Gas discharge image display

In the gas discharge image display of this invention, the peak value of a write pulse supplied to one of two electrodes of each of fluorescent lamps aligned in a matrix form is substantially equal to the peak value of a sustain pulse supplied to that electrode. Therefore, when a row line drive circuit or a column line drive circuit supplies, in a sustain period of a fluorescent lamp to be discharged, a write pulse to another fluorescent lamp aligned in the same row or column of the matrix form, a voltage at the fluorescent lamp to be discharged can be made constant in the sustain period.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to improvement in drive control of a gas 
discharge image display including a plurality of gas discharge lamps as 
light sources for use in an image display unit, an electric bulletin board 
or the like. 
2. Description of Related Art 
FIG. 1 is a perspective view of a fluorescent lamp included in a 
conventional gas discharge image display disclosed in, for example, U.S. 
Pat. No. 5,444,335. In FIG. 1, a reference numeral 1 denotes a fluorescent 
lamp, a reference numeral 2 denotes a cylindrical glass bulb included in 
the fluorescent lamp 1, a reference numeral 3 denotes a fluorescent layer 
formed on substantially a half of the inner wall of the glass bulb 2, and 
a reference numeral 4 denotes a light output section on which the 
fluorescent layer 3 is not formed. Within the glass bulb 2, a rare gas 
such as xenon is sealed at a predetermined pressure. On the outer wall of 
the glass bulb 2 where the fluorescent layer 3 is formed, external 
electrodes 5a and 5b are provided so as to together form a picture element 
6. 
One florescent lamp 1 includes a plurality of, for example, sixteen picture 
elements 6. In FIG. 1, merely three picture elements are shown. 
FIG. 2 shows a gas discharge image display 7 formed by aligning a plurality 
of (for example, 3.times.n) fluorescent lamps 1 of FIG. 1. FIG. 3 shows 
drive circuits for these fluorescent lamps 1, adjacent three of which are 
respectively used as red, green and blue (hereinafter referred to as R, G 
and B) light sources. 
FIG. 3 is a block diagram of a drive unit of the conventional gas discharge 
image display described in the aforementioned U. S. P., wherein a 
reference numeral 7 denotes a gas discharge image display, and a reference 
numeral 6 denotes one picture element including the external electrodes 5a 
and 5b. 
In FIG. 3, a reference numeral 8 denotes an X drive circuit (data drive 
circuit) connected with each column line (X line) formed by mutually 
connecting one of the electrodes on one side (for example, the electrode 
5a) of each longitudinally aligned picture element 6, and a reference 
numeral 9 denotes a Y drive circuit (scanning drive circuit) connected 
with each row line (Y line) formed by mutually connecting the other 
electrode on the other side (for example, the electrode 5b) of each 
laterally aligned picture element 6. 
In FIG. 3, the line numbers of the X lines are indicated as XR1, XG1, XB1, 
. . . and XBn, and the line numbers of the Y lines are indicates as Y1, 
Y2, . . . and Yn. 
As is shown in FIG. 3, the X line is a line formed by mutually connecting 
one electrode of each of the picture elements 6 included in one 
fluorescent lamp, and the Y line is a line formed by connecting the other 
electrode of each of the picture elements 6 positioned at the same row of 
the plural laterally aligned fluorescent lamps. 
The operation of this drive unit will now be described. Each fluorescent 
lamp 1 has a characteristic that it emits light as a result of the 
discharge when a predetermined or larger voltage (hereinafter referred to 
as the discharge start voltage) is applied between the external electrodes 
5a and 5b and it never emits light under application of a voltage smaller 
than the predetermined voltage. 
Common lines of the X drive circuit 8 and the Y drive circuit 9 are 
connected with each other. Therefore, when a difference in voltages 
respectively applied to the X line and the Y line by the X drive circuit 8 
and the Y drive circuit 9 exceeds the discharge start voltage, the picture 
element 6 positioned at the intersection of the X and Y lines emits light 
because a discharge occurs. Since the Y line is a scanning line, the 
picture elements are successively or arbitrarily scanned in the Y 
direction by the Y drive circuit 9 for the voltage application. Since the 
X line is a data line, in accordance with the timing of scanning the Y 
line of a given picture element 6 where discharge light emission is 
desired to be caused, the X line connected to this picture element is 
supplied with a voltage. Ill this manner, the picture element at the 
intersection emits light as a result of the discharge. 
Thus, it is possible to cause the discharge light emission in an arbitrary 
picture element so as to display an image. Such a fluorescent lamp 1 has a 
function to easily retain two states, that is, a discharge light emitting 
state and an off state (which function is hereinafter referred to as the 
memory function). As a drive system utilizing this memory function, memory 
drive system is adopted. In the memory drive system, the operation period 
is divided into a write period, a sustain period and an erase period. A 
picture element which has been discharged in the write period retains its 
discharge light emission during the sustain period by applying a voltage 
lower than the discharge start voltage at appropriate intervals (which 
voltage is designated as the sustain pulse). When the application of the 
sustain pulse is stopped or the applied voltage is lowered ill the erase 
period, the discharge light emission of the picture element stops. 
Accordingly, this drive system call attain a displayed image with high 
luminance as compared with the other known drive systems such as refresh 
drive system in which a picture element emits light only in a scanning 
period. 
When the memory drive system is adopted, all the picture elements are 
substantially always supplied with the sustain pulse. The discharge light 
emission of an arbitrary picture element can be controlled by conducting 
write scanning (at a high voltage) and erase scanning (at a low voltage). 
FIG. 4 shows the waveforms of drive voltages in the memory drive system 
disclosed in the above described patent, wherein the waveforms of voltages 
applied to an X line (data line), a Yi line (scanning line) and a Yj line 
(scanning line), and voltages applied between the X and Yi lines and 
between the X and Yj lines are shown in this order from the top of the 
drawing. 
In FIG. 4, XSP and YSP are sustain pulses supplied to the X and Y lines, 
respectively, and XWP and YWP are write pulses supplied to the X and Y 
lines, respectively. In this figure, the Yj line merely means a line 
adjacent to the Yi line. 
The X line serving as a data line is supplied with the write pulse XWP in 
accordance with the content of an image to be displayed, and is fixed at 
the GND potential (shown as 0 in FIG. 4) when the write pulse is not 
applied. At this point, the peak value of the pulse XWP) is sufficiently 
higher than the peak value of the pulse XSP for attaining a stable 
display. The Y line serving as a scanning line is supplied with a positive 
or negative pulse in accordance with the operation periods. 
As a result, the waveforms of the voltage applied between the X and Y lines 
are obtained as those shown in the fourth (waveform X Yi) and the fifth 
(waveform X-Yj). The peak value obtained by overlapping the pulses XWP and 
YWP (shown as 60 in FIG. 4) is sufficiently higher than the discharge 
start voltage. Furthermore, a voltage applied when the pulse YSP is not 
supplied is lower than a voltage sufficiently high for retaining the 
discharge. Therefore, a picture element at the intersection of the X and 
Yi lines starts its discharge light emission in the write period, retains 
the discharge light emission in the sustain period, and stops the 
discharge light emission in the erase period. 
Another type of fluorescent lamps like one disclosed in U.S. application 
Ser. No. 08/545,274 now U.S. Pat. No. 5,668,443 (filed by the Applicant) 
can be used in such an image display, apart from that shown in FIG. 1. The 
fluorescent lamp disclosed in this application is shown in FIGS. 5A and 
5B. 
FIG. 5A is a partially exploded perspective view of the fluorescent lamp, 
and FIG. 5B is a vertically sectional view thereof. In these figures, a 
reference numeral 11 denotes the fluorescent lamp including an external 
electrode and an internal electrode, and a reference numeral 12 denotes a 
glass bulb included in the fluorescent lamp 11. 
A reference numeral 13 denotes the internal electrode inserted from one end 
portion of the glass bulb 12 into the glass bulb 12, a reference numeral 
14 denotes the external electrode disposed on the outer wall of the glass 
bulb 12, and a reference numeral 15 denotes a fluorescent layer formed on 
the inner wall of the glass bulb 12. 
A reference numeral 16 denotes a transparent light output section disposed 
at the upper end of the glass bulb 12. A rare gas such as xenon is sealed 
within the glass bulb 12 at a predetermined pressure. A reference numeral 
49 denotes an AC power supply for allowing the fluorescent lamp 11 to emit 
light. 
A plurality of such fluorescent lamps 11 are connected with one another as 
is shown in FIG. 3, so as to form a gas discharge image display 7. 
Differently from the fluorescent lamp 1, the two electrodes of the 
fluorescent lamp 11 are not symmetrically disposed. Therefore, apart from 
the case where the image display is driven by using an AC waveform in 
which symmetrical positive and negative waves are repeated, in driving the 
image display by using a pulse signal including asymmetrical positive and 
negative waves such as the waveform X-Yi shown in FIG. 4, the 
characteristics of the fluorescent lamp 11 (Such as a voltage value of a 
pulse required for attaining stable emission) are varied depending upon 
which electrode is supplied with a positively (or negatively) biased 
potential. 
In such a case, when the image display is used without consideration of the 
polarities of the pulse signal, a high supply voltage is uneconomically 
required, or a stable operation cannot be disadvantageously attained. 
Since the conventional gas discharge image display has the aforementioned 
configuration, the peak value of the sustain pulse in the sustain period 
varies depending upon whether another pulse XWP for starting discharge 
light emission of another picture element at a different intersection from 
that of the X and Yi lines (hereinafter referred to as other line write 
operation) is applied (as is shown as a period 3! in FIG. 4) or is not 
applied (as is shown as a period 2! in FIG. 4). As a result, the 
intensity of the discharge occurring at the rise of the sustain pulse is 
varied, resulting in disadvantageously fluctuating the emission intensity. 
As another problem, the required voltage value of a pulse can be 
unnecessarily increased depending upon combination of supply of the two 
types of the pulse signals to the two electrodes. 
SUMMARY OF THE INVENTION 
The present invention was devised to overcome the aforementioned problems, 
and one object of the invention is providing a gas discharge image display 
in which emission intensity is scarcely fluctuated by the other-line write 
operation. 
The gas discharge image display of this invention comprises a plurality of 
discharge lamps, disposed in a matrix form, each having a characteristic 
of a predetermined discharge start voltage and including a dielectric 
cylindrical container in which a rare gas is sealed and first and second 
electrodes disposed oil the cylindrical container, the discharge lamps 
forming row lines by mutually connecting the first electrodes of the 
discharge lamps disposed in a lateral direction of the matrix form and 
forming column lines by mutually connecting the second electrodes of the 
discharge lamps disposed in a longitudinal direction of the matrix form; 
and a row line drive circuit and a column line drive circuit connected 
with the row lines and the column lines, respectively, for applying pulse 
voltages to the row lines and the column lines, the row line drive circuit 
and the column line drive circuit simultaneously supplying write pulses 
having polarities reverse to each other to a row line and a column line to 
which a discharge lamp to be discharged is connected, so as to apply a 
voltage exceeding the discharge start voltage to the discharge lamp to be 
discharged, and the row line drive circuit and the column line drive 
circuit supplying sustain pulses to the row line and the column line at 
timing different from timing of supplying the write pulses, so as to apply 
a voltage lower than the discharge start voltage to the discharge lamp to 
be discharged. In this gas discharge image display, a peak value of the 
write pulse supplied to one of the first and second electrodes is 
substantially equal to a peak value of the sustain pulse supplied to the 
electrode. 
Accordingly, even when a write pulse for the other-line write operation is 
supplied in the sustain period of the discharge lamp to be discharged, the 
peak value of the write pulse can be retained as in the case where the 
write pulse for the other-line write operation is not supplied. Therefore, 
emission luminance is not varied in the sustain period. 
Another object of the invention is providing a gas discharge image display 
which can decrease the sustain start voltage for a discharge when a first 
electrode which is a internal electrode disposed into the cylindrical 
container and a second electrode which is a external electrode disposed on 
outer wall of the cylindrical container are used. 
In the present gas discharge image display, the write pulses and the 
sustain pulses have such polarities that the internal electrode first 
works as a negative electrode and the external electrode subsequently 
works as the negative electrode in each discharge lamp after a period when 
no voltage is applied by the row line drive circuit and the column line 
drive circuit. 
In the present gas discharge image display, the write pulses are supplied 
ill a period when the internal electrode of the discharge lamp works as 
the negative electrode. 
Therefore, the discharge can be stably sustained at a low voltage, 
resulting in decreasing the sustain voltage. 
Still another object of the invention is providing a gas discharge image 
display in which the discharge between the internal electrode and the 
external electrode call be easily caused. 
Alternatively, the gas discharge image display of this invention comprises 
a plurality of discharge lamps, disposed in a matrix form, each having a 
characteristic of a predetermined discharge start voltage and including a 
dielectric cylindrical container which has different diameters in an axial 
direction and in which a rare gas is sealed, a first electrode disposed 
into the cylindrical container, and second and third electrodes disposed 
on outer walls of portions having the different diameters of the 
cylindrical container, the discharge lamps forming row lines by mutually 
connecting the first electrodes of the discharge lamps disposed in a 
lateral direction of the matrix form and forming column lines by mutually 
connecting the second electrodes of the discharge lamps disposed in a 
longitudinal direction of the matrix form, and the third electrode being 
connected with the second electrode in each discharge lamp; and a row line 
drive circuit and a column line drive circuit connected with the row 
lines, and the column lines, respectively, for applying pulse voltages to 
the row lines and the column lines, the row line drive circuit and the 
column line drive circuit simultaneously supplying write pulses having 
polarities reverse to each other to a row line and a column line to which 
a discharge lamp to be discharged is connected, so as to apply a voltage 
exceeding the discharge start voltage to the discharge lamp to be 
discharged, and the row line drive circuit and the column line drive 
circuit supplying sustain pulses to the row line and the column line at 
timing different from timing of supplying the write pulses, so as to apply 
a voltage lower than the discharge start voltage to the discharge lamp to 
be discharged. 
Accordingly, the discharge between the external electrode serving as the 
third electrode and the internal electrode can be caused without using 
additional driving circuits. 
The above and further objects and features of the invention will more fully 
be apparent from the following detailed description with accompanying 
drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The present invention will now be described referring to the accompanying 
drawings showing the embodiments thereof. 
Embodiment 1 
In FIG. 6, a reference numeral 11 denotes a fluorescent lamp included in a 
gas discharge image display of this invention, a reference numeral 12 
denotes a glass bulb (container) included in the fluorescent lamp 11 and 
having two portions with different diameters in the axial direction, a 
reference numeral 12a denotes the large-diameter portion of the glass bulb 
12, and a reference numeral 12b denotes the small-diameter portion of the 
glass bulb 12. 
A reference numeral 13 denotes an internal electrode, that is, a first 
electrode, inserted from one end of the small-diameter portion 12b of the 
glass bulb 12 into the glass bulb 12. A reference numeral 14 denotes an 
external electrode, that is, a second electrode, disposed on the outer 
wall of the large-diameter portion 12a of the glass bulb 12. A reference 
numeral 15 denotes a fluorescent layer formed on the inner wall and the 
inner bottom of the large-diameter portion 12a of the glass bulb 12. 
A reference numeral 16 denotes a transparent light output section disposed 
at the upper end (at the left end in FIG. 6) of the large-diameter portion 
12a of the glass bulb 12. A rare gas such as xenon is sealed within the 
glass bulb 12 at a predetermined pressure. 
FIG. 7 is a block diagram showing a drive unit of a gas discharge image 
display of this invention. A reference numeral 17 denotes the gas 
discharge image display, and a reference numeral 18 denotes a picture 
element including the fluorescent lamp 11. A reference numeral 19 denotes 
a column line drive circuit (data drive circuit) connected to each column 
line formed by mutually connecting the same one of the electrodes (for 
example, the external electrode 14) of each luminescent lamp 11 aligned in 
the longitudinal direction. A reference numeral 20 denotes a row line 
drive circuit (scanning drive circuit) connected to each row line formed 
by mutually connecting the other electrode (for example, the internal 
electrode 13) of each fluorescent lamp 11 aligned in the lateral 
direction. 
Now, the operation of the gas discharge image display will be described. 
When a voltage exceeding a discharge start voltage is applied to a column 
line and a row line by the column line drive circuit 19 and the row line 
drive circuit 20, respectively, the picture element 18 (i.e., the 
fluorescent lamp 11) at the intersection of the lines discharges and emits 
light. Since the row line is a scanning line, the picture elements are 
successively or arbitrarily scanned in the longitudinal direction for the 
voltage application. Since the column line is a data line, when the row 
line connected to a picture element which is desired to be discharged for 
light emission is scanned, a voltage is applied to the column line 
connected to that picture element, so as to cause the discharge light 
emission of that picture element at the intersection. 
FIG. 8 shows the waveforms of drive voltages in the present gas discharge 
image display, wherein the waveforms of voltages applied to a column line 
(data line) X, row lines (scanning lines) Yi, Yj and Yk, and voltages 
applied between the X and Yi lines, the X and Yj lines, and the X and Yk 
lines resulting from the voltage application to these lines are shown in 
this order from the top. In FIG. 8, XSP and YSP are sustain pulses 
supplied to the data and scanning lines, respectively, and XWP and YWP) 
are write pulses supplied to the data and scanning lines, respectively. At 
this point, the peak value of the pulse XWP is set at a value 
substantially equal to or slightly lower than the peak value of the pulse 
XSP. 
The row line is a scanning line, and is supplied with a voltage pulse in 
accordance with the operation period, which is divided into a write 
period, a sustain period and an erase period. In contrast, the column line 
is a data line, and is arbitrarily supplied with the write pulse XWP in 
accordance with the content of an image to be displayed. The sustain pulse 
XSP is always regularly applied. In FIG. 8, the widths of the pulses XWP 
and YWP are substantially the same. 
Now, a voltage pulse applied to the column line X (hereinafter referred to 
as the X line) for attaining a display as shown in FIG. 9 (wherein 
fluorescent lamps 11a and 11c emit light and a fluorescent lamp 11b is 
off) will be exemplified. In successively scanning the row lines, the 
write pulse XWP is applied to the X line when the write pulse YWP is 
applied to the row line Yi (hereinafter referred to as the Yi line) (as in 
a period 1! shown in FIG. 8). When the write pulse YWP is applied to the 
row line Yj (hereinafter referred to as the Yj line) (as in a period 2! 
shown in FIG. 8), the write pulse XWP is not applied to the X line. When 
the write pulse YWP is applied to the row line Yj (hereinafter referred to 
as the Yj line) (as in a period 3! shown in FIG. 8), the write pulse XWP 
is applied to the X line. As a result, the waveform of the drive voltage 
applied to the X line is obtained as that shown in the first of FIG. 8. 
At this point, with regard to the fluorescent lamp 11a at the intersection 
of the X line and the Yi line, the fluorescent lamp 11a starts discharging 
in the write period of the Yi line (i.e., the period 1!), retains the 
discharge in the sustain period (i.e., the periods 2! and 3!). However, 
the waveforms of the voltages applied to the fluorescent lamp 11a in the 
periods 2! and 3! are different from each other depending upon whether 
or not the pulse XWP is applied. 
As described above, the peak value of the write pulse XWP is larger than 
that of the sustain pulse XSP in the conventional gas discharge image 
display. Therefore, the voltage applied between the X and Yi lines in the 
period 3! is higher than in the period 2!. In the present gas discharge 
image display, however, since the peak values of the write pulse XWP and 
the sustain pulse XSP are substantially the same, there is no difference 
in the voltage applied between the X and a Yi lines in the periods 2! and 
3!. As a result, a difference in the intensity between the discharge 
occurring in the period 2! and that occurring in the period 3! is 
decreased, and hence, the variation of the emission luminance caused by 
the other-line write operation can be decreased. 
In the present gas discharge image display, the emission luminance of the 
luminescent lamp (picture element) at the intersection of the X and Yi 
lines is measured with varying the number of the other-line write 
operation, the results of which are shown in FIG. 10. In FIG. 10, the 
ordinate indicates the emission luminance, and the abscissa indicates the 
number of the other-line write operation. This graph reveals that the 
increase of the emission luminance be suppressed to be very small when the 
peak value (VxWP) of the write pulse XWP is the same as the peak value 
(VxSP) of the sustain pulse XSP as compared with the case where they are 
different. 
Each of the row lines Yi through Yk is supplied with the write pulse YWP 
with a different polarity from that of the sustain pulse YSP when each 
line is scanned (selected). As a result, the waveform of the voltage 
applied between the X and Yi lines is obtained as that shown in the fifth 
(waveform X-Yi) of FIG. 8. In the write period of the Yi line (i.e., the 
period 1! FIG. 8), a voltage obtained as the sum of the peak values of 
the pulses XWP and YWP is applied to the luminescent lamp 11a at the 
intersection of the X and Yi lines. 
Since the voltage obtained as the sum of the peak values of the pulses XWP 
and YWP is set to be higher than the discharge start voltage, the 
luminescent lamp 11a discharges. Furthermore, the waveform of the voltage 
applied between the X and Yj lines is obtained as that shown in the sixth 
of FIG. 8. A voltage applied to the luminescent lamp 11b at the 
intersection of the X and Yj lines in the write period of the Yj line 
(i.e., the period 2!) has the peak value of the pulse YWP because the 
write pulse XWP is not applied. Since the peak value of the pulse YWP is 
set to be lower than the discharge start voltage, the luminescent lamp 11b 
does not discharge. 
Moreover, a voltage applied to the luminescent lamp 11a at the intersection 
of the X and Yi lines in the period 3! has the peak value of the pulse 
XWP because the write pulse XWP is applied but the write pulse YWP is not 
applied. Since the peak value of the pulse XWP is set to be lower than the 
discharge start voltage, the luminescent lamp 11a does not discharge also 
in this case. In this manner, the discharge occurs only in the luminescent 
lamp positioned at the intersection of the column line supplied with the 
pulse XWP and the row line supplied with the pulse YWP, and thus, a matrix 
drive system of the gas discharge image display can be realized. 
Embodiment 2 
The variation in the discharge start voltage is measured in the present gas 
discharge image display with the width of the sustain pulses XSP and YSP 
being constant and by using the width (t1) of the write pulses XWP and YWP 
as a parameter. FIG. 11A shows the waveform of a drive voltage used in the 
measurement, and a voltage V at which the discharge stably occurs during 
the pulse width t1 is measured by using the width t1 as the parameter. The 
results obtained in the measurement are listed in FIG. 11B. 
The variation in the sustain start voltage (i.e., the minimum voltage 
required to sustain a discharge) in a sustain period is measured with the 
width of the write pulses being constant and by using the width (t2) of a 
sustain pulse XSP as a parameter. FIG. 12A shows the waveform of a drive 
voltage used in the measurement, and a voltage V at which the discharge 
stably occurs at a point A of FIG. 12A is measured by using the pulse 
width t2 as the parameter. The results obtained in the measurement are 
listed in FIG. 12B. 
FIG. 11B reveals that the discharge start voltage becomes lower as the 
width t1 of the write pulses is larger, and FIG. 12B reveals that the 
sustain start voltage becomes lower as the width t2 of the sustain pulse 
is smaller. Accordingly, a necessary voltage can be decreased by 
increasing the width of the write pulse and decreasing the width of the 
sustain pulse, which call be an advantage in the configuration of an image 
display. In the actual waveform of the drive voltage, it is necessary to 
consider the sum of the widths of the pulses XWP and XSP as the width of 
the sustain pulse, as is obvious from the waveform in the period 3! of 
FIG. 8. 
Therefore, when the width of the pulse XWP is increased in order to 
increase the width of the write pulse and the width of the sustain pulse 
is made constant, the sum of the widths of the pulses XWP and XSP is also 
increased. Thus, the above-described conditions are found to conflict each 
other. Accordingly, in practical use, a point of compromise between these 
conditions is obtained. Specifically, the sum of the widths of the pulses 
XWP and XSP is set to be as small as possible, and under this condition, 
an optimal width of the pulse XSP for attaining the maximum width of the 
pulse XWP is obtained. At this point, it goes without saying that the 
width of the write pulses XWP and YWP is advantageously set to be larger 
than the width of the sustain pulse XSP. 
In other words, when the width of the write pulses (XWP and YWP) is larger 
than that of the sustain pulse (XSP), the drive voltage call be decreased 
in the resultant image display. 
Embodiment 3 
The structure of the fluorescent lamp 11 shown in FIG. 6 is different from 
that of the fluorescent lamp 1 shown in FIG. 1, and specifically, the two 
electrodes have different shapes. Also, the waveform of the voltage 
applied between the X and Yi lines shown in FIG. 8 are not symmetrical 
with zero as the center of symmetry. Therefore, the characteristics are 
slightly changed depending upon which electrode is supplied with a 
positive pulse signal. 
The present gas discharge image display is driven, after a rest period in 
which no pulse voltage is applied, by using a drive voltage with a 
waveform for first using the internal electrode 13 as a negative electrode 
and subsequently using the external electrode as the negative electrode. 
Then, the image display is driven by using a drive voltage with a waveform 
for first using the external electrode 14 as the negative electrode and 
subsequently using the internal electrode 13 as the negative electrode. 
The sustain start voltages are measured in these two cases by using the 
width of the sustain pulse (XSP) as a parameter. 
FIG. 13A shows the former waveform, FIG. 13B shows the latter waveform, and 
FIG. 13C shows the results of the measurement. As is obvious from the 
results, the sustain start voltage can be decreased by applying the 
voltage with the waveform for first using the internal electrode 13 as the 
negative electrode and subsequently using the external electrode 14 as the 
negative electrode. Thus, this waveform is found to be more advantageous 
for the configuration of the drive circuit. 
Embodiment 4 
The present gas discharge image display is driven by using a drive voltage 
with a waveform for performing a write operation during pulse application 
using the internal electrode 13 as the negative electrode. Then, the image 
display is driven by using a drive voltage with a waveform for performing 
a write operation during pulse application using the internal electrode 13 
as the positive electrode. The sustain start voltages are measured in 
these two cases by using the width of the sustain pulse (XSP) as a 
parameter. FIG. 14A shows the former waveform, FIG. 14B shows the latter 
waveform, and FIG. 14C shows the results of the measurement. As is obvious 
from the results, the sustain start voltage can be decreased by using the 
voltage with the waveform for performing the write operation during the 
internal electrode 13 working as the negative electrode. Thus, this 
waveform is found to be more advantageous in the configuration of the 
drive circuit. 
Embodiment 5 
FIG. 15 shows another embodiment of this invention, wherein a fluorescent 
lamp 31 included in the present image display has another external 
electrode 21, that is, a third electrode, provided on the outer wall of 
the small-diameter portion 12b (similarly to a fluorescent lamp described 
in U.S. application Ser. No. 08/545,274 now U.S. Pat. No. 5,668,443 filed 
by the Applicant). An electrode provided on the outer wall of the 
large-diameter portion 12a is an external electrode 14a, that is, the 
second electrode. In this lamp, as disclosed in U.S. application Ser. No. 
08/545,274, now U.S. Pat. No. 5,668,443 a discharge is caused by applying 
a voltage between an internal electrode 13 and the external electrode 21. 
Owing to the presence of space charges generated by this discharge 
(hereinafter referred to as the auxiliary discharge), a discharge between 
the internal electrode 13 and the external electrode 14a (hereinafter 
referred to as the main discharge) can be easily caused. 
At this point, as is shown in FIG. 16, the external electrode 21 is 
connected with the external electrode 14a disposed on the outer wall of 
the large-diameter portion 12a. In FIG. 16, the waveform of a drive signal 
for the fluorescent lamp of FIG. 15 is shown together with the structure 
of the fluorescent lamp. When this fluorescent lamp is driven by supplying 
a signal 50 (corresponding to the waveform X-Yi of FIG. 8), namely, by 
setting the peak value of the sustain pulse (XSP and YSP) to be equal to 
or larger than a value necessary for starting the auxiliary discharge 
(which naturally does not exceed a value necessary for starting the main 
discharge), the auxiliary discharge can be always caused. As a result, 
there is no need to provide a circuit for generating a signal for driving 
the external electrode 21. 
Embodiment 6 
FIGS. 17 and 18 show still another embodiment of the invention using the 
fluorescent lamp 31 including the external electrode working as the third 
electrode. In the waveform shown in FIG. 18, one sustain signal 51 is 
inserted between an erase period and a subsequent write period. 
When the signal 50 shown in FIG. 16 is used, not only the main discharge 
but also the auxiliary discharge are halted in an erase period. As a 
result, the auxiliary discharge is halted immediately before a write 
period, which spoils the effect of the auxiliary discharge by half. 
Therefore, by inserting the sustain signal 51, at least one auxiliary 
discharge is caused immediately before a write period. Thus, the main 
discharge call be easily caused. 
Embodiment 7 
FIGS. 19 and 20 show still another embodiment of the invention using the 
fluorescent lamp 31 including the external electrode working as the third 
electrode. As is shown in FIG. 19, an auxiliary pulse 52 which is 
different from the signal supplied to the external electrode 11a and the 
internal electrode 13 is supplied to an external electrode 21, that is, 
the third electrode, disposed on the outer wall of the small-diameter 
portion and the internal electrode 13. In FIG. 20, the drive waveform of 
the auxiliary pulse 52 is shown as Ai. An auxiliary discharge is caused 
merely immediately before a write period by using the auxiliary pulse 52 
applied to the external electrode 21. By causing the auxiliary discharge 
only immediately before the write period, the power consumed through the 
auxiliary discharge call be minimized, which can make contribution to 
decreasing the power consumption of the entire image display. 
As described above, in the gas discharge image display of the invention, 
the peak value of a write signal applied to a column line (or a row line) 
for starting a discharge is substantially the same as the peak value of a 
sustain signal. As a result, the change of emission intensity caused by 
the other-line write operation can be effectively decreased. 
Furthermore, since the polarities of a write signal and a sustain signal 
are made different, the matrix drive of the gas discharge image display 
can be attained. 
Since the width of a write pulse is made larger than the width of a sustain 
pulse, discharge light emission can be stably sustained. 
In addition, each fluorescent lamp is discharged to emit light by using all 
AC signal so that, after a rest period, the internal electrode working as 
the first electrode is first used as a negative electrode and the external 
electrode working as the second electrode is subsequently used as the 
negative electrode. Therefore, a sustain voltage can be effectively 
decreased. 
Since the write operation is performed in the fluorescent lamp when the 
internal electrode is used as the negative electrode, the sustain voltage 
can be decreased. 
Furthermore, the second and third electrodes provided on the outer wall of 
a cylindrical container are driven by using the same signal. As a result, 
the write operation can be stably performed. 
At least one sustain signal is inserted between an erase signal for halting 
a discharge and a write signal subsequently following the erase signal. As 
a result, the write operation can be more stably performed. 
Furthermore, the third electrode disposed on the outer wall of the 
cylindrical container is supplied with a drive signal merely immediately 
before a write signal. Therefore, power consumption can be decreased. 
As this invention may be embodied in several forms without departing from 
the spirit of essential characteristics thereof, the present embodiments 
are therefore illustrative and not restrictive, since the scope of the 
invention is defined by the appended claims rather than by the description 
preceding them, and all changes that fall within metes and bounds of the 
claims, or equivalence of such metes and bounds thereof are therefore 
intended to be embraced by the claims.