Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
2001-02-05
2004-11-16
Eisen, Alexander (Department: 2674)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C315S169400
Reexamination Certificate
active
06819307
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a flat panel display device, and more particularly to a plasma display panel that is capable of improving the discharge efficiency and the brightness. Also, the present invention is directed to a method of driving said plasma display panel.
2. Description of the Related Art
Generally, a plasma display panel (PDP) radiates a fluorescent body by an ultraviolet with a wavelength of 147 nm generated during a discharge of He+Xe or Ne+Xe gas to thereby display a picture including characters and graphics. Such a PDP is easy to be made into a thin film and large-dimension type. Moreover, the PDP provides a very improved picture quality owing to a recent technical development. The PDP is largely classified into a direct current (DC) driving system and an alternating current (AC) driving system. The DC-type PDP causes an opposite discharge between an anode and a cathode provided at a front substrate and a rear substrate, respectively to display a picture. On the other hand, the AC-type PDP allows an alternating voltage signal to be applied between electrodes having dielectric layer therebetween to generate a discharge every half-period of the signal, thereby displaying a picture. Since such an AC-type PDP uses a dielectric material which allows a wall charge to be accumulated on the surface thereof upon discharge, it produces a memory effect.
Referring to
FIG. 1
, the AC-type PDP includes a front substrate
1
provided with a sustaining electrode pair
10
, and a rear substrate
2
provided with an address electrode
4
. The front substrate
1
and the rear substrate
2
are spaced in parallel to each other with having barrier ribs
3
therebetween. A mixture gas, such as Ne−Xe or He−Xe, etc., is injected into a discharge space defined by the front substrate
1
, the rear substrate
2
and the barrier ribs
3
. The sustaining electrode
10
makes a pair by two within a single of plasma discharge channel. Any one of the sustaining electrode pair
10
is used as a scanning/sustaining electrode that responds to a scanning pulse applied in an address interval to cause an opposite discharge along with the address electrode
4
while responding to a sustaining pulse applied in a sustaining interval to cause a surface discharge with the adjacent sustaining electrodes
10
. Also, the remaining one of the sustaining electrode pair
10
is used as a common sustaining electrode to which a sustaining pulse is applied commonly. On the front substrate
1
provided with the sustaining electrodes
10
, a dielectric layer
8
and a protective layer
9
are disposed. The dielectric layer
8
is responsible for limiting a plasma discharge current as well as accumulating a wall charge during the discharge. The protective film
9
prevents a damage of the dielectric layer
8
caused by the sputtering generated during the plasma discharge and improves the emission efficiency of secondary electrons. This protective film
9
is usually made from MgO. The barrier ribs
3
for dividing the discharge space are extended perpendicularly at the rear substrate
2
. On the surfaces of the rear substrate
2
and the barrier ribs
3
, a fluorescent material
5
excited by a vacuum ultraviolet lay to generate a visible light is provided.
In such an AC-type PDP, one frame consists of a number of sub-fields so as to realize gray levels by a combination of the sub-fields. For instance, when it is intended to realize 256 gray levels, one frame interval is time-divided into 8 sub-fields. Further, each of the 8 sub-fields is again divided into a reset interval, an address interval and a sustaining interval. The entire field is initialized in the reset interval. The discharge pixel cells on which a data is to be displayed are selected by the address discharge in the address interval. The selected discharge pixel cells sustain the discharge in the sustaining interval. The sustaining interval is lengthened by an interval corresponding to 2
n
depending on a weighting value of each sub-field. In other words, the sustaining interval involved in each of first to eighth sub-fields increases at a ratio of 2
0
, 2
1
, 2
3
, 2
4
, 2
5
, 2
6
and 2
7
. To this end, the number of sustaining pulses generated in the sustaining interval also increases into 2
0
, 2
1
, 2
3
, 2
4
, 2
5
, 2
6
and 2
7
depending on the sub-fields. The brightness and the chrominance of a displayed image are determined in accordance with a combination of the sub-fields. However, the three-electrode, AC surface-discharge PDP has problems in that, since a voltage required for the sustaining discharge is high, the power consumption is large and that the discharge and light-emission efficiency upon sustaining-discharge between the sustaining electrode pair is low.
In order to solve these problems of the three-electrode, AC surface-discharge PDP, there has been suggested a PDP provided with four sustaining electrodes.
Referring to FIG.
2
and
FIG. 3
, the conventional five-electrode PDP includes a sustaining electrode pair
13
and
16
and a trigger electrode pair
30
and
36
formed on a front substrate
20
, and an address electrode
17
formed on a rear substrate
18
. The trigger electrode pair
30
and
36
is provided between the sustaining electrode pair
13
and
16
to cause a trigger discharge by a wall voltage produced upon address-discharge and an application voltage, thereby initiating a sustaining electrode. The sustaining electrode pair
13
and
16
forms a pair within a single plasma discharge channel. Any one of the sustaining electrode pair
13
and
16
is used as a scanning/sustaining electrode that responds to a scanning pulse applied in an address interval to cause an opposite discharge along with the address electrode
17
while responding to a sustaining pulse applied in a sustaining interval to cause a surface discharge with the adjacent sustaining electrode
13
or
16
. Also, the remaining one of the sustaining electrode pair
13
and
16
is used as a common sustaining electrode to which a sustaining pulse is applied commonly. The sustaining electrode pair
13
and
16
causes a sustaining discharge by a wall voltage formed by the trigger discharge generated between the trigger electrode pair
30
and
36
and an application voltage. The sustaining electrode pair
13
and
16
and the trigger electrode pair
30
and
36
have a line width smaller than transparent electrodes
28
and
34
and includes metal bus electrodes
26
and
32
formed at one edge of the transparent electrodes
28
and
34
, respectively. A dielectric layer
23
and a protective layer
24
are disposed on the front substrate
20
to cover the sustaining electrode pair
13
and
16
and the trigger electrode pair
30
and
36
. Wall charges produced upon plasma display are accumulated in the dielectric layer
23
. The protective film
24
prevents a damage of the dielectric layer
23
caused by the sputtering generated during the plasma discharge and improves the emission efficiency of secondary electrons. Barrier ribs
25
and a fluorescent material
22
are formed on the rear substrate
18
provided with the address electrode
17
.
When the sustaining electrode pair
13
and
16
of the five-electrode PDP is compared with the sustaining electrode pair
10
of the three-electrode PDP, a distance between the sustaining electrode pair
13
and
16
is longer than that between the electrode pair
10
. Thus, the five-electrode PDP has a better light-emission efficiency than the three-electrode PDP upon discharge.
However, as shown in
FIG. 4
, the five-electrode PDP concentrates the sustaining discharge upon the middle portion of the discharge cell. The PDP having such a structure has a problem in that only a portion of energy produced upon sustaining-discharge excites the fluorescent material. In other words, only a portion of energy produced during the sustaining discharge excites the fluorescent material while the remaining energy other than the energy exciting
Ahn Young Joon
Kang Seok Dong
Eisen Alexander
Fleshner & Kim LLP
LG Electronics Inc.
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