Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
1999-06-28
2002-10-29
Hjerpe, Richard (Department: 2674)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S061000, C345S062000, C345S063000, C345S068000, C345S074100, C345S055000, C315S167000, C315S168000, C315S169100, C315S169400, C313S484000, C313S491000, C313S514000, C313S517000, C313S520000
Reexamination Certificate
active
06473061
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to plasma display panel drive method and apparatus, and particularly to plasma display panel drive method and apparatus which is capable of preventing an generation of contour noise and making to be high a brightness level.
2. Related Art of the Invention
Recently, there have been actively developed the plasma display panel, hereinafter PDP, which facilitates to manufacture it and to implement a large screen. The PDP uses conventionally a gases discharging phenomenon and allows a picture to be displayed by visible rays emitted from a fluorescent material which becomes in a emitting light by vacuum ultraviolet rays generated at the gases discharge.
Referring to
FIG. 1
, there is shown a discharging cell
30
included in the PDP of an alternating current system having three electrodes. The discharging cell
30
includes an upper glass substrate
10
loaded with a sustaining electrode pair thereon and a lower glass substrate
20
loaded with an address electrode
22
thereon. The upper glass substrate
10
, which is used as a face for displaying the picture, is arranged in parallel with the lower glass substrate
20
by a barrier rib (not shown), as shown in FIG.
1
. The sustaining electrode pair consists of a scanning/sustaining electrode
14
and a sustaining electrode
16
formed side by side on the upper glass substrate
10
. An upper dielectric layer
12
and a protective layer
18
are sequentially coated on the upper glass substrate
10
formed with the scanning/sustaining electrode
14
and the sustaining electrode
16
thereon. The address electrode
22
is formed on the lower glass substrate
20
to intersect with the sustaining electrode pair in perpendicular. On the lower glass substrate
20
having the address electrode
22
, there are sequentially formed a lower dielectric layer
24
and a fluorescent material layer
26
. Finally, a discharging gas is injected into a discharging space
28
provided by the barrier rib.
The discharging cell
30
having the structure as described above is selected by an address discharge caused between the address electrode
22
and the scanning/sustaining electrode
16
. In the selected discharging cell
30
, a sustaining discharge is caused between the scanning/sustaining electrode
14
and the sustaining electrode
16
to generate the vacuum ultraviolet rays. The vacuum ultraviolet rays allows the fluorescent material
26
to become in the emitting light, thereby generating the visible rays. Such a PDP of the alternating current system controls the number of the sustaining discharge to realize a stepwise brightness, i.e., a gray scale. The number of the sustaining discharge is recognized by users and manufacturers as an important factor determining the brightness of the PDP and a discharge efficiency. Actually, a rectangular pulse having the frequency of 10 KHz to 100 KHz is applied to the PDP of the AC system in order to perform the sustaining discharge. In this case, the sustaining discharge is generated once per sustaining pulse in a moment. Also, charged particles generated at the sustaining discharge move along with the polarity of the electrode on the discharging path formed between the sustaining electrode pair, thereby creating spatial electric charges into the discharging space of the cell
30
. The sustaining discharge can not be maintained since the discharging voltage into the discharging space drops down to the voltage lower than a discharging start voltage due to the spatial electric charges. Consequently, in the PDP of AC system using the sustaining pulse, the discharging efficiency becomes low because the sustaining discharge is generated once in a moment per sustaining pulse.
To solve such a disadvantage in the PDP of the AC system, there is developed a PDP of radio frequency (RF) system. The PDP of RF system includes discharging cells as shown in FIG.
2
. The discharging cell of
FIG. 2
includes a RF electrode
42
formed on the below face of an upper substrate
40
, a data electrode
52
disposed on a lower substrate
50
, a scanning electrode
56
loaded on a dielectric layer to intersect with the data electrode
52
in perpendicular, a fluorescent material layer
60
coated the inner wall of a barrier rib
58
. The dielectric layer
54
is disposed on the lower substrate
50
having the data electrode
52
thereon. If a driving voltage responding to a data signal is applied cross the data electrode
52
and the scanning electrode
56
, an address discharge is caused to generate charged particles into the discharging cell. The charged particles become in a vibratory movement (or a swing movement) due to a vibratory electric field caused by a RF signal that provides across the scanning electrode
56
and the RF electrode
42
. Then, the discharging gases ionize and excite continuously by the vibrate movement of the charged particles to generate continuously a discharge during a discharging period. Consequently, the PDP of the RF system has a physical effect such as a positive column having a higher discharging efficiency in a glow discharge. The RF signal to applied to the PDP of the RF system is a rectangular pulse (or a sine wave signal) having the frequency of sever MHz to sever tens MHz. However, it the charged particles and the ions are directly impacted to the barrier rib
58
, the charged particle and the ion is re-combined and a light energy is converted into a thermal energy. Due to this, the light efficiency of the PDP becomes low. To prevent the leakage of the light, the polarity of the RF signal changes alternatively along with the vibrate width of the charged particle and the ion. Therefore, in the PDP using the RF discharge, the discharging efficiency enhances largely.
FIG. 3
illustrates the entire electrode configuration of the PDP having the discharging cells as shown in FIG.
2
. As shown in
FIG. 3
, the PDP of RF system includes first to mth address electrode lines X
1
to Xm arranged to oppose to column lines, first to nth scanning electrode lines Y
1
to Yn arranged to oppose to row lines, and a RF electrode lines arranged in parallel with the scanning electrode lines Yl to Yn. The one ends of the RF electrode lines are connected each other. There provides the discharging cell
70
in each intersection of the address electrode lines Xl to Xm, the scanning electrode lines Y
1
to Yn and RF electrode lines. The scanning electrode lines Y
1
to Yn each is opposed to the RF electrode lines. The scanning electrode lines Yl to Yn and the RF electrode lines enable the RF discharge to be generated.
Such a PDP of RF system is driven by a PDP driving technique of address and display separation (ADS) system. In the PDP driving technique of ADS system, a single frame is divided into a number of sub-fields. Each sub-field is separated again into a preliminary discharging interval, an address discharging interval and a sustain discharging interval. The preliminary discharging interval and the address discharging interval become always same but the sustain discharging interval is different according to a brightness level. For example, if the single frame is divided into 8 sub-fields SF
1
to SF
8
, the sustain discharging interval involved in each of 8 sub-fields SF
1
to SF
8
has a weighted value increasing at a ratio of 1, 2, 4, 8, 16, 32, 64 and 128, and the gray scale is implemented by combining the sustain discharging intervals. Also, the sub-field periods corresponding to each bit of the video data are proceeded at a fixed sequence of SF
1
→SF
2
→SF
3
→SF
4
→SF
5
→SF
6
→SF
7
→SF
8
.
As described above, the PDP driven by the method of modulating discharge time becomes to display the picture depending on the total quantity of the lights emitted during each sub field period. Due to this, an integration characteristic of lights established by the PDP drive method is not identified with a visual characteristic accepted by the eyes of human. As a result, the contour noise is generated in th
Choi Jeong Pil
Lim Geun-Soo
Paik Woo Hyun
Park Myung Ho
Yoo Eun Ho
Hjerpe Richard
LG Electronics Inc.
Zamani Ali
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