a longitudinally elongated strip is disposed in parallel relationship with and adjacent to each of the X and Y electrodes as shown in FIGS. 1 and 2 and has normally applied thereto the sustaining voltage as above described while the X and Y electrodes are only applied with the half illumination pulses and the half extinction pulses as above described. Alternatively, only one set of the auxiliary electrodes may be operatively associated with either one of the arrays of the X or Y electrodes and have applied thereto a bipolar sustaining voltage. In the latter case, only the half illumination and extinction pulses are also applied to the X and Y electrodes.

Referring now to FIG. 4 wherein like reference numerals designate the components identical to those shown in FIG. 1, there is illustrated a panel display device constructed in accordance with the principles of the present invention. The arrangement illustrated is substantially identical to that shown in FIG. 1 excepting that one auxiliary electrode 50 or 52 of any suitable electrically conducting material in the form of a longitudinally elongate strip is disposed in parallel relationship with and adjacent to each of the Y and X electrodes 12 and 18 respectively. The electrodes 50 and 52 are called hereinafter auxiliary Y and X electrodes respectively while the electrodes 12 and 18 are called hereinafter main Y and X electrodes respectively.

As shown in FIG. 5 wherein like reference numerals designate the components identical to those illustrated in FIG. 2, the auxiliary Y electrodes 50 are connected together to a connection point 54 subsequently connected to the source 36 of sustaining voltage and the auxiliary X electrode 50 are connected together to a connection point 55 which is, in turn, connected to the source 40 of sustaining voltage. In FIG. 5 there are shown a signal 26' including a half illumination pulse P.sub.y or a half extinction pulse Q.sub.y to control an electric discharge and a signal 28' including a half illumination pulse P.sub.x or a half extinction pulse Q.sub.x to control an electric discharge. The signals 26' and 28' from respective pulse generator circuits such as the circuits 26 and 28 shown in FIG. 2 are adapted to be applied to a selected one or ones of the main Y electrodes 12 and to a selected one of the main X electrodes 18 respectively whenever it is to do so. Only for purpose of illustration, such pulse generator circuits are not illustrated in FIG. 5.

The operation of the arrangement as shown in FIG. 5 will now be described with reference to FIG. 6 wherein there are illustrated waveforms developed at various points in the arrangement of FIG. 5. A sustaining voltage as shown at waveform A in FIG. 6, is normally applied to all the auxiliary Y electrodes 50 through the common connection point 54 while a sustaining voltage as shown at waveform B in FIG. 6, is normally applied to all the auxiliary X electrodes 52 through the common connection point 55'. As in the arrangement of FIG. 2, this results in the development of the resultant sustaining voltage as shown at waveform E in FIG. 6 across a discharge gap 24 formed between insulating layers 14 and 26 as shown in FIG. 4. That is, the sustaining voltage is in the form of a pulse train including pulses of one polarity alternating pulses of other polarity.

Under these circumstances, a half illumination pulse P.sub.y as shown at waveform D in FIG. 6 and also shown on the upper portion of FIG. 5 is applied to a selected one or ones of the main Y electrodes 12 while at the same time a half illumination pulse P.sub.x as shown at waveform C in FIG. 6 and also shown on the lefthand portion of FIG. 5 is supplied to a selected one or ones of the main X electrodes 18. As in the arrangement of FIG. 2, an illumination pulse P exceeding a voltage V.sub.f for initiating an electric discharge across the discharge gap 24 is developed across that gap between a pair of adjacent pulses of the sustaining voltage as shown in FIG. 6, waveform E. This results in the occurrence of an electric discharge or discharges at a luminous point or points lying at a point or points of intersection of the selected main Y and X electrodes as viewed in FIG. 5.

Any electric discharge such as formed as above described has a some spatial extent as determined by the length of the associated discharge gap and the others. Therefore a wall charge is formed across the discharge gap about an axis of discharge 56 for those Y and X electrodes having applied thereto respective half illumination pulses to have a spatial extent about that axis of intersection. The term axis of discharge is defined by a straight line perpendicularly intersecting the longitudinal axes of two orthogonal electrodes and extending between the insulating layers 14 and 18 (see FIG. 4). In FIG. 5 the spatial extent of the wall charge is shown as being confined by a dotted circle 58 having a center on the axis of discharge 56. It is known that such a wall charge has a region of circular cross section with a radius of from 0.1 to 0.4 millimeter formed about an axis of discharge for those main Y and X electrodes having respective half illumination pulses applied thereto.

It is to be understood that the auxiliary Y and X electrodes 50 and 52 respectively be disposed with respect to the mating main Y and X electrodes 12 and 18 respectively such that an axis of discharge 60 for the former electrodes is within the region of the associated wall charge 58 located about an axis of discharge 56 for the mating main electrodes.

As in the arrangement of FIG. 2, a pair of half illumination pulses P.sub.y and P.sub.x (see FIG. 6, waveforms C and D) are simultaneously applied to the selected one or ones of the main Y and X electrodes respectively to form an illumination pulse P developed between a pair of adjacent pulses of the sustaining voltage which pulse exceeds a discharge initiation voltage V.sub.f as shown at waveform E in FIG. 6. Then the next pulse of the sustaining voltage is applied to the auxiliary Y electrode 50 to cause the wall charge and the sustaining pulse to be added to each other at and applied to an axis of discharge 62 for the auxiliary Y and main X electrodes 50 and 18 respectively. This results in the occurrence of an electric discharge on the axis of discharge 62 or each of the associated axes 62. This electric discharge inverts the polarity of the associated wall charge or charges held up to that time resulting in the electric discharge halting.

Thereafter a further pulse of the sustaining voltage is applied to the auxiliary X electrode 52 to be added to the inverted wall charge on an axis of discharge 64 for the auxiliary X and main Y electrodes 52 and 12 respectively to cause an electric discharge on that axis or each of similar axes across the discharge gap 24. This electric discharge again inverts the polarity of the wall charge thereby to halt the electric discharge.

The process as above described is repeated to intermittently cause electric discharges adjacent to the axis of discharge 56 thereby to permit points on and adjacent to the axis 56 or each of the similar axes to be maintained in the intermittently luminous mode of operation.

The wall charge is inverted in polarity as shown at waveform F in FIG. 6 and the electric discharges are caused as shown at waveform G in FIG. 8.

On the other hand, if it is desired to put luminous points as above described in its non-luminous mode of operation even though the succeeding pulses of the sustaining voltages would be successively applied to the associated auxiliary Y and X electrodes 50 and 52 then a pair of half extinction pulses Q.sub.y and Q.sub.x as shown at waveforms D and C in FIG. 6 can be simultaneously applied to the associated main Y and X electrodes 12 and 18 respectively. This causes an extinction pulse Q (see FIG. 6, E) to be developed across the discharge gap between a pair of adjacent pulses of the sustaining voltage as shown in FIG. 6, waveform E as in the arrangement of FIG. 2. This results also in the occurrence of an electric discharge on the axis of discharge 56. This electric discharge similarly inverts the polarity of the associated wall charge. In that event, however, the application of the next pulse of the sustaining voltage to the associated auxiliary Y electrode 50 results in the disappearance of the wall charge. Thus even if the succeeding pulses of the sustaining voltages are alternately applied to the auxiliary Y and X electrodes, no discharge will occur. This means that the luminous point or points in question is impossible to be brought into its luminous mode of operation.

FIG. 7 shows a modification of the present invention wherein one of the arrays of auxiliary electrodes as shown in FIGS. 4 and 5 is omitted. The arrangement illustrated is identical in construction to that shown in FIG. 4 except for the ommision of one of the arrays of auxiliary electrodes, or of the arrays of auxiliary X electrodes and like reference numerals have been employed to identify the components identical to those shown in FIG. 4. In the arrangement of FIG. 7 is is noted that the sustaining voltage applied to the auxiliary Y electrodes 50 is in the form of a train of bipolar rectangular pulses as shown in FIG. 8.

As in the arrangement as shown in FIG. 5, half illumination pulses P.sub.y and P.sub.x are simultaneously and selectively applied to the main Y and X electrodes 12 and 18 respectively while the sustaining voltage continues to be supplied to the auxiliary Y electrodes 50. Under these circumstance, the sustaining voltage at a point of intersection of any one of the auxiliary Y electrodes and any one of the main X electrodes without auxiliary electrodes as viewed in FIG. 9 is similar to that at a corresponding point of intersection in the arrangement of FIG. 5. This is because each of the main X electrodes 12 is held at a level of null voltage unless the main X electrode has applied thereto a half illumination pulse .sub.x or a half extinction pulse Q.sub.x and because the auxiliary Y electrode has not only the positive polarity but also the negative polarity of the sustaining voltage applied thereto. Thus electric discharges are caused as above described in conjunction with FIGS. 4, 5 and 6. Therefore a wall charge is formed in a space 58 about the axis of discharge 56 for each pair of main Y and X electrodes 12 and 18 respectively and an electric discharge is intermittently caused about the axis of discharge 62 each time the sustaining voltage is inverted in polarity.

Also with a pair of half extinction pulses Q.sub.y and Q.sub.x simultaneously applied to a selected pair or pairs of main Y and X electrodes 12 and 18 respectively, the wall charge or charges is or are inverted in polarity. The application of the next pulse of the sustaining voltage to the auxiliary Y electrodes 50 causes the erasion of the wall charge or charges because the wall charge or charges at the time is or are of a potential tending to decrease the sustaining voltage to offset the latter. Thus the succeeding pulses of the sustaining voltage are applied to the auxiliary Y electrodes with no electric discharge. That is, the luminous mode of operation is not entered.

The present invention has several advantages. For example, a position where light is to be emitted and a time interval for which light continues to be emitted can be controlled only by adjusting the half illumination or extinction pulses applied to the main Y and X electrodes. This attributes to the construction of the present invention wherein one auxiliary electrode is disposed in close parallel relationship each of the main electrodes of at least one electrode arrays while the sustaining voltage continues to be applied to the auxiliary electrodes. Therefore the circuit for applying the sustaining voltage to the auxiliary electrodes can be separated away from the circuits for applying the illumination and extinction pulses to the main electrodes. This results in the elimination of the necessity of providing adder circuits for adding the pulses of the sustaining voltage to each other, adding the half illumination pulses to each other and adding the half extinction pulses to each other which circuits have been previously required. Further in view of the separation of the circuits as above described, it is very facilitated to provide a measure to counter malfunctions due to noise and also it is possible to simplify the circuit configuration. In addition, the plasma display panel as a whole can be formed into a simple construction and very easily manufactured. This is because only one of the arrays of auxiliary electrodes may be used.

While the present invention has been illustrated and described in conjunction with a few preferred embodiments thereof it is to be understood that numerous changes in the details of construction and the arrangement and combination of parts may be resorted to without departing from the spirit and scope of the present invention. For example, while the array of the auxiliary X electrodes has been omitted it is to be understood that the array of the auxiliary Y electrodes may be omitted. Also the array of the main Y electrodes may be disposed at any desired angles rather than right angles to the array of the main X electrodes.

Claims

What we claim is:

1. A plasma display device comprising, in combination, a first plane, an array of first main electrodes in the form of longitudinally elongated strips disposed in substantially parallel relationships in said first plane, an array of first auxiliary electrodes disposed in said first plane so that each of said first auxiliary electrodes runs in substantially parallel relationship with and adjacent to a different one of said first main electrodes, a second plane disposed in spaced parallel relationship with said first plane to form a discharge gap therebetween, an array of second main electrodes in the form of longitudinally elongated strips disposed in substantially parallel relationship in said second plane to be at a predetermined angle to said array of first main electrodes, an array of second auxiliary electrodes disposed in said second plane so that each of said second auxiliary electrodes runs in substantially parallel relationship with and adjacent to a different one of said second main electrodes, first circuit means for selectively applying a first voltage pulse to the main electrodes of each of said arrays of main electrodes to initiate and terminate an electric discharge thereacross, and second circuit means for successively applying second voltage pulses to said arrays of first and second auxiliary electrodes so as to develope a pulse train including pulses of one polarity alternating pulses of opposite polarity thereacross whereby said electric discharge is followed by electric discharges intermittently caused across those first and second auxiliary electrodes disposed adjacent to the first and second main electrodes applied with said first voltage pulses.

2. A plasma display device as claimed in claim 1 wherein said first voltage pulses are less in magnitude than a discharge voltage for said discharge gap and simultaneously applied in opposite polarity relationship to selected ones of said first and second main electrodes to initiate and terminate said electric discharge thereacross with the sum of the first voltage pulses.

3. A plasma display device as claimed in claim 2 wherein said array of first auxiliary electrodes in said first plane extends substantially perpendicularly to said array of second auxiliary electrodes in said second plane to arrange luminous points in a pair of orthogonal directions.

4. A plasma display device as claimed in claim 3 wherein a pair of transparent or translucent insulating sheets high in insulation resistance are interposed in spaced relationship between said first and second planes to temporarily hold a wall charge formed about said luminous point.

5. A plasma display device as claimed in claim 1 further comprising a pair of first and second transparent or translucent insulating sheets high in insulation resistance interposed in spaced relationship between said first and second planes, a first transparent or translucent holding plate disposed outside said first insulating sheet to cooperate with the latter to hold said arrays of first main and auxiliary electrodes therebetween, a second transparent or translucent holding plate disposed outside said second insulating sheet to cooperate with latter to hold said arrays of second main and auxiliary electrodes therebetween, a frame member cooperating with said first and second insulating sheets to form a hermetically closed discharge space between said insulating sheets, and an amount of gas filling said discharge space.

6. A plasma display device comprising, in combination, means in a first plane and means in a second plane disposed in spaced parallel relationship to form a discharge gap therebetween, said means in said first plane comprising an array of first main electrodes in the form of longitudinally elongated strips disposed in substantially parallel relationship in said first plane, said means in said second plane comprising an array of second main electrodes in the form of longitudinally elongated strips disposed in substantially parallel relationship in said second plane to be at a predetermined angle to said array of first main electrodes, an array of auxiliary electrodes disposed in a selected one of said first and second planes to that each of said auxiliary electrodes runs in parallel relationship with and adjacent to a different one of those main electrodes disposed in the selected plane, first circuit means for selectively applying a voltage pulse to the main electrodes of each of said arrays of main electrodes to initiate and terminate an electric discharge thereacross, and second circuit means for successively applying a train of bipolar voltage pulses across said array of axuiliary electrodes and that array of amin electrodes opposite to said array of auxiliary electrodes whereby said electric discharge is followed by electric discharges intermittently caused across said discharge gap.