U.S. patent number 3,881,129 [Application Number 05/314,738] was granted by the patent office on 1975-04-29 for gas discharge device having a logic function.
This patent grant is currently assigned to Fujetsu Limited. Invention is credited to Shizuo Andoh, Hiroshi Furuta, Norihiko Nakayama, Toshinori Urade.
United States Patent |
3,881,129 |
Nakayama , et al. |
April 29, 1975 |
**Please see images for:
( Certificate of Correction ) ** |
Gas discharge device having a logic function
Abstract
A gas discharge device which has less external terminals than
discharge cells formed by intersections of electrodes and which is
driven to achieve a logical multiplying or like logical operation
between the external terminals and the electrodes forming the
discharge cells.
Inventors: |
Nakayama; Norihiko (Kobe,
JA), Furuta; Hiroshi (Akashi, JA), Andoh;
Shizuo (Kobe, JA), Urade; Toshinori (Kobe,
JA) |
Assignee: |
Fujetsu Limited (Kawasaki,
JA)
|
Family
ID: |
11742708 |
Appl.
No.: |
05/314,738 |
Filed: |
December 13, 1972 |
Foreign Application Priority Data
|
|
|
|
|
Dec 15, 1971 [JA] |
|
|
46-10167 |
|
Current U.S.
Class: |
345/67;
345/60 |
Current CPC
Class: |
H01J
11/00 (20130101) |
Current International
Class: |
H01J
17/49 (20060101); H05b 037/00 () |
Field of
Search: |
;315/169R,169TV |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Rolinec; Rudolph V.
Assistant Examiner: Dahl; Lawrence J.
Attorney, Agent or Firm: Staas & Halsey
Claims
What is claimed is:
1. A method for controlling a discharge in gas discharge apparatus
comprised of first support means for supporting first, second and
third electrodes, each disposed in a first direction and covered
with a first dielectric layer, said third electrode being disposed
between said first and second electrodes; second support means for
supporting a fourth electrode spaced from and disposed to traverse
said first, second and third electrodes and covered with a second
dielectric layer; and envelope means for confining a discharge gas
between said first and second dielectric layers; said method
comprising the steps of:
applying between said third and fourth electrodes a first control
voltage of a magnitude insufficient to produce a discharge in said
discharge gas; and
applying a second control voltage selectively to said first and
second electrodes, said second control voltage being selected to be
of a magnitude higher than the discharge voltage between said first
and fourth electrodes and the discharge voltage between the second
and fourth electrodes, wherein
said first control voltage impressed between said third and fourth
electrodes is selected to be lower than a first lowered discharge
voltage established between said third and fourth electrodes when a
discharge is produced on only one of said first and second
electrodes by said second control voltage, and to be higher than a
second, further lowered discharge voltage established between said
third and fourth electrodes when a discharge is produced on each of
said first and second electrodes by said second control voltage
whereby a discharge is produced across said discharge gas between
said third and fourth electrodes as a result of the impression of
said second control voltage to said first and second electrodes and
of said first control voltage between said fourth and third
electrodes.
2. A method for controlling a discharge in gas discharge apparatus
according to claim 1, wherein said first control voltage impressed
between said third and fourth electrodes is selected to be lower
than a discharge voltage therebetween, and said second control
voltage is impressed to both of said first and second electrodes
and is so selected to be of a magnitude to establish a composite
electric field of sufficiently high intensity to produce a
discharge across said discharge gas between said third and fourth
electrodes in association with said first control voltage, whereby
the discharge is produced across said discharge gas between said
third and fourth electrodes as a result of a logical multiplying
operation by the impression of said second control voltage to said
first and second electrodes.
3. A method for controlling a discharge in gas discharge apparatus
according to claim 1, wherein the magnitude of said first control
voltage is so selected to produce a discharge in cooperation with
the effect produced on said discharge gas by said second control
voltage when it is impressed to one of said first and second
electrodes, whereby a discharge is produced across said discharge
gas between said third and fourth electrodes as a result of a
logical multiplying operation by the impression of said second
control voltage to one of said first and second electrodes.
4. A method for controlling a discharge in gas discharge apparatus
comprised of first support means for supporting first, second and
third electrodes, each disposed in a first direction and covered
with a first dielectric layer; second support means for supporting
a fourth electrode spaced from and disposed to traverse said first,
second and third electrodes and covered with a second dielectric
layer, said third electrode disposed between said first and second
electrodes; and envelope means for confining a discharge gas
between said first and second dielectric layers, said method
comprising the steps of:
a. impressing a control voltage to at least one of said first and
second electrodes to produce a discharge across said discharge gas
from said fourth electrode to one of said first and second
electrodes; and
b. impressing, to said third electrode, an auxiliary pulse for
establishing a wall charge at the portion of the surface of said
first dielectric layer corresponding to said third electrode, due
to the discharge resulting from the effect of said control voltage
on the surface of said first dielectric layer corresponding to at
least one of said first and second electrodes; and
c. applying to said third electrode an inquiry pulse selected so
that the sum of said inquiry pulse and a wall voltage produced by
said attracted wall charge exceeds a discharge voltage, to effect a
discharge across said discharge gas between said third and fourth
electrodes in response to the impression of said control voltage to
at least one of said first and second electrodes.
5. A method for controlling a discharge in gas discharge apparatus
comprised of first support means for supporting first, second and
third electrodes, each disposed in a first direction and covered
with a first dielectric layer; second support means for supporting
a fourth electrode spaced from and disposed to traverse said first,
second and third electrodes and covered with a second dielectric
layer, said third electrode disposed between said first and second
electrodes; and envelope means for confining a discharge gas
between said first and second dielectric layers, said method
comprising the steps of:
a. impressing a control voltage to at least one of said first and
second electrodes to produce a discharge across said discharge gas
between said fourth electrode and said one electrode;
b. impressing to said third electrode an auxiliary pulse for
establishing at the surface of said first dielectric layer
corresponding to said third layer, a wall charge due to the
discharge resulting from the effect of said control voltage on the
surface of said first dielectric layer corresponding to said one
electrode; and
c. applying to said third electrode an inquiry pulse of a magnitude
selected so that, in the absence of said wall charge, it exceeds a
discharge voltage but that, in the presence of said wall charge,
the difference between said inquiry pulse and a wall voltage
produced by said wall charge is lower than said discharge voltage,
whereby the discharge between said third and fourth electrodes is
effected as a result of a NOT-logic operation by the impression of
said control voltage to at least one of said first and second
electrodes when said inquiry pulse is impressed.
6. A method for a controlling a discharge in gas discharge
apparatus comprised of first support means for supporting
pluralities of each of first, second and third electrodes disposed
in a plurality of electrode groups, each of said groups comprising
a plurality of pairs of electrodes, each said pair including a
first and a second electrode and having a corresponding third
electrode disposed between said first and second electrodes of said
pair at least one of said first, second and third electrodes, said
first electrodes of each electrode group being connected in common
to a respectively associated one of first common terminals
respectively corresponding to said groups, and said electrodes of
the corresponding pairs of said plural electrode groups being
connected in common to a respectively associated one of second
common terminals, said third electrodes of all said electrode
groups being connected to a third common terminal, said first,
second and third electrodes being covered with a first dielectric
layer, second support means for supporting a fourth electrode
spaced from and disposed to traverse said first, second and third
electrodes and covered with a second dielectric layer; and envelope
means for confining a discharge gas between said first and second
dielectric layers, said method comprising the steps of;
a. applying between said fourth electrode and said third electrodes
a first control voltage of a magnitude insufficient to produce a
discharge across said discharge gas; and
b. applying a second control voltage to a selected one of each of
said first and second common terminals for application thereof in
turn to the first and second electrodes connected to said selected
first and second common terminals, the first and second control
voltage being of respective magnitudes selected to produce in
cooperation with each other a discharge across said discharge gas
between the third electrode disposed between said first and second
electrodes of the pair to said first and second electrodes of which
said second control voltage is applied, and said fourth
electrode.
7. A method for controlling a discharge in gas discharge apparatus
according to claim 20, wherein selected ones of said third
electrodes define first output electrodes and the remaining ones of
said third electrodes define second output electrodes and there is
further included a plurality of said fourth electrodes traversing
said first and second electrodes, said method further comprising
the step of applying the first control voltage individually and in
sequence to said plurality of said fourth electrodes, whereby the
discharge produced across said discharge gas between said third
electrodes and said one of said fourth electrodes as a result of
the impression of said second control voltage to both of said first
and second electrodes and of said first control voltage between
said fourth and third electrodes and of said first control voltage
between said fourth and third electrodes is shifted sequentially to
successive ones of said fourth electrodes in accordance with the
said application of said first control voltage individually and in
sequence to said plurality of said fourth electrodes.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a gas discharge device having a logical
function whose external terminals are less in number than the
number of discharge cells.
2. Description of the Prior Art.
In a gas discharge device known under the name of a plasma display
panel, electrodes covered with dielectric layers are disposed in
opposing relation and Neon or like discharge gas is sealed between
the opposed electrodes. A voltage higher than a firing voltage is
applied between the opposed electrodes to produce a discharge spot,
after which, by impression of an alternating sustain voltage lower
than a discharge voltage, the potential difference between the
sustain voltage applied and a wall voltage produced by the
discharge spot exceeds the discharge voltage and the discharge spot
is produced each time the polarity of the sustain voltage is
reversed. Namely, the sustain voltage is impressed to the opposed
electrodes and a write-in voltage is applied between selected ones
of the electrodes, by which the discharge spot is produced at the
intersection of the selected electrodes, thus enabling a display.
However, when the plasma display panel becomes large-sized, the
number of electrodes increases and connection with external
circuits becomes difficult and a drive circuit becomes complicated
and expensive.
Further, there has also been proposed a panel structure such that
the discharge spot is shifted by sequential impression of a voltage
to the electrodes of the one group to provide a display in the
manner of an electric sign. Also in this case, however, the number
of write-in electrodes for producing a first discharge spot
increases with an increase in the display area and connection with
external circuits is not easy as described previously.
SUMMARY OF THE INVENTION
One object of this invention is to provide a gas discharge device
which is provided with less external terminals than electrodes
forming discharge cells and a simplified drive circuit.
Another object of this invention is to provide a gas discharge
device which is adapted so that a logical operation is achieved
with a plurality of electrodes forming discharge cells.
Briefly stated, the gas discharge device according to this
invention is such that either row or column electrodes are used as
first and second electrodes and third electrodes are each disposed
between the first and second electrodes. The first electrodes are
connected to a common terminal for each electrode group; the second
electrodes are connected to terminals common to those of all the
electrode groups; and the third electrodes are connected to a
common terminal. Only when a voltage is impressed to selected ones
of the first and second electrodes and a voltage is impressed to
the third electrode disposed therebetween, a discharge spot is
produced on the third electrode.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1A to 1C are diagrams for explaining the principle of the
operation of this invention;
FIG. 2 is a diagram for explaining electrode arrangements in one
example of this invention;
FIGS. 3A to 3C and FIGS. 4A to 4F are diagrams for explaining an
impression voltage;
FIG. 5 is a diagram for explaining the electrode arrangements in
another example of this invention;
FIG. 6 is a diagram for explaining the principle of the operation
of the electrode arrangement of FIG. 5;
FIG. 7 is a diagram for explaining an impression voltage for a
logical multiply operation of resistance channel coupling;
FIG. 8 is a diagram for explaining electrode arrangements of a NOT
circuit of resistance channel coupling;
FIG. 9 is a diagram for explaining an impression voltage upon the
electrode arrangement of FIG. 8;
FIG. 10 is a diagram for explaining an electrode arrangement of a
flip-flop circuit;
FIG. 11 is a detailed, cross-sectional view of the electrode
arrangement of FIG. 10; and
FIG. 12 is a diagram for explaining an impression of voltage upon
the electrode arrangement of FIGS. 10 and 11.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 shows diagrams for explaining the principle of this
invention. FIG. 1A is a top plan view showing the electrode
arrangements; FIG. 1B shows its cross-sectional view; and FIG. 1C
shows an electric field distribution diagram. Reference character
X1 indicates a first electrode, X2 a second electrode, X3 a third
electrode and Y an electrode disposed to cross them at right angles
thereto in opposing relation. The electrodes X1, X2 and X3 are
formed by printed wiring techniques or the like on a base plate 1
as of glass and the electrodes X1, X2 and X3 are covered with a
dielectric layer 2 of low-melting-point glass or the like. The
electrode Y is similarly formed on a base plate 3 as of glass and
covered with a dielectric layer 4. A mixed discharge gas, composed
of for example Ne 95 percent, and N.sub.2 5 percent, is sealed
within the space 5 defined between the opposing dielectric layers 2
and 4.
Upon impression of a voltage to the third electrode X3, an electric
field such as shown at line (1) of FIG. 1C is established and the
impression voltage is set lower than a discharge voltage.
Impressing voltages to the third and first electrodes X3 and X1,
the resulting electric field distribution becomes such as shown at
line (2) of FIG. 1C and the voltages are set so that a composite
maximum value may not reach the discharge voltage. Further,
impressing voltages to the electrodes X1, X2 and X3, the resulting
electric field distribution becomes such as depicted at line (3) of
FIG. 1C and, in this case, the voltages are set so that a composite
value on the third electrode X3 may reach the discharge voltage.
Supposing that a discharge voltage between the electrodes Y and X3
in the case of neither electrodes X1 nor X2 is set at a voltage, in
the case of either electrodes X1 or X2 is set at a voltage and in
the case of both electrodes X1 and X2 are set at voltages
respectively taken as V.sub.f0, V.sub.F1 and V.sub.F2, they bear
such a relation as V.sub.f0 >V.sub.F1 >V.sub.F2. Accordingly,
it is possible to achieve a logical multiplying operation
X1.X2=X3.
In the foregoing, the logical multiplying operation is effected in
the non-discharge mode of the first and third electrodes X1 and X3,
but the same operation can also be achieved in the discharge mode
of them. Namely, a discharge voltage between the electrodes X3 and
Y in the case of a discharge spot being produced at the
intersection of the electrodes X1 and Y, or X2 and Y is taken as
V.sub.f1 ; if a discharge voltage between the electrodes X3 and Y
in the case of no discharge spot being produced at the both
intersections is taken as V.sub.f0 ; and if a discharge voltage in
the case of discharge spots being produced at the both
intersections is taken as V.sub.f2, they bear such a relation as
V.sub.f0 >V.sub.f1 >V.sub.f2. This is a phenomenon resulting
from plasma coupling due to the discharge spot. Therefore, if a
voltage V3 impressed between the electrodes X3 and Y is selected so
that V.sub.f1 >V.sub.3 >V.sub.f2, it is possible to achieve
the same operation as the aforesaid logical multiplying operation
of non-discharge mode.
FIG. 2 illustrates the electrode structure of one example of this
invention. Of electrodes A11 to Anm and B11 to Bmn (which are row
electrodes), first and second electrodes A11 to A1m and B11 to Bm1
constitute a first electrode group; first and second electrodes A21
to A2m and B12 to Bm2 constitute a second electrode group; and,
similarly, first and second electrodes An1 to Anm and B1n to Bmn
constitute an nth electrode group. The first electrodes A11 to A1m,
A21 to A2m and An1 to Anm of the first, second and nth electrode
groups are connected to terminals A1, A2 and An, respectively. The
second electrodes B11, B12, . . . and B1n of the first, second, . .
. and nth electrode groups are connected to a terminal B1; the
second electrodes B21, B22, . . . and B2n of the first, second, . .
. and nth electrode groups are connected to a terminal B2; and,
similarly, the second electrodes Bm1, Bm2, . . . and Bmn of the
first, second, . . . and nth electrode groups are connected to a
terminal Bm. Further, third electrodes C11 to Cnm, each disposed
between the first and second electrodes, are connected to a common
terminal C1. Then, electrodes Y1 to Yk, which are column
electrodes, are disposed to cross the row electrodes at right
angles thereto in opposing relation and only the electrode Y1 is
disposed opposite to the first, second and third electrodes. The
electrodes Y1 to Yk are sequentially supplied with voltages and,
for example, every third ones of them are connected to buses SA, SB
and SC respectively and the voltages to be impressed to the buses
SA, SB and SC may be such sustain voltages which lap at the
beginning and end thereof periodically and in time.
Impressing a voltage to the terminals, for example, A1, B1 and Bm,
discharge spots are produced between the electrode Y1 and those A11
to A1m, B11 to B1n and Bm1 to Bmn. At an instant of impressing a
voltage to the terminal C1, discharge spots are produced between
the electrode Y1 and those C11 and C1m, and upon application of a
voltage to the electrode Y2, the discharge spots shift to the
intersections of the electrodes C11 and C1m with the electrode Y2.
Namely, the first and second electrodes of the respective electrode
groups perform the functions of writing electrodes of a self-shift
panel. In this case, the number of the terminals is n+m but writing
cam be effected at nxm points, so that the number of the terminals
is considerably smaller than the number of electrodes employed in
the prior art. According to this invention, in a conventional
device using, for example, 128 electrodes or terminals, if n=8 and
m=16, addressing can be achieved with such number of terminals as
n+m=24. Similarly, in the case of 256 electrodes, if n= 16 and m=
16, the number of terminals is 32 and in the case of 512
electrodes, if n= 16 and m= 32, the number of terminals is 48.
Then, it is possible to achieve addressing with a logical multiply
that A.sub.i.B.sub.j =C.sub.ij (i,j= 1, 2, 3. . . ).
FIGS. 3A, 3B and 3C are diagrams for explaining impression voltage
waveforms. Voltages V.sub.A and V.sub.B shown in FIGS. 3A and 3B
which are impressed to the first and second electrodes A.sub.ij and
B.sub.ji are selected substantially equal to each other; in the
case of the discharge mode, they are selected such that V.sub.A
=V.sub.B >V.sub.f0, and in the case of the non-discharge mode,
they are selected such that V.sub.F1 >V.sub.A =V.sub.B
.congruent.V.sub.F2. While, a voltage V.sub.C shown in FIG. 3C
which is applied to the third electrode C.sub.ij is selected so
that V.sub.f1 >V.sub.c >V.sub.f2 or V.sub.F1 >V.sub.C
>V.sub.F2 as described previously. No limitation is imposed on
the number of pulses of the voltages V.sub.A and V.sub.B (which may
be one or more waves).
In FIG. 2, the spacing, for example, between the first and second
electrodes A12 and B11 is shown to be equal to that between the
electrodes A11 and B11 but it may also be narrowed. Further, where
a third electrode C211 is provided between the electrodes B11 and
A12 and connected to a terminal C2 as indicated by a broken line,
when the terminals A1 and B1 are selected, either one of the
electrodes C11 and C211 can be selected by selecting either one of
the terminals C1 and C2. Accordingly, if n= 8 and if m= 8,
addressing of 128 discharge cells can be achieved with such a
number of terminals as n+ m= 16. If n= 16 and if m= 16, addressing
of 512 discharge cells is possible with 32 terminals.
FIGS. 4A to 4F, inclusive, are diagrams for explaining the voltage
waveforms in the case of selecting the terminals C1 and C2. In the
case of writing with an electrode C.sub.ij selected, the voltage to
the terminal C2 is cut off as depicted in FIG. 4F at an instant
when a voltage is impressed to the terminals Ai and Bj as shown in
FIGS. 4A and 4B. In the case of writing with an electrode C2ij
selected, the voltage to the terminal C1 is cut off as depicted in
FIG. 4E when the voltage is applied to the terminals Ai and Bj as
shown in FIGS. 4C and 4D. The voltages V.sub.A, V.sub.B, V.sub.C1
and V.sub.C2 in this case are also selected in the same manner as
in the foregoing. In FIGS. 3 and 4, in the case of the discharge
mode, it is also possible that a first pulse voltage or a pulse
voltage impressed a half cycle thereafter to the terminal Ai and Bj
is selected higher than V.sub.f0 ; that a sustain voltage Vs less
than V.sub.f0 is applied thereafter; that, during the impression of
the above voltage, in the voltage impressed to the terminal C1
and/or C2, the pulse voltage of desired period is selected higher
than V.sub.f2 and the pulse voltage of other period is selected in
the sustain voltage Vs. Further, in the case of the non-discharge
mode, it is also possible to achieve writing by impressing the
sustain voltage V.sub.S to the terminals Ai and C1 or C2 and
impressing a pulse voltage higher than V.sub.F2 to the terminal C1
or C2 as in the case of a query pulse. This provides an advantage
that an erasing operation is easy because the relatively low
sustain voltage V.sub.S is impressed after writing.
FIG. 5 illustrates the electrode structure of another example of
this invention, in which the first and second electrodes are formed
to extend with the third electrode therebetween and the electrodes
opposite thereto are also similarly constructed. In the present
example, when voltages are selectively impressed to electrodes, for
example, XA1, XB2 and XC1 and those YA1, YB1 and YC1, a discharge
spot is produced at the intersection of the electrodes XC12 and
YC11. Namely, in FIG. 6, the peak values of the impressed voltages
are selected so that only where electrodes XAi, XBj and YAk, YBh
are simultaneously selected and voltages are applied to electrodes
XC and YC, a discharge spot is produced at the intersection of the
electrodes XC and YC. This is possible in both the cases of the
discharge mode and the non-discharge one.
This example corresponds to a conventional plasma display device of
the type that, by selecting the X- and Y- direction electrodes, a
discharge spot is produced at their intersection. For example, if n
= 8 and if m = 8, the total number of terminals of the X- and Y-
direction electrodes is (n + m ) .times. 2 = 32, with which it is
possible to address 128.sup.2 discharge cells. On the other hand,
the conventional device requires 128 .times. 2 terminals and this
invention substantially decreases the number of terminals. Namely,
the relation between the number of terminals P of a conventional
device and the number of terminals Q in the present invention can
be expressed by an approximate equation 2.sqroot.P.congruent.Q and,
according to the present invention, the number of terminals can be
decreased by geometrical progression.
Further, in the example of FIG. 5, a display can also be provided
by connecting the electrodes YA11, YB11, . . . in the manner shown
in FIG. 2. In this case, the electrodes connected to the terminals
YC1 and YC2 are omitted. Further, condition for producing the
discharge spot is such that XAi.XBj.Yk=XC.
With this invention, the number of terminals can be made as much as
one order than that of electrodes as described above, so that the
connection with external circuit becomes easy and the electrode
selection can be achieved by the incorporated logical multiply
operation mechanism without using a resistance-diode matrix of the
prior art. Accordingly, the space can be saved and the cost of the
device can be lowered. Further, the manufacture does not become
especially complicated. For example, the electrodes and wires
interconnecting the electrodes and the terminals are formed on a
base plate as of glass; insulating layers are formed on the parts
of the intersections of the wires; and then wire for
interconnecting the electrodes and the respective groups are formed
on the insulating layers. This invention increases only two
manufacturing processes as compared with the prior art, but the
device of this invention can easily be manufactured by the
application of techniques for producing an integrated circuit.
In the example of FIGS. 1A to 1C, a logical multiply operation can
also be achieved by resistance channel coupling such that a
resistance film is formed on the dielectric layer 4 covering the
electrodes Y in their lengthwise direction and a wall charge
produced by discharge scatters along the resistance film and flows
into adjacent channel regions.
Also in this case, the firing voltage is selected such that even if
a wall charge produced by discharge of either one of the electrodes
X1 and X2 flows in the electrode X3, no discharge is caused by the
electrode X3 except that when discharge is produced by the
electrodes X1 and X2 and a wall charge resulting therefrom flows in
the electrodes X3, discharge is caused by the electrode X3. The
wall charge flowing into adjacent discharge cell regions reaches
its maximum value after a certain period of time and the time
therefor becomes shorter with a decrease in the resistance value of
the resistance film.
FIG. 7 shows one example of an impression voltage waveform for
achieving the logical multiply operation by the above-described
resistance channel coupling. When discharge is produced by
simultaneous impression of a voltage to the electrodes X1 and X2,
the voltage is cut off and then a pulse PW attracting wall charges
on the electrodes X1 and X2 is applied to the electrode X3, by
which the wall charges are caused to move rapidly, providing a
high-speed operation and accuracy of the operation. Where only
either one of the electrodes X1 and X2 causes discharge, the
resulting wall charge V.sub.W on the electrode X3 becomes V.sub.W1
and where the both electrodes X1 and X2 cause discharge, the
resulting wall charge becomes such that V.sub.W2
.congruent.2V.sub.W1 and discharge is caused by the potential
difference between the wall charge V.sub.W2 and a subsequent
voltage impressed to the electrode X3. The voltage applied to the
electrode X3 in this case is the sustain voltage V.sub.S.
Next, an OR circuit will be described. In the case of the discharge
mode, if an impression voltage V3 applied to the electrode X3 is
selected so that V.sub.f0 >V3>V.sub.f1, a logical summing
operation of (X1)+(X2)=X3 can be achieved. In the case of the
non-discharge mode, the impression voltage is selected such that a
discharge spot may be produced on the electrode X3 with the
composite value of the electric field distributions shown in the
middle of FIG. 1C. Further, in the case of using the resistance
channel coupling, a logical summing operation can be achieved by
impressing such a voltage that a discharge spot may be produced due
to the potential difference between it and the wall charge V.sub.W1
or by impressing, subsequent to the pulse PW, a voltage V.sub.O
selected higher than the sustain voltage V.sub.S and such that
V.sub.F >V.sub.0 +V.sub.W1 where V.sub.F is a discharge
voltage.
Next, a NOT circuit will be described. FIG. 8 shows its electrode
arrangements and FIG. 9 one example of impression voltage
waveforms. Reference character RF indicates a resistance film. This
is the case of employing the resistance channel coupling and either
one of electrodes A and B may be left out. An electrode Z is
supplied with the pulse PW attracting the wall charge and then with
a pulse V.sub.N of the same polarity as the pulse PW. The value of
the pulse V.sub.N is selected so that discharge is caused when the
wall charge is close to "O". When, discharge is caused at the
electrode A and the resulting wall charge is attracted to the
electrode Z, the wall voltage V.sub.W1 of the polarity cancelling
the field produced by V.sub.N is produced and if the discharge
voltage is taken as V.sub.F, the result is that V.sub.F >V.sub.N
-V.sub.W1 and no discharge is caused. However, if no discharge is
caused at the electrodes A, V.sub.F <V.sub.N, so that discharge
is caused by the pulse V.sub.N. Therefore, a NOT logic operation
A=Z can be carried out. A pulse V.sub.O indicated by a broken line
is a pulse for the logical summing operation and it is selected so
that V.sub.F <V.sub.O +V.sub.W1.
Where the electrodes A, B and Z are disposed very close to one
another, there is a phenomenon that when the same voltage is
applied to the electrodes and discharge is produced at one of
adjacent electrodes, discharge is difficult to be caused at the
other electrode. Such a proximity effect is usually caused where
the spacing between the electrodes is less than 400.mu. or so,
although it is different according to the device's dimensions and
to the kind of a gas used. Therefore, where the electrodes A, B and
Z are disposed close to one another and connected as shown in FIG.
8, when discharge is caused at the electrodes A and B, no discharge
is produced at the electrode Z and when no discharge is caused at
the electrodes A and B, discharge is produced at the electrode Z.
Namely, the aforementioned NOT logic operation is performed. This
is based on plasma coupling and no resistance channel is
required.
In the case of a NOR circuit, a logical operation A+B=Z can be
achieved by using the electrodes A and B which are separated in
FIG. 8 as control electrodes. In the case of a NAND circuit, a
logical operation A.B=Z can be effected by using the electrodes A
and B which are separated as control electrodes and selecting the
pulse V.sub.N such that (V.sub.N -V.sub.W2)<V.sub.F <(V.sub.N
-V.sub.W1).
FIG. 10 illustrates an example of a flip-flop circuit construction
and FIG. 11 is a cross-sectional view of its principal parts.
Reference numerals 11 and 13 designate base plates as of glass, 14
and 12 dielectric layers, and 15 the space defined between the
opposing dielectric layers. Reference characters A, B and Y
indicate electrodes. The illustrated flip-flop circuit utilizes the
aforementioned proximity effect and the electrodes A and B both
serve as control and output electrodes. In FIG. 11, assuming that a
discharge is caused at the electrode A, when a positive voltage is
applied to the electrodes A and B and a negative voltage is applied
to the electrode Y, negative and positive charges are stored in the
dielectric layers 14 and 12 overlying the electrodes A and Y
respectively and negative charges are also attracted to the
electrode B, so that the negative charges act to cancel the
impressed voltage. Consequently, after once produced, the discharge
is continuously generated only at the electrode A by continuous
impression of the usual sustain voltage V.sub.S. Then, impressing a
reverse pulse voltage V.sub.R of the same polarity as the sustain
voltage V.sub.S and of high peak value prior to the application of
the sustain voltage V.sub.S as shown in FIG. 12, the discharge at
the electrode A is stopped and instead a discharge is generated at
the electrode B. The voltage V.sub.R is selected to exceed the
discharge voltage V.sub.F. With this voltage V.sub.R, discharges
are caused at the both electrodes A and B and a wall charge
V.sub.WA of the electrode A is thereby greatly increased to cause a
discharge, and hence become attenuated. While, the level of a wall
charge V.sub.WB of the electrode B is raised by the voltage V.sub.R
and the discharge is continued by the subsequent sustain voltage
V.sub.S as in usual writing operation. Accordingly, each time the
voltage V.sub.R is impressed, a discharge is caused alternately at
the electrodes A and B to provide the operation of the flip-flop
circuit. Reference numeral V.sub.E indicates an erasing pulse,
which provides ensured operation, but the flip-flop operation can
be carried out by the reverse pulse V.sub.R without using the
erasing pulse V.sub.E.
As has been described in the foregoing, the present invention
enables various logical operations by selecting the spacing between
the electrodes or impression voltages and their polarity, and the
output can be derived by a light detector, a discharge current
detector or shift of the generated discharge spot. Hence, the
device of this invention can be adapted for a wide range of
uses.
With the present invention, a logical operation is achieved with
one part of the electrodes of a plasma display panel and the number
of external terminals can be made smaller than that of the
electrodes by the use of the logic circuit as described in the
foregoing, so that the number of drive circuits for driving the
display device can be reduced to provide for simplified
construction.
It will be apparent that this invention is not limited specifically
to the foregoing examples and that various modifications and
variations may be effected without departing from the scope of the
spirits defined in the appended claims.
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