Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
1999-06-24
2002-05-07
Hjerpe, Richard (Department: 2674)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C315S169100
Reexamination Certificate
active
06384802
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a plasma display panel and a driving method and apparatus thereof, and more particularly to a plasma display panel and a driving method and apparatus that can improve a brightness.
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 permits it to be easily 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 can be classified into an alternating current(AC) driving system making a surface discharge and a direct current(DC) driving system in accordance with its driving system.
Referring to
FIG. 1
, there is shown a PDP driving apparatus of AC system that includes a PDP
10
having a pixel matrix consisting of mxn discharge cells
1
. In the PDP
10
, m scanning/sustaining electrode lines Y
1
to Ym and m common sustaining electrode lines Z
1
to Zm are alternately formed, in parallel, on an upper substrate(not shown). Also, n address electrode lines X
1
to Xn are formed on a lower substrate(not shown) in a direction perpendicular to the scanning/sustaining electrode lines Y
1
to Ym and the common sustaining electrode lines Z
1
to Zm. Each of the mxn discharge cells
1
is arranged in a matrix pattern at intersections among the scanning/sustaining electrode lines Y
1
to Ym, the common sustaining electrode lines Z
1
to Zm and the address electrode lines X
1
to Xn. A barrier rib(not shown) is formed on the lower substrate in parallel with the address electrode lines XX
1
to Xn to divide the discharge cells
1
arranged at the vertical direction.
Further, the PDP driving apparatus of AC driving system includes first and second address drivers
6
A and
6
B connected to the address electrode lines X
1
to Xn of the PDP
10
, a scanning/sustaining driver
2
connected to the scanning/sustaining electrode lines Y
1
to Ym of the PDP
10
, and a common sustaining driver
4
connected to the common sustaining electrode lines Z
1
to Zm of the PDP
10
. The first address driver
6
A is connected to odd-numbered address electrode lines X
1
, X
3
, . . . , Xn−3, Xn−1 and the second address driver
6
B is connected to even-numbered X electrodes X
2
, X
4
, . . . , Xn−2, Xn to apply a video data to each address electrode line X
1
to Xn. The scanning/sustaining driver
2
is connected to m scanning/sustaining electrode lines Y
1
to Ym to select a scanning line to be displayed and to cause a sustaining discharge at the displayed scanning line. The common sustaining driver
4
is commonly connected to m common sustaining electrode lines Z
1
to Zm to apply an identical waveform of voltage signal to all the common sustaining electrode lines Z
1
to Zm, thereby causing a sustaining discharge.
In such a PDP, one frame consists of a number of sub-fields, and a gray level is realized 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 an address interval and a sustaining interval. A discharge initiated at each of the discharge cells selected in the address interval is sustained during 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. A brightness and a chrominance of a displayed image are determined in accordance with a combination of the sub-fields.
However, the PDP shown in
FIG. 1
has a problem in that, since it causes a discharge within a discharge area provided in a minute size of discharge cell
1
, its brightness and its discharge efficiency is low. More specifically, the PDP allows a negative glow discharge to lead the entire luminescence. The negative glow discharge results in a low brightness because a luminescence occurs in an ionized process. On the other hand, a luminescence occurring upon positive column discharge is leaded by a luminescence caused by an excitation, the brightness becomes very high. In a PDP having a very small independent discharge area, the positive column discharge area becomes small within each discharge area.
FIG. 2
shows brightness of adjacent discharge cells
1
A and
1
B shown in FIG.
1
. When an A discharge cell
1
A and a B discharge cell
1
B arranged in the adjacent scanning lines are discharged, each discharge cell
1
A and
1
B is emitted at the glow discharge area. At this time, the brightness of the A discharge cell
1
A and the B discharge cell
1
B has a maximum value within each discharge area while having a minimum value in their boundary. Accordingly, even when all the two adjacent discharge cells
1
A and
1
B are discharged, a sufficient brightness is not provided. A scheme of increasing a size of the discharge area enough to enlarge the positive column area may be considered, but a size of each discharge cell and therefore a size of the discharge area must be limited so as to meet a desired resolution within a certain screen dimension. Accordingly, since the discharge area is reduced so much that the numbers of lines and discharge cells becomes larger as a resolution becomes higher, a brightness and a discharge efficiency are more deteriorated.
A scheme for improving a brightness by reducing the number of sustaining electrode lines has been disclosed in Japanese Patent Laid-open Gazette No. Pyung 9-16050. The PDP shown in
FIG. 1
requires 2 m electrode lines, i.e., m scanning/sustaining electrode lines Y
1
to Ym and m common sustaining electrode lines while the suggested PDP requires only a total (m−1) scanning electrode lines and a sustaining electrode line with respect to m scanning lines.
The suggested PDP is driven in the interlacing system for displaying a picture by constructing one frame by a number of sub-fields, each of which is divided into odd-numbered fields and even-numbered fields. In the odd-numbered fields, an address discharge is caused by applying data pulses corresponding to only the odd-numbered scanning lines to the address electrode lines and, at the same time, applying scanning pulses to (m/2)−1 scanning electrode lines arranged between m/2 sustaining electrode lines. In the sustaining interval, a sustaining discharge is generated between the corresponding scanning electrode line and the adjacent sustaining electrode lines. Then, in the even-numbered fields, an address discharge is generated by applying data pulses corresponding to only the even-numbered scanning lines to the address electrode lines and, at the same time, applying scanning pulses sequentially to the scanning electrode lines. In the sustaining interval, a sustaining discharge is generated between the corresponding scanning electrode line and the adjacent sustaining electrode lines.
As described above, the suggested PDP reduces the number of sustaining electrode lines into a half of that in the prior art to lengthen a length between the scanning electrode lines, so that it can improve a brightness and a discharge efficiency. Also, according to the suggested PDP, since the number of electrode lines is reduced, it has been expected as a strategy favorable to an implementation of high resolution. However, the suggested PDP has a drawback in that, since it can be applied to only a display device of interlace system such as television, its application range must be limited. Therefore, the suggested PDP fails to be applied to a display d
Fleshner & Kim LLP
Hjerpe Richard
LG Electronics Inc.
Nguyen Frances
LandOfFree
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