Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
1999-11-15
2003-01-07
Hjerpe, Richard (Department: 2674)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S054000, C345S063000, C345S066000, C345S068000
Reexamination Certificate
active
06504519
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a plasma display panel that is capable of improving the brightness as well as preventing a mis-discharge. Also, the present invention is directed to apparatus and method of driving the 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 PDP with an AC driving system is expected to be preferred for future display devices because it has advantages in the use of a low voltage drive and a prolonged life in comparison to the PDP of a DC driving system. Also, the PDP of an alternating current driving system allows an alternating voltage signal to be applied between electrodes having dielectric layers therebetween to generate a discharge every half-period of the signal, thereby displaying a picture. Since such an AC driving system for a PDP uses a dielectric material, the surface of the dielectric material is charged with electricity. The AC-type PDP allows a memory effect to be produced by a wall charge accumulated on the dielectric material due to the discharge.
Referring to FIG.
1
and
FIG. 2
, the AC-type PDP includes a front substrate
1
provided with a plurality of sustaining electrodes
10
, and a rear substrate
2
provided with a plurality of address electrodes
4
. The front substrate
1
and the rear substrate
2
are spaced in parallel and have a plurality of 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
and the rear substrate
2
and the barrier ribs
3
. Each sustaining electrode
10
consists of a transparent electrode
6
and a metal electrode
7
. The transparent electrode
6
is usually made from Indium—Tin—Oxide and has an electrode width of about 300 &mgr;m. Usually, the metal electrode
7
has a three-layer structure of Cr—Cu—Cr and has an electrode width of about 50 to 100 &mgr;m. This metal electrode
7
plays a role to increase a resistance of the transparent electrode to a high resistance to thereby reduce a voltage drop. Such a sustaining electrode
10
makes a pair within a single plasma discharge channel. Any one of the pair of sustaining electrode
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 an 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 sustaining electrode
10
adjacent to the sustaining electrode
10
used as the scanning/sustaining electrode is used as a common sustaining electrode to which a sustaining pulse is applied commonly. A distance a, between the sustaining electrodes
10
making a pair is set to be approximately 100 &mgr;m. 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 damage of the dielectric layer
8
caused by a sputtering generated during the plasma discharge and improves an emission efficiency of secondary electrons. This protective film is usually made from MgO. Barrier ribs
3
for dividing the discharge space are extended perpendicularly at the rear substrate
2
, and the address electrode
4
is formed between the barrier ribs
3
. On the surfaces of the barrier ribs
3
and the address electrodes
4
, a fluorescent layer
5
excited by a vacuum ultraviolet ray to generate a visible light is provided.
As shown in
FIG. 3
, the PDP
20
has mxn discharge pixel cells
11
arranged in a matrix pattern. At each of the discharge pixel cells
11
, scanning/sustaining electrode lines Y
1
to Ym, hereinafter referred to as “Y electrode lines”, and common sustaining electrode lines Z
1
to Zm, hereinafter referred to as “Z electrode lines”, and address electrode lines X
1
to Xn, hereinafter referred to as the “X electrode lines” are crossed with respect to each other. The Y electrode lines Y
1
to Ym and the Z electrode lines Z
1
to Zm consist of the sustaining electrode
10
making a pair. The X electrode lines X
1
to Xn consist of the address electrodes
4
.
FIG. 3
is a schematic view of a PDP driver shown in FIG.
1
. In
FIG. 3
, the PDP driver includes a scanning/sustaining driver
22
for driving the Y electrode lines Y
1
to Ym, a common sustaining driver
24
for driving the Z electrode lines Z
1
to Zm, and first and second address drivers
26
A and
26
B for driving the X electrode lines X
1
to Xn. The scanning/sustaining driver
22
is connected to the Y electrode lines Y
1
to Ym to thereby select a scanning line and cause a sustaining discharge at the selected scanning line. The common sustaining driver
24
is commonly connected to the Z electrode lines Z
1
to Zm to apply sustaining pulses with the same waveform to all the Z electrode lines Z
1
to Zm, thereby causing the sustaining discharge. The first address driver
26
A supplies odd-numbered X electrode lines X
1
, X
3
, . . . , Xn−3, Xn−1 with video data, whereas the second address driver
26
B supplies even-numbered X electrode lines X
2
, X
4
, . . . , Xn−2, Xn with video data.
In such a 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
11
to data are selected by the address discharge in the address interval. The selected discharge pixel cells
11
sustain the discharge in the sustaining interval. The sustaining interval is lengthened by an interval corresponding to 2
n
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.
FIG. 4
shows signals applied so as to drive the AC-type PDP. In
FIG. 4
, the AC-type PDP is driven with a drive cycle being divided into a reset interval for initializing the entire field, an address interval for selecting the discharge pixel cells
11
displaying data, and a sustaining interval for sustaining a discharge of the selected discharge pixel cells
11
. Reset pulses RPx and RPz are applied to the X electrode lines X
1
to Xn and the Z electrode lines Z
1
to Zm in the reset interval. A reset discharge is generated between all the X electrode lines X
1
to Xn and all the Z electrode lines Z
1
to Zm within the PDP
20
by the reset pulses RPx and RPx to thereby initialize the entire field. In the address interval, a writing pulse WP including data for one line is applied to the X electrode lines X
1
to Xn and scanning pulses −SCP
1
, −SCP
2
, . . . , −SCPm synchronized with the writing pulse WP are sequentially applied to the Y electrode lines Y
1
to Ym. Then, an ad
Lee Eun Cheol
Ryu Ju Youn
Abdulselam Abbas
LG Electronics Inc.
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