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Publication numberUS3673461 A
Publication typeGrant
Publication dateJun 27, 1972
Filing dateJun 8, 1970
Priority dateJun 8, 1970
Publication numberUS 3673461 A, US 3673461A, US-A-3673461, US3673461 A, US3673461A
InventorsMark F Eisenberg
Original AssigneeBurroughs Corp
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Circuit for driving the cathodes of a display device
US 3673461 A
Abstract
A multiphase circuit for driving the cathodes of a gas cell display device utilizing transistor drivers for sequentially driving each phase and switching circuitry cooperating with the drivers for de-energizing the previously "on" cathodes and rapidly shutting off the previously operating driver. The cells energized by an "on" cathode are caused to glow when there is a concurrent signal on the proper anode. The output of each driver is coupled to a switching transistor which, when caused to conduct, feeds a standoff voltage to a preceding phase and the collector of the driver associated with that phase, rapidly restoring the phase to a voltage level below the ionization point of the gas cells. A resistor across the emitter and base of the switching transistor maintains a proper bias and a diode across its collector and emitter protects the switching transistor from surges at shutdown.
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United States Patent Eisenberg 51 June 27, 1972 CIRCUIT FOR DRIVING THE CATHODES OF A DISPLAY DEVICE [72] Inventor: Mark F. Eisenberg, North Plainfield, NJ.

[73] Assignee: Burroughs Corporation, Detroit, Mich.

[22] Filed: June 8, 1970 [21] Appl.No.: 44,434

Primary Examiner-Roy Lake Assistant Examiner-Lawrence J. Dahl Attorney-Kenneth L. Miller and Charles S. Hall [57] ABSTRACT A multiphase circuit for driving the cathodes of a gas cell display device utilizing transistor drivers for sequentially driving each phase and switching circuitry cooperating with the drivers for de-energizing the previously on" cathodes and rapidly shutting off the previously operating driver. The cells energized by an on" cathode are caused to glow when there is a concurrent signal on the proper anode. The output of each driver is coupled to a switching transistor which, when caused to conduct, feeds a standoff voltage to a preceding phase and the collector of the driver associated with that phase, rapidly restoring the phase to a voltage level below the ionization point of the gas cells. A resistor across the emitter and base of the switching transistor maintains a proper bias and a diode across its collector and emitter protects the switching transistor from surges at shutdown.

7 Clainm, 6 Drawing Figures PATENTEDJum I972 3, 573 .461

sum 10F s (PRIOR ART) FIG. 2

FIG. 6. |oo 5b \"IZO/ loo 4o M. F. EISENBERG ATTORNEY PATENTEDJum I972 3.673.461

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CELLS 50A CELLS 50B CELLS 50C CELLS 500 IOOA I I I CATHODE IO'OB I I VOLTAGE IOOC I I IOOD I I I I H t2 t3 t4 t5 INVENTOR M. F. El SEN BERG ATTORNEY CIRCUIT FOR DRIVING 'II'IE CA'II-IODES OF A DISPLAY DEVICE BACKGROUND OF THE INVENTION The present circuit relates to panel display devices of the type which include large numbers of gas-filled cells arrayed in rows and columns and energizable selectively to display a character, message or any other form of display. Such devices have just begun to be commercially feasible with the problems of many prior art devices being solved by various techniques such as the improved driver circuit of this invention. In general, such display devices have included at least two electrodes, an anode and a cathode, for each cell, and a separate driver circuit for each cathode and each anode, or for each column of cathodes and each row of anodes, for applying thereto the voltage needed to turn on each cell and generate visible glow therein.

In a recent development panel structures, utilizing glow transfer between neighboring cells, have allowed a phase driving technique to be employed where grouped cathode drivers of relatively low voltage output energize a number of columns of cathodes simultaneously, but only a neighbor to a previously on column will be sufficiently ionized to conduct and emit glow. Therefore, while a number of columns of cells are potentially energized by the output of a particular phase a driver, only the column of cells defined by a cathode adjacent to the previously energized column will glow when the row anodes are energized.

Prior art driver circuits used in the improved multiphase systems were essentially the same as those used where a driver was associated with each column cathode. They comprised a transistor, or other active element, driver whose output was connected to the particular column or phase to be energized. A clock pulse on the control electrode of these drivers caused them to conduct while the absence of the pulse stopped conduction. Once the pulse was removed, a period of time was required to allow the driver to stop conducting and to bring the energized stage to a voltage level below an ionizing state. The reset time was excessively long for high speed displays and a greater amount of power was required than was theoretically needed. Also, prolonged glow could appear in the column in which conduction was supposed to have ceased.

It is, therefore, the object of this invention to rapidly shut down a previously driven stage of a multistage cathode driver circuit of a gas cell display device and to rapidly restore its voltage to a non-ionizing level while simultaneously driving the desired phase.

SUMMARY OF THE INVENTION To accomplish the above object the invention utilizes a driver which, when caused to conduct by an activating pulse drives the cathodes of the gas cell display panel associated with its output phase and simultaneously causes a switching circuit to energize. The output of a transistor in the switching circuit is fed to the adjacent cathode activated by the previous phase to rapidly restore it to a non-ionizing voltage. This output from the on phase also cuts off current flow from the driver of the previously activated stage.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a gas cell display panel with which the invention may be utilized;

FIG. 2 is a sectional view along the lines 2-2 in FIG. 1, with the dimensions and number of display cells being changed to simplify the drawing;

FIG. 3 is a schematic representation of the panel of FIG. 1 and an electronic system in which it may be operated;

FIG. 4 shows qualitatively the anode current which flows in some of the cells of the panel of FIG. 3 during a portion of a cycle of operation;

FIG. 5 shows cathode voltages applied to some of the cells in the panel of FIG. 3 during a portion of a cycle of operation;

FIG. 6 is a circuit diagram of the three phase cathode driver circuitry of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT A gas-filled display device 10, with which the invention may be utilized is shown in FIGS. 1 and 2 in the form of a flat panel and comprises a sandwich of flat plates including a central plate 20 of glass or ceramic, a top viewing plate 30 of glass, and a bottom plate 40 of glass or ceramic. The central plate 20 is provided with rows and columns of holes or cells 50, and it has a top surface 60 and a bottom surface 70. The cells 50 are operated as information display cells and are filled with a gas of the type which can sustain cathode glow.

The device 10 is provided with a top set of parallel electrodes and a bottom set of parallel electrodes 100, with the sets being perpendicular to each other and arrayed so that each cell has two electrodes, one at the top of the cell and one at the bottom of the cell. A cell is fired and caused to glow by the application of suitable potentials to the electrodes 80 and which cross each other at the particular cell. In the following description, the upper electrodes are considered to be anodes, and the lower electrodes are considered to be cathodes, and, for purposes of this description, the device 10 is oriented so that the anodes are row electrodes and each is aligned with a row of cells, and the cathodes are column electrodes and each is aligned with a column of cells.

The electrodes may be flat metal strips, or they may be wires, and they may be seated in slots or depressions, either in the central plate or in the top or bottom plates, if desired. In addition, the upper conductors 80, if they are flat strips, are provided with holes 90 (FIG. 2) where they overlay cells 50 to permit a glowing or fired cell to be seen by a viewer looking through top plate 30 when the device 10 is in operation. Viewability of cells can also be achieved if electrodes 80 are wires which are narrower than the cells 50 and do not cover the cells completely.

The central plate 20 and the top and bottom glass plates 30 and 40 are usually rectangular, with the top and bottom plates being somewhat larger than the center plate (shown only in FIG. 2) to permit a sealing material 42, such as a glass frit, to be placed between them to seal all of the plates together in a gas-tight assembly. The row and column conductors extend beyond the edges of the plates so that they can be readily connected to electrical circuitry.

It is known that a gas cell, which is exhibiting glow, generates excited particles including gas ions, electrons, uncharged metastable atoms, and the like. Means are provided for permitting selective gas communication and the flow of such excited particles from a glowing or fired cell to ad jacent cells in the panel, particularly for permitting communication in the direction in which glow is to be propagated from cell to cell. This free flow and availability of excited particles facilitates the selective transfer of glow from a fired cell to an adjacent cell. This permits a simplification in the drive circuitry which is described in greater detail below.

One arrangement for providing the desired gas communication comprises slots fonned in the central plate 20. The slots may be provided at various locations in the plate 20 as described in copending application Ser. No 850,984 of coownership herewith. Depending on the mode of operation of a panel, the slots 120 may extend between adjacent anodes and/or between adjacent cathodes, as will be clear from the description below.

A display panel 10 utilizing the invention may include any desired number of rows and columns of display cells 50 for displaying a message and, in addition, a group of cells 508 known as starter cells, or particle-supply cells, for providing excited particles for expediting the tumon of the information display cells 50. In one embodiment of such a display panel, including circuitry, illustrated schematically in FIG. 3, display panel 10 includes columns of display cells 50A, 50B, 50C, etc., and a column of particle-supply cells 508 to the left of the column of cells 50A. Each cell 508 is connected to the adjacent cell 50A by a slot 120. In addition, the particle-supply cells are connected together by column slots 126. The cells 508 have their own column cathode 100S connected to a suitable power source or driver 161, and they share the anode electrodes 80 with the display cells 50. The particle-supply cells 50S need not be, and are preferably not, seen by a viewer and may be obscured by the upper anode electrodes associated therewith.-

The panel 10 of FIG. 3 also includes a keep-alive" mechanism or a source of first electrons which, as is well known in the art, are required to initiate glow discharge in a gas cell. The keep-alive mechanism comprises a column of gas cells 123 positioned in operative relation with the supply cells 505 and having their own anode 124 and cathode 125. Such cells 123 are constantly energized and glowing but are concealed from view. The keep-alive mechanism may comprise just a single cell 123 adjacent to one of the supply cells 508 and having its own anode 124 and cathode 125 connected to voltage supply Vk, by means of which it is continuously energized and held on and glowing.

In general terms, the display panel 10 is operated in a scanning mode in which each column of display cells is turned on, in turn, from left to right, and the glow in each column is modulated in accordance with input signal information. The scanning operation is repeated continuously at such a rate that a stationary but changeable message is displayed by the panel.

in one mode of operation of panel 10, operating potential is first applied to the particle-supply cells 505, and these cells turn on with the aid of the keep-alive cells 123. These cells 508 are also referred to as reset cells since they serve to reset the column scan of the display panel to the first column. The glowing gas incells 50S produces excited particles which diffuse in all directions and through slots 120 to the adjacent OFF cells 50A. Next, operating potentials are removed from cells 508 and are applied to cells 50A in the first column of display cells, and these cells 50A turn onrelatively easily because of the excited particles which have diffused to them through slots 120, and because of the excited particles still present in the extinguished cells 508 which are attracted to them by the applied potentials. As cells 50A turn on," the glow in them is modulated in accordance with input signal information applied to the'row anodes 80. While cells 50A are on," excited particles diffuse from them through slots 120 to cells 508. Next, operating potentials are removed from cells 50A, and they are applied to cells 508, and cells 508 are energized, just as cells 50A had turned on previously. The glow in cells 503 is then modulated in accordance with input information on anodes 80. Each column of cells, in turn, is turned on" in this same way, with new signal infonnation being applied to anodes 80 as each new column is turned on, and, when the last column is reached, the cycle is repeated, at such a rate that a message is displayed in the panel.

Considering FIG. 3 in greater detail, circuitry for operating the panel 10 includes a source of information signals 144, of any suitable type, which is coupled to the inputs of recirculating shift registers 145. The outputs of the shift registers 145 are individually coupled to and operate anode drivers 130, which are in the form of current sources connected to the row anodes 80. A clock circuit 164 operating in the range of 5 to 20 Kb: is connected to and operates in synchronism the information source 144, the shift registers 145, and a counter 162.

The column cathode electrodes 100A, 1008, 100C, etc., of panel are connected in groups to form three sequential stages, the first, second and third cathodes being connected respectively, to each third subsequent cathode. Thus, the cathodes 100A, 100D and 1006 are interconnected; and the cathodes 100C, 100F and 100! are interconnected. Each of these groups of cathodes is connected respectively to outputs 160A, 1608 and 160C of multiphase driver or switching circuitry 160 for applying operating potentials to the cathode groups. Negative-going pulses are applied by the driver circuitry 160, and these cooperate with corresponding relatively positive anode voltages, generated by the anode drivers 130, to initiate and control cell glow. Counter 162 operates the cathode driver outputs 160A, 1608 and 160C sequentially and, as noted, the counter is coupled to a clock circuit 164 to provide the required synchronism between the energization of the respective cathodes and the application of signal information to the anodes, as known in the art.

In the operation of the panel 10, first, all of the anode current drivers 130 are turned on to apply an energizing level of positive potential to all of the row anode electrodes 80, and, at the same time, a potential, negative with respect to the anodes, is applied to the cathode 1005 by driver 161, whereby current flows through the particle-supply cells 508, and they turn on" and glow. The tum-on of cells 508 is facilitated by the keep-alive cells 123. As cells 508 glow, they generate excited particles which diffuse into slots and into the first column of display cells 50A.

Next, cathode driver 161 of cells 508 is turned off, and the first cathode driver output 160A is energized to apply a negative potential to cathode 100A associated with cells 50A. This also has the effect of applying a negative potential to cathodes 100D and 100G associated with cells 50D and 50G, respectively, but these cells have not been partially ionized by a neighbor cell and do not conduct. All of the current sources are still set at the level which provided the tum-on current for cells 508, so that a rapid glow transfer to cells 50A is achieved.

Typical anode current curves and cathode voltage curves are shown in FIGS. 4 and 5. During the transfer or switching period, when driver 161 is turned off the first cathode driver output A is in operation, the resultant potential across cells 50A combines with the excited particles present in cells 50A by diffusion, and the large numbers of particles attracted by the applied potential, to cause cells 50A to turn on" and current flows through cells 50A. The potential on the anodes 80 then drops to a relatively low level.

The more remote cells 50D and 50G, which are also coupled to the first cathode driver output 160A, do not have the proper combination of applied voltage and accessibility to the supply of excited particles to cause them to turn on" and glow. The reason for this is that, either because the lifetime of the excited particles of the cells is short or because they are removed at the cell walls or electrodes, these particles are available for only a relatively short time, and they are not likely to travel, at least in any quantity, farther than one column of cells. However, the primed adjacent cells require much less voltage for activation than the reset cells 508, and the unprimed cells do not conduct, so that the panel can consequently be scanned with only three column drivers 160A, 1603, 160C regardless of the number of cathodes in the panel.

The waveforms of FIG. 4 illustrate the turn-on anode current flowing through all cells 50A at time tl, which represents the time at which operating potential is first applied to cells 50A by driver 160A, as shown in FIG. 5.

Shortly after cells 50A are turned on by output 160A, the anode current flow through the drivers 130 is modulated in accordance with the received signal information. This modulation is a control of the anode current level at various levels between a very low level which is insufficient to render the cell visible and a very high level which is sufficient to produce a very bright glow discharge. Also, it includes intermediate levels to produce a gray scale display. Once set, the current level remains fixed for one column scan period, although this is not essential, but the level is changed as the scan proceeds from column to column, as required by the signal information from source 144, to produce a display corresponding to such information.

At time :2, the first cathode driver output 160A is turned off, and the second cathode driver output 1605 is turned on, to apply cathode potential to cells 508, the potential also being applied to cells 505 and 501-1. Simultaneously, the intensity of the current flow from the anode drivers 130 (FIG. 3) is increased to a high level, so that a rapid transfer of the glow to the second column of cells 508 is achieved, facilitated by the transfer of clouds of excited particles through slots 120.

This transfer operation is repeated for each column of cells along the entire display device from left to right until the last column of cells is reached, and its selected cells are turned on at the desired levels, at which time all cathode drivers 160 are turned off and the starter or reset cells 508 are energized again by driver 161, and the cycle is repeated.

The foregoing scanning cycle is repeated continuously at a sufficient rate, such as 50 to 20 Khz, that the cells which are energized for only short periods during each scan appear to remain on, without any visible flicker, and display a stationary but changeable message. As the signal inputs to the anode current drivers change, the modulated anode currents also change and so does the visible message.

An improved three stage circuit employing active elements for driving the cathodes 100A 100K is shown in FIG. 6. NPN transistors 171, 170, 172 have their bases respectively connected to inputs 163, 166, 165 from counter 162 and their collectors respectively connected to outputs 160A, 1608 and 160C of the driver circuitry 160. The emitters of the transistors 171, 170, 172 are grounded.

PNP transistors 174, 175, 176 have their collectors respectively connected to the collectors of transistors 171, 170, 172, and their emitters connected to a 1 l0 volt stand-off voltage at 180. Protective diodes 183, 184, 185 have their anodes respectively connected to the emitters of transistors 174, 175, 176 and to the l volt stand-off voltage 180. The cathodes of protective diodes 183, 184, 185 are respectively connected to the collector outputs of transistors 171, 170, 172. Biasing resistors 177, 178, 179 are respectively connected between the l 10 volt standoff voltage 180 and the bases of transistors 174, 175, and 176. Resistors 187, 173 and 186 respectively couple the collector outputs of the driving transistors 171, 170, 172 to the bases of the switching transistors 176, 174, 175. With no signal applied at inputs 163, 166 or 165 of driver circuitry 160 there is no current flow in the system thereby maintaining the l 10 volt stand-off voltage 180 at the collectors of transistors 171, 170, 172.

Referring to FIGS. 3, 5, and 6, at time 22 the first cathode driver having output 160A is turned off and the second cathode driver having output 160B receives a pulse from counter 162 at input 166 of the driver circuitry 160. FIG. 6 shows the driving circuit 160 for providing the three phase signals at 160A, 1608, and 160C. A positive signal from counter 162, on input 166 is fed to the base of driver transistor 170, causing it to conduct. As driving transistor 170 is turned on, transistor 171 is simultaneously turned off by returning its base potential to ground through input 163 from counter 162. The voltage at the collector of the driving transistor 170 will be pulled to ground potential while in a conducting state. This signal will be coupled through resistor 173 to the base of transistor 174. The potential, therefore, at the base of 174 will be negative withrespect to the l 10 volts at the emitter. Since transistor 174 is an NPN type it will be turned on as its base is driven in a negative direction.

Prior to the turning on of transistor 170 no current flow was produced at output 1608 and the potential at node 181, between the collector of transistor 175 and resistor 173 was held at approximately 110 volts. With no current flow in this phase the voltage at note 182 at the base of transistor 174 was also 110 volts. Since both the base and emitter of transistor 174 were at the same potential of l 10 volts prior to the turn on of transistor 170, transistor 174 was in a non-conducting state. A positive goingsignal to transistor 170 will cause it to conduct and its output coupled through resistor 173 will bias transistor 174 into a conducting state. Current from the 110 volt source at the emitter of transistor 174 will, therefore, be fed through the collector and to the previous stage. Switching transistors 175, 176, similarly, when caused to conduct, feed current from the 1 10 volt supply to the previously on" stage.

For example, if the anode electrode potential for anode driver 130 is in the neighborhood of 200 volts, the difference in potential between the anode and a turned on cathode at ground potential would be 200 volts. Providing the glow transfer conditions, previously discussed, exist at the on" cathode column, the gas in the selected cells of the cathode column will completely ionize and glow. When the 110 volt stand-off voltage is fed to the cathodes associated with output 160A, for example, the difference in potential is sufficiently small as not to cause the cells in columns A, 100D or 1006 to glow even though the related anode is energized.

The potential on the cathodes associated with output 160C at this time is similarly at 1 l0 volts, since there is no current flow in that particular phase. The volts previously placed on the phase associated with output C has no path for current flow and the phase is kept at this level until current flow is resumed. The output at 160B, on the other hand, is substantially at ground potential while is conducting, as was previously discussed. The potential difference, therefore between the anodes and cathodes of columns 100B, 100E and 1001i may be as high as 250 volts. This is sufficient to cause selected cells connected to the 1608 output to fire, providing of course that a neighbor column sufliciently excites the cells, as previously discussed (i.e., by glow transfer). The current from the l 10 volts being fed through 174 also forces transistor 171 to turn off faster by pumping more current into its collector. The speed of turn-off of transistor 171 is greatly increased and output 160A can be clamped at 1 10 volts in the order of a microsecond.

It is possible to have a surge of over 110 volts at output 160A when this phase is shut off. To protect transistor 174, diode 183 keeps the transistor from being reverse biased. Thus if the voltage tries to rise above 110 volts at 160A the diode 183 will clamp the potential of 160A at 110 volts. Similarly diodes 184, 185 protect their respective transistors 175, 176.

As a positive going signal is fed to the base of transistor 172 (corresponding to t3 in FIG. 5), transistor 170 is simultaneously shut off. The collector of 172 and the base of transistor are pulled toward ground potential, as in the previous stage. Transistor 175 is then turned on thereby permitting current from the l 10 volt stand-off voltage supply to pass through transistor 175 to the collector of transistor 170 aiding in a shorter turn off time for that device. Transistor 174 is turned off at this time by the positive 110 volt potential at node 182 from resistor 173 and node 181. The cathodes associated with output 160C are now at ground potential and may cause the associated cells to fire should the conditions previously disclosed be met. Since the electrodes associated with the output 160A are essentially capacitors when in a non-discharge mode the cathodes maintain their 110 volt potential. Transistor 171 as previously discussed is also non-conducting.

When a positive signal from the counter output 163 (corresponding to t4 on FIG. 5) is applied to the base of transistor 171 it is turned on while transistor 172 is simultaneously turned off. The collector of transistor 171 and the output 160A are now pulled to ground potential. The base of transistor 176 is also brought toward ground potential thereby turning on transistor 176. Current from the 110 volt stand-off voltage supply is then passed through transistor 176, decreasing the time required to shut off transistor 172 and clamping the cathodes associated with output 160C at 110 volts (i.e., preventing firing of the cells associated with those cathodes). The potential at 174 is maintained at 110 volts by the capacitive effect of the electrodes, ,as previously discussed. The cathodes associated with the turned off transistors 170 and 172 maintain their charge since there is no path provided for leakage current, once these transistors have been turned off.

As can be seen from the above explanation selected phases of the display device may be activated and, through efiicient switching means, the previously on stage can be positively and quickly turned off.

While the preferred embodiment, as disclosed above, utilizes transistors as the active elements in the driver and switching circuitry it can be seen, by one skilled in the art, that other active elements may be substituted therefor. The

preferred embodiment also drives cathodes associated with gas cells of a display device but any set of electrodes which are to be sequenced in rapid order may be driven by the disclosed circuitry. I claim 1. A multiphase circuit for energizing and de-energizing electrodes of a display device, said electrodes being respectively associated with individual phases of said circuit, com prising:

driving means individual to each of said phases for changing the potential on said electrodes associated therewith from a non-energized state to an energized state,

input trigger means for selectively activating said driving means, and a a plurality of active means respectively responsive to the activation of individual ones of said driving means for rapidly restoring to a non-energized state the electrodes energized by a previously activated driving means.

2. The multiphase circuit of claim 1 wherein said electrodes are interconnected in groups, each group being associated with an individual phase of said circuit, said trigger means causing said driving means to be activated sequentially, and each driving means having one of said active means responsive to its activation for rapidly shutting ofi the previously activated driving means in addition to restoring to a non-energized state the electrodes energized thereby.

3. The circuit according to claim 2 wherein said active means includes a transistor biased to conduction by the activation of said driving means.

4. The circuit according to claim 3 also including diode protective means coupled to said active means for preventing reverse biasing of said active means during said rapid shutting off of said previously activated driving means.

5. A circuit for energizing and de-energizing electrodes, the electrodes being interconnected in groups comprising:

a plurality of pulse-triggered drivers having their outputs connected respectively to said groups of electrodes,

means for sequentially triggering said drivers into substantially full conduction for energizing said groups of electrodes, and

individual de-energization means coupled to the output of each of said drivers and responsive to the conduction thereof for rapidly shutting off the previously triggered driver and for rapidly restoring the group of electrodes energized thereby to a non-energized state.

6. A display device comprising:

a display panel having a plurality of gas-filled display cells arranged in rows and columns,

first electrodes individually associated with each row of cells and second electrodes individually associated with each column of cells for energizing said gas-filled cells,

said second electrodes being interconnected in groups,

means applied to said first electrodes for producing an operating potential therein,

pulse-triggered means individual to each of said groups of second electrodes for energizing said groups,

counter means for sequentially triggering said individual energizing means, and

potential-applying switching means actuated by the output of each said individual energizing means for shutting off the previously triggered energizing means, restoring the electrodes energized thereby to a non-energized state, and rapidly de-energizing the related gas-filled cells.

7. In a display device having anode and cathode electrodes,

a high speed cathode driver circuit comprising:

a plurality of driver means for selectively energizing said cathode electrodes,

counter means for sequentially activating and deactivating said driver means, and

transistor means coupled between each of the outputs of said driver means and actuated by the output of the activated driver means for rapidly reducing to a de-energized state a previo rsly ensrgi ed electrode.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2995682 *Jan 28, 1960Aug 8, 1961Sylvania Electric ProdSwitching circuit for use with electroluminescent display devices
US3509420 *May 2, 1968Apr 28, 1970Burroughs CorpDriver circuits for display devices with spurious glow eliminating circuit
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3793629 *Jan 5, 1973Feb 19, 1974Philips CorpElectrical display devices
US3826949 *Jun 27, 1972Jul 30, 1974Sony CorpDisplay device and method of making the same
US3971465 *Nov 27, 1974Jul 27, 1976Burroughs CorporationSelf-scanning electrostatic print head for a dot matrix printer
US4887074 *Jan 20, 1988Dec 12, 1989Michael SimonLight-emitting diode display system
DE2246047A1 *Sep 20, 1972Apr 4, 1974Litton Industries IncDarstellungsanordnungen
Classifications
U.S. Classification345/60, 348/E03.14
International ClassificationH01J17/49, H04N3/12, G09G3/29
Cooperative ClassificationG09G3/29, H04N3/125, H01J17/494
European ClassificationH04N3/12G, G09G3/29, H01J17/49D2