US3778674A - D. c. gas discharge display apparatus with pulse train memory sustaining potential - Google Patents

D. c. gas discharge display apparatus with pulse train memory sustaining potential Download PDF

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US3778674A
US3778674A US3778674DA US3778674A US 3778674 A US3778674 A US 3778674A US 3778674D A US3778674D A US 3778674DA US 3778674 A US3778674 A US 3778674A
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display
pulses
sustaining
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C Lustig
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WALTER E HELLER WESTERN Inc
Sperry Corp
Babcock Display Products Inc
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    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01JELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J17/00Gas-filled discharge tubes with solid cathode
    • H01J17/38Cold-cathode tubes
    • H01J17/48Cold-cathode tubes with more than one cathode or anode, e.g. sequence-discharge tube, counting tube, dekatron
    • H01J17/49Display panels, e.g. with crossed electrodes, e.g. making use of direct current
    • H01J17/492Display panels, e.g. with crossed electrodes, e.g. making use of direct current with crossed electrodes

Abstract

Display apparatus comprises d.c. gas discharge display cells with a sustaining potential thereacross comprising a pulse train with pulse amplitude, pulse duration and pulse spacing such that an ignited cell is reignited upon application of each sustaining pulse and an extinguished cell remains extinguished upon application of the sustaining pulses unless ignited or extinguished by external means.

Description

United States atent n91 Lustig 1 Dec. 11, 1973 1 1 D. C. GAS DISCHARGE DISPLAY APPARATUS WITH PULSE TRAIN MEMORY SUSTAINING POTENTIAL [75] Inventor: Claude D. Lustig, Lexington, Mass.

[73] Assignee: Sperry Rand Corporation, New

York, N.Y.

[22] Filed: Apr. 14, 1972 [21] Appl. No.: 244,011

[52] US. Cl 315/169 R, 315/169 TV [51] Int. Cl. H05b 37/00 [58] Field of Search 315/169 R, 169 TV [56] References Cited UNITED STATES PATENTS 3/1961 Smith 315/845 4/1971 Mayer et a1 ..315/169R 3,626,241 12/1971 Ngo 315/169 R X 3,689,912 9/1972 Dick 315/169 R X 3,600,626 8/1971 Kupsky 315/169 R X Primary Examiner-Roy Lake Assistant Examiner-Hugh D. .laeger Att0rneyl*loward P. Terry 57] ABSTRACT Display apparatus comprises d.c. gas discharge display cells with a sustaining potential thereacross comprising a pulse train with pulse amplitude, pulse duration and pulse spacing such that an ignited cell is reignited upon application of each sustaining pulse and an extinguished cell remains extinguished upon application of the sustaining pulses unless ignited or extinguished by external means.

7 Claims, 5 Drawing Figures RESERVOlR ADDRESS 1 N6 Cl RCUlTY MEMORY PULSE SOURCE PATENTEDDEB 11 ms 37 95 PLASMA RESERVOIR/W ADDRESSING cmcuwv HIO ME-MORY PULSE SOURCE PATENIEUUEE 11 ms ELECTRON ELECTRON DENSITY CURRENT DENSITY VOLTAGE CURRENT 3778.674 SHEET 3 (IF 3 V3ORV3 Y I I ELECTRON DENSITY I Y |N LIT CELLS P X 36 I I- AMBIENT ELECTRON I DENSITY IN [1 n UNLIT CELLS AMBIENT ELECTRON DENSITY IN UNLIT CELLS D. C. GAS DISCHARGE DISPLAY APPARATUS WITH PULSE TRAIN MEMORY SUSTAINING POTENTIAL BACKGROUND OF THE INVENTION 1. Field of the Invention The invention pertains to d.c. gas discharge display apparatus, particularly with regard to the memory sustaining potential thereof.

2. Description of the Prior Art D.C. gas discharge display devices are known in the prior art that include a plurality of gas discharge display memory cells. Conventionally, a dc. gas discharge sustaining potential of amplitude intermediate the ignition and extinction potentials of the cell gas discharges is applied across the array of memory cells. Thus, whenever a discharge is selectively ignited in a cell, the cell remains ignited thereby providing memory. Similarly, a cell once extinguished remains extinguished until selectively reignited. One type of such gas discharge display apparatus is known in the art as the x-y addressed display panel. In such devices, a plurality of anodes are disposed orthogonally with respect to a plurality of cathodes, the intersections thereof forming an x-y grid. The d.c. sustaining potential is applied between all of the cathodes with respect to all of the anodes. To selectively ignite a cell, the potential is increased at a selected x-electrode and at a selected y-electrode such that only the potential at the intersection of the selected electrodes exceeds the firing potential of the gas, thus igniting a discharge at the selected cell. When the increased potentials are removed, the sustaining potential maintains the discharge ignited. A similar procedure is utilized in extinguishing an ignited cell by reducing the potentials on a selected x and a selected yelectrode.

D.C. gas discharge display panels having a plurality of memory cells with d.c. sustaining potential thereacross may also ignite selected memory cells by selectively applying preionization thereto. Examples of such displays are described in US. patent application Ser. No. 90,538 filed Nov. 18, 1970 entitled Digitally Addressable Gas Discharge Display Apparatus by Claude D. Lustig and Albert W. Baird III and US. Pat. application Ser. No. 161,584 filed July I2, 1971 entitled Gas Discharge Display Apparatus by Theodore H. Bonn, both assigned to the assignee of the present invention.

It has been found with such display panels that when reasonable sustaining potentials are applied across the memory cells, arcing between the cell electrodes frequently occurs reslting in display instability or damage to the devices. A prior art solution to this instability problem has been to utilize a resistor in series with each of the display cell discharges thus limiting the current flow and hence precluding arc formation In many applications of such panels, it is frequently desirable to utilize large arrays of display memory cells. In such panels, the inclusion of a large number of individual resistors results in substantial constructional difficulties. Furthermore, it is not possible to utilize a single resistor in series with an array of cells, since the current drawn by igniting several cells results in a voltage drop across the series resistor thus reducing the sustaining voltage appearing across the array of cells. Hence, increasing difficulty is encountered when attempting to ignite larger numbers of cells. This voltage dependence on the number of cells ignited causes further display instabilities.

Because of the attendant difficulties in designing a stable large-scale d.c. gas discharge display panel with memory, practitioners in the art turned their attention to ac. display panels, a wide variety of which are known in the art. In such panels, the electrodes are electrically insulated from the gas plasma thus preventing arc instabilities. It was discovered, however, that the ac. panels are constructionally more complicated than the d.c. panels thus resulting in higher manufacturing costs for the a.c. display devices. Additionally, the a.c. panels require somewhat larger potentials than do the d.c. panels thus complicating the attendant panel circuitry and again increasing the cost thereof. In addition, the ac. display panels are not normally compatible with some of the simple d.c. addressing arrangements developed for the d.c. type of panels. Such a simple d.c. addressing arrangement is disclosed in said Ser. No. 90,538.

SUMMARY OF THE INVENTION The present invention provides a stable d.c. panel display with memory in which are formation is prevented without the use of resistors in series with the gas discharges by utilizing a pulse train sustaining potential. The pulse amplitude, pulse duration and pulse spacing are selected such that a cell once ignited is continuously reignited by the sustaining pulses and a cell once extinguished remains extinguished during the application of the sustaining pulses. The duration of the pulses is sufficiently narrow and the spacing between the pulses is sufficiently wide such that are formation is prevented. Thus, it is appreciated that with the d.c. sustaining potentials of the prior art devices, when substantial current surges develop, an arc may be formed causing damage to the display device and the associated circuitry. Utilizing the pulse train sustaining potential of the invention, the sustaining voltage pulse is too narrow to permit an arc to develop. Thus, the invention provides greater display stability without utilizing series resistors and particularly for large scale arrays of memory cells. I

An attendant advantage of the invention is that less operating power is required and hence less power dissipation and heat generation occurs in gas discharge devices utilizing the invention as compared to the prior art d.c. arrangements, including those which do not incorporate series resistors.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a portion of a gas discharge display panel suitable for incorporating in the invention.

FIG. 2 is a sectional elevation view of the panel of FIG. 1 taken along the line 2-2 of FIG. 1.

FIG. 3 is a current-voltage characteristic curve of a typical cold cathode gas discharge utilizing d.c. excitation.

FIG. 4 is a waveform diagram illustrating waveforms useful in explaining the operation of the invention.

FIG. 5 is a current-voltage characteristic curve of a cold cathode gas discharge utilizing pulsed excitation in accordance with the invention.

DESCRlPTlON OF THE PREFERRED EMBODIMENT Referring to FlG. 1, a portion of a gas discharge display panel suitable for incorporating the invention and of the type described in said Ser. No. 90,538 is illustrated. Since the structure and operation of such a display panel is discussed in detail in said Ser. No. 90,538, only a concise description thereof will be given here for brevity.

The apparatus includes a display memory section comprising a plurality of gas discharge display cells. Adjacent to the display section 10 are a stack of ad dressing electrodes ll, only the last addressing anode 12 in the stack 11 being illustrated. Adjacent to the stack of addressing electrodes i1 is a gas plasma reservoir not shown herein for simplicity.

The display section 10 of the panel includes a display anode structure 13 which may, for convenience, com prise a metal plate with a matrix of apertures therethrough. The display section 10 also includes a cathode structure 14 which may be instrumented by a metal plate with a matrix of apertures therethrough in a manner similar to the cathode plate 13. An insulator plate 15, having a matrix of apertures therethrough, is disposed between the plates l3 and 14. A transparent face plate 16, through which a display pattern may be viewed, is also included in the display section 10. Two perforated insulated plates 17 and 18 are disposed between the cathode plate 14 and the transparent face plate 16 to inhibit sputtering of material from the cathode plate 14 to the face plate 16, which sputtered material would tend to obscure the display.

A perforated insulator plate 19 is interposed between the display anode plate 13 and the addressing anode l2. lt will be appreciated that the plates 12-.19 are disposed adjacent one another in stacked arrangement with the matrices of apertures through the respective plates aligned to form gas conductive channels and sealed around the edges to form a gas tight structure in the manner described in said Ser. No. 90,538.

Addressing circuits 2% are included for selectively applying potentials to the portions of the addressing anode plate 12 as well as to the portions of the remaining addressing anode plates of the addressing stack 11 in the manner described in detail in said Ser. No. 90,538.

The apparatus of FIG. 1 also includes memory pulse source circuits 25. The circuits 25 apply a sustaining pulse train waveform between the display anode plate 13 and the display cathode plate 1d in accordance with the concepts of the invention in a manner to be described.

It will be appreciated that the display anode plate 13 and the display cathode plate 14 together with the insulator plate define a plurality of gas discharge display cells in the manner described in said Ser. No. 90,538. For example, the aperture 26 in the insulator plate 35 defines a gas discharge cell whose anode and cathode electrodes are provided by the portions of the plates 13 and 14 adjacent the aperture 26, respectively.

With the memory pulse source circuits 25 providing a sustaining voltage pulse train waveform between the display electrodes 13 and 14 in a manner to be described in accordance with the invention, a display cell of the memory section 10 is selectively ignited in the manner described in detail in said Ser. No. 90,538. The

manner in which a memory cell is ignited will be explained briefly herein for completeness. With appropriate addr'essing potentials applied by the addressing circuits 24 to the portions of the anodes of the addressing stack lll, a gas plasma column will be extended from the plasma reservoir to impinge upon a selected aperture in the addressing anode 12. For example, when the aperture 27 is addressed through the stack of electrodes iii, a gas plasma column 30 is extended from the reservoir to impinge upon the aperture 2'7 and then through to the aperture 28 in the display cathode plate 13. Since the sustaining voltage pulse train is applied between the display electrodes 13 and 14, a gas discharge is ignited in the memory cell 26 by the ionization introduced thereat by the plasma column 30. when the addressing potentials from the circuits 24 are removed, thus terminating the application of the plasma column 30 to the aperture 28, the display .cell 26 remains ignited because of the sustaining action of the pulse train provided by the circuits 25 in a manner to be described Thus it will be appreciated that an information pattern may be displayed by the memory section 10 by selective ignition of the display cells thereof. A displayed pattern may be erased by momentarily removing the sustaining potential waveform from the electrodes 13 and M.

Referring to FIG. 2, in which like reference numerals indicate like components with respect to FlG. 1, an elevation view taken in section along the line 22 of FIG. 1 is illustrated to further aid in understanding the construction and arrangement of the elements of FIG. 1.

A cold cathode gas discharge normally requires a lower voltage to sustain the discharge than is required to ignite it. A sustaining voltage applied to an array of gas discharge cells will not cause ignition of any of the cells until a voltage higher than the sustaining voltage is applied to selected cells or until the firing voltage of selected cells is lowered, for example, by local preionization. The cells in the array have memory in the sense that the cells will remain lit after the original ignition instrumentations, e.g., the higher voltage pulse or the preionization, are removed.

Referring to FlG. 3, the current-voltage characteristic of a typical cold cathode d.c. gas discharge is illustrated. Point P represents a typical operating condition with a sustaining voltage which may be applied from a sustaining voltage source through a resistor in series with the discharge as indicated by the legend V Alternatively, the sustaining voltage V may be applied from a voltage source without a series resistor as indicated by the legend V Operation without a series resistor is necessary if many display cells are to be sustained from the same power supply to avoid variations in cell voitages as different numbers of cells are ignited. Memory is obtained because the voltage across a cell must be increased to V before ignition occurs. Once a cell has been ignited it can be sustained with a lower voltage, for example V because strong space charge fields are established at the cell cathode increasing its emission efficiency.

It will therefore be appreciated that in prior art d.c. gas discharge display panels, i.e., panels having the cell electrodes in contact with the discharge and operated with d.c. potentials, a d.c. sustaining potential is conventionally applied across the display cells so as to effect the memory function. As previously discussed, the use of a d.c. sustaining potential has attendant disadvantages. Therefore, in accordance with the invention, the memory pulse source 25 of FIG. 1 provides a pulse train as illustrated in FIG. 4a with pulses of duration t, amplitude V and spacing T. This pulse train sustaining waveform, as illustrated in FIG. 4a, is applied between the anode plate 13 and the cathode plate 14 of the display cells of FIG. 1. It will be appreciated that circuits for providing pulse trains such as that of FIG. 4a are well known in the art and will not be further described for brevity.

with the pulse train sustaining waveform of FIG. 4a applied across the memory cells 10 of FIG. 1, the electron density of lit cells may follow a curve 35 as illustrated in FIG. 4b and the electron density of unlit cells may not rise above the level 36 as further illustrated in FIG. 4b. Thus, in lit cells when breakdown occurs during the application of a sustaining pulse of duration t, the electron density within the cell increases to a relatively large value and decays during the time interval T between voltage pulses to a minimum value Y. When the electron density decays to the point Y, the next sustaining pulse occurs, again firing the cell and increasing the electron density therein to a large value. It will be appreciated that the parameters of the pulse sustaining waveform of FIG. 4a must be chosen such that the electron density in lit cells remains sufficiently high between pulses so as to continuously reignite the cells upon application of each of the sustaining pulses. In unlit cells, however, the parameters of the pulse train sustaining waveform of FIG. 4a are chosen such that the electron density within the unlit cells remains below a point X which is significantly lower than point Y. Thus in unlit cells, the electron density does not achieve a value such that the sustaining pulses can produce ignition therein. FIG. 40 illustrates the current drawn by lit cells during application of the sustaining pulse train of FIG. 4a.

Thus, it is appreciated that memory is obtained because the duration 1 of the applied voltage pulses is chosen to be sufficiently short that the pulses will cause ignition only in cells which were lighted during the previously occurring pulse, since the electron density therein is relatively high. In addition the interval T between pulses is selected to be sufficiently short so that the electron density at the times the voltage pulses are applied is still appreciably higher than the ambient electron density in cells which have not been ignited, as illustrated by points Y and X, respectively, of FIG. 4b.

Referring to FIG. 5, a dc. current-voltage gas discharge characteristic similar to that shown in FIG. 3 is illustrated. When the pulse train sustaining voltage of FIG. 4a is of amplitude V an operating condition of point Q is established. Should the pulse train sustaining waveform amplitude be V then an operating condition of point Q will be established. It is appreciated that the pulse amplitudes V or V are normally chosen near the firing potential V of the gas discharge. The peak voltages V;, or V may be substantially below or above V respectively, depending upon the values of t and T. For large values of T and small values oft an amplitude V will normally be chosen above V and for small values of T and large values of t, a peak voltage V will normally be chosen below the firing potential V Choices of: and T will depend on the gas composition of the discharge since breakdown conditions and electron density decay rates vary as a function of the gas composition. It will be appreciated that the peak voltages V or V may take on a wide range of values less than, equal to and above the firing voltage V of the gas.

The pulse train sustaining waveform of FIG. 4a will not by itself cause ignition. In order to ignite a selected cell, either ionization is introduced to raise the ambient electron density level X to the level Y (FIG. 4b) or alternatively, one or more of the sustaining voltage pulses is increased in amplitude or width or both. The former cell ignition method would be utilized with display panels of the type described in said Ser. No. 90,538 or said Ser. No. 161,584 by the methods described therein. The latter ignition method would be utilized in X-Y addressed panels of a type known in the art where the amplitude or width of the sustaining pulses on an X conductor as well as on a Y conductor would be increased to cause ignition selectively at the cell located at the intersection of the conductors. A cell may be erased in an X-Y addressed panel by decreasing the sustaining potentials at selected X and Y conductors in order to decrease the potential at the intersections thereof to below the extinction voltage of the discharge. In panels of the type illustrated in said Ser. No. 90,538 or said Ser. No. 161,584, the cells may be erased by momentarily disrupting the application of the sustaining pulse train.

It will be appreciated that the principles of the invention may be applied to a wide variety of display panel configurations with a wide variety of parameters selectable for the puse train sustaining potential. Once the principles of the invention as explained above are understood, the dimensions of the display panels and the parameters of the pulse train sustaining waveform may be chosen in accordance with the well known gas discharge laws.

For example, a gas discharge display panel that provides satisfactory operation is designed as follows. With reference to FIGS. .l and 2 the cathode I4 is a 0.005 inch thick nickel-iron alloy plate with a square 32 X 32 array of apertures 0.014 inches in diameter with a 0.031 inch center-to-center spacing. The anode plate 13 is similar in construction to the cathode plate 14 with the exception that the aperture diameters are 0.010 inches. The anode plate 13 and the cathode plate 14 are separated by a glass sheet 15 wich is 0.006 inches thick with 0.018 inch diameter apertures therethrough. Two identical perforated glass sheets 17 and 18 separate the cathode plate 14 from the front glass cover plate 16 to reduce sputtering.

Such a panel filled with neon and mercury vapor at torr pressure operates properly with a pulse train sustaining waveform with V3=205 volts, t=2 microseconds and T=14 microseconds. The operating current waveform for such a configuration is illustrated in FIG. 30. Since the (1.0. firing voltage V for this panel is 210 volts, the value of V;., of 205 volts demonstrates operation with the amplitude of the sustaining pulses below V Operational parameter measurements were made on this panel with regard to average power dissipation per cell, display cell memory margin, and display cell uniformity; where memory margin is a measure of the difference between the voltage pulse amplitudes required to fire and extinguish the array of cells and uniformity is a measure of the range of extinction voltage pulse amplitudes with regard to the array of cells. It was found, for the above-described panel, that the average power dissipation per cell was about one-half that required for a dc. sustaining potential applied without series resistance. The memory margin for the cells was slightly less than that obtainable with a dc sustaining potential but was significantly greater than that obtained with a typical prior art ac. plasma display panel. The cell uniformity for the above'described panel was found to be satisfactory for operation in practical applications of the invention.

The above-described panel was also operated with a pulse train sustaining waveform having V =220 volts, [=2 microseconds and T 2l microseconds. Since, as previously described, the dc. firing voltage V is 210 volts, the value of V demonstrates operation with the amplitude of the sustaining pulses above V A memory margin was obtained similar to that of the device utilizing the previously described pulse train sustaining waveform.

In a somewhat different operating mode, waveforms such as those illustrated in H6. 4 (d and e) are also obtainable when utilizing a sustaining waveform with increased pulse duration and spacing as compared to that previously described, for example with i=4 microseconds and T=4O microseconds. In this mode the gas takes longer to break down and the effective duty cycle and, hence, power dissipation are further reduced as compared to a dc. sustaining potential by about a factor of 3. However, the memory margin obtained under this condition is considerably lower.

Results similar to those described above are also ob tained with Penning mixture (for example, 99.5 percent neon and 0.5 percent argon) and mercury vapor at 100 torr pressure. However, under pulsed conditions in accordance with the invention a greater memory margin can be provided than is obtainable with a dc. sustaining voltage. This is because the short voltage pulse durations do not allow the formation of an appreciable density of metastable neon atoms on which the Penning effect, i.e., the ionization of argon atoms by collision with metastable neon atoms, depends. Thus under pulsed conditions the firing voltage is disproportionately high, resulting in an increased memory margin. For example, with t=l microsecond and T=8 microseconds a memory margin, defined as %(V;V )/V;, of 0.5 is obtained, relative to a value of 0.35 under dc. sustaining voltage conditions. it will be appreciated that other gas compositions which exhibit the penning effect may also be utilized in practicing the invention to obtain the increased memory margin compared to do. operation as described above.

The afore-described embodiments of the invention have been described in terms of particular ionizable gases. It will be appreciated that a wide variety of suitable ionizable gases are available for use in practicing the invention.

It will be appreciated from the foregoing that the present invention provides substantially increased stability against arc formation for plasma displays without resistors in series with the discharges. When a substantial current surge develops in prior art d.c. devices, an arc can be initiated causing damage to the device and the associated circuitry. In the pulsed memory mode of the present invention, the sustaining pulses are too short to permit an arc to develop. Furthermore, the slope of the curve of average current versus voltage is less for the pulsed mode of operation than the slope of the dc. voltagecurrent curve which also improves the stability without requiring series resistors.

The present invention provides lower operating power and hence less power dissipation and heat loss in the gas discharge device as compared to the prior art configurations. Although the peak currents and the voltages associated with the gas discharge sustaining function of the present invention may be higher than in the prior art dc. voltage sustaining situation, the low duty cycle of the pulsed mode waveform provides a net power reduction even compared to the minimum d.c. sustaining potential required to provide memory in a given configuration. This is particularly important for high resolution devices which may contain a high density of cells operating at high peak currents. It is furthermore appreciated that the present invention provides the possibility for dimming the display. The cell brightness may be varied by altering the duty cycles of the applied sustaining voltage waveforms.

While the invention has been described in its preferred embodiments, it is to be understood that the words which have been used are words of description rather than limitation and that changes within the purview of the appended claims may be made without departing from the true scope and spirit of the invention in its broader aspects.

1 claim:

I. In d.c. gas discharge display apparatus display cathode means,

display anode means,

said display cathode means and said display anode means defining d.c. gas discharge memory cell means for containing an ionizable gas,

said cathode and anode means being internal to said cell means and in contact with said gas, and

pulse soure means coupled without any discharge current limiting resistors to said cathode and anode means for applying a gas discharge sustaining pulse train therebetween, the pulses thereof being of such amplitude and duration and the spacing between said pulses being such that an ignited memory cell is reignited and an extinguished memory cell remains extinguished upon application of said pulses.

2. ln d.c. gas discharge display apparatus display cathode means,

display anode means,

said display cathode means and said display anode means defining d.c. gas discharge memory cell means for containing an ionizable gas, said cathode and anode means being internal to said cell means and in contact with said gas,

addressing means for extending gas discharge columns to selected memory cells thereby increasing the level of ionization therein, and

pulse source means coupled without any dicharge current limiting resistors to said cathode and anode means for applying a gas discharge sustaining pulse train therebetween, the pulses thereof being of such amplitude and duration and the spacing between said pulses being such that a selected memory cell is ignited by said sustaining pulses in the presence of said increased level of ionization from said extended column and is reignited upon application of subsequent pulses and extinguished memory calls remain extinguished upon application of said pulsesv tion.

6. In the apparatus of claim 5 in which said ionizable gas comprises a penning mixture.

7. In the apparatus of claim 2 in which said pulse source means includes means for providing said sustaining pulse train, the pulses thereof being of such amplitude and duration and the spacing between said pulses being such that less net sustaining power is required with respect to utilizing a minimum possible d.c.

sustaining potential.

Notice of Adverse Decision in Interference In Interference No. 98,614, involving Patent No. 3,77 8,674, C. D. Lustig, DC. GAS DISCHARGE DISPLAY APPARATUS WITH PULSE TRAIN MEMORY SUSTAINING POTENTIAL, final judgment adverse to the patentee was rendered Apr. 30, 197 5, as to claims 1, 2, 3, 4, 5, 6 and 7.

[Oyficz'al Gazette August 5,1975]

Claims (7)

1. In d.c. gas discharge display apparatus display cathode means, display anode means, said display cathode means and said display anode means defining d.c. gas discharge memory cell means for containing an ionizable gas, said cathode and anode means being internal to said cell means and in contact with said gas, and pulse soure means coupled without any discharge current limiting resistors to said cathode and anode means for applying a gas discharge sustaining pulse train therebetween, the pulses thereof being of such amplitude and duration and the spacing between said pulses being such that an ignited memory cell is reignited and an extinguished memOry cell remains extinguished upon application of said pulses.
2. In d.c. gas discharge display apparatus display cathode means, display anode means, said display cathode means and said display anode means defining d.c. gas discharge memory cell means for containing an ionizable gas, said cathode and anode means being internal to said cell means and in contact with said gas, addressing means for extending gas discharge columns to selected memory cells thereby increasing the level of ionization therein, and pulse source means coupled without any dicharge current limiting resistors to said cathode and anode means for applying a gas discharge sustaining pulse train therebetween, the pulses thereof being of such amplitude and duration and the spacing between said pulses being such that a selected memory cell is ignited by said sustaining pulses in the presence of said increased level of ionization from said extended column and is reignited upon application of subsequent pulses and extinguished memory calls remain extinguished upon application of said pulses.
3. In the apparatus of claim 2 in which said pulse source means includes means for providing said pulses with amplitudes less than the firing potential of said ionizable gas.
4. In the apparatus of claim 2 in which said pulse source means includes means for providing said pulses with amplitudes at least as great as the firing potential of said ionizable gas.
5. In the apparatus of claim 2 in which said ionizable gas comprises a gas exhibiting the penning effect, for increasing the memory margin of said memory cell means with respect to d.c. sustaining potential operation.
6. In the apparatus of claim 5 in which said ionizable gas comprises a penning mixture.
7. In the apparatus of claim 2 in which said pulse source means includes means for providing said sustaining pulse train, the pulses thereof being of such amplitude and duration and the spacing between said pulses being such that less net sustaining power is required with respect to utilizing a minimum possible d.c. sustaining potential.
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US3921021A (en) * 1971-05-04 1975-11-18 Burroughs Corp Display panel having memory
US6084559A (en) * 1996-02-15 2000-07-04 Matsushita Electric Industrial Co., Ltd. Plasma-display panel of high luminosity and high efficiency, and a driving method of such a plasma-display panel

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US2977505A (en) * 1957-09-27 1961-03-28 Ibm Information storage in glow discharge devices
US3573542A (en) * 1968-03-28 1971-04-06 Control Data Corp Gaseous display control
US3600626A (en) * 1969-11-26 1971-08-17 Burroughs Corp Multicell display device having communication paths between adjacent cells
US3626241A (en) * 1969-12-24 1971-12-07 Bell Telephone Labor Inc Gray scale gaseous display
US3689912A (en) * 1970-12-16 1972-09-05 Bell Telephone Labor Inc Gaseous display driver circuits

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3921021A (en) * 1971-05-04 1975-11-18 Burroughs Corp Display panel having memory
US6084559A (en) * 1996-02-15 2000-07-04 Matsushita Electric Industrial Co., Ltd. Plasma-display panel of high luminosity and high efficiency, and a driving method of such a plasma-display panel

Also Published As

Publication number Publication date
JPS4918232A (en) 1974-02-18
NL7304924A (en) 1973-10-16
GB1392593A (en) 1975-04-30
FR2180062B1 (en) 1976-09-10
IT980194B (en) 1974-09-30
DE2318749A1 (en) 1973-10-25
FR2180062A1 (en) 1973-11-23

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