Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
2000-12-01
2003-08-19
Saras, Steven (Department: 2675)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S060000, C345S055000
Reexamination Certificate
active
06608611
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method of driving a plasma display panel, and more particularly to an address driving method of a plasma display panel that permits a stable high-speed addressing.
2. Description of the Related Art
Generally, a plasma display panel (POP) 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. 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. Such a PDP typically includes a surface-discharge alternating current (AC) type PDP that has three electrodes as shown in FIG.
1
and is driven with an alternating current voltage.
FIG. 1
is a perspective view of a discharge cell of a conventional three-electrode, AC-type PDP. Referring to
FIG. 1
, the discharge cell includes an upper substrate
10
provided with a sustaining electrode pair
12
and
14
, and a lower substrate
20
provided with an address electrode
22
. The upper substrate
10
and the lower substrate
20
are spaced, in parallel to each other, with having a barrier rib
26
therebetween. A mixture gas such as Ne—Xe or He—Xe, etc. is injected into a discharge space defined by the upper substrate
10
and the lower substrate
20
and the barrier rib
26
. Any one electrode
12
of the sustaining electrode pair
12
and
14
is used as a scanning/sustaining electrode that responds to a scanning pulse applied in the address interval to cause an opposite discharge along with the address electrode
22
, and responds to a sustaining pulse applied in the sustaining interval to cause a surface discharge along with the adjacent sustaining electrode
14
. The sustaining electrodes
14
adjacent to the sustaining electrode
12
used as the scanning/sustaining electrode are used as a common sustaining electrode to which a sustaining pulse is applied commonly. On an upper substrate
10
provided with the sustaining electrode pair
12
and
14
, an upper dielectric layer
16
and a protective film
18
are disposed. The upper dielectric layer
16
is responsible for limiting a plasma discharge current as well as accumulating a wall charge during the discharge. The protective film
18
prevents a damage of the upper dielectric layer
16
caused by a sputtering generated during the plasma discharge and improves an emission efficiency of secondary electrons. This protective film
18
is usually made from MgO. The address electrode
22
crosses the sustaining electrode pair
12
and
14
and is supplied with a data signal for selecting cell to be displayed. A lower dielectric layer
24
is formed on the lower substrate
20
provided with the address electrode
22
. The barrier ribs
26
for dividing the discharge space are extended perpendicularly on the lower dielectric layer
24
. The surfaces of the lower dielectric layer
24
and the barrier rib
26
is coated with a fluorescent material
28
excited by a vacuum ultraviolet ray to generate a red, green or blue visible light.
The PDP discharge cell having the structure as described above sustains a discharge by a surface discharge between the sustaining electrode pair
12
and
14
after being selected by an opposite discharge between the address electrode
22
and the scanning/sustaining electrode
12
. The fluorescent material
28
is radiated by an ultraviolet ray generated during the sustaining discharge to emit a visible light into the exterior of the cell. In this case, a discharge sustaining interval, that is, a sustaining discharge frequency of the cell is controlled to realize a gray scale required for an image display.
An arrangement of the entire electrode lines and discharge cells of the AC surface-discharge PDP is as shown in FIG.
2
. In
FIG. 2
, the discharge cell
30
is positioned at each intersection among m address electrode lines X
1
to Xm, n scanning/sustaining electrode lines Y
1
to Yn and n common sustaining electrode lines Z
1
to Zn. The address electrode lines X
1
to Xm are divided into odd-numbered lines and even numbered lines to be individually driven at the upper and lower portion thereof, respectively. The scanning/sustaining electrode lines Y
1
to Yn are individually driven while the common sustaining electrode lines Z
1
to Zn are commonly driven.
Such a PDP driving method typically includes a sub-field driving method in which the address interval and the discharge sustaining interval are separated. In the sub-field driving method as shown in
FIG. 3
, one frame 1F is divided into n bits for example, 8 sub-fields SF
1
to SF
8
corresponding to each bit of an 8-bit image data, and each sub-field SF
1
to SF
8
is again divided into a reset interval RPD, an address interval APP and a discharge sustaining interval SPD. The reset interval RPD is an interval for initializing the discharge cell, the address interval APD is an interval for generating a selective address discharge in accordance with a logical value of a video data, and the sustaining interval SPD is an interval for allowing a discharge to be sustained at the discharge cell
12
in which the address discharge has been generated. The reset interval RPO and the address interval APD are equally allocated in each sub-field interval. A weighting value with a ratio of 2
0
:2
1
:2
2
: . . . :2
n−1
, i.e., 1:2:4:8:16:32:64:128 is given to the discharge sustaining interval SPD to express a gray scale by a combination of the discharge sustaining intervals SPD.
FIG. 3
is waveform diagrams of driving signals applied to the PDP shown in
FIG. 2
in a certain one sub-field interval SFi. In the reset interval RPD, a priming pulse Pp is commonly applied to the scanning/sustaining electrode lines Y
1
to Yn and the common sustaining electrode lines Z
1
to Zn. By this priming pulse Pp, a reset discharge is generated between each common sustaining electrode and each scanning/sustaining electrode of the entire discharge cells
30
to initialize the discharge cells
30
. By the reset discharge, a large amount of wall charges are formed at the common sustaining electrode and the scanning/sustaining electrode of each discharge cell
30
.
Subsequently, a self-erasure discharge is generated at the discharge cells by the large amount of wall charges to eliminate the wall charges and leave a small amount of charged particles. These small amount of charged particles help an address discharge in the following address interval. In the address interval APD, a scanning voltage pulse SCp is applied line-sequentially to the scanning/sustaining electrode lines Y
1
to Yn. At the same time, a data pulse Dp according to a logical value of a data is applied to the address electrode lines X
1
to Xm. Thus, an address discharge is generated at discharge cells to which the scanning voltage pulse SCp and the data pulse Dp are simultaneously applied. Wall charges are formed at the discharge cells in which the address discharge has been generated. During this address interval, a desired constant voltage is applied to the common sustaining electrode lines Z
1
to Zn to prevent a discharge between each address electrode line and each common sustaining electrode line. In the sustaining interval SPD, a sustaining pulse Sp is alternately applied to the first to mth scanning/sustaining electrode lines Y
1
to Ym and the common sustaining electrode lines Z
1
to Zn. Accordingly, a sustaining discharge is generated continuously only at the discharge cells formed with the wall charges by said address discharge to emit a visible light. Then, in a separate erasure interval EPD, an erasing pulse Ep is applied to the common sustaining electrode lines Z
1
to Zn to interrupt the sustained discharge.
In the conventional AC, surface-discharge PDP driven as described above, there has been used a scheme of lengthening a pulse width Td of address drive pulses Dp and SCp into more than 2.5 &mgr;s or enlarging a voltage level of the
Fleshner & Kim LLP
LG Electronics Inc.
Moyer Michael J.
Saras Steven
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