Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
2002-02-26
2004-11-09
Tran, Henry N. (Department: 2674)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S060000, C315S169100, C315S169300, C315S169400
Reexamination Certificate
active
06816136
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for driving a plasma display panel (PDP) and more particularly to an alternating current (AC) discharging-type PDP which provides a display in a form of a matrix.
The present application claims priority of Japanese Patent Application No.
2001-052851
filed on Feb. 27, 2001, which is hereby incorporated by reference.
2. Description of the Related Art
A conventional PDP and a method for driving the conventional PDP will be described below by referring to the attached prior art drawings.
FIG. 23
is a cross-sectional view showing main portions of the conventional PDP. The conventional PDP includes a front insulating substrate
1
a
and a rear insulating substrate
1
b
both being made from glass. On the front insulating substrate la are formed a scanning electrode
2
and a sustaining electrode
3
both being made from transparent conductive material. In order to reduce resistance values of the scanning electrode
2
and the sustaining electrode
3
, trace electrode
4
is stacked on each of the scanning electrode
2
and the sustaining electrode
3
. A first dielectric layer
9
is formed in a manner that it covers the scanning electrode
2
and the sustaining electrode
3
. Moreover, a protecting layer
10
used to protect the first dielectric layer
9
and made from magnesium oxide or a like is formed. On the rear insulating substrate
1
b
is formed a data electrode
5
extending in a direction orthogonal to the scanning electrode
2
and sustaining electrode
3
. Also, a second dielectric layer
11
which covers the data electrode
5
is formed. On the second dielectric layer
11
is formed a rib
7
extending in a same direction as the data electrode
5
extends and is used to partition a discharging cell
12
(
FIG. 24
) making up a unit portion for displaying in the conventional PDP. On a side face of the rib
7
and on a surface of the second dielectric layer
11
where the rib
7
has not been formed is formed a phosphor layer
8
used to convert ultraviolet rays emitted by a discharge of a discharging gas to visible light. Generally, in a PDP which performs a display in multiple colors, a phosphor layer
8
is formed by putting a necessary phosphor on each region partitioned by ribs to acquire various colors. Therefore, all the phosphor layers
8
corresponding to one piece of the data electrode
5
use phosphors of a same type.
Space being sandwiched between the front insulating substrate
1
a
and the rear insulating substrate
1
b
and being partitioned by the rib
7
serves as a discharging space
6
to be filled with helium, neon, xenon, or a like, or their mixed gas. In the conventional PDP being configured as above, a discharge occurs between the scanning electrode
2
and the sustaining electrode
3
(hereinafter the discharge occurring between the scanning electrode
2
and sustaining electrode
3
is referred to as a surface discharge
100
).
FIG. 24
is a schematic diagram illustrating an arrangement of electrodes used in the conventional PDP. As shown in
FIG. 24
, one discharging cell
12
is placed at a point of intersection of one piece of the scanning electrode
2
, one piece of the sustaining electrode
3
, and one piece of the data electrode
5
which intersects the scanning electrode
2
and the sustaining electrode
3
at right angles. The scanning electrode
2
is connected to a scanning driver integrated circuit (IC)
21
so as to individually apply a scanning voltage pulse. The sustaining electrode
3
is connected to a sustaining circuit
22
, in order to provide pulses each having a common waveform, in a manner that all the sustaining electrodes
3
are electrically and commonly connected at an end of a panel or on a driving circuit. The data electrode
5
is connected to a data driver integrated circuit (IC)
23
so as to individually provide a data pulse.
Next, various selective displaying operations of the discharging cell
12
employed in the conventional PDP will be described by referring to FIG.
25
.
FIG. 25
is a timing chart illustrating a voltage pulse being applied to each electrode (the scanning electrode
2
, the sustaining electrode
3
and data electrode
5
) in the conventional method for driving the conventional PDP. In
FIG. 25
, a pre-discharging period A is a period during which a preparation is made to induce an easy discharge in a subsequent selective operation period B. The selective operation period B is a period during which an ON or OFF state of each of the discharging cells
12
for displaying is selected. A discharge sustaining period C is a period during which each of all the selected discharging cells
12
for displaying is discharged. A discharge sustaining terminating period D is a period during which the discharge for displaying is stopped.
FIGS. 26A
,
26
B,
26
C,
26
D, and
26
E show schematic diagrams illustrating a state of a wall charge in the discharging cell
12
during the pre-discharging period A and the selective operation period B in the conventional driving method. Each of states shown in
FIGS. 26A
to
26
E corresponds to a state occurring at each of times t
1
to t
5
shown in
FIG. 25
, respectively. Moreover, in the conventional driving method, a reference potential between a pair of electrodes electrically made up of the scanning electrode
2
and the sustaining electrode
3
(hereinafter the pair of electrodes electrically made up of the scanning electrode
2
and the sustaining electrode
3
is referred to as “surface electrodes”) is set so as to be a sustaining voltage Vos which is required to sustain the discharge during the discharge sustaining period C. Therefore, a electric potential of the scanning electrode
2
or the sustaining electrode
3
being higher than the sustaining voltage Vos being the reference potential is defined as a electric potential of positive polarity and a electric potential of the scanning electrode
2
or the sustaining electrode
3
being lower than the sustaining voltage Vos being the reference potential as a electric potential of negative polarity. Moreover, a reference potential of the data electrode
5
is set to be 0 (zero) V.
First, during the pre-discharging period A, a sawtooth-shaped pre-discharging pulse Pops having its ultimate potential Vops of positive polarity is applied to the scanning electrode
2
while a rectangular pre-discharging pulse Popc having its electric potential being 0 (zero) V of negative polarity is applied to the sustaining electrode
3
. A difference in ultimate potentials between the scanning electrode
2
and sustaining electrode
3
occurring at a time of application of the pre-discharging pulse Pops is a electric potential Vops. The electric potential Vops is set, in advance, at a value exceeding a discharge initiating threshold voltage between the scanning electrode
2
and sustaining electrode
3
. A non-disclosed experiment of the inventor of the present invention shows that the discharge initiating threshold voltage between the scanning electrode
2
and sustaining electrode
3
is within a range of 230 V to 250 V and therefore the electric potential Vops is preferably set to be about 300 V. By application of the sawtooth-shaped pre-discharging pulse Pops to the scanning electrode
2
and of the rectangular pre-discharging pulse Popc to the sustaining electrode
3
, a voltage of the sawtooth-shaped pre-discharging pulse Pops rises and, from a time point when a voltage between the scanning electrode
2
and the sustaining electrode
3
exceeds the discharging initiating threshold voltage, as shown in
FIG. 26A
, a feeble surface discharge occurs between the scanning electrode
2
and sustaining electrode
3
(at the time of t
1
). The feeble surface discharge continues to occur while the electric potential of the sawtooth-shaped pre-discharging pulse Pops is rising, and stops when the electric potential of the sawtooth-shaped pre-discharging pulse Pops has reached the ultimate potential Vops and a change in the electric p
Araki Kota
Homma Hajime
Tanaka Yoshito
NEC Corporation
Tran Henry N.
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