Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
2001-10-26
2004-01-20
Mengistu, Amare (Department: 2673)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S067000
Reexamination Certificate
active
06680717
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a driving method of a plasma display panel, and more specifically to a driving method of a plasma display panel of an alternate current discharge type and a matrix display scheme.
A first example of a conventional plasma display panel and a method for driving the same will be described with reference to the drawings.
FIG. 12
is a partial sectional view of the conventional plasma display panel. The conventional plasma display panel includes two insulating substrates
1
a
and
1
b
formed of glass and constituting a front plate and a back plate.
On the insulating substrate
1
a
, transparent scan electrodes
2
and sustain electrodes
3
are formed, and trace electrodes
4
are formed to lay over the scan electrodes
2
and the sustain electrodes
3
to reduce a resistance value of these electrodes. In addition, a first dielectric layer
9
is formed to cover the scan electrodes
2
and the sustain electrodes
3
. Furthermore, a protection layer
10
of magnesium oxide or another is formed to protect the dielectric layer
9
from an electric discharge.
On the insulating substrate
1
b
, data electrodes
5
are formed to extend orthogonally to the scan electrodes
2
and the sustain electrodes
3
. A second dielectric layer
11
is formed to cover the data electrodes
5
. On the second dielectric layer
11
, a partition
7
is formed to extend in the same direction as that of the data electrode and to confine display cells which are a unit of display. Furthermore, a phosphor layer
8
, which converts a ultraviolet radiation generated by an electric discharge in an electric discharge gas, to a visible light, is formed on a side surface of the partition
7
and on a surface of the dielectric layer
11
on which the partition
7
is not formed.
Furthermore, a space sandwiched between the insulating substrates
1
a
and
1
b
and confined by the partition
7
constitutes an electric discharge space filled up with an electric discharge gas which is formed of helium, neon, xenon and a mixed gas of those gases.
In the plasma display panel constituted as mentioned above, a surface electric discharge
100
is generated between the scan electrode
2
and the sustain electrode
3
.
FIG. 13
is a diagram of illustrating an electrode location in the conventional plasma display panel. One display cell
12
is formed on each intersection between one scan electrode
2
and one sustain electrode
3
and one data electrode
5
extending orthogonally to these electrodes. The scan electrodes
2
are individually connected to a scan driver integrated circuit (IC)
21
so that a scan voltage pulse is individually applied to each scan electrode. All the sustain electrodes
3
are electrically connected in common to a sustain circuit
22
at a panel end or on a driving circuit, so that only a common waveform is applied to the sustain electrodes. In addition, the data electrodes
5
are connected to a data driver integrated circuit (IC)
23
so that a data pulse can be individually applied to each data electrode.
Now, various selective display operations of the display cell will be described.
FIG. 14
is a timing chart for illustrating voltage pulses applied to various electrodes in a first conventional driving method. In addition,
FIG. 15
is a diagram for illustrating a wall electric charge within the display cell during a selection period B in the first conventional driving method. In
FIG. 14
, a period A is a preliminary electric discharge period for facilitating generation of an electric discharge in a succeeding selection period, and a period B is a selection period for on-off selecting the luminescence of each display cell. A period C is a sustain period for causing an illuminant electric discharge in all the selected display cells, and a period D is a sustain extinguishing period for extinguishing the illuminant electric discharge. Here, in this first conventional driving method, a reference potential of a surface electrode composed of the scan electrodes
2
and the sustain electrodes
3
is a sustain voltage Vos for sustaining the electric discharge during the sustain period C. Therefore, in connection with the scan electrode
2
and the sustain electrode
3
, a potential higher than the sustain voltage Vos is called to have a positive polarity, and a potential lower than the sustain voltage Vos is called to have a negative polarity. In addition, in connection with the potential of the data electrode
5
, 0V is considered to be a reference.
First, in the preliminary electric discharge period A, a positive sawtooth preliminary electric discharge pulse Vops is applied to the scan electrodes
2
, and simultaneously, a negative rectangular preliminary pulse Vopc is applied to the sustain electrode
3
. The pulse-height value of these preliminary electric discharge pulses is set to exceed an electric discharge starting threshold value between the scan electrode
2
and the sustain electrode
3
. Accordingly, when the preliminary electric discharge pulses Vops and Vopc are applied to the corresponding electrodes, the voltage of the sawtooth preliminary electric discharge pulse Vops increases, and after a voltage between both the electrodes exceeds the electric discharge starting threshold value, a weak electric discharge occurs between the scan electrode
2
and the sustain electrode
3
. As a result, a negative wall electric charge is formed on the scan electrode
2
, and a positive wall electric charge is formed on the sustain electrode
3
.
Succeeding to the preliminary electric discharge pulses Vops, a negative sawtooth preliminary electric discharge extinguishing pulse Vope is applied to the scan electrode
2
. At this time, the potential of the sustain electrode
3
is fixed to the sustain voltage Vos. With application of the preliminary electric discharge extinguishing pulse Vope, the wall electric charge formed on the scan electrode
2
and the sustain electrode
3
is extinguished. Here, even after the wall electric charge is extinguished, space-charges such as electrons and ions and active particles such as quasi-stable particles generated in the preliminary electric discharge exists in the electric discharge space
6
, even if those are a little amount. In addition, the extinction of the wall electric charge during the preliminary electric discharge period A includes adjustment of the wall electric charge in order to cause the succeeding operations such as the selection operation and the sustain electric discharge to be carried out in a good condition.
In the selection period B, after all the scan electrodes
2
are maintained at a base potential Vobw once, a negative scan pulse Vow is sequentially applied to each scan electrode
2
, and a data pulse Vod corresponding to a display data is individually applied to each data electrode
5
. During this period, a positive auxiliary scan pulse Vosw is applied to the sustain electrode
3
. Here, the scan pulse Vow and the data pulse Vod are set to ensure that a voltage difference between confronting electrodes constituted of the scan electrode
2
and the data electrode
5
never exceeds the electric discharge starting threshold voltage when only either one of the scan pulse Vow and the data pulse Vod is applied, but exceeds the electric discharge starting threshold voltage when both the scan pulse Vow and the data pulse Vod are superposed. On the other hand, the auxiliary scan pulse Vosw is set to ensure that when the auxiliary scan pulse Vosw is superposed with the scan pulse Vow, a voltage difference between surface electrodes constituted of the scan electrode
2
and the sustain electrode
3
never exceeds an electric discharge starting threshold voltage between the surface electrodes.
Accordingly, in only the display cell applied with the data pulse Vod in time with application of the scan pulse Vow, a space electric discharge (generated between confronting electrodes) occurs between the scan electrode
2
and the data electrode
5
as shown in FIG.
15
. At this time, since
Mengistu Amare
NEC Corporation
Young & Thompson
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