U.S. patent number 3,803,449 [Application Number 05/139,533] was granted by the patent office on 1974-04-09 for method and apparatus for manipulating discrete discharge in a multiple discharge gaseous discharge panel.
This patent grant is currently assigned to Owens-Illinois, Inc.. Invention is credited to Larry J. Schmersal.
United States Patent |
3,803,449 |
Schmersal |
April 9, 1974 |
METHOD AND APPARATUS FOR MANIPULATING DISCRETE DISCHARGE IN A
MULTIPLE DISCHARGE GASEOUS DISCHARGE PANEL
Abstract
There is disclosed unique methods and apparatus for manipulating
the discharge condition of selected discharge sites of a multiple
discharge gas discharge panel having transversely oriented,
insulated, row-column conductor arrays. Periodically applied
alternating pulses, particularly width modulated square pulses are
used to sustain as well as manipulate the discharge condition of
selected discharge sites in the panel.
Inventors: |
Schmersal; Larry J. (Toledo,
OH) |
Assignee: |
Owens-Illinois, Inc. (Toledo,
OH)
|
Family
ID: |
22487123 |
Appl.
No.: |
05/139,533 |
Filed: |
May 3, 1971 |
Current U.S.
Class: |
345/71;
345/209 |
Current CPC
Class: |
G09G
3/294 (20130101); G09G 3/293 (20130101); G09G
3/296 (20130101); G09G 3/297 (20130101) |
Current International
Class: |
G09G
3/28 (20060101); H05b 037/00 () |
Field of
Search: |
;315/169,169TV |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Saalbach; Herman Karl
Assistant Examiner: Dahl; Lawrence J.
Attorney, Agent or Firm: Zegeer; Jim Wedding; Donald
Keith
Claims
1. A method of manipulating the discharge condition of a gas
discharge information storage panel device having transversely
oriented dielectrically insulated conductors on opposite sides of a
thin gaseous discharge medium, which comprises applying a
periodically alternating pulse potential across said gas by
applying, in selectively timed relation, a first sequence of
electrical pulses to the conductors oriented in a first direction
and a second sequence of electrical pulses to conductors oriented
in a second direction transverse relative to the direction of said
conductors oriented in said first direction whereby the gaseous
medium between said conductors has said periodically alternating
pulse potential applied thereto, and constitutes a sustaining
potential for discharges at any site in said panel device and
modulating at least one electrical parameter of at least one pulse
of a sequence as applied to
2. The invention defined in claim 1 wherein the electrical
parameter that
3. The invention defined in claim 2 wherein a second of the
electrical parameters that is modulated is the amplitude of said
electrical pulses.
4. The invention defined in claim 2 wherein the time duration of
any of said electrical pulses is no greater than the time required
for substantially all electrons produced on a discharge to collect
on a surface of a dielectrically insulated conductor and an
insignificant number of ions produced during said discharge are
collected on an opposing
5. The invention defined in claim 2 wherein the pulse width is
widened so as to store information at a selected discharge site,
said selected site being located at the cross over point of a
selected pair of transverse
6. The invention defined in claim 2 wherein the pulse width is
narrowed so as to remove stored information at a selected discharge
site, said selected site being located at the cross over point of a
selected pair of
7. The invention defined in claim 1 wherein said pulse is deleted
on at least a plurality of conductors of one array so as to bulk
erase
8. The invention defined in claim 2 wherein said pulse width is
narrowed on at least a plurality of conductors of one array so as
to bulk erase
9. The invention defined in claim 2 wherein said pulse width is
widened for a selected time interval on at least a plurality of
conductors of one
10. A method of lengthening the life of a gas discharge storage
device having insulated conductors supplying gas discharge
condition initiating pulse potentials to the gas medium for
effecting one or more discharges therein, comprising
terminating said pulse potentials prior to impaction of significant
number
11. The method of claim 10 including the step of applying an ion
repulsing potential to said conductors following termination of
said discharge
12. The method of conditioning for reliable discharge manipulation
all discharge sites of a multiple discharge site gas discharge
panel wherein the sites are defined and located by transverse
row-column conductor arrays, said conductor arrays being isolated
from the gas by a charge storage layer of non conductive material,
and a synchronized sequence of rectangular shaped pulses are
applied to said row and said column conductors in the arrays,
respectively, which comprises periodically lengthening the time
interval of one of the pulses applied to all
13. The invention defined in claim 12 wherein information is
entered and removed on said panel by modulating the time interval
of said rectangularly shaped pulses and wherein in said step of
periodically lengthening the time interval is for a longer time
interval than the time
14. The invention defined in claim 2 wherein the pulse width is
under about
15. The invention defined in claim 14 wherein the pulse width is
between
16. The invention defined in claim 10 wherein said pulse width is
between
17. The invention defined in claim 12 wherein said pulse width is
between
18. In a system for manipulating and sustaining discrete discharge
sites of a gas discharge display panel wherein periodically
alternating pulses are continually applied to all conductors in
row-column conductor arrays of said panel, said conductors being
insulated from the gas, improvement in the means for manipulating
the discharge condition of discharge sites located by selected ones
of said row and column conductors, respectively, comprising means
for modulating the time duration of at least one of said
periodically alternating pulses to thereby alter the charge stored
at said
19. The invention defined in claim 18 wherein said pulse time
duration is initially selected to be such that during a discharge
interval, the electrons produced on discharge are stored and the
pulse terminated prior
20. The invention defined in claim 18 wherein said means for
modulating includes at least one conductor multiplex selection
circuit for selecting individual ones of said conductors
respectively and modulating the time
21. The invention defined in claim 20 wherein said multiplex
selection circuit includes means for adding a voltage increase to
the pulse whose
22. The invention defined in claim 20 wherein there is at least one
multiplex selection circuit for the row conductors and at least one
for
23. The invention defined in claim 22 wherein each selection
circuit includes means for adding a voltage increase to the pulse
whose time
24. The invention defined in claim 19 wherein said time duration is
less
25. The invention defined in claim 24 wherein said time duration is
between
26. The invention defined in claim 18 wherein said means for
modulating the time duration includes circuit means for
periodically simultaneously lengthening the time duration of a
pulse applied to all conductors of an array beyond that necessary
to initiate or terminate discharges, to
27. The invention defined in claim 18 including means for
simultaneously shortening the time duration of pulses applied to
all conductors of an array below the time duration necessary to
effect a discharge at any site.
28. The invention defined in claim 18 including means for
simultaneously lengthening the time duration of pulses applied to
all conductors of an array to at least the time duration necessary
to effect discharges at all sites located by said all conductors.
Description
The present invention is directed to providing a new method and
apparatus for sustaining, writing and erasing information on a
gaseous discharge panel of the non-cellulated type disclosed in
Baker et al. U.S. Pat. No. 3,499,167 and type disclosed in Bitzer
et al. U.S. Pat. No. 3,559,199. In the Baker et al. patent there is
disclosed a gas discharge display/memory device in which a pair of
glass plate members are joined in spaced apart relation, the glass
plate members carrying dielectrically coated multiple conductor
arrays, the row and column conductor arrays in the active panel
area being comprised of conductors extending parallel to the long
direction of the plates, respectively. The plates are joined by a
spacer sealant with their long axes transverse to each other with
the cross points of the conductor arrays defining a matrix or array
of discrete discharge sites each of which is discretely
manipulatable by control of the potentials applied to the
conductors.
Typically, the maintaining potentials for the discharge in such
panels and the discrete sites is constituted by a periodically
applied voltage, normally designated as the sustainer voltage. In
the past, such voltage could be a sine wave, square wave as well as
a number of other waveforms. In some cases, "gaps" were provided in
the sustainer voltage so as to permit addressing of discrete sites
in the panel as is disclosed in the aforementioned Bitzer patent
(as also disclosed in Mayer et al. U.S. Pat. No. 3,573,542).
Moreover, the discharge condition manipulating voltages may be
bipolar pulse potentials which are algebraically combined in
various ways and at various times with the sustainer potential to
manipulate the discharge condition, particularly in rapidly turning
off a selected discrete discharge site which has previously been
turned on.
In accordance with the present invention, the operation of
sustaining, writing and erasing information e.g. discrete
discharges and selected discharge sites in a discharge panel of the
general type disclosed in the aforementioned Baker et al. patent,
may be accomplished by a constant amplitude pulse square wave
sustainer with no additional circuitry required. Address
operations, as well as sustain operations are accomplished entirely
by means of modulation of the square wave pulses so as to control
the strength of the discharge. In addition, it is possible to
accomplish panel conditioning operations by means of a further
extension of this concept. Moreover, by utilizing a sustaining
waveform of the character disclosed herein, the aging is reduced;
that is, the change in electrical characteristics of the panel, as
a function of time for which they are burned or turned on, is
improved. In addition, this type of sustainer and control can yield
more light output and be more efficient than previous sustainer
systems.
With regard to circuit requirements, one primary advantage over
previous write/erase/sustain electronic systems for manipulating
the discharge condition of selected discharge sites of a gaseous
discharge panel, is that this invention permits elimination of
roughly half of the circuits required in previous address system.
Previous address systems, as indicated above, separated the
functions of the sustain operation circuitry from the write/erase
circuitry. The present invention accomplishes this operation within
the framework of the sustainer and control circuits therefore. This
invention may require more sustainers than in previous systems,
however, as will appear further hereinafter, the multiplexing
approach to such sustainers provides a degree of flexibility not
heretofore available.
The invention also permits writing or erasing on either the
positive or negative cycles of the sustainer at no additional cost
since this means that the sustainer must produce a write or an
erase pulse of an opposite polarity which the sustainers are easily
capable of providing. Moreover, only one power supply will be
required for writing and erasing and sustaining as well as even
conditioning the panel. With respect to the panel itself, there are
a number of notable advantages resulting from this invention. In
previous sustainer voltage designs, there were a number of
difficulties. When the sustainer voltage was at a sine waveform,
the discharges were not intense enough and did not produce enough
light. However, in square waves, even though enough light was
produced, the high current tended to limit panel life. All
waveforms, obviously, cause some modification of single individual
discharge site characteristics as a function of time. It is
believed that a significant contributor to this alteration in
discharge site characteristic is the discharge current, and, more
specifically, the ion current as opposed to the electron current in
the discharge. The present invention produces more light with
increased efficiency and at the same time reduces panel aging by
limiting ion impaction processes.
BRIEF DESCRIPTION OF THE DRAWINGS
The above and other objects, advantages and features of the
invention will become more apparent from the following
specification and drawings wherein:
FIG. 1 is a simplified diagram of a gaseous discharge panel device
and electrical diagram incorporating the invention,
FIG. 2 is an explanatory partial cross-sectional view, enlarged,
but not to proportional scale,
FIGS. 3A, 3B are simplified waveform diagrams illustrating one
basic feature of the invention,
FIG. 4A is a diagram showing the relation of electron and ion
currents in a discharge at one selection site as plotted against
time, and FIG. 4B shows the site characteristics as a function of
sustained pulse width for constant wall charging as well as the
peak current and change in wall voltage as a function of the
difference between firing voltage and applied sustain voltage,
FIGS. 5A, 5B and 5C illustrate three sustain waveforms which may be
used in the practice of the invention,
FIG. 6 shows the vertical or column sustain multiplexing circuit,
incorporating the invention,
FIG. 7 shows the horizontal or row sustain multiplexing circuit
incorporating the invention,
FIGS. 8A-8J shows the sustain and erase waveforms,
FIG. 9 shows the sustain waveforms for single discharge site
operation,
FIGS. 10A are waveforms for illustrating the bulk panel write
operation, FIG. 10B are wave forms for illustrating the bulk panel
erase operation, and FIG. 10C are waveforms for illustrating the
electronic "conditioning" operation panel and,
FIGS. 11A-11E are another set of waveforms for illustrating other
aspects of the voltage conditions for the write and erase
operations.
The discharge current of a selected discharge site in a gaseous
discharge display panel of the type referenced in the above
mentioned Baker et al. and Bitzer et al. patent consists
essentially of an electron and an ion current. The electrons are
attracted to and collect upon one boundary wall of the site (the
one which is instantaneously positive) and the ions to the opposite
or opposing wall or boundary for the discharge site, such
boundaries being defined by a dielectric or insulating coating on a
crossed conductor pair locating the site. The light output
resulting from the discharge is due almost solely to those
electrons which are energized or excited sufficiently to emit light
as a spindown from a higher energy state. The ion current
contributes little or nothing to the light output but does
contribute to the wall charging (see FIG. 4A). It is believed that
one of the primary causes of panel degredation due to light is the
bombardment of ions against the wall of a discharge site. This
causes cratering and other chemical and electrical changes in the
surface (FIG. 2 Sx and Sy) at each discharge site. The ions having
heavier mass, travel at a lower velocity. However, their impact is
1/2MV.sup.2. It has been found that the current discharge resulting
from both the ion and electron do not change to any great extent if
the sustainer width is in excess of 10 microseconds. This suggests
that the collection time required for roughly 90 percent of the
ions as well as 100 percent of the electrons is in that range. The
electron and collection time is around 500 nanoseconds. If the
sustainer pulse width is made to be considerably below 10
microseconds the result would be that fewer ions will be collected
at the wall. This results in reduced wall voltage but, at the same
time aging is reduced. While it is possible, and within the
contemplation of this invention, to terminate the sustainer pulse
voltage immediately after collection of all the electrons, to
thereby minimize the number of ions which will impact the wall of
the discharge unit, this may require that the sustainer voltage be
increased in amplitude. A basic aspect of this invention is that it
makes use of the fact that the amount of wall charge transfered per
each discharge is a function of the applied voltage and the
duration for which that voltage is applied.
In FIG. 1, a gaseous discharge display panel 10, constructed
generally in the manner disclosed in Baker et al. U.S. Pat. No.
3,499,167 is constituted by a pair of support plates 11 and 12 on
which are placed row (x) conductors 13 and column (y) conductors
14, the conductor arrays having dielectric or insulative coatings
15 and 15, respectively, applied thereto. The respective plates are
joined in spaced apart relation by spacer sealant means 17 to form
a thin gaseous discharge chamber in which may be placed a
neon-argon gaseous mixture as is disclosed in Nolan application
Ser. No. 764,577 filed August 1968. Other gaseous discharge mediums
may likewise be incorporated in the panel but the improvement
achieved by the use of the gas mixture recited above permits the
panels to be operated without thermal shock and at the same time
with good and efficient light output and memory margins. The
individual conductors 13-1, 13-2 . . . 13-N in row conductor array
13 are driven by a row conductor sustainer multiplexing circuitry
20 and the column conductors are driven by column conductor
sustainer multiplexing matrix 21. The selection matrices 20 and 21
receive input signals from a signal source, not shown, but which
may be a computer, keyset, tape, card reader or other data
source.
Referring now to FIG. 2, a section of the panel 10 is shown in
greatly enlarged cross-section to facilitate explanation of a basic
aspect of the present invention and, is to be considered in
relation to the waveforms illustrated in FIGS. 3A, 3B and
relationships shown in FIGS. 4A and 4B. As noted above, the
conductor arrays 13 and 14 are dielectrically or insulatively
isolated from the gaseous discharge medium 9 by thin dielectric
coatings on the conductor array which form charge storage surfaces
Sx and Sy for charges 25 and 26 produced on discharge. Basically,
two forms of charges are produced namely, ions 25 and electrons 26.
The time frame for the sweeping of charge particles from the gas
volumn between the surfaces Sx and Sy is dependent upon the applied
potential, spacing between the gap surfaces, gas pressure,
composition etc., has been set forth above. It will be noted in
this connection, and with reference to FIG. 3, the waveform shown
is the waveform of the sustainer voltage as applied across to gas
from conductor arrays 13 and 14. In FIG. 3A, it is shown as a
rectangular or square waveform and in FIG. 3B the current flow to
the panel corresponding to the discharges occurring during the
applied sustainer voltage are shown. The steep rise of the
sustainer voltage there is a capacitive charging current which is
indicated by the numeral 30 in waveform 3B. This capacitive
charging current charges the panel capacitance. Immediately
following the charging of the panel capacitance, there is a surge
of current constituted by ionization of the gas. This surge current
or discharge current 31 is the condition illustrated in FIG. 2
between conductor 31-1 and conductor 14-1. In this case, the
collection of electrons 25 opposite conductor 14-1 after a period
of time constitutes an internal bias voltage and is sufficient to
oppose the applied potential and hence terminate the discharge.
This termination of the discharge is indicated by a termination or
cessation of the flow of discharge current in FIG. 3B.
On alternation of the sustainer potential, as indicated at 35 (and
the .+-. signs) there is a small panel charging current 32 in the
opposite direction. And, assuming that the sustainer voltage is
maintained for a given period of time, at least the 10 microsecond
interval mentioned above, there will be a subsequent discharge 33
whereby the electrons 25 will be collected upon the dielectric
surfaces opposite conductor 13-1 and at the crossing point thereof
with conductor 14-1 to reverse the charge conditions shown in FIG.
2. This is illustrated in FIG. 2 between conductor 14-2 and
conductor 13-1, wherein ions 26 are tending to move towards the
conductor 14-3 and the electrons 25 as collected upon the surface
of dielectric storage member 15. When the sustainer potential
reverses again on the next period or interval, as is illustrated at
341 there will again be a small current 30' to charge capacitance
of the panel and following that, and again assuming that the
sustainer waveform exists or is present at the level illustrated
for the time interval mentioned above, there will be another
discharge current surge as indicated at 31' and the cycle repeats
itself.
Referring now to FIG. 4, an enlarged drawing of the applied
sustainer voltage Vs as it appears across the gas is illustrated
wherein the rise time or "front porch" is shown as dotted portions
of the waveform; the current pulses 30, 32 to charge the
capacitance of the panel has not been shown. The main current surge
is labeled as the "electron discharge current" and the second time
interval is labeled as ion discharge current. As indicated, the
collection time required for roughly 90 percent of the ions 26 as
well as 100 percent of the electrons 25 can be easily within a 10
microsecond interval so that if the sustainer voltage pulse width
is controlled, the ion collection time may be controlled. In the
following table there is compared the sustainer pulse width of 2
microseconds and 9 microseconds. The panel had 128 row conductors
and 128 column conductors, the conductors being spaced at 33 1/3
lines per inch with a discharge gap of about 4 mils and a
dielectric coating between 1 to 2 mils thick with a pulsed square
wave having a tsr of about 100 nanoseconds rise time and a .tau.sp
of about 27.5 microseconds. The number of discharge sites were on a
64 .times. 64 matrix or 4,096. ##SPC1##
From the foregoing table It will be noted that the voltages of the
panel for two different conditions goes up by roughly 20 volts and
the current drops in half with a light output increase by
approximately 50 percent as one goes from 9 microseconds to a 2
microsecond sustaining pulse width.
In FIG. 5, a number of different types of sustainer voltage
waveform which can be used in accordance with the invention are
illustrated. In all cases, the write and erase functions as well as
the collection of ions is controlled by controlling the widths of
the sustaining voltage wave form. The preferred waveform or the
most efficient one, is shown in FIG. 5A. In this waveform, a
negative voltage swing is used to deaccelerate the ions and permit
them to impact the wall at reduced velocity. However, it will be
appreciated that this negative voltage swing is not necessary in
order to achieve the improved results set forth hereinabove.
FIGS. 6 and 7 illustrate typical circuits which may be used in
practicing the invention. Although only a four line system is shown
in each case, it is obvious that it may be expanded to any size,
binary or decimal on either axis (x or y) with sector at a time
address capability or with random access capability.
The invention requires x and y sustainer generator sources which
may be similar to those shown in Wojcik application Ser. No.
135,022 filed Apr. 19, 1971, now U.S. Pat. No. 3,742,294 issued
June 26, 1973, but this invention is not limited to this type. The
outputs of such sustainer sources should be matched in terms of
logically controlled output pulse width uniformity. Control and
modulation of pulse width can be accomplished in accordance with
the circuits shown in FIGS. 6 and 7.
Referring to FIGS. 6 and 7, a portion of the vertical or columns
sustain address circuitry (FIG. 6) and the horizontal or row
sustain address circuitry (FIG. 7) are illustrated, respectively.
It will be appreciated that various other arrangements can be used
for supplying width modulated, square wave sustainer pulses to the
individual row and column conductors. However, the embodiments
illustrated in FIGS. 6 and 7 are preferred because this permits
multiplexing of the sustainer generators. The diode selection
matrix circuitry per se is disclosed in detail in Johnson
application Ser. No. 60,402 filed Aug. 3, 1970 and entitled
"Selection and Addressing Circuitry for Matrix Type Gas Display
Panel". However, an important difference is incorporated in the
present invention in that the sustainer voltage per se is used to
sustain, erase and write as well as perform other operations with
regard to manipulating the discharge sites of the panel.
Specifically, in FIG. 6, the numerals 50-1, 50-2, 50-3 . . . 50-N
indicate the connection points of this matrix to individual column
conductors or panel lines. Thus, 50-1 would be connected to
vertical or column conductor 14-1 . . . etc. to supply pulse width
modulated potentials to the column conductors and with respect to
FIG. 7, the horizontal or row conductors 13-1, 13-2 on the panel
are served or supplied with pulse width modulated potential from
the point in the matrix designated 60-1, 60-2 . . . 60-N,
respectively. Moreover, each such point 50 and 60 is, in effect,
the nodal point of a matrix selection element, each nodal point
including diodes D1 and D2 and a resistor the anode of diode D1 and
the cathode of diode D2 are connected to the nodal point for
pulsing in one polarity direction whereas, the opposite situation
prevails in connection with the horizontal address circuitry shown
in FIG. 7 namely, the diodes D3 and D4, respectively, which occupy
the same electrical position in the circuitry as do diodes D1 and
D2 in the circuit of FIG. 6, have their cathode and anode,
respectively, connected to the nodal point serving the conductor
line on the panel. It will be appreciated that this arrangement may
be reversed and the polarity circuitry shown to supply the row
conductors may be used to supply the column conductors and vice
versa.
As shown, all of the resistors R1, R2 . . . in a row of the
vertical or column sustain matrices, respectively, are connected
through a switching transistors TC1 to a source of supply potential
VCC. This voltage VCC may be used with a small control voltage
(.DELTA.V) to increase the select write voltage margin, if
necessary. The purpose of this added voltage is that in the event
that a half-select write operation range is not sufficient for a
good reliable panel electronic performance, the half-select margin
may be increased by this modification. There are other methods by
which the select voltage may be increased by the voltage .DELTA.V.
It should be noted that in all cases this need not actually be a DC
voltage but may be a pulse voltage occurring only during the
portion of the write cycle or any other portion of the cycle as may
be required. Thus, this pulse voltage could be added into the
system at the VCC source by means of either a transformer in series
(at point TRA, for example) with the power supply line so as to
induce a pulse at the proper time. By properly choosing the winding
of the transformer the sustain power supply voltage could be
utilized. As an alternate technique, one could use a floating power
supply with associated transistor switching circuitry to provide
either VCC or VCC modified as the output going to the point
designated in FIG. 6. As an alternative, capacitances can be made
an integral part of the panel 10, using the coatings 15 and 16 as
dielectric for coupling such voltages to the conductor arrays.
In FIG. 6, the multiplexing operates as follows: when LF1 is on
then all of the outputs (50-1, 50-N) are then driven to the VCC
voltage.
If transistor LE1 is on, then all the outputs associated with that
vertical line are driven low (50-1 and 50-3) so that LE1 or LE2
cannot be on when LF1 is on. If LD1 and LD2 with LE1 and LE2 can be
used to select one output to the VCC + .DELTA.V level, and the rest
low, which is a situation illustrated in FIG. 6 wherein LV1 is on,
LB2 is off, LE1 is on, and LE2 is off, this causes V2 to go high
with all other low. LF1 is not used in addressing but only in
sustaining.
Referring now to FIG. 7 showing the row sustain address multiplex
circuitry 20, the multiplexing operation is as follows: when LC1 is
on then all of the outputs (60-1, 60-2 . . . 60-N) are driven low
or to ground potential. When LA1 or 2 is on then all of the outputs
associated with the vertical line driven thereby are high (at the
voltage VCC); that is, the lines 60-1 and 60-3 are on. LA1 and LA 2
cannot be on when LC1 is on. Moreover, lines LA1 and LA2 with LB1
and LB2 may be used to select one output to ground with all other
outputs at the high voltage level of VCC. As shown in FIG. 7, LB1
is on, LB2 is off, LA1 is on and LA2 is off so that this causes
line 60-2 to be at ground potential with all other lines 60-1,
60-3, and 60-N to be at the high VCC voltage level. Moreover, LC1
and LA1 and LA2 may be used to sustain the panel in this
configuration.
In order to more fully explain and illustrate various aspects of
the invention, particularly regarding the erase operations, there
is shown in FIG. 8 voltage waveforms for illustrating a single
discharge site erase operation. In this illustration, the
horizontal and vertical sustainer waveforms are illustrated in FIG.
8A and 8B respectively. The application of the horizontal select
and horizontal non select voltage pulses are shown in lines 8C and
8D respectively and the vertical select and vertical non select
voltage wave forms are shown in lines 8E and 8F respectively.
Waveform 8G shows the sustain voltage as seen by a single site. It
will be noted that the normal sustain voltage preceding the erase
operation or erase cycle occurs within the interval indicated and
modifies only the pulse width of the sustainer voltage at the
selected site. In the case illustrated, the normal sustainer pulse
width is narrowed so that while there may be a small charging
current to charge a panel capacitance, the sustainer voltage is
removed, effectively, prior to the initiation of the discharge so
that there is no discharge during the half cycle of sustainer. This
removal of the sustainer thereby permits, during that time interval
participation of some of the stored charge so that on the next half
cycle, which is still in the same direction as the previous half
cycle having had a normal discharge, there is still not another
discharge because the charges are still bucking in effect the
applied potential thereby providing additional time for dissipation
of the stored charge. Hence, when the next pulse voltage appears,
even though it will be the noraml sustaining voltage and of normal
width, due to the dissipation of the stored charge as described,
there will be subsequent discharge at that sight.
FIG. 9 illustrates a single write operation and waveforms. The
method for providing 1) bulk write, 2) bulk erase and 3) electronic
conditioning (as described in the aforementioned Baker et al. and
Bitzer et al. patents) using the same constant voltage sustainer
signal is shown in FIG. 10. Notice that the erase pulse is slightly
narrower than the normal sustain pulse width and that the write
pulse width is wider than the normal sustain pulse width. The
electronic conditioning pulse width is even wider than the normal
write pulse width but less than 15 ms. Note also the required
sequence with respect to conditioning, writing and erasing as to
permissible places where it might occur with respect to the phase
of the sustain waveform. It is not illustrated, but it is obvious
that the inverted signals could just as easily be generated since
there is control over the pulse duration for either the zero
condition or the Vs sustainer amplitude level. The anticipated
range of sustained pulse width which may be utilized in this
technique is between 0.8 microseconds to 5 microseconds in
duration.
From the foregoing it is apparent that by means of the present
invention:
1. write/erase operations for the panel are accomplished by means
of controlling the sustainer pulse width alone;
2. there is elimination of cost with respect to write/erase
circuitry and the elimination of power supplies associated with
same;
3. the number of lines going to the panel to be used to control the
panel are significantly reduced and is in direction proportion to
the number of sustainers for each plane, x or y (assuming that
conductor selection matrice diodes and resistor are on the panel as
in my patent application Ser. No. 62,015 filed Aug. 7, 1970);
4. the manner in which the actual address function may be
manufactured into the panel by leaving holes in the dielectric in
combining selected lines for proper connection to the various
sustainers;
5. this write/erase technique uses a method of increasing panel
life through circuits;
6. electronic "conditioning" may well be also incorporated into the
same technique;
7. bulk erase operation; and
8. bulk write operation;
9. the particular waveforms contemplated herein applies narrow
square pulses which cause a discharge to occur and after the
electrons have flowed across the gap and established the wall
charge, this potential is removed so that the ions which are slower
moving particles due to their mass, do not have an electric field
to impact them into the dielectric or wall surfaces Sx and Sy,
respectively. As a result, the extent to which ions are driven into
the glass wall at Sx and Sy sites which is considerably reduced by
this waveform. This method is specially advantageous to square wave
drive since the discharge current is approximately 10 times that of
sine wave discharge.
The invention is not to be limited to the exact forms shown and
described herein for many changes and modifications may be made,
some of which are suggested herein, within the scope of the
following claims.
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