US3925697A - Helium-xenon gas mixture for gas discharge device - Google Patents

Abstract

There is disclosed a gas discharge device gas mixture consisting essentially of about 0.1 to 5 percent atoms of xenon and about 99.9 to 95 percent atoms of a helium-based composition, the mixture having a pressure of 100 to 700 Torr, this mixture to be used in a color phosphor gas discharge display/memory device so as to provide adequate stimulation of phosphors in a gas discharge display panel with low operating voltages and without a pronounced visible discharge emission to distort phosphor colors.

Description

Unite States Patent [191' Fein et all.

[ Dec. 9, 1975 HELIUM-XENON GAS MIXTURE FOR GAS DISCHARGE DEVICE [75] Inventors: Michael E. Fein, Toledo; David C. Hinson, Whitehouse, both of Ohio [73] Assignee: Owens-Illinois, Inc., Toledo, Ohio [22] Filed: Oct. 24, 1972 [21] Appl. No.: 300,162

[52] US. Cl. 313/223; 313/485 [51] Int. Cl. H01J 17/20 [58] Field of Search 313/108 R, 108 B, 185,

313/223, 224, 485; 315/169 R, 169 TV [56] References Cited UNITED STATES PATENTS 3,499,167 3/1970 Baker et a1. 315/169 3,622,829 11/1971 Watanabe 313/108 R 3,701,658 lO/1972 Clark 96/36.1

3,704,386 11/1972 Cola 313/108 B 3,798,501 3/1974 Miller 315/169 TV OTHER PUBLICATIONS D E. Gray, Coordinating Editor, American Institute of Physics Handbook, Second Edition, Copyright 1963, McGraw-Hill Book C0., Inc.

Primary Examiner-Ronald J. Stern Assistant ExaminerRichard A. Rosenberger Attorney, Agent, or Firm--Donald Keith Wedding [57] ABSTRACT There is disclosed a gas discharge device gas mixture consisting essentially of about 0.1 to 5 percent atoms of xenon and about 99.9 to 95 percent atoms of a helium-based composition, the mixture having a pressure of 100 to 700 Torr, this mixture to be used in a color phosphor gas discharge display/memory device so as to provide adequate stimulation of phosphors in a gas discharge display panel with low operating voltages and without a pronounced visible discharge emission to distort phosphor colors.

12 Claims, 5 Drawing Figures US, Patent Dec. 9, 1975 Sheet 2 of3 3,925,697

h l I'll I II I IIIIIIIIIIIIII II I IIIIIIIIIIIIII I p I I a 5 i I 5 I l E v I p I I I 5 5 I I I a I I 5 I I'III "IIII III I I'II/ III IIII II US. Patent Dec. 9, 1975 Sheet 3 of3 3,925,697

ffiLF/ iF-Z HELlUM-XENON GAS MIXTURE FOR GAS DISCHARGE DEVICE.

BACKGROUND OF THE INVENTION This, inventionrelates to an improvement in gas discharge devices, especially colorphosphor-containing multiple gas discharge display/memory devices which have an electrical memory and which are capable of producing a visual display or representation of data such as numerals, letters, radar displays, aircraft displays, binary words, educational displays, etc. Incorporated in the device is an ionizable gaseous medium consisting of a mixture of gases which will stimulate the phosphors with low operating voltages without pronounced visible discharge emission to distort phosphor colors.

Multiple gas discharge display and/or memory panels of one particular type with which the present invention is concerned are characterized by an ionizable gaseous medium, usually a mixture of at least two gases at an appropriate gas pressure, in a thin gas chamber or space between a pair of opposed dielectric charge storage members which are backed by conductor (electrode) members, the conductor members backing each dielectric member typically being appropriately oriented so as to define a plurality of discrete gas discharge units or cells.

In some prior art panels the discharge cells are additionally defined by surrounding or confining physical structure such as apertures in perforated glass plates and the like so as to be physically isolated relative to other cells. In either case, with or without the confining physical structure, charges (electrons, ions) produced upon ionization of the elemental gas volume of a selected discharge cell, when proper alternating operating potentials are applied to selected conductors thereof, are collected upon the surfaces of the dielectric at specifically defined locations and constitute an electrical field opposing the electrical field which created them so as to terminate the discharge for the remainder of the half cycle and aid in the initiation of a discharge on a succeeding opposite half cycle of applied voltage, such charges as are stored constituting an electrical memory.

Thus, the dielectric layers prevent the passage of substantial conductive current from the conductor members to the gaseous medium and also serve as collecting surfaces for ionized gaseous medium charges (electrons, ions) during the alternate half cycles of the AC. operating potentials, such charges collecting first on one elemental or discrete dielectric surface area on alternate half cycles to constitute an electrical memory.

An example of a panel structure containing nonphysically isolated or open discharge cells is disclosed in U.S. Pat. No. 3,499,167 issued to Theodore C. Baker et al.

An example of a panel containing physically isolated cells is disclosedin thearticle by D. L. Bitzer and H. G. Slottow entitled ThePlasma Display Panel A Digitally Addressable Display With Inherent Memory, Proceeding of the Fall Joint Computer Conference, IEEE, San Francisco, Calif., Nov. 1966, pages 541-547. Also reference is made to U.S. Pat. No.

In the constructionof'the panel, a'continuous volume of ionizable gas is confined'between a pair of dielectric surfaces backed by conductor arrays typically forming matrix elements. The cross conductor arrays may be orthogonally related (but any other configuration of conductor arrays may be used) to define a plurality of opposed pairs of charge storage areas on the surfaces of the dielectric bounding or confining the gas. Thus, for a conductor matrix having H rows and C columns the number of elemental or discrete areas will be twice the number of such elemental discharge cells.

In addition, the panel may comprise a so-called monolithic structure in which the conductor arrays are created on a single substrate and wherein two or more arrays are separated from each other and from the gaseous medium by at least one insulating member. In such a device the gas discharge takes place not between two opposing electrodes, but between two contiguous or adjacent electrodes on the same substrate; the gas being confined between the substrate and an outer retaining wall. 1

It is also feasible to have a gas discharge device wherein some of the conductive or electrode members are in direct contact with the gaseous medium and the remaining electrode members are appropriately insulated from such gas, i.e., at least one insulated electrode.

In addition to the matrix configuration, the conductor arrays may be shaped otherwise. Accordingly, while the preferred conductor arrangement is of the crossed grid type as discussed herein, it is likewise apparent that where a maximal variety of two dimensional display patterns is not necessary, as where specific standardized visual shapes (e.g., numerals, letters, words, etc.) are to be formed and image resolution is not critical, the conductors may be shaped accordingly, i.e., a segmented display.

The gas is one which produces visible light or invisible radiation which stimulates a phosphor (if visual display is an objective) and a copious supply of charges (ions and electrons) during discharge.

Inprior art a wide variety of gases and gas mixtures have been utilized as the gaseous medium ina gas discharge device. Typical of such gases include CO; CO halogens, nitrogen; NH oxygen; water vapor; hydro-. gen; hydrocarbons; P 0 boron fluoride, acid fumes; TiCl Group VIII gases; air; H 0 vapors of sodium, mercury, thallium, cadmium, rubidium, and cesium; carbon disulfide, laughing gas; H 8; deoxygenated air; phosphorus vapors; C H CH naphthalene vapor; anthracene; freon; ethyl .alcohol; methylene bromide; heavy hydrogen; electron attaching gases; sulfur hexafluoride; tritium; radioactive gases; and the rare or inert gases.

In the preferred prior art practice, the gaseous medium comprises at least one rare gas, more typically at least two, selected from helium, neon, argon, krypton, or xenon.

In an open cell Baker et al. type panel, the gas pressure and the electric field are sufficient to laterally confine charges generated on discharge within elemental or discrete dielectric areas within the perimeter of such areas, especially in a panel containing non-isolated discharge cells. As described in the Baker et al. patent, the space between the dielectric surfaces occupied by the gas is such as to permit photons generated on discharge in a selected discrete or elemental volume of gas to pass freely through the gas space and strike surface areas of dielectric remotefrom the selected discrete volumes, such remote, photon struck dielectric surface areas thereby emitting electrons was to condition at least one elemental volume other than the elemental volume in which the photons originated.

With respect to the memory function of a given discharge panel, the allowable distance or spacing between the dielectric surfaces depends, inter alia, on the frequency of the alternating current supply, the distance typically being greater for lower frequencies.

While the prior art does disclose gaseous discharge devices having externally positioned electrodes for initiating a gaseous discharge, sometimes called electrodeless discharge, such prior art devices utilized frequencies and spacing or discharge volumes and operating pressures such that although discharges are initiated in the gaseous medium, such discharges are ineffective or not utilized for charge generation and storage at higher frequencies; although charge storage may be realized at lower frequencies, such charge storage has not been utilized in a display/memory device in the manner of the Bitzer-Slottow or Baker et al. invention.

The measure of the electrical memory function of the device is its memory margin. The term memory margin is defined herein as where V, is the half amplitude of the smallest sustaining voltage signal which results in a discharge every half cycle, but at which the cell is not bi-stable and V is the half amplitude of the minimum applied voltage sufficient to sustain discharges once initiated. The memory margin improves as it approaches unity.

It will be understood that the basic electrical phenomenon utilized in this invention is the generation of charges (ions and electrons) alternately storable at pairs of opposed or facing discrete points or areas on a pair of dielectric surfaces backed by conductors connected to a source of operating potential. Such stored charges result in an electrical field opposing the field produced by the applied potential that created them and hence operate to terminate ionization in the elemental gas volume between opposed or facing discrete points or areas of dielectric surface. The term sustain a discharge means producing a sequence of momentary discharges, at least one discharge for each half cycle of applied alternating sustaining voltage, once the elemental gas volume has been fired, to maintain alternate storing of charges at pairs of opposed discrete areas on the dielectric surfaces.

As used herein, a cell is in the on state when a quantity of charge is stored in the cell such that on each half cycle of the sustaining voltage, a gaseous discharge is produced.

In addition to the sustaining voltage, other voltages may be utilized to operate the panel, such as firing, addressing, and writing voltages.

A firing voltage is any voltage, regardless of source, required to discharge a cell. Such voltage may be completely external in origin or may be comprised of internal cell wall voltage in combination with externally originated voltages.

An addressing voltage is a voltage produced on the panel X Y electrode coordinates such that at the selected cell or cells, the total voltage applied across the cell is equal to or greater than the firing voltage whereby the cell is discharged.

A writing voltage is an addressing voltage of sufficientmagnitude to make it probable that on subsequent sustaining voltage half cycles, the cell will be in the on state.

In the operation of a multiple gaseous discharge device, of the type described hereinbefore, it is necessary to condition the discrete elemental gas volume of each discharge cell by supplying at least one free electron thereto such that a gaseous discharge can be initiated when the cell is addressed with an appropriate voltage signal.

The prior art has disclosed and practiced various means for conditioning gaseous discharge cells.

One such means of panel conditioning comprises a so-called electronic process whereby an electronic conditioning signal or pulse is periodically applied to all of the panel discharge cells, as disclosed for example in British patent specification 1,161,832, page 8, lines 56 to 76. Reference is also made to U.S. Pat. No. 3,559,190 and The Device Characteristics of the Plasma Display Element by Johnson et al., IEEE Transactions On Electron Devices, September, 1971. However, electronic-conditioning is self-conditioning and is only effective after a discharge cell has been previously conditioned; that is, electronic conditioning involves periodically discharging a cell and is therefore a way of maintaining the presence of free electrons. Accordingly, one cannot wait too long between the periodically applied conditioning pulses since there must be at least one free electron present in order to discharge and condition a cell.

Another conditioning method .comprises the use of external radiation, such as flooding part or all of the gaseous medium of the panel with ultraviolet radiation. This external conditioning method has the obvious disadvantage that it is not always convenient or possible to provide external radiation to a panel, especially if the panel is in a remote position. Likewise, an external UV source requires auxiliary equipment. Accordingly, the use of internal conditioning is generally preferred.

One internal conditioning means comprises using internal radiation, such as by the inclusion of a radioactive material.

Another means of internal conditioning, which we call photon conditioning, comprises'using one or more so-called pilot discharge cells in the on-state for the generation of photons. This is particularly effective in a so-callecl open cell construction (as described in the Baker et a1. patent) wherein the space between the dielectric surfaces occupied by the gas is such as to permit photons generated on discharge in a selected discrete or elemental volume of gas (discharge cell) to pass freely through the panel gas space so as to condition other and more remote elemental volumes of other discharge units. In addition to or in lieu of the pilot cells, one may use other sources of photons internal to the panel.

Internal photon conditioning may be unreliable when a given discharge unit to be addressed is remote in distance relative to the conditioning source, e.g., the pilot cell. Accordingly, a multiplicity of pilot cells may be required for the conditioning of a panel having a large geometric area. In one highly convenient arrangement, the panel matrix border (perimeter) is comprised of a plurality of such pilot cells.

In gas discharge devices of the aforementioned types, phosphors may be appropriately positioned within the device so as to be excited by radiation from the gas discharge of the-device. For example, in a memory'charge storage device of the Baker et al. type, phosphors can be positioned on or be embedded in one or more charge storage dielectric surfaces, such as disclosed in US. Pat. No. 3,701,658 issued Oct. 31, 1972 to Robert N. Clark, and assigned to the same assignee as the instant application.

The presence of the phosphors within the device can be utilized to provide color display, the color being the result of radiation emitted by an excited phosphor alone or in combination with radiation emitted by the gas discharge, such as disclosed in copending US. patent application Ser. No. 199,802, filed Nov. 17, 1971 by Felix H. Brown and Maclin S. Hall and assigned to the same assignee as the instant application.

In the prior art, phosphor panels of the gas discharge display/memory type have been operated with various gas mixtures, especially rare gas fills such as pure xenon or Penning mixtures of xenon in neon. Such. neonbased mixtures frequently emit a pronounced visible discharge which tends to distort phosphor colors.

SUMMARY OF THE INVENTION In accordance with this invention, there has been discovered a gas mixture which provides adequate stimulation of phosphors in a gas discharge display panel while also providing low operating voltages without a pronounced visible discharge emission to distort phosphor colors.

More particularly, in accordance with this invention, there is provided a gaseous mixture for a multiple gas discharge display phosphor device, said gaseous mixture consisting essentially of about 0.1 to percent atoms of xenon and about 99.9 to 95 percent atoms of a heliumbased composition.

As used herein, the helium-based composition is de-. fined as consisting essentially of about 95 to 100 percent atoms of helium and 5 to 0 percent atoms of another gaseous component, such as already mentioned hereinbefore, particularly one or more members selected from neon, krypton, nitrogen, argon, and mercury.

The gas mixture has a pressure of about 100 to about 700 Torr with a pressure times discharge gap distance range of 200 Torr-mils to about 7000 Torr-mils.

It has been shown that He-Xe Penning mixtures of this invention provide about the same performance in phosphor panels as do Ne-Xe mixtures, except that the helium-based mixture emits a lower visibility discharge. The low visibility of the helium-xenon discharge is desirable in order to improve phosphor color distinguishability.

In the practice of this invention, it is contemplated using anysuitable luminescent phosphor. In the preferred embodiment, the phosphor is photoluminescent. The term photoluminescent phosphor" includes quite generally all solid and liquid, inorganic and organic materials capable of converting an input of absorbed photons into an output of photons of different energy, the output comprising visible lightof a brightness and intensity sufficient for visual display.

Typical photoluminescent phosphors contemplated include, not by way of limitation, both activated and non-activated compounds, e.g., the sulfides such as zinc sulfides, 'zinc-cadmium sulfides, zinc-sulfo-selenides; the silicates such as zinc silicates, zinc beryllosilicate, Mg silicates; the t ungstates such as calcium tungstates, magnesium tungst'ates; the phosphates, bo-

rates, and arsenates such as calcium phosphates, cadmium borates, zinc borates, magnesium arsenates; ant theoxides and the halides such as self-activated zinc oxide, magnesium fluorides, magnesium flyorogerma nate. Typical activators include, not by way of limita tion, Mn, Eu, Ce, Pb, etc.

In one highly preferred embodiment, there is utilizet a phosphor P1 as defined by JEDEC Electrode Tubt Council, Publication No. 16A of January 1966, reviser February 1969.

In another preferred embodiment hereof, there is uti lized a gas discharge display/memory device containin; at least one dielectric charge storage surface, the phos phor being appropriately applied to such dielectric.

In such embodiment, the phosphor may be applied t the dielectric by way of any convenient method includ ing, not by way of limitation, vapor deposition; vacuun deposition; chemical vapor deposition, wet spraying o settling upon the dielectric a mixture or solution of thphosphor suspended or dissolved in a liquid, follower by evaporation of the liquid; silk screening; dry spray ing of the phosphor upon the dielectric; electron bear evaporation; plasma flame and/or are spraying and/o deposition; thermal evaporation; laser evaporation; R or induction heating evaporation; sputtering targe techniques; and/or attachment of the phosphor to th dielectric as disclosed in the US. Pat. No. 3,701,658 t- Robert N. Clark, and assigned to the assignee of the ir stant patent application.

In accordance with the broad practice of this inver tion, it is contemplated applying the phosphor to th dielectric (surface or sub-surface) in any suitable gec metric shape, pattern, or configuration, symmetrical c asymmetrical as disclosed for example in the copendin US. patent application Ser. No. 98,846, filed Dec. It 1970 by Felix H. Brown and Robert F. Schaufele, an assigned to the assignee of the instant patent applicz tion.

DESCRIPTION OF THE DRAWINGS Reference is made to the accompanying drawing and the hereinafter discussed figures shown thereon.

FIG. I is a partially cut-away plan view of a gaseoi discharge display/memory panel as connected to a di: grammatically illustrated source of operating potei tials.

FIG. 2 is a cross-sectional view (enlarged, but not i proportional scale since the thickness of the gas vo ume, dielectric members and conductor arrays ha been enlarged for purposes of illustration) taken c lines 2 2 of FIG. 1.

FIG. 3 is an explanatory partial cross-sectional vie similar to FIG. 2 (enlarged, but not to proportion scale).

FIG. 4 is an isometric view of a gaseous discharge di play/memory panel.

FIG. 5 is a view of a discrete dielectric area at a di charge cell.

The invention utilizes a pair of dielectric films 10 a1 11 separated by a thin layer or volume of a gaseous (1 charge medium l2,'the medium 12, at each element gas volume 30, producing a copious supply of charg (ions and electrons) which are alternately collectal: on the surfaces of the dielectric members at opposed facing elemental or discrete areas X and Y defined the conductor matrix on non-gas-contacting sides the dielectric members, each dielectric member pri enting large open surface areas and a plurality of pa of elemental X and Y areas (see FIG. 3). The dotted lines 30' are imaginary lines to show a boundary of one elemental volume 30. While the electrically operative structural members such as the dielectric members 10 and 11 and conductor matrixes 13 and 14 are all relatively thin (being exaggerated in thickness in the drawings) they are formed on and supported by rigid nonconductive support members 16 and 17 respectively.

In the instant shown in FIG. 3, a conditioning discharge about the center of elemental volume 30 has been initiated by application to conductor 13-1 and conductor 14-1 firing potential V, as derived from a source 35 of variable phase, for example, and source 36 of sustaining potential V, (which may be a sine wave, for example). The potential V, is added to the sustaining potential V, as sustaining potential V increases in magnitude to initiate the conditioning discharge about the center of elemental volume 30 shown in FIG. 3. There, the phase of the source 35 of potential V has been adjusted into adding relation to the alternating voltage from the source 36 of sustaining voltage V, to provide a voltage V,, when switch 33 has been closed, to conductors 13-1 and 14-1 defining elementary gas volume 30 sufficient (in time and/or magnitude) to produce a light generating discharge centered about discrete elemental gas volume 30. At the instant shown, since conductor 13-1 is positive, electrons 32 have collected on and are moving to an elemental area of dielectric member 10 substantially corresponding to the area of elemental gas volume 30 and the less mobile positive ions 31 are beginning to collect on the opposed elemental area of dielectric member 11 since it is negative. As these charges build up, they constitute a back voltage opposed to the voltage applied to conductors 13-1 and 14-1 and serve to terminate the discharge in elemental gas volume 30 for the remainder of a half cycle.

During the discharge about the center of elemental gas volume 30, photons are produced which are free to move or pass through gas medium 12, as indicated by arrows 37, to strike or impact remote surface areas of photoemissive dieletric members 10 and 11, causing such remote areas to release electrons 38. Electrons 38 are, in effect, free electrons in gas medium 12 and condition each other discrete elemental gas volume for operation at a lower firing potential V, which is lower in magnitude than the firing potential V, for the initial discharge about the center of elemental volume 30 and this voltage is substantially uniform for each other elemental gas volume.

The phosphor 100 is applied to at least one of the dielectric members 10, 11 as shown in FIGS. 3 and 5. Although the phosphors are shown in a donut or ring configuration surrounding the intersection of electrodes 1 1 and 12, other shapes are possible as demonstrated in the above-mentioned copending U.S. Patent application Ser. No. 98,846 filed Dec. 16, 1970 by Felix H. Brown and Robert F. Schaufele.

Preferably, one or both of nonconductive support members 16 and 17 pass light produced by discharge in the elemental gas volumes. Preferably, they are transparent glass members and these members essentially define the overall thickness and strength of the panel. For example, the thickness of gas layer 12 as determined by spacer is usually under 10 mils and preferably about 4 to 6 mils, dielectric layers 10 and 11 (over the conductors at the elemental or discrete X and Y areas) are usually between 1 and 2 mils'thick, andfconductors 13 and 14 about 8,000 angstroms thick. However, support members 16 and 17 are much thicker (particularly in larger panels) so as to provide as much ruggedness as may be desired to compensate for stresses in the panel. Support members 16 and 17 also serve as heat sinks for heat generated by discharges and thus minimize the effect of temperature on operation of the device. If it is desired that only the memory function be utilized, then none of the members need be transparent to light.

Except for being nonconductive or good insulators the electrical properties of support members 16 and 17 are not critical. The main function of support members 16 and 17 is to provide mechanical support and strength for the entire panel, particularly with respect to pressure differential acting on the panel and thermal shock. As noted earlier, they should have thermal expansion characteristics substantially matching the thermal expansion characteristics of dielectric layers 10 and 11. Ordinary 74 inch commercial grade soda lime plate glasses have been used for this purpose. Other glasses such as low expansion glasses or transparent devitrified glasses can be used provided they can withstand processing and have expansion characteristics substantially matching expansion characteristics of the dielectric coatings 10 and 11. For given pressure differentials and thickness of plates, the stress and deflection of plates may be determined by following standard stress and strain formulas (see R. J. Roark, Formulas for Stress and Strain, McGraw-Hill, 1954).

Spacer 15 may be made of the same glass material as dielectric films 10 and 11 and may be an integral rib formed on one of the dielectric members and fused to the other members to form a bakeable hermetic seal enclosing and confining the ionizable gas volume 12. However, a separate final hermetic seal may be effected by a high strength devitrified glass sealant 15S. Tubulation 18 is provided for exhausting the space between dielectric members 10 and 11 and filling that space with the volume of ionizable gas. For large panels small beadlike solder glass spacers such as shown at 158 may be located between conductor intersections and fused to dielectric members 10 and 11 to aid in withstanding stress on the panel and maintain uniformity of thickness of gas volume 12.

Conductor arrays 13 and 14 may be formed on support members 16 and 17 by a number of well-known processes, such as photoetching, vacuum deposition, stencil screening, etc. In the panel shown in FIG. 4, the center-to-center spacing of conductors in the respective arrays is about 17 mils. Transparent or semi-transparent conductive material such as tin oxide, gold or aluminum can be used to form the conductor arrays and should have a resistance less than 3000 ohms per line. Narrow opaque electrodes may alternately be used so that discharge light passes around the edges of the electrodes to the viewer. It is important to select a conductor material that is not attacked during processing by the dielectric material.

It will be appreciated that conductor arrays 13 and 14 may be wires or filaments of copper, gold, silver or aluminum or any other conductive metal or material. For example 1 mil wire filaments are commercially available and may be used in the invention. However, formed in situ conductor arrays are preferred since they may be more easily and uniformly placed on and adhered to the support plates 16 and 17.

Dielectric layer members and 11 are formed of an inorganic material and are preferably formed in situ as an adherent film or coating which is not chemically or physically effected during bake-out of the panel. One such material is a solder glass such as Kimble SG-68 manufactured by and commercially available fromthe assignee of the present invention.

This glass has thermalexpansion characteristics substantially matching the thermal expansion characteristics of certain soda-lime glasses, and can be used as the dielectric layer when the support members 16 and 17 are soda-lime glass plates. Dielectric layers 10 and 11 must be smooth and have a dielectric strength of about 1000 v. and be electrically homogeneous on a microscopic scale (e.g., no cracks, bubbles, crystals, dirt, surface films, etc.). In addition, the surfaces of dielectric layers 10 and 11 should be good photoemitters of electrons in a baked out condition. Alternatively, dielectric layers 10 and 11 may be overcoated with materials designed to produce good electron emission, as in U.S. Pat. No. 3,634,719, issued to Roger E. Ernsthausen. Of course, for an optical display at least one of dielectric layers 10 and 11 should pass light generated on discharge and be transparent or translucent and, preferably, both layers are optically transparent.

The preferred spacing between surfaces of the dielectric films is about 3 to 6 mils with conductor arrays 13 and 14 having center-to-center spacing of about 17 mils.

The ends of conductors 14-1 14-4 and support member 17 extend beyond the enclosed gas volume 12 and are exposed for the purpose of making electrical connection to interface and addressing circuitry 19. Likewise, the ends of conductors 13-1 13-4 on support member 16 extend beyond the enclosed gas volume l2 and are exposed for the purpose of making electrical connection to interface and addressing circuitry 19.

The device shownin FIG. 4 is a panel having a large number of elemental volumes similar to elemental volume 30 (FIG. 3). In this case more room is provided to make electrical connection to the conductor arrays 13 and 14, respectively, by extending the surfaces of support members 16' and 17 beyond seal 15S, alternate conductors being extended on alternate sides. Conductor arrays 13' and 14 as well as support members 16' and 17' are transparent. The dielectric coatings are not shown in FIG. 4 but are likewise transparent so that the panel may be viewed from either side.

As in known display systems, the interface and addressing circuitry or system 19 may be relatively inexpensive line scan systems or the somewhat more expensive high speed random access systems. In either case, it is to be noted that a lower amplitude of operating potentials helps to reduce problems associated with the interface circuitry between the addressing system and the display/memory panel, per se. Thus, by providing a panel having greater uniformity in the discharge characteristics throughout the panel, tolerances and operating characteristics of the panel with which the interfacing circuitry cooperate, are made less rigid.

We claim:

1. In a process for operating a multiple gas discharge display device comprising a multiplicity of gas discharge cells and an ionizable gaseous medium, the improvement which comprises utilizing the combination of at least one phosphor and an ionizable gaseous medium capable upon discharge of emitting radiation exciting the phosphor and consisting essentially of about 0.1 to 5 percent atoms of xenon and about 99.9 to percent atoms of a helium-based composition, said helium-based composition consisting essentially of about 95 to percent atoms of helium and about 5 to 0 percent atoms of another gaseous component selected from neon, krypton, nitrogen, argon and mercury, and applying an operating voltage to at least one of said gas discharge cells to stimulate said phosphor in the device without a pronounced visible discharge emission to distort phosphor colors.

2. The invention of claim 1 wherein the device is of the display/memory type and contains at least one dielectrically insulated electrode.

3. The invention of claim 1 wherein the gaseous medium isat a pressure of about 100 Torr to 700 Torr. 4. In an article of manufacture comprising a multiple gas-discharge phosphor display device containing an ionizable gaseous medium, the improvement wherein the gaseous medium consists essentially ofabout 0.1 to 5 percent atoms of xenon and 99.9 to 95 percent atoms of a helium-based composition, said helium-based composition consisting essentially of about 95 to 100 percent atoms of helium and about 5 to 0 percent atoms of another gaseous component selected from neon, krypton, nitrogen, argon and mercury.

5. The invention of claim 4 wherein the device is of the display/memory type and contains at least one dielectrically insulated electrode.

6. The invention of claim 4 wherein the gaseous medium is at a pressure of about 100 Torr to 700 Torr.

7. As a composition of matter, an ionizable gaseous mixture for a gas discharge display phosphor device, said mixture consisting essentially of about 0.1 to 5 percent atoms of xenon and about 99.9 to 95 percent atoms of a helium-based composition, said heliumbased composition consisting essentially of about 95 to 100 percent atoms of helium and about 5 to 0 percent atoms of another gaseous component selected from neon, krypton, nitrogen, argon and mercury.

8 The invention of claim 7 wherein the gaseous mixture is at a pressure of about 100 to 700 Torr.

9. In the operation of a gaseous discharge display/- memory device'characterized by an ionizable gaseous mediumin a gas chamber formed by a pair of dielectric material members having opposed charge storage surfaces, which dielectric material members are respectively backed by a series of parallel electrode members, the electrode members behind each dielectric material member being transversely oriented with respect to the electrode members behind the opposing dielectric material member so as to define a plurality of discrete discharge volumes, each constituting a discharge unit, and wherein the .gas is selectively ionized and discharged within each discharge unit by operating voltages applied to the transversely oriented electrode members, the improvement which comprises utilizing the combination of a phosphor on at least one of said dielectric material members at each discharge unit and an ionizable gaseous medium capable upon discharge of emitting radiation exciting said phosphor and consisting essentially of about 0.1 to 5 percent atoms of xenon and about 99.9 to 95 percent atoms of helium-based composition, said helium-based composition consisting essentially of about 95 to 100 percent atoms of heliurr and about 5 to.0 percent atoms of another gaseous component selected from neon, krypton, nitrogen argon and mercury, and applying an operating voltagc to at least one of said gas discharge cells to stimulate the respective phosphor in the device without a pronounced visible discharge emission to distort phosphor colors.

10. The invention of claim 9 wherein the gaseous mixtureis at a pressure of about 100 to 700 Torr.

11. In a gaseous discharge display/memory device comprising an ionizable gaseous medium in a gas chamber formed by a pair of opposed dielectric material bodies having charge storage surfaces in contact with said ionizable gaseous medium, said charge storage surfaces being backed by electrode members, the electrode members behind each charge storage surface being transversely oriented with respect to the electrode members behind the opposing charge storage surface so'as to provide a plurality of electrode intersections, each defining a discharge unit, the improvement consisting of the combination of phosphor means on at percent atoms of helium and about 5 to 0 percent atoms of another gaseous component selected from neon, krypton, nitrogen, argon and mercury, whereby upon discharge of at least one of said discharge cells to stimulate the respective phosphor in the device there is no pronounced visible discharge emission to distort phosphor colors.

12. The invention of claim 11 wherein the gaseous mixture is at a pressure of about to 700 Torr.

Claims (12)

1. In a process for operating a multiple gas discharge display device comprising a multiplicity of gas discharge cells and an ionizable gaseous medium, the improvement which comprises utilizing the combination of at least one phosphor and an ionizable gaseous medium capable upon discharge of emitting radiation exciting the phosphor and consisting essentially of about 0.1 to 5 percent atoms of xenon and about 99.9 to 95 percent atoms of a helium-based composition, said helium-based composition consisting essentially of about 95 to 100 percent atoms of helium and about 5 to 0 percent atoms of another gaseous component selected from neon, krypton, nitrogen, argon and mercury, and applying an operating voltage to at least one of said gas discharge cells to stimulate said phosphor in the device without a pronounced visible discharge emission to distort phosphor colors.

2. The invention of claim 1 wherein the device is of the display/memory type and contains at least one dielectrically insulated electrode.

3. The invention of claim 1 wherein the gaseous medium is at a pressure of about 100 Torr to 700 Torr.

4. In an article of manufacture comprising a multiple gas discharge phosphor display device containing an ionizable gaseous medium, the improvement wherein the gaseous medium consists essentially of about 0.1 to 5 percent atoms of xenon and 99.9 to 95 percent atoms of a helium-based composition, said helium-based composition consisting essentially of about 95 to 100 percent atoms of helium and about 5 to 0 percent atoms of another gaseous component selected from neon, krypton, nitrogen, argon and mercury.

5. The invention of claim 4 wherein the device is of the display/memory type and contains at least one dielectrically insulated electrode.

6. The invention of claim 4 wherein the gaseous medium is at a pressure of about 100 Torr to 700 Torr.

7. As a composition of matter, an ionizable gaseous mixture for a gas discharge display phosphor device, said mixture consisting essentially of about 0.1 to 5 percent atoms of xenon and about 99.9 to 95 percent atoms of a helium-based composition, said helium-based composition consisting essentially of about 95 to 100 percent atoms of helium and about 5 to 0 percent atoms of another gaseous component selected from neon, krypton, nitrogen, argon and mercury.

8. The invention of claim 7 wherein the gaseous mixture is at a pressure of about 100 to 700 Torr.

9. In the operation of a gaseous discharge display/memory device characterized by an ionizable gaseous medium in a gas chamber formed by a pair of dielectric material members having opposed charge storage surfaces, which dielectric material members are respectively backed by a series of parallel electrode members, the electrode members behind each dielectric material member being transversely oriented with respect to the electrode members behind the opposing dielectric material member so as to define a plurality of discrete discharge volumes, each constituting a discharge unit, and wherein the gas is selectively ionized and discharged within each discharge unit by operating voltages applied to the transversely oriented electrode members, the improvement which comprises utilizing the combination of a phosphor on at least one of saiD dielectric material members at each discharge unit and an ionizable gaseous medium capable upon discharge of emitting radiation exciting said phosphor and consisting essentially of about 0.1 to 5 percent atoms of xenon and about 99.9 to 95 percent atoms of helium-based composition, said helium-based composition consisting essentially of about 95 to 100 percent atoms of helium and about 5 to 0 percent atoms of another gaseous component selected from neon, krypton, nitrogen, argon and mercury, and applying an operating voltage to at least one of said gas discharge cells to stimulate the respective phosphor in the device without a pronounced visible discharge emission to distort phosphor colors.

10. The invention of claim 9 wherein the gaseous mixture is at a pressure of about 100 to 700 Torr.

11. IN A GASEOUS DISCHARGE DISPLAY/MEMORY DEVICE COMPRISING AN IONIZABLE GASEOUS MEDIUM IN A GAS CHAMBER FORMED BY A PAIR OF OPPOSED DIELECTRIC MATERIAL BODIES HAVING CHARGE STORAGE SURFACES IN CONTACT WITH SAID IONIZABLE GASEOUS MEDIUM, SAID CHARGE STORAGE SURFACES BEING BACKED BY ELECTRODE MEMBERS, THE ELECTRODE MEMBERS BEHIND EACH CHARGE STORAGE SURFACE BEING TRANSVERSELY ORIENTED WITH RESPECT TO THE ELECTRODE MEMBERS BEHIND THE OPPOSING CHARGE STORAGE SURFACE SO AS TO PROVIDE A PLURALITY OF ELECTRODE INTERSECTIONS, EACH DEFINING A DISCHARGE UNIT, THE IMPROVEMENT CONSISTING OF THE COMBINATION OF PHOSPHOR MEANS ON AT LEAST ONE OF SAID DIELECTRIC MATERIAL MEMBERS AT EACH DISCHARGE UNIT AND AN IONIZABLE GASEOUS MEDIUM CAPABLE ON DISCHARGE OF EMITTING RADIATION EXCITING SAID PHOSPHOR SAID CONSISTING ESSENTIALLY OF ABOUT 0.1 TO 5 PERCENT ATOMS OF XENON AND ABOUT 99.9 TO 95 PERCENT ATOMS OF HELIUM BASED COMPOSITION, SAID HELIUM-BASED COMPOSITION CONSISTING ESSENTIALLY OF ABOUT 95 TO 100 PERCENT ATOMS OF HELIUM AND ABOUT 5 TO 0 PERCENT ATOMS OF ANOTHER GASEOUS COMPONENT SELECTED FROM NEON, KRYPTON, NITROGEN, ARGON AND MERCURY, WHEREBY UPON DISCHARGE OF AT LEAST ONE OF SAID DISCHARGE CELLS TO STIMULATE THE RESPECTIVE PHOSPHOR IN THE DEVICE THERE IS NO PRONOUNCED VISIBLE DISCHARGE EMISSION TO DISTORT PHOSPHOR COLORS.

12. The invention of claim 11 wherein the gaseous mixture is at a pressure of about 100 to 700 Torr.

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