Driving system for a gas discharge panel

Abstract

A driving system for a gas discharge panel having a shift layer and a display layer, in which a priming fire is shifted with the shift layer and a write voltage is impressed on the display layer at a position corresponding to the priming fire shifted to achieve writing. For erasing the written display, the priming fire is shifted to a position where the display is to be erased and a sustain voltage impressed on the display layer is cut off to neutralize wall charges, and then the sustain voltage is impressed again to the display layer, thereby to erase the display at the position of the priming fire.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a gas discharge panel driving system, and more particularly to a gas discharge panel driving system in which a display provided on the panel is erased with a priming fire.

2. Description of the Prior Art

A gas discharge panel of the type in which a priming fire is shifted and a display is provided by effecting a writing operation in accordance with the timing for shifting the priming fire, has been proposed by the present applicant. For example, as shown in FIG. 1, electrodes 2 are provided on a base plate 1 as of a glass; a dielectric layer 3 as of low-melting-point glass is coated thereon; electrodes 7 are provided on a base plate 6 similar to plate 1; a dielectric layer 8 is coated thereon; electrodes 5 covered with dielectric layers 4 are disposed intermediate between the two base plates disposed opposite to each other; the peripheral edges of the base plates 1 and 6 are sealed together; and a discharge gas such as neon or the like is sealed in the spaces defined between the electrode assembly 5 and the opposing base plates. The electrodes 5 are each disposed apart from the adjacent ones or holes, and grooves are formed in the electrode assembly so as to permit intercommunication of the upper and lower discharge gas spaces. The electrodes 2 (except a start electrode s) are periodically connected to buses A, B and C. For example, if a voltage higher than a discharge voltage is impressed between the electrode s connected to a bus S and the electrode a1 connected to the bus A, a discharge is produced between the electrodes s and a1. If this discharge voltage is taken as V.sub.F, if a discharge voltage due to the fire priming effect wherein electrons, ions and metastable atoms produced by the discharge are scattered to produce a discharge initial current to lower the discharge voltage is taken as V.sub.F1, and if a voltage V to be impressed between the buses A and B is selected such that V.sub.F >V>V.sub.F1, a discharge is caused between the electrodes a1 and b1. Then, upon impression of the voltage V between the buses B and C, a discharge is produced between the electrodes b1 and c1 due to the fire priming effect. Namely, the priming fire is shifted by surface discharge. Further, if discharge voltages between the electrodes 5 and 7 in the presence and absence of the fire priming effect of the shift layer are taken as V.sub.F.sub.' and V.sub.F2 respectively and if their relationships with a write voltage V.sub.W, a sustain voltage V.sub.S and a wall voltage V.sub.Q are established such that V.sub.F.sub.' >V.sub.W >V.sub.F2 and that V.sub.Q + V.sub.S >V.sub.F.sub.', writing can be achieved by impressing the write voltage V.sub.W between the electrodes 5 and 7 at the position of the priming fire shifted. For example, by impressing the write voltage V.sub.W between the electrodes 5 and x5 at the time of shifting the priming fire between the electrodes a2 and b2, writing can be achieved at that position. In this case, it is possible to connect the electrodes 5 to a bus Y in common to them and select the electrodes 7, that is, the electrodes x1, x2, . . . , or select the electrodes 5 and connect the electrodes 7 to a common bus. In the former case, it is suitable to dispose the electrodes 7 to intersect the electrodes 2 at right angles thereto.

In the foregoing, the priming fire is shifted by surface discharge and a display is produced by a discharge between the opposing electrodes but it is also possible to achieve shifting of the priming fire by the discharge between the opposing electrodes and provide a display by surface discharge.

SUMMARY OF THE INVENTION

This invention has for its object to achieve a display erasing operation with a priming fire in such a gas discharge panel as described above.

The driving system of this invention is adapted for use with a gas discharge panel having a shift layer and a display layer and includes is circuitry for providing a priming fire that is shifted to an erasing position; for impressing a sustain voltage to the display layer and for interrupting the sustain voltage for an erase interval whereby wall charges at the erasing position are neutralized by the priming fire; and then, for applying the sustain voltage again to the display layer.

These and other objects and benefits of this invention will become apparent from the following description taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of the principal part of a gas discharge panel having a shift layer and a display layer;

FIG. 2 is a waveform diagram for explaining the operation of one example of this invention;

FIG. 3 is a cross-sectional view of the principal part of another example of the gas discharge panel of this invention having the shift layer and the display layer; and

FIGS. 4 and 5 are circuit diagrams showing drive circuits for the examples of this invention, respectively.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 2 shows examples of waveforms for explaining the operation of one example of this invention. Reference characters VA, VB and VC designate voltages to be applied to the buses A, B and C in FIG. 1. A priming fire is shifted by surface discharge. Reference character VXY indicates a sustain voltage for impression between the electrodes 5 and 7. Small circles identify write voltages, which can be superimposed on the sustain voltage. Since the priming fire is shifted by the electrodes 2 of a first layer 1, this layer will hereinafter be referred to as a shift layer, and since a display is produced by the electrodes 5 and 7 of second and third layers 4 and 8, these layers will hereinafter be referred to as a display layer. In the case of a display being provided on the display layer, charges produced by the discharge are stored in the dielectric layer to provide wall charges to thereby store and display written information. The display can be erased by neutralizing the wall charges. The erasing can be achieved, for example, by cutting off the sustain voltage for a little while but this requires an appreciable amount of time and introduces the possibility of erasing the display desired to be retained. To avoid such defects, in the present invention, the priming fire is shifted to a position where the display is desired to be erased and then the sustain voltage is cut off. Namely, the period TE indicates this operation. The wall charges are neutralized by the priming fire and, thereafter, even if the sustain voltage is impressed, no discharge is produced at the position where the display has been erased. In the other area where the priming fire does not lie, neutralization of the wall charges is not caused by the temporary interruption of the sustain voltage, so that the display is not erased.

By impressing an auxiliary erasing voltage to the display layer in the period TE, the erasing time is remarkedly shortened. In the case of impressing a voltage lower than the discharge current while a discharge initial current is applied, a current of extremely increased level flows substantially in proportion to the initial current. By the impression of a voltage lower than an erasing pulse voltage for a usual display panel, that is, the erasing auxiliary voltage, the current is increased substantially at the position of the priming fire, thereby to facilitate neutralization of the wall charge. Further, since the amount of space charges is very small at those areas where the priming fire does not exist, such neutralizing action is not performed at these areas.

By impressing the auxiliary erasing voltage to selected ones of the electrodes 5 and 7, it is possible to select discharge cells corresponding to the position of the priming fire shifted to ensure accurate erasing.

In the foregoing example, the shift layer shifts the priming fire by surface discharge and the display layer effects memorizing and displaying by a discharge between the opposing electrodes, but it is also possible to shift the priming fire by the discharge between the opposing electrodes and effect memorizing and displaying by the surface discharge. Further, it is also possible to adapt both of the shift layer and the display layer for the surface discharge or the discharge between the opposing electrodes. The buses of the shift layer may be operated in a three-phase mode or more and can be selected four- or five- phase as desired.

Since the display provided on the display layer at the shifted position of the priming fire can be erased as described previously, partial retouching of the display can be readily achieved by rewriting after erasing one part of the written content. Further, negative writing can also be effected by partial erasing as described above while producing a discharge in each of the discharge cells.

FIG. 3 shows in section the principal part of another example of this invention, in which the electrodes 5 of the second layer in FIG. 1 are left out. In FIG. 3, electrodes 12 formed on a base plate 11 and covered with a dielectric layer 13 are sequentially connected to the buses A', B' and C' to make up a shift layer and electrodes 15 coated with a dielectric layer 16 are disposed on a base plate 14. In this case, the priming fire is shifted by the surface discharge, for example, by sequential impression of a voltage to successive pairs of the buses A', B' and C'. By impressing a write voltage to the electrodes x1, x2, x3, . . . at the position to which the priming fire has been shifted, a display is provided by a discharge caused between the electrodes 12 and 15. The sustain voltage is impressed between the electrodes 12 and 15. In this case, the electrodes 15 can instead be disposed to intersect the electrodes 12 at approximately right angles thereto, and the write voltage is selectively applied to the electrodes 15 corresponding to the shifted position of the priming fire. In those cells having been discharged by the write voltage, the discharge is repeated to provide the display each time the polarity of the sustain voltage is reversed by the wall charge, so that also in the case of erasing the display, the priming fire is shifted to a position where it is desired to erase the display and the sustain voltage is interrupted as described previously. Since the wall charge is thereby neutralized, when the sustain voltage is impressed again, no discharge is caused because the wall charge has been neutralized. Namely, erasing is accomplished.

With the present invention, writing is achieved by impressing a write voltage in accordance with the timing of shifting of a priming fire, and erasing is effected by neutralizing the wall charge at the erasing position by means of the priming fire, as performed in a gas discharge panel having a shift layer and a display layer, and as has been described in the foregoing. Accordingly, this invention does not necessitate the impression of an erasing voltage, and hence is free from a half selection trouble, and partial retouching of a display and negative writing can easily be accomplished.

FIG. 4 illustrates one example of a drive circuit for a gas discharge panel in which both the shift layer and the display layer are of the type producing a discharge between opposing electrodes. The shift layer has a keep alive electrode k, a new line reset electrode nr, an X shift electrode group 20 and a Y electrode group 21; while, the display layer has a Y electrode group 22 and an X electrode group 23. In the case of displaying one character with 5.times.7 dots, each set of seven electrodes of the Y electrode groups 21 and 22 forms one line.

An input signal In is applied to a received signal separating circuit 24 to separate the following signals: an X address shift command xa, a new line signal nls, a write command w, an erase command e, data d, a synchronizing signal ss and a line address la, from one another.

The synchronizing signal ss is applied to a clock generator 28 to provide a clock pulse a, which is fed to a .pi. phase shifter 29 to produce a clock pulse b shifted from the clock a by .pi. phase.

The X address shift command xa is supplied through a gate G1 to a ring counter 25. Transistors Qa, Qb and Qc are controlled by outputs from gates G4, G5 and G6 Transister Q5 is turned on by the clock pulse b to impress the voltage V.sub.SH, which is supplied to its collecter, to the Y electrodes 21. Transister Q6, whose collecter is connected to the emitter of transister Q5, is turned on by the clock pulse a, and then the Y electrodes 21 are grounded through transister Q6. The transistors Qa, Qb and Qc thereby are sequentially enabled to apply a voltage V.sub.SH as a shift voltage to buses A, B and C. Further, a voltage V.sub.SL lower than that V.sub.SH is impressed to the buses through a transistor Q1 since this voltage V.sub.SL serves as an erasing voltage, the speed of erasing by the shift voltage can be increased greatly. The voltage V.sub.SH is applied through a transistor Q2 to the keep alive electrode k to produce a priming fire at all times. The received signal separating circuit 24 has provided therein a counter for memorizing the position of the priming fire shifted by the X address shift command xa.

Upon generation of the new line signal nls, the gate G2 is closed by a signal applied through an inverter IV1, so that the gates G4, G5 and G6 are also closed to turn off all of the transistors Qa, Qb and Qc thereby to erase the entirety of the corresponding line of the display irrespective of the position of the priming fire. A transistor Q3 is actuated by the output from the gate G3 to impress the voltage V.sub.SH to the new line reset electrode nr to produce a priming fire. Namely, the priming fire is generated by the new line signal nls at the start point for the line. A transistor Q4 is operated by the clock pulse b and its emitter electrode is grounded to discharge charges stored therein. Transistors Q5 and Q6 are connected to impress the voltage V.sub.SH to the Y electrodes 21.

In the display layer, the clock pulse a is applied to a transistor Q9 through a gate G9, whereby the sustain voltage V.sub.S is applied to the Y electrodes 22 through corresponding diodes 31 and the Y electrodes 22 are grounded through a transistor Q19 which is supplied with the clock pulse b. Further, the X electrodes 23 are supplied with the sustain voltage V.sub.S and grounded through transistors Q21, Q20 which are supplied with the clock pulses a and b respectively. Namely, the sustain voltage V.sub.S is impressed to cells formed at the intersecting points of the X and Y electrodes 23 and 22.

Upon generation of the write command w, a one-shot multivibrator 26 operates to open the gate G7 with its output to apply the clock pulse a to a transistor Q7, and transistors Q10 to Q16 are enabled selectively by the data d to impress the write voltage V.sub.W to the corresponding Y electrodes 22 through related resistors 30. As to the Y electrodes 22 which do not effect writing, the line address la prevents the application of the write voltage V.sub.W thereto by controlling the operation of transistors Q17 and Q18 through inverters IV3 and IV4 and gates G11 and G12. During the operation of the one-shot multivibrator 26, an input waiting command wt is supplied through a gate G10 and inverter IV2 to close, or disable, the gates G1 and G9.

Upon generation of the erase command e, a one-shot multivibrator 27 operates to open the gate G8 to turn on the transistor Q8 and supply an auxiliary erasing voltage V.sub.E to the collectors of transistors Q10 to Q16. The erase command e is produced when the shifted position of the priming fire as memorized by the counter of the received signal separating circuit 24 coincides with the specified position to be erased. By the output from the one-shot multivibrator 27, the gate G1 is closed to stop shifting of the priming fire in the shift layer and the gate G9 is closed to stop impression of the sustain voltage V.sub.S. As a result of this, the display on the display layer is erased by the priming fire on the shift layer. At this time, the auxiliary erasing voltage V.sub.E is impressed to ensure erasing. Further, selective erasing can also be achieved by selective impression of the auxiliary erasing voltage and by selecting the period of stopping the impression of the sustain voltage V.sub.S in accordance with the data d.

FIG. 5 shows another example of the drive circuit, in which the same reference numerals and characters as those in FIG. 4 indicate the same elements. In this example, where the priming fire is produced by the new line signal nls at the start point and shifted, the line, in which the priming fire is shifted, is selected by the line address signals la. Namely, a gate G13 is opened by a line address la1, so that a transistor Qnl is turned on to apply a priming fire to a new line reset electrode nr1, thus enabling writing and erasing in that line. Since a gate 14 is opened by a line address la2, a transistor Qn2 is turned on to apply a priming fire to a new line reset electrode nr2. Thus, the priming fire shifting line is selected, so that no resistor-diode matrix circuit is required and the circuitry on the side of the display layer is simplified.

In the foregoing examples of FIGS. 4 and 5, the gas discharge panel has been described to have the X and Y electrodes 20 and 21 in the shift layer and X and Y electrodes 23 and 22 in the display layer, but the X electrodes 23 can be deleted by causing the shift layer to effect the shift operation by the discharge between opposing electrodes as described previously and by causing the display layer to effect the display operation by the surface discharge with the Y electrodes 22 being used in pairs.

Moreover, it is also possible to omit the Y electrodes 21 of the shift layer, in which case the shift operation is achieved by the surface discharge of the X electrodes 20 and the display operation of the display layer is effected by the discharge between opposing electrodes.

It will be apparent that many modifications and variations may be effected without departing from the scope of the novel concepts of this invention.

Claims

What is claimed is:

1. An energizing system for a gas discharge display including a first base plate and a first set of electrodes disposed thereon with a dielectric layer disposed over said first set of electrodes, and a second base plate and a second set of electrodes disposed thereon in opposite relationship to said first set of electrodes and defining a region for confining a discharge gas therebetween, said energizing system comprising:

a. priming means for applying a discharge voltage to a selected one of successive electrode pairs of said second set to establish a priming fire therebetween;

b. shift means for sequentially applying a shift voltage to remaining successive such pairs of electrodes of said second set thereby to shift said priming fire thereto;

c. write means for applying a write signal to a selected electrode of said first set to establish a discharge at an intersection of said selected electrode and an electrode pair of said second set on which the priming fire is shifted whereby a wall charge is stored at a corresponding position upon said dielectric layer;

d. sustain means for applying a sustain voltage to said first set of electrodes; and

e. erase means having an address means for identifying a position defined by said first set of electrodes to be erased and for causing said shift means to shift a priming fire to an electrode pair of said second set corresponding to the said address identified position of the first set of electrodes, said erase means further including means operating in conjunction with said address means for terminating the application of the sustain voltage by said sustain means to said first set of electrodes for a predetermined period whereby the shifted priming fire neutralizes the wall charge stored upon said dielectric layer at said address identified position thereof, corresponding to the shifted position of the priming fire.

2. The energizing system as claimed in claim 1, wherein said erase means effects the reapplication of the sustain voltage to the electrodes of said first set after the predetermined period.

3. The energizing system as claimed in claim 1, wherein said erasing means includes an auxiliary erasing means for applying an auxiliary erasing voltage for a selected period to said first set of electrodes during said predetermined period thereby to increase the rate of neutralization of the wall charges.

4. The energizing system as claimed in claim 1, wherein there is included a third set of electrodes disposed intermediate said first and second set of electrodes and at substantially right angles thereto, said write means applies the write signals between said selected electrode of said first set and the electrodes of said third set in timed relation with the shifting of the priming fire to the corresponding electrode pair of said second set, thereby to establish said wall charge at said corresponding position upon said dielectric layer, and said sustain means applies said sustain voltage between said first and third sets of electrodes.

5. The energizing system as claimed in claim 1, wherein said write means is operative to apply a write signal to a selected one of said first electrodes in timed relation with the shifting of the priming fire to the corresponding electrode pair of said second set thereby to establish a corresponding wall charge at the corresponding position upon said dielectric layer which was previously erased.

6. A discharge display panel system comprising:

a. a display panel comprising a shift layer having first and second sets of electrodes disposed in spaced relationship at substantially right angles to each other to define intersections, a display layer with third and fourth sets of electrodes disposed in spaced relationship at substantially right angles to each other to define intersections respectively corresponding to the intersections of said shift layer, said display and said shift layers being disposed in opposed relation for receiving a discharge gas therebetween, and a dielectric storage layer associated with said display layer;

b. priming means for applying a discharge voltage to selected electrodes of said first set thereby to establish a priming fire therebetween;

c. shift means for sequentially selecting electrodes of said first set and for applying a shift voltage between the sequentially selected electrodes of said first set and the electrodes of said second set thereby to shift the priming fire sequentially across said shift layer;

d. sustain means for applying a sustain voltage between the electrodes of said third and fourth sets;

e. write means for selecting one of said third set of electrodes and for applying a write signal between the said selected one of said third set of electrodes and the electrodes of said fourth set in timed relation to the application of the shift voltage between the corresponding selected electrode of said first set and the electrodes of said second set to effect a discharge at the thus defined intersection, whereby a wall charge is stored upon said dielectric layer at a corresponding position; and

f. erase means for terminating for a predetermined interval, the application of the sustain voltage by said sustain means in timed relation to the selection and application of the shift voltage to an electrode of said first set corresponding to an intersection of said display layer, whereby the shifted priming fire neutralizes the wall charge stored at the said corresponding position upon said dielectric layer.

7. The display system as claimed in claim 1, wherein there are further provided memory means for storing an indication of the position of the priming fire in said shift layer in accordance with the sequential selection of said first electrodes and means for initiating the operation of said erase means in response to a correspondence of the shifted priming fire position and the intersection position of the display layer desired to be erased.

8. The display system as claimed in claim 6, wherein said third set of electrodes is divided into sub-groups of electrodes corresponding to lines of information to be displayed upon said display panel, and there is included line address means for controlling the application of write signals selectively to said sub-groups of electrodes of said third set.

9. The display system as claimed in claim 6, wherein said second set of electrodes is divided into sub-groups of electrodes corresponding to lines of information to be displayed upon said display panel, and there are included new line reset electrodes respectively associated with said sub-groups of said second set of electrodes, means for generating a new line signal, address means for generating a line address signal corresponding to the new line reset electrode associated with the desired sub-group of electrodes, and control means responsive to a new line signal and to a line address signal for applying a discharge voltage to said new line reset electrode and said desired sub-group of electrodes to produce a priming fire to be shifted therebetween.

10. A driving system for a gas discharge display having a shift layer and a display layer disposed to receive a discharge gas therebetween, each layer including respective pluralities of electrodes defining positions in the respective layers, with a position in one layer corresponding at least in part to a position in the other layer, and the plurality of electrodes of the display layer being covered with a dielectric layer, said driving system comprising:

means for applying a sustain voltage to the electrodes of said display layer;

means for identifying an electrode of the display layer corresponding to a position of the dielectric layer storing a wall charge to be neutralized;

means for establishing a priming fire in said shift layer;

means for sequentially applying a shift voltage to successive electrodes of said shift layer to shift the priming fire to a position thereof corresponding to the identified electrode of said display layer; and

means responsive to shifting of said priming fire to said position corresponding to the identified electrode of said display layer for interrupting application of said sustain voltage by said sustain voltage applying means to said electrodes of said display layer for a predetermined time, the sustain voltage being reapplied by said sustain voltage applying means after the said predetermined time.

11. A method of driving a gas discharge display having a first base plate and a first set of electrodes disposed thereon with a dielectric layer disposed over said first set of electrodes, and a second base plate and a second set of electrodes disposed thereon in opposite relationship to said first set of electrodes and defining a region for confining a discharge gas therebetween, and wherein a sustain voltage is normally applied to said set of electrodes and information is written onto said display by applying a write signal to a selected electrode of said first set to establish a discharge at said selected electrode and thereby to produce and store a wall charge at a corresponding position upon said dielectric layer, the method comprising the steps of:

applying a discharge voltage selectively to the electrodes of said second set in succession, to establish a priming fire at each successively selected said electrode;

addressing an electrode of said first set, corresponding to a position of said dielectric layer storing the wall charge;

sequentially applying a shift voltage to successive electrodes of said second set thereby to shift the priming fire to the electrode of the second set corresponding to the addressed electrode of the first set;

detecting correspondence of the position of the shifted fire to the addressed electrode of said first set of said first base plate;

terminating the application of the sustain voltage to said first set of electrodes during a predetermined period while the shifted position of the priming fire on the second base plate corresponds to the addressed position of said first base plate, thereby to neutralize the wall charge; and

reapplying the sustain voltage to said first set of electrodes after the said predetermined period.

12. The energizing method as claimed in claim 10 wherein the step of applying a write signal comprises applying a write signal simultaneously to each electrode of said first set thereby to effect negative writing of information.