Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
2000-11-22
2004-05-18
Awad, Amr (Department: 2675)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C313S583000, C315S169400
Reexamination Certificate
active
06738032
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a plasma display panel, and more particularly to a plasma display panel that is capable of minimizing a brightness difference.
2. Description of the Related Art
Recently, a plasma display panel (PDP) feasible to a manufacturing of a large-dimension panel has been highlighted as a flat panel display device. The POP typically includes a three-electrode, alternating current (AC) surface discharge PDP that has three electrodes and is driven with an AC voltage as shown in FIG.
1
.
Referring to
FIG. 1
, a discharge cell of the three-electrode, AC surface discharge PDP includes a scanning/sustaining electrode
12
Y and a common sustaining electrode
12
Z formed on an upper substrate
10
, and an address electrode
20
X formed on a lower substrate
18
. On the upper substrate
10
in which the scanning/sustaining electrode
12
Y is formed in parallel to the common sustaining electrode
12
Z, an upper dielectric layer
14
and a protective film
16
are disposed. Wall charges generated upon plasma discharge are accumulated in the upper dielectric layer
14
. The protective film
16
prevents a damage of the upper dielectric layer
14
caused by the sputtering generated during the plasma discharge and improves the emission efficiency of secondary electrons. This protective film
16
is usually made from MgO. A lower dielectric layer
22
and barrier ribs
24
are formed on the lower substrate
18
provided with the address electrode
20
X, and a fluorescent material
26
is coated on the surfaces of the lower dielectric layer
22
and the barrier ribs
24
. The address electrode
20
X is formed in a direction crossing the scanning/sustaining electrode
12
Y and the common sustaining electrode
12
Z. The barrier ribs
24
is formed in parallel to the address electrode
20
X to prevent an ultraviolet ray and a visible light generated by the discharge from being leaked to the adjacent discharge cells. The fluorescent material
26
is excited by an ultraviolet ray generated upon plasma discharge to produce a red, green or blue color visible light ray. An active gas for a gas discharge is injected into a discharge space defined between the upper/lower substrate and the barrier rib.
As shown in
FIG. 2
, such a discharge cell is arranged in a matrix type. In
FIG. 2
, the discharge cell
1
is provided at each intersection among scanning/sustaining electrode lines Y
1
to Ym, common sustaining electrode lines Z
1
to Zm and address electrode lines X
1
to Xn. The scanning/sustaining electrode lines Y
1
to Ym are sequentially driven while the common sustaining electrode lines Z
1
to Zm are commonly driven. The address electrode lines X
1
to Xn are driven with being divided into odd-numbered lines and even-numbered lines.
Such a three-electrode, AC surface discharge PDP is driven with being separated into a number of sub-fields. In each sub-field interval, a light emission having a frequency proportional to a weighting value of a video data is conducted to provide a gray scale display. For instance, if a 8-bit video data is used to display a picture of 256 gray scales, then one frame display interval (e.g., 1/60 second=16.7 msec) in each discharge cell
1
is divided into 8 sub-fields SF
1
to SF
8
. Each sub-field is again divided into a reset interval, an address interval and a sustaining interval. A weighting value at a ratio of 1:2:4:8: . . . :128 is given in the sustaining interval. Herein, the reset interval is a period for initializing the discharge cell; the address interval is a period for generating a selective address discharge in accordance with a logical value of a video data; and the sustaining interval is a period for sustaining the discharge in a discharge cell in which the address discharge has been generated. The reset interval and the address interval are equally assigned in each sub-field interval.
The scanning/sustaining electrode lines Y and the common sustaining electrode lines Z of the plasma display panel receive a driving waveform via a pad portion
30
shown in FIG.
3
. Referring to
FIG. 3
, the pad portion
30
includes pads
31
for receiving a driving waveform from a driving waveform supply, and connecting parts
32
for applying the driving waveform inputted to the pads
31
to the scanning/sustaining electrode lines Y or the common sustaining electrode lines Z. Each pad
31
is connected to a connector
34
of the driving waveform supply as shown in FIG.
4
. The driving waveform supply applies the driving waveform inputted to the scanning/sustaining electrode lines Y or the common sustaining electrode lines Z to the connectors
34
. The driving waveform inputted to the connectors
34
is applied, via the pads
31
and the connecting parts
32
, to the scanning/sustaining electrode lines Y or the common sustaining electrode lines Z. In this case, a longitudinal width of each connector
34
is formed to be narrower than a width of an effective display part in which a picture is to be displayed in compliance with a trend toward a slim-type PDP. Thus, a width of the pad
31
set in correspondence with a longitudinal width of the connector
34
also is formed narrowly. Accordingly, a length of a connecting part
32
provided between the pads
31
and the electrodes Y and Z formed at the periphery of the effective display part becomes longer than that of a connecting part
32
provided between the pads
31
and the electrodes Y and Z formed at the center portion of the effective display part. More specifically, a length sum L
1
+L
2
of a pad
31
and a connecting part
32
for supplying a driving waveform to the electrodes Y and Z formed at the center portion of the effective display part is different from a length sum L
3
+L
4
of a pad
31
and a connecting part
32
for supplying a driving waveform to the electrodes Y and Z formed at the periphery of the effective display part. If the lengths of the pads
31
and the connecting parts
32
provided at the pad portion
30
are different depending on their position, then a voltage applied from the pad portion
30
to the electrodes Y and Z becomes different. In other words, the electrodes Y and Z receiving a driving waveform via L
3
and L
4
is supplied with a smaller voltage than the electrodes Y and Z receiving a driving waveform via L
1
and L
2
due to a voltage drop. More specifically, the electrodes Y and Z formed at the periphery of the effective display part generates a voltage drop because they receive a driving waveform via the long connecting part L
3
. Thus, a brightness difference is generated between the periphery and the center of the effective display part. Also, since the conventional pad portion
30
has a large angle at a portion in which the electrodes Y and Z formed at the periphery of the effective display part are connected to the connecting part
32
, a breakage may be generated in the course of a electrode fabricating process of the pad portion
30
. Furthermore, the conventional pad portion
30
has a problem in that, since the conventional pad portion
30
also has a large angle at a portion in which the connecting part
32
and the pad
31
formed at the periphery of the pad portion
30
are connected to each other also, a breakage is generated in the course of its electrode fabricating to cause a product badness or deteriorate the productivity.
Meanwhile, the pad portion may be arranged in correspondence with the periphery of the effective display part as shown in
FIG. 5
in consideration of a location of the connector or the circuit arrangement, etc. Referring to
FIG. 5
, a pad portion
38
is arranged to correspond to a first periphery
40
of the effective display part. Each pad
36
is connected to each connector
44
. A driving waveform inputted from the connector
44
is applied, via a connecting part
34
, to the electrodes Y and Z provided within the effective display part. If the pad portion
38
is formed at the first periphery
40
of the effective display part, then a le
Awad Amr
Fleshner & Kim LLP
LG Electronics Inc.
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