US3781587A

US3781587A - Gas discharge display apparatus

Info

Publication number: US3781587A
Application number: US00311067A
Authority: US
Inventors: C Lustig; A Baird
Original assignee: Sperry Rand Corp
Current assignee: WALTER E HELLER WESTERN Inc; Sperry Corp; Microsemi Corp Power Management Group
Priority date: 1972-12-01
Filing date: 1972-12-01
Publication date: 1973-12-25
Anticipated expiration: 1990-12-25
Also published as: GB1448682A; IT997848B; FR2209209A1; DE2359970A1; NL7316446A; JPS4997568A; FR2209209B1

Abstract

A gas discharge display panel including reservoir cells for providing ionizable gas and a plurality of gas discharge display memory cells. Included are a plurality of addressing electrodes each having a plurality of apertures therethrough, the electrodes being arranged in superposed configuration so that the apertures align to form gas conductive channels extending from the reservoir cells to the display memory cells. The addressing electrodes are adapted for connection to sources of selectable electrical potential whereby gas discharge columns are extended from the reservoir cells through selected channels thereby igniting gas discharges in selected display memory cells.

Description

United States Patent 91 Lustig et al. I

[111 3,781,587 [451 Dec 25, 1973 GAS DISCHARGE DISPLAY APPARATUS [75] Inventors: Claude D. Lustig, Lexington; Albert W. Baird, III, Burlington, both of Mass.

[73] Assignee: Sperry Rand Corporation, Great Neck, NY.

[22] Filed: Dec. 1, 1972 21 Appl. No.: 311,067

[52] US. Cl. 313/217, 313/220, 315/169 TV [51] Int. Cl. H01] 61/06 [58] Field of Search 313/217, 220

Primary Examiner-Roy Lake Assistant ExaminerDarwin R. Hostetter Attorney-Howard P. Terry [57] ABSTRACT A gas discharge display panel including reservoir cells for providing ionizable gas and a plurality of gas discharge display memory cells. lncluded are a plurality of addressing electrodes each having a plurality of apertures therethrough, the electrodes being arranged in superposed configuration so that the apertures align to form gas conductive channels extending from the reservoir cells to the display memory cells. The addressing electrodes are adapted for connection to sources of selectable electrical potential whereby gas dis charge columns are extended from the reservoir cells through selected channels thereby igniting gas discharges in selected display memory cells.

15 Claims, 6 Drawing Figures obcde PATEHIED BECZ 5 E375 SHEEI b BF 5 OOOOOO O0 O0 PATENIEDHEEZSIQH 3.731.587

SHEEISUFS W 8888 88888 II 88888 W 0 00000 00000 00000 00000 00000 00000 00000 00000 00000 01 4 1 00000 00000 00000 00000 Ml 00000 Il00000 |l00000 M00000 I 00000 00000 00000 00000 ULOOOOOIW 00000 H 00000,"! 00000 L 00000 00000 00000 0000GT 00000 00000 00000 00000 H 8 88 8 88888 888 l 00000 0 0 00 00000 00000 00000 M00000, M00000 00000 1'00000 00000 00000 00000 00000 00000 m 00000,"! 00000 l| 00000, II 00000 W 00000 00000 00000 00000- 0000 000 00000 00000 00000 00000 00000 00000 I 000 0||00000 0000 |l 0 000 0 00000 0000 0 I 00000 00000 00000 00000 h 7 00000 00000 00000 00000 'I00000,l 00000 I' 0000 00000 I I 1L [1 00000 00000! 88088 88088 00000 00000 0 0 00000 00000 00000 b00000 ,88888'88888 88888 88888 [1 00000 00000 |\100000l\| 000000;

7 00000 00000 00000 00000 My 00000 H 000004 000003!" 00000 1 02 8 I 3 F G 3 SUSTAINING VOLTAGES FIG.l0.

FIG.4.

' l GAS DISCHARGE DISPLAY APPARATUS BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to gas discharge display panel apparatus particularly of the type suitable for the display of symbol and graphical information' 2. Description of the Prior Art Gas discharge display panels are known in the prior art that utilize dot-matrix display formats for the visual presentation of information. A dot-matrix display panel is defined as apparatus incorporating a matrix of points which may be selectively lit to display patterns of information. Such a dot-matrix display is described in US. Pat. application Ser. No. 90,538 filed Nov. 18, 1970 in the names of Claude D. Lustig and Albert W. Baird III entitled Digitally Addressable Gas Discharge Display Apparatus" and assigned to the assignee of the present invention. Additional gas discharge dot-matrix display panel configurations were described in US. Pat. application Ser. No. 161,584 filed July 12, 1971 in the name of Theodore H. Bonn, entitled Gas Discharge Display Apparatus and US. Pat. application Ser. No. 244,01 1, filed Apr. 14, 1972 in the name of Claude D. Lustig,

'entitled D.C. Gas Discharge Display Apparatus with Pulse Train Memory Sustaining Potential, both assigned to the assignee of present invention. Briefly, the device described in said Ser. No. 90,538 comprises a reservoir of ionizable gas and a plurality of gas discharge display memory cells. The device includes a plurality of addressing electrodes each having a plurality of apertures therethrough.. The addressing electrodes are arranged in superposed configuration so that the apertures align to form gas-conductive channels extending from the reservoir to the display memory cells. The addressing electrodes are connectible to sources of selectible electrical potential whereby gas discharge plasma columns are extended from the reservoir through selected channels igniting gas discharges in selected display memory cells.

Although such a display device is suitable for most purposes, limitations arise in applications requiring relatively large numbers of display points. This is so since the reservoir of ionized gas must extend over the entire matrix of display points and thegas therein maintained uniformly ionized over the entire area of the reservoir. With such a reservoir, 'one channel of the addressing anodes tends to draw current before the other channels can do so and thus the single channel has access-to a large number of electrons contained in the reservoir. Thus an excessively large current is extracted leaving little plasma for the other cells. Difficulties are also encountered when endeavoring to ignite simultaneously a plurality of cells. In addition, large area ionized gas reservoirs may be exceedingly difficult and hence expensive to manufacture and may require prohibitively large quantities of electrical power.

With the display panel of said Ser. No. 90,538 when large numbers of display points are utilized, large numbers of super-posed and aligned addressing electrodes are consequently required, further complicating constructional procedures and increasing manufacturing costs. Additionally, the binary addressing scheme of these panels are not particularly commensurate with alphanumeric display requirements utilizing, for example, a conventional X 7 matrix of dots for each symbol.

SUMMARY OF THE INVENTION The present invention overcomes the disadvantages of the prior art discussed with respect to said Ser. No. 90,538 while retaining the advantages thereof. The present invention comprises a gas discharge display having a plurality of gas discharge display memory cells and reservoir means for providing ionizable gas. The display includes a plurality of addressing electrodes each having a plurality of apertures therethrough. The addressing electrodes are arranged in superposed configuration so that the apertures align to form gas conductive channels extending from the reservoir means to the display memory cells. The addressing electrodes are adapted for connection to sources of selectible electrical potential whereby gas discharge plasma columns are extended from the reservoir means through selected channels thereby igniting gas discharges in selected display memory cells.

The problems associated with a single channel extracting an excessively large amount as discussed above with respect to said Ser. No. 90,538, are obviated by utilizing means for partitioning the reservoir into a plurality of essentially isolated cells.

The problems associated with the high cost and high power consumption of a large area ionized gas reservoir are obviated by configuring the reservoir so that sub-sections of it may be selectivelyignited by means of an X-Y selection arrangement.

The problems associated with requiring large numbers of addressing anodes discussed above with regard to said Ser. No. 90,538 are obviated by utilizing control anodes with portions arranged commensurate with the display of symbolic or graphic data such as alphanumeric characters utilizing, for example, a S X 7 dot-matrix symbol block for each character.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1, comprised of FIGS. 1a, 1b and 1c, is an exploded perspective view of a preferred embodiment of the invention where FIG. 1a illustrates the reservoir means, FIG. 1b illustrates the addressing electrode means, and FIG. 1c illustrates the display memory cell I means;

FIG. 2' is an elevation view of one of the addressing anodes of FIG. lb;

FIG. 3 is an elevation view of one of the display memory electrode plates of FIG. 1c illustrating a modification thereof; and

FIG. 4 is a chart illustrating how FIGS. la, lb and 1c combine to form FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT thereof are comprised of any suitable insulating material. A suitable choice of materials may, for example, be nickel-iron alloy (51 percent nickel and 49 percent iron) of a type in wide spread commercial usage in electron tube devices and soda-lime glass, respectively. The coefficients of thermal expansion of these materials are substantially identical providing manufacturing advantages well appreciated in the art.

The display panel illustrated in FIG. 1 is adapted to be filled, by any convenient method (not shown), with a suitable ionizable gas such as, for example, neon or a Penning mixture (99.5 percent neon and 0.5 percent argon) or other suitable mixtures to which mercury vapor may or may not be added.

Referring to FIG. 1a the reservoir 10 is comprised of a reservoir anode plate 13, an electrically insulating plate 14, a reservoir cathode plate 15, another electrically insulating plate 16, an electrically insulating spacer plate 17 and a cover plate'20. An additional electrically insulating plate 21 is'included to electrically isolate the reservoir 10 from the addressing electrodes of FIG. lb in a manner to be described. Each of the plates 13-16 and 21 has a matrix of apertures therethrough arranged in rows and columns. The matrix of apertures in each plate may be comprised of a plurality of sub-matrices, for example 5 X 7 sub-matrices of apertures, convenient for defining the symbols to be displayed.

Plates 13-17, 20 and 21 are assembled to form a reservoir adapted to be filled with an ionizable gas as previously described. The plates 13-15 and 21 are superposed, i.e., stacked with respect to each other so that the respective matrices of apertures are in alignment, the corresponding apertures through the anode plate 13, the cathode plate 15 and the interposed insulating plate 14 defining a plurality of gas discharge reservoir cells. The apertured insulating

plates

14 and 16 provide means for isolating the gas discharge reservoir cells from each other thus providing means for partitioning the reservoir into isolated gas discharge reservoir cells. The electrically insulating spacer plate 17 includes

openings

22 and 23 each of which encompasses a plurality of the reservoir cells. The

openings

22 and 23 provide weak coupling between the reservoir cells in a manner and for reasons to be discussed. The plate 17 also includes a member 24 for structural rigidity. It will be appreciated that the member 24 is not germain to the invention and may optionally be utilized as required.

A source of ionizing potential 25 is included for applying gas discharge ionizing potentials between the reservoir anodes 13 and the reservoir-cathodes thus ionizing the gas in the reservoir cells. The source may provide square voltage pulses for the purpose of ionizing the gas in the reservoir cells. Alternatively, to reduce the probability of arc formation, the source 25 may provide voltage pulses containing a step where the voltage amplitude during the earlier part of the pulse is higher than the amplitude in the later part of the pulse. Another alternative voltage waveform which may be utilized to reduce arc formation is where the source 25 provides a burst of short voltage pulses to ionize the gas in the reservoir cells with the amplitude of the pulses providing either a square envelope or an envelope containing a step as described above. These pulses may be conveniently synchronized with the pulses used to operate the memory display section 12 as discussed in said Ser. No. 244,01 1. Voltage waveforms of the type described may be generated by the source 25 utilizing conventional circuitry well known in the art.

For convenience, the reservoir 10 may be configured in an X-Y selection arrangement. Accordingly, the reservoir anode plate 13 is comprised of substantially parallel electrically

conductive strips

26 and 27 electrically insulated from each other and the reservoir cathode plate 15 is similarly comprised of substantially parallel electrically

conductive strips

30 and 31 electrically insulated from each other and oriented transversely with respect to the

strips

26 and 27. The source of ionizing potential 25 selectively provides gas discharge ionizing potentials between the anode strips 26 and 27 and the cathode strips 30 and 31 by conventional switching means, not shown for simplicity. Accordingly, the gas discharge reservoir cells in the intersection. of a selected reservoir anode strip and a selected reservoir cathode strip may be selectively ignited. For example, with gas discharge ionizing potential applied between the

strips

26 and 31, the gas discharge reservoir cells in the

submatrices

32, 33, 34 and 35 are ignited thus providing sources of plasma for the corresponding portions of the display panel in a manner to be described.

Although each of the reservoir electrodeplates 13 and 15 is illustrated as comprising two parallel electrode strips, it will be appreciated that in practice each plate will comprise larger numbers of strips, the anode strips of the plate 13 being oriented orthogonally with respect to the cathode strips of the plate 15 thus dividing the reservoir 10 into groups of independently ionizable reservoir cells. Alternatively, the

reservoir electrode plates

13 and 15 may each be a unitary structure whereby all of the reservoir cells will be ignited and extinguished substantially simultaneously upon application and removal, respectively, of ionization potential from the source 25. 7

As previously mentioned, the electrically insulating apertured plate 21 electrically isolates the reservoir 10 of FIG. la from the contiguously stacked addressing electrodes of FIG. 1b.

Referring now to FIG. 1b, the stack of addressing electrodes 11 is comprised of

addressinganode plates

40, 41, 42 and 43 each of which has a plurality of apertures therethrough forming a matrix configuration in a manner similar to that described with respect to the plates of FIG. 1a. interposed between the addressing

anode plates

40, 41, 42 and 43 are electrically insulating plates 44, 45 and 56, respectively, each having a matrix of apertures therethrough in a manner similar to that described with respect to the addressing anode plates 40-43.

The addressing anode plate 40 is comprised of substantially parallel electrically conductive addressing

strips

50, 51, 52 and 53. Each of the strips -53 encompasses a plurality of rows of the matrix of apertures, for example 7 of the rows corresponding to the heights of the symbol defining 5 X 7 sub-matrices. The addressing strips 50 and 52 are electrically connected to each other as are the strips 51 and 53 for reasons to be explained.

The addressing anode plate 41 is comprised of substantially parallel electrically conductive addressing strips 54, 55, 56 and 57 oriented orthogonally with respect to the strips 50-53. Each of the strips 54-57 encompasses a plurality of columns of the matrix of apertures, for example five of the columns corresponding to the widths of the symbol defining 5 X 7 sub-matrices. The addressing strips 54 and 56 are electrically connected to each other as are the strips 55 and 57 for reasons to be discussed.

The addressing anode plate 42 is comprised of a plurality of electrically conductive strips 60 substantially parallel to the strips 50-53. Each of the strips 60 encompasses a row of the matrix of apertures through the plate 42, thus defining the symbol to be displayed in a manner to be described. The strips 60 are arranged in groups of seven strips each corresponding to the seven rows of the symbol defining 5 X 7 sub-matrices. The strips 60 are interconnected in a to-and-fro arrangement in a manner to be clarified hereinafter with respect to FIG. 2.

The addressing anode plate 43 is comprised of a plurality of electrically conductive addressing strips 61 substantially parallel to the strips 54-57. Each of the strips 61 encompasses a column of the matrix of apertures through the plate 43. The strips 61 are arranged in groups of five strips each corresponding to the columns of the symbol defining 5 X 7 sub-matrices. The strips 61 are interconnected in a to-and-fro arrangement in a manner to beexplained with respect to FIG. 2.

Referring now to FIG. 2 an elevation view of the plate 43 is illustrated. As previously described with respect to FIG. 1b, each of the strips 61 encompasses a row of the matrix of apertures through the plate 43. The strips 61 are interconnected in a to-and-tro pattern by means of interconnecting strips 62. The

strips

61 and 62 are interconnected in substantially the same plane to form five non-overlapping strips disposed in a to-and-fro manner in the plane of the addressing plate 43. It is appreciated that each of the five continuous strips encompasses one column of each of the 5 X 7 sub-matrices of the matrix of apertures through the plate 43. For example, the strip 61a encompasses the left-most column of the sub-matrices 63-66 and 73-76 and the right-most columns of the sub-matrices 67, 70-72, 77 and 80-82. In a similar manner, the strips 61b-61e encompass the remaining columns, respectively, of the symbol defining 5 X 7 sub-matrices 63-67, 70-77 and 80-82.

Referring again to FIG. 112, it will be appreciated that the addressing strips 60 of the addressing anode plate 42 are arranged in a to-and-fro configuration in a manner similar to that illustrated in FIG. 2 except that the rows of the sub-matrices are encompassed by 7 continuous electrically conductive strips.

The addressing strips 50-57, 60 and 61 are connected to addressing circuits 83 which comprise conventional circuits for selectively applying either a positive or a negative potential to each of the addressing strips in a manner and for reasons to be discussed.

The plurality of gas discharge display memory cells 12 of the display panel are illustrated in FIG. 1c and are I stacked contiguously with respect to the addressing electrodes of FIG. lb. The display memory cells of the present invention are similar to those disclosed in said Ser. No. 90,538 and said Ser. No. 244,011.

Referring now to FIG. 10, the gas discharge display memory cells 12 are comprised of a display memory anode plate 84 and a display memory' cathode plate 85. An electrically insulating plate 86 is interposed between the

plates

84 and 85. A transparent face plate 87, through which a display pattern may be viewed, is also included in the display memory cell section 12. Two electrically insulating

plates

90 and 91 are disposed between the cathode plate and the transparent face plate 87 to inhibit sputtering of material from the cathode plate 85 to the face plate 87 which sputtered material would tend to obscure the display. Additionally, an electrically insulating plate 92 is disposed between the display memory anode plate 84 and thc addressing anode plate 43 (FIG. 1b).

Each of the plates 84-86 and -92 has a matrix of apertures therethrough identical to those through the plates described with respect to FIGS. 1a and lb. The plates of FIG. 1c are disposed adjacent one another in superposed, i.e., stacked, arrangement with the matricesof apertures through the respective plates aligned to form the plurality of gas discharge display memory cells 12 in the manner disclosed in said Ser. No. 90,538 and said Ser. No. 244,01 1. I

A suitable source 93 of gas discharge sustaining potential is connected across the anode plate 84 and the cathode plate 85 to provide gasvdischarge sustaining potential thereto in the manner described in said Ser. No. 90,538 or said Ser. No. 244,0l l.

It will be appreciated that the plates of FIG. lb are superposed, i.e., stacked,lwith respect to each other so that the respective matrices of apertures align to form a plurality of gas conductive channels extending respectively fromm the reservoir cells 10 of FIG. la to the plurality of gas discharge memory display cells 12 of FIG. 10. Furthermore, all of the plates of FIG. 1 are contiguously superposed and sealed at the edges thereof by any convenient means (not shown) to form a gas tight structure. Alternatively, the plate members forming the display panel may be mounted inside a gas tight envelope (not shown) with electrical connections made through gastight seals in the envelope.

The operating principles of the display panel illustrated in FIG. 1 are similar to those discussed in said Ser. No. 90,538 and said Ser. No. 244,011 and will be briefly explained herein for completeness. The gas contained in the reservoir cells 10 at the intersection of two of the reservoir electrode strips 26, 27, 30 and 31 is ionized by the source of potential 25 causing a glow discharge at the reservoir cathodeplate 15 at the cells thus energized. The gas discharge sustaining potential is applied across the display memory cells 12 by the source 93. By suitable application by the addressing circuits 83 of positive and negative potentials selectively to the addressing strips of the addressing anodes 40-43, gas discharge plasma columns are extended therethrough in selected channels to emerge from the selected apertures in the addressing anode plate 43. The columns may be further extended by application of a positive potential to the display anode 84. Particles from the excited gas discharge plasma columns enter the associated ones of the display memory cells 12 partially ionizing the gas therein and causing ignition thereof by the voltage applied by the source 93. The source 93 maintains the discharges in' the selected memory cells after the discharge columns have been extinguished by removing the addressing potentials. The displayed pattern of information in the memory cells 12 may be erased by a momentary reduction or removal of the sustaining potential from the source 93.

The detailed operation of the display panel of FIG. I will now be explained in terms of displaying a symbol in the sub-matrix 77 of the display memory cells 12 of FIG. 10. The source 93 of FIG. 10 provides the sustaining potential to the plurality of gas discharge display memory cells 12. The source 25 of FIG. 1a provides gas discharge ionizing potential across the reservoir electrode strips 26 and 31 thus igniting the reservoir cells of the sub-matrices 32-35. The addressing circuits 83 are activated to provide positive potentials to the ad dressing strips 50, 52, 54 and 56 of the addressing anode plates 40 and 41, the remaining strips of these plates having negative potentials applied thereto. Under these conditions, gas discharge plasma columns are extended through the sub-matrices of apertures in the addressi'ng'strip 50 aligned with the sub-matrices 32 and 34 of the reservoir and are inhibited from passage through the apertures of ,the addressing strip 51. Since the reservoir cells corresponding to the addressing strips 52 and 53 are not lit, plasma columns are not extended therethrough. Of the discharge columns passing through the strip 50, only those incident upon the strip 54 of the plate 41 are transmitted therethrough. Those columns incident upon the strip 55 are inhibited from further passage. Thus, it is appreciated that by the application of the addressing potentials described above, gas discharge columns are extended through the apertures of the 5 X 7 symbol defining sub-matrix 77, the strips of the plate 40 defining the height of the submatrix and the strips of the plate 41 defining the width thereof.

With the symbol defining sub-matrix 77 selected by the addressing electrode plates 40 and 41, gas discharge plasma columns are incident upon the apertures of this sub-matrix of the plate 42. Addressing potentials are applied to the addressing

strips

60 and 61 of the

plates

42 and 43, respectively, by the addressing circuits 83 to extend the plasma columns through the

plates

42 and 43 to define the symbols. An addressing potential is applied to the display anode 84 to extend the plasma columns from the plate 43 to the plate 84, to ignite the selected display memory cells 12 in the manner previously described. Once ignited, a pattern of lit cells will be maintained energized by the sustaining potential from the source 93 until erased by a momentary reduction or removal of this potential. Addressing potentials may be applied to the addressing

strips

60 and 61 so as to simultaneously ignite a plurality of the memory cells of a sub-matrix or the potentials may be applied to ignite a single cell. In this manner, the segments comprising alphanumeric characters or graphical display elements may be sequentially'energized to form the symbols. For example, if it is desired to simultaneously ignite a column of apertures of the sub-matrix 77, positive addressing potentials are applied to all of the addressing strips 60 and to the one addressing strip 61 associated with the column of apertures to be ignited. Similarly, if it is desired to simultaneously ignite a row of the apertures of the sub-matrix 77, a positive potential is applied to all of the addressing strips 61 and to the one addressing strip 60 associated with the desired row. When it is desired to simultaneously ignite selected cells in a column of the submatrix 77, positive potential is applied to the addressing strip 61 associated with that column and to selected addressing strips 60 associated with the selected apertures in the column that are to be ignited. When a single display memory cell is to be lit, the selected addressing

strips

60 and 61, at the intersection thereof, have positive potential applied thereto to light the cell.

Thus, it is appreciated that by appropriate application of potentials to the strips and 61, a wide variety of alphanumeric characters and graphical symbols may be displayed and stored in the sub-matrix 77 of the plurality of gas discharge display memory cells 12. in a similar manner other sub-matrices of the display may be selected for the formation and storage ofsymbols by appropriate application of potentials to the addressing anode plates 40 and 41.

The amplitudes of the positive potentials applied by the addressing circuits 83 to the respective addressing anodes 4043 and the display memory anode 84 are selected in increasing fashion to correspond to the increasing distances of the respective anodes from the reservoir 10 in accordance with the well known gas discharge laws. The voltages must also be selected to preclude' gas discharge breakdown between any of the electrodes 13 and 40-43 in the manner described in said Ser. No. 90,538. Breakdown must further be prevented between the display memory anode 84 and any of the

electrodes

13, 15 and 40-43. This may be accomplished in the manner described in said Ser. No. 90,538. The potentials provided by the addressing circuits 83 may be narrow pulses having durations sufficient to ignite the display memory cells 12, which once ignited are so maintained by the source 93.

Since no series resistors are utilized in the circuits of the display memory cells 12, voltage drops do not occur when a large number of cells are ignited, thus preventing faulty cell ignition prevalent in devices requiring these resistors.

It will be appreciated from the foregoing that when it isdesired to simultaneously ignite a plurality of display memory cells 12, the plasma current drawn from the associated reservoir cells 10 will divide substantially equally amongst the associated channels because of the isolation between reservoir cells provided by the

apertured reservoir plates

14 and 16. Thus, the problem associated with the display panel of said Ser. No. 90,538 as discussed above where one of the channels draws much of the available current before the other channels can do so, is obviated in the present invention. Since the statistical time lag for breakdown in the individual reservoir cells could be large and diverse, suitable interaction between the reservoir cells is provided by the reservoir spacer plate 17 providing weak coupling between the cells. The coupling between the cells is weak since the thickness of the spacer plate 17 is selected to be of a small value. In this way, some ionized particles can diffuse amongst the reservoir cells to provide prompt and uniform ionization of the gas in the cells but prevent large plasma currents from being drawn between cells. It is believed that a suitable value for the thickness of the spacer plate 17 is somewhat less than the width of the plasma sheath that surrounds the reservoir cathode 15. Additionally, it is believed that should the number of addressing anode plates be increased, the thickness of the apertured plate 16 should be increased.

In one embodiment of the display panel of the present invention, the following parameters were found to be suitable in a 32 X 32 array operating on the principles described above. The cells of the panel were on a center to center spacing of 0.03l inch. The thicknesses of the

plates

14, 16 and 17 were 0.006 inch. Satisfactory performance was obtained with aperture diameters in the range of 0.010 to 0.014 inch for the

reservoir electrode plates

13 and 15. Since the reservoir current required for operation is proportional to the thickness of the reservoir cathode plate 15, satisfactory'performance was obtained with a cathode thickness of 0.0025 inch and it is believed that smaller thicknesses should be possible. The thickness of the display memory cathode plate 85 was also 0.0025 inch. The thicknesses of the addressing electrode plates 40-43 were 0.005 inch and the apertures therethrough were 0.010 inch in diameter. The thicknesses of the insulating plates 21 and 44-46 were 0.006 inch with 0.018 diameter apertures therethrough. The panel operated with a pressure of 100 torr of neon gas.

It will be appreciated that when the reservoir 10 includes X-Y addressing, an economical mode of opera tion is obtained. For example, the reservoir cathode may be divided into N strips and the reservoir anode 1'3 into M strips orthogonal to the cathode strips. Thus, by means of M+M circuits any one of the N M sections in the reservoir may be ignited. The advantages of this mode of operation are:

l. The total number of reservoir cells which have to be ignited simultaneously in the reservoir is relatively small so that some form of current limitation may be incorporated to prevent arc formation;

2. The net power dissipation in the reservoir 10 is reduced resulting in reduced heating and lower circuit costs; and

3. The X-Y partitioning may result in fewer addressing anode plates in embodiments of the invention.

The reservoir 10 is constructed such that the individual reservoir cells thereof perform independently when a plurality of channels areactivated. The current therefore divides approximately equally amongst the channels. For optimum addressing of the channels, almost complete isolation is utilized between the reservoir cells. The plate 17, however, may be included to provide' at most weak coupling amonst the reservoir cells to achieve prompt and uniform ionization of the gas in the cells. Additionally, the openings such as 22 and 23 in the plate 17 may conveniently be utilized as an evacuation space during the pumping operations in the manufacturing procedures for the panel.

It will be appreciated that when larger numbers of X-Y reservoir electrode strips than those illustrated are utilized, additional sub-matrix defining addressing strips must be utilized in the addressing plates 40 and 41 with strips associated with corresponding locations with respect to the reservoir intersections commonly connected. The lengths of the row and column addressing strips in'the addressing

plates

42 and 43 would be lengthened to accommodate the additional submatrices of apertures. It will furthermore be appreciated that should the reservoir 10 be constructed without X-Y addressing where all of the reservoir cells are simultaneously ignited, the interconnections amongst the strips of the addressing plates 40 and 41 would not be utilized and each strip would be separately addressed to individually actuate the individual 5 X 7 symbol defining sub-matrices. Alternatively, if the reservoir 10 is constructed with X- Y addressing such that each reservoir intersection encompasses one 5 X 7 symbol defining sub-matrix, the addressing plates 40 and 41 would not be required.

Although the present invention has been described in terms of an X-Y addressed reservoir, other reservoir configurations may also be utilized such as a scanning reservoir of the type described in said Ser. No. l6l,584. With a scanning reservoir where the reservoir sections comprise a symbol defining sub-matrices, only the row and column defining addressing

plates

42 and 43 would be required.

The reservoir 10 has been described hereinabove with the anode plate 13 and the cathode plate 15 positioned as illustrated in FIG. la. It is believed that the positions of these plates may be interposed with respect to each other with a possible repositioning of the spacer plate 17.

From the foregoing, it will be appreciated that when utilizing the arrangement of the addressing strips of the plates 4043, fewer addressing plates are generally required than when utilizing the addressing plate arrangement of said Ser. No. 90,538. Further advantages accrue to the to-and-fro interconnection arrangement described above of interconnecting many non-adjacent addressing anode strips in one plane. The to-and-fro arrangement eliminates the need for the conventional interconnection schemes utilizing through plate connectors. A to-and-fro interconnected addressing plate is readily constructed by initially having the ends of the continuous strips connected together. and cutting off the connecting portions following assembly of the panel in the manner of the conventional lead-frame technique. Furthermore, although the to-and-fro inter connecting arrangement has only been illustrated with regard to the

plates

42 and 43, this construction may also be advantageously utilized with regard to the plates 40 and 41. Although the to-and-fro interconnection arrangement provides the advantages discussed, the strips of the addressing plates 40-43 may be fabricated and interconnected by more conventional means such as utilizing silk screening with through plate connectors in constructing a display panel incorporating aspects of the invention.

The addressing electrode plates 40-43 have been described in terms of the relative positions illustrated in FIG. 1b. lt will be appreciated that these plates may have other positions relative to each other to achieve the same effect. Although the display panel of the present invention has been described in terms of electrically conductive plates and electrically insulating plates interleaved with respect to each other, it is understood that the panel may alsobe constructed by depositing the illustrated electrode strips on insulating substrates.

As previously described, the addressing electrode plates 40-43 are particularly suited to the display of symbol information such as that of the alphanumeric type. The term symbol as used herein is also meant to include graphical display elements which combine to form a graphical display.

The present display panel has been described herein in terms of the reservoir 10 as illustrated in FIG. 1a and the addressing electrode plates 11 as illustrated in FIG. 1b. It will be appreciated that alternatively, the addressing plates 11 may be utilized with reservoirs of the type described in said Ser. No. 161,5 84 and the reservoir 10 may be utilized with addressing plate arrangements of the type illustrated in said Ser. No. 90,538 or .said Ser. No. 161,584. It will further be appreciated that although the present display panel was described in terms of the display memory cells 12 of FIG. 10, the display memory cell arrangements of said Ser. No. 90,538 and said Ser. No. 161,584 may also be utilized. However, with the arrangement of FIG. 10 of the present application, the cathode plate 85 at which the glow discharge occurs is closer to the viewing plate 87 than the anode plate 84 which positions the displayed information closer to the viewer than with the converse arrangement to provide an efficacious display.

It is often a requirement in display panels of the type described herein to provide an indicium indicating which symbol defining submatrix is active for the entry of a character. This is particularly desirable in installations where characters may be entered into the panel by means of a manually operated keyboard. Such indicia may be conveniently provided by the arrangement of FIG. 3.

Referring now to FIG. 3, an elevation view of one of the display memory electrode plates of FIG. 1c, including a modification thereof to provide such indicia, is illustrated. It is appreciated that this modification can be effected with either the memory cathode plate 85 or the memory anode plate 84 of FIG. 1b. It is believed that it is simpler to modify the cathode plate 85. The modified cathode plate 85 comprises two

portions

100 and 101 electrically insulated from each other and adapted for connection independently to sources of gas discharge sustaining potential provided by the voltage source 102. The portion 100 of the plate 85 contains the plurality of 5 X 7 symbol defining sub-matrices previously discussed and the portion 101 Of the plate 85 includes the active sub-matrix indicia. In a preferred embodiment of the invention, these indicia may take the form of rows of display memory cells disposed beneath the sub-matrices respectively. Such indicia may be considered as a cursor for indicating a particular sub-matrix.

In operation, the voltage source 102 provides sustaining potential independently to the

portions

100 and 101 of the plate 85 with respect to the plate 84. A particular group of cursor cells may selectively be ignited in the manner hereinabove described. When it is desired to change the position of the cursor cells, the sustaining potential may be reduced or removed from the portion 101 erasing the lit cursor cells and addressing potentials applied as previously described, to ignite cursor cells in another location on the portion 101. Thus it is appreciated that the cursor cells may be extinguished and ignited without disturbing the symbols stored at the sub-matrices of the portion 100. It is also appreciated that in order to accommodate a cursor configuration as illustrated in FIG. 3, additional apertures (not shown) would be required through the remaining plates of the display panel corresponding to the apertures of thee cursor, and an additional addressing strip in .plate 42 would be required to selectively address the cursor cells. Although the cursor arrangement has been described in terms of rows of cells beneath the sub-matrices, respectively, other indicating arrangements of cells may be utilized to the same effect.

It is often a desideratum'with equipment of the character described herein to provide means for indicating which of the display memory cells 12 are lit. Such an indication is often required where the apparatus is utilized as a memory, and computer interrogation to determine the state of the cells of the memory is desired.

Referring to FIG. la, a current sensor 95 is included and is selectively connectible by conventional switching arrangements to the

reservoir electrode plates

13 and 15. In order to interrogate the status of a particular memory cell 12 (FIG. addressing potentials are applied by the circuit 83 (FIG. 1b) so as to extend a plasma column from the selected memory cell back to the reservoir 10 (FIG. la). If the selected memory cell 12 is lit such a plasma column will be generated, the resulting current being detected by the current sensor 95.

If the selected display cell is not lit, a plasma column will not be extended and current will not be sensed.

Thus the status of the memory cells 12 may be determined by the current sensor 95. It is appreciated that in this mode of operation the memory cells 12 provide the function of a plasma reservoir in the sense described hereinabove for the reverse operation.

While the invention has been described in its preferred embodiment, 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. I

We claim:

1. Gas discharge display apparatus comprising reservoir means for containing an ioniz'able gas,

means in said reservoir means for partitioning said reservoir means into at least partially isolated gas discharge reservoir cells at most weakly coupled to each other,

a plurality of gas discharge display memory cell means, and

a plurality of addressing electrode means interposed between said reservoir means and said display memory cell means and each having a plurality of apertures therethrough,

said plurality of addressing electrode means being in superposed arrangement with respect to each other with said apertures aligned to form a plurality of gas conductive channels extending, respectively, from said reservoir cells to said display memory cell means,

said plurality of addresssing electrode means being adapted for connection to sources of selectible electrical potential for selectively applying potentials to said addressing electrode means to selectively extend gas discharge columns in said channels from said reservoir means to said display memory cell means for igniting gas displays in selected display memory cell means.

2. The apparatus of claim 1 in which each said reservoir cell includes reservoir means adapted for connection to a source of ionizing potential for ionizing said ionizable gas.

3. The apparatus of claim 2 in which said reservoir electrode means comprises reservoir anode means and reservoir cathode means.

4. The apparatus of claim 3 in which said partitioning means comprises apertured 'plate means of electrically insulating material associated with said reservoir cathode means.

5. The apparatus of claim 1 in which said reservoir means includes means for at most weakly coupling said reservoir cells to each other.

6. The apparatus of claim 1 in which said reservoir means comprises first reservoir electrode plate means having a plurality of apertures therethrough coupled with said gas conductive channels, respectively,

first electrically insulating plate means adjacent said first reservoir electrode plate means having a plurality of apertures therethrough,

second reservoir electrode plate means adjacent said first electrically insulating plate means having a spacer plate means adjacent said second electrically insulating plate means having openings therethrough each being associated with pluralities of said apertures for providing said weak coupling between said reservoir cells, and

cover plate means adjacent said spacer plate means,

the above mentioned plate means being in superposed arrangement with respect to each other to form said reservoir means with said apertures aligned whereby to form said reservoircells, respectively,

said first and second insulating plate means forming said partitioning means,

said first and second reservoir electrode .plate means being adapted for connection to a source of ionizing potential for ionizing said gas in said reservoir cells.

7. The apparatus of claim 6 in which said first reservoir electrode plate means comprises substantially parallel first electrically conductive strips electrically insulated from each other, and

said second reservoir electrode plate means comprises substantially parallel second electrically conductive strips electrically insulated from each other and transverse to said first strips.

8. The apparatus of claim 7 in which the intersections of said first and second strips are associated with pluralities of said apertures.

9. The apparatus of claim 8" in which said first and second reservoir electrode plate means comprise reservoir anode means and reservoir cathode means, respectively, said strips being adapted for selective connection to a source of ionizing potential for ionizing the gas in the reservoir cells at the intersections of the energized strips.

10. Gas discharge display apparatus for displaying symbols comprising reservoir means for containing an ionizable gas,

a plurality of gas discharge display memory cell means arranged in rows and columns,

' first addressingelectrode plate means interposed between said reservoirmeans and said display memory cell means with a plurality of apertures therethrough arranged in rows and columns and having substantially parallel first electrically conductive addressing strips each encompassing. a plurality of rows of said apertures to define the height of said symbols,

second addressing electrode plate means interposed between said reservoir means and said display memory cell means with a plurality of apertures therethrough arranged in rows and columns and having substantially parallel second electrically conductive addressing stripseach encompassing a plurality of columns of said apertures to define the width of said symbols, and

third and fourth addressing electrode plate means interposed between said reservoir means and said display memory cell means each with a plurality of apertures therethrough arranged in rows and columns and having third and fourth electrically con-.

ductive addressing strips, respectively, substantially parallel to said first and second strips, respectively, for defining said symbols,

said first, second, third and fourth addressing electrode plate means being in superposed arrangement with respect to each other with said apertures aligned to form a plurality of gas conductive chan nels extending from said reservoir means to said display memory cell means, respectively,

said first and second addressing electrode plate means being adapted for connection to sources of selectible electrical potential for selectively applying potentials thereto for selectively extending gas discharge columns in said channels from said reservoir means to define the height and width of said symbols,

said third and fourth addressing electrode plate means being adapted for connection to sources of selectible electrical potential for selectively applying potentials thereto for selectively extending gas discharge columns in said channels from said reservoir means to said display memory cell means for igniting gas discharges in selected display memory cell means to form said symbols.

11. The apparatus of claim 10 in which said third electrically conductive addressing strips encompass said rows of said apertures, respectively, and

said fourth electrically conductive addressing strips encompass said columns of said apertures, respectively.

12. The apparatus of claim 11 in which at least one of said addressing electrode plate means includes electrically conductive interconnecting strips in substanbetween said reservoir means and said display memorycell means and each having a plurality of apertures therethrough,

said plurality of addressing electrode means being in superposed arrangement with respect to each other with said apertures aligned to form a plurality of gas conductive channels extending from said reservoir means to said display memory cell means, respectively,

said plurality of addressing electrode means being adapted for connection to sources of selectible electrical potential for selectively applying potentials to said addressing electrode means to selectively extend gas discharge columns in said channels from said reservoir means to said display means for igniting gas discharges in selected dis- .play memory cell means,

said plurality of gas discharge display memory cell means comprising first and second display memory electrode means one of which having two portions electrically insulated from each other and adapted for connection to sources of gas discharge sustaining potential, respectively,

said plurality of gas discharge display memory cell means being arranged in a matrix of rows and columns comprising a plurality of sub-matrices for displaying said symbols and a plurality of indicia cells associated, respectively, with said sub-matrices,

said sub-matrices and said indicia cells being arranged on said two portions of said display memory electrode means, respectively, whereby said indicia cells may be ignited and extinguished independently of said symbols.

14. The apparatus of claim 13 in which said indicia cells associated with each said sub-matrix comprise a row of cells beneath said sub-matrix.

15. Gas discharge display apparatus comprising reservoir means for containing an ionizable gas,

a plurality of gas discharge display memory cell means,

said plurality of addressing electrode means being said plurality of addressing electrode means being further adapted forconnection to sources of selectible electrical potential for selectively applying potentials to said addressing electrode means to selectively extend gas discharge columns in said channels from lit display memory cell means to said reservoir means, and

means coupled with said reservoir means for sensing current associated with said gas discharge columns extended from said lit display memory cell means tosaid reservoir means thereby providing indications of the lit cells.

Claims

1. Gas discharge display apparatus comprising reservoir means for containing an ionizable gas, means in said reservoir means for partitioning said reservoir means into at least partially isolated gas discharge reservoir cells at most weakly coupled to each other, a plurality of gas discharge display memory cell means, and a plurality of addressing electrode means interposed between said reservoir means and said display memory cell means and each having a plurality of apertures therethrough, said plurality of addressing electrode means being in superposed arrangement with respect to each other with said apertures aligned to form a plurality of gas conductive channels extending, respectively, from said reservoir cells to said display memory cell means, said plurality of addresssing electrode means being adapted for connection to sources of selectible electrical potential for selectively applying potentials to said addressing electrode means to selectively extend gas discharge columns in said channels from said reservoir means to said display memory cell means for igniting gas displays in selected display memory cell means.

4. The apparatus of claim 3 in which said partitioning means comprises apertured plate means of electrically insulating material associated with said reservoir cathode means.

6. The apparatus of claim 1 in which said reservoir means comprises first reservoir electrode plate means having a plurality of apertures therethrough coupled with said gas conductive channels, respectively, first electrically insulating plate means adjacent said first reservoir electrode plate means having a plurality of apertures therethrough, second reservoir electrode plate means adjacent said first electrically insulating plate means having a plurality of apertures therethrough, second electrically insulating plate means adjacent said second reservoir electrode plate means having a plurality of apertures therethrough, spacer plate means adjacent said second electrically insulating plate means having openings therethrough each being associated with pluralities of said apertures for providing said weak coupling between said reservoir cells, and cover plate means adjacent said spacer plate Means, the above mentioned plate means being in superposed arrangement with respect to each other to form said reservoir means with said apertures aligned whereby to form said reservoir cells, respectively, said first and second insulating plate means forming said partitioning means, said first and second reservoir electrode plate means being adapted for connection to a source of ionizing potential for ionizing said gas in said reservoir cells.

7. The apparatus of claim 6 in which said first reservoir electrode plate means comprises substantially parallel first electrically conductive strips electrically insulated from each other, and said second reservoir electrode plate means comprises substantially parallel second electrically conductive strips electrically insulated from each other and transverse to said first strips.

9. The apparatus of claim 8 in which said first and second reservoir electrode plate means comprise reservoir anode means and reservoir cathode means, respectively, said strips being adapted for selective connection to a source of ionizing potential for ionizing the gas in the reservoir cells at the intersections of the energized strips.

10. Gas discharge display apparatus for displaying symbols comprising reservoir means for containing an ionizable gas, a plurality of gas discharge display memory cell means arranged in rows and columns, first addressing electrode plate means interposed between said reservoir means and said display memory cell means with a plurality of apertures therethrough arranged in rows and columns and having substantially parallel first electrically conductive addressing strips each encompassing a plurality of rows of said apertures to define the height of said symbols, second addressing electrode plate means interposed between said reservoir means and said display memory cell means with a plurality of apertures therethrough arranged in rows and columns and having substantially parallel second electrically conductive addressing strips each encompassing a plurality of columns of said apertures to define the width of said symbols, and third and fourth addressing electrode plate means interposed between said reservoir means and said display memory cell means each with a plurality of apertures therethrough arranged in rows and columns and having third and fourth electrically conductive addressing strips, respectively, substantially parallel to said first and second strips, respectively, for defining said symbols, said first, second, third and fourth addressing electrode plate means being in superposed arrangement with respect to each other with said apertures aligned to form a plurality of gas conductive channels extending from said reservoir means to said display memory cell means, respectively, said first and second addressing electrode plate means being adapted for connection to sources of selectible electrical potential for selectively applying potentials thereto for selectively extending gas discharge columns in said channels from said reservoir means to define the height and width of said symbols, said third and fourth addressing electrode plate means being adapted for connection to sources of selectible electrical potential for selectively applying potentials thereto for selectively extending gas discharge columns in said channels from said reservoir means to said display memory cell means for igniting gas discharges in selected display memory cell means to form said symbols.

11. The apparatus of claim 10 in which said third electrically conductive addressing strips encompass said rows of said apertures, respectively, and said fourth electrically conductive addressing strips encompass said columns of said apertures, respectively.

12. The apparatus of claim 11 in which at least one of said addressing electRode plate means includes electrically conductive interconnecting strips in substantially the same plane as said addressing strips for interconnecting said addressing strips to form a predetermined number of continuous non-overlapping strips disposed in a to-and-fro manner on said addressing electrode plate means.

13. Gas discharge display apparatus for displaying symbols comprising reservoir means for containing an ionizable gas, a plurality of gas discharge display memory cell means, and a plurality of addressing electrode means interposed between said reservoir means and said display memory cell means and each having a plurality of apertures therethrough, said plurality of addressing electrode means being in superposed arrangement with respect to each other with said apertures aligned to form a plurality of gas conductive channels extending from said reservoir means to said display memory cell means, respectively, said plurality of addressing electrode means being adapted for connection to sources of selectible electrical potential for selectively applying potentials to said addressing electrode means to selectively extend gas discharge columns in said channels from said reservoir means to said display means for igniting gas discharges in selected display memory cell means, said plurality of gas discharge display memory cell means comprising first and second display memory electrode means one of which having two portions electrically insulated from each other and adapted for connection to sources of gas discharge sustaining potential, respectively, said plurality of gas discharge display memory cell means being arranged in a matrix of rows and columns comprising a plurality of sub-matrices for displaying said symbols and a plurality of indicia cells associated, respectively, with said sub-matrices, said sub-matrices and said indicia cells being arranged on said two portions of said display memory electrode means, respectively, whereby said indicia cells may be ignited and extinguished independently of said symbols.

15. Gas discharge display apparatus comprising reservoir means for containing an ionizable gas, a plurality of gas discharge display memory cell means, a plurality of addressing electrode means interposed between said reservoir means and said display memory cell means and each having a plurality of apertures therethrough, said plurality of addressing electrode means being in superposed arrangement with respect to each other with said apertures aligned to form a plurality of gas conductive channels extending from said reservoir means to said display memory cell means, respectively, said plurality of addressing electrode means being adapted for connection to sources of selectible electrical potential for selectively applying potentials to said addressing electrode means to selectively extend gas discharge columns in said channels from said reservoir means to said display memory cell means for igniting gas discharges in selected display memory cell means, said plurality of addressing electrode means being further adapted for connection to sources of selectible electrical potential for selectively applying potentials to said addressing electrode means to selectively extend gas discharge columns in said channels from lit display memory cell means to said reservoir means, and means coupled with said reservoir means for sensing current associated with said gas discharge columns extended from said lit display memory cell means to said reservoir means thereby providing indications of the lit cells.