Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
2000-11-17
2003-09-23
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
06624799
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a radio frequency plasma display panel, and more particularly to a radio frequency plasma display panel that is capable of reducing a height of a barrier rib and a frequency of a radio frequency signal as well as improving a light-emission efficiency.
2. Description of the Related Art
Recently, a plasma display panel (PDP) feasible to the fabrication of large-scale panel has been available for a flat panel display device. The PDP takes advantages of a fact that an ultraviolet ray generated by a gas discharge radiates a fluorescent material to generate a visible light, thereby displaying a picture. There has been actively made a study as to a radio frequency PDP that is capable of dramatically improving a discharge efficiency and a brightness in comparison to the conventional alternating current (AC) surface discharge PDP. In the radio frequency PDP, electrons making an oscillating motion within a discharge space continuously ionize a discharge gas by a radio frequency of hundreds of MHz to make a continuous discharge for most discharge time. Such a radio frequency discharge has the same physical characteristic as a positive column at a glow discharge structure.
FIG. 1
is a section view showing the structure of a discharge cell in a conventional radio frequency PDP employing the above-mentioned radio frequency discharge. In
FIG. 1
, the discharge cell includes a radio frequency electrode
12
provided on an upper substrate
10
, a data electrode
18
and a scanning electrode
22
provided on a lower substrate
16
in such a manner to be perpendicular to each other, and barrier ribs
28
provided between the upper substrate
10
and the lower substrate
16
. The radio frequency electrode
12
applies a radio frequency signal. A first dielectric layer
14
is formed on the upper substrate
10
provided with the radio frequency electrodes
12
. The data electrode
18
applies a data signal for causing an address discharge to select cells to be displayed. The scanning electrode
22
applies a scanning signal for said address discharge. Also, the scanning electrode
22
is opposed to the radio frequency electrode
12
in such a manner to be used as a counterpart electrode of the radio frequency electrode
12
. Between the data electrodes
18
and the scanning electrodes
22
is provided a second dielectric layer
20
for charge accumulation and isolation. On the second dielectric layer
20
provided with the scanning electrodes
22
, a third dielectric layer
24
for charge accumulation and a protective film
26
are sequentially disposed. The barrier ribs
28
shut off an optical interference between the cells. In this case, since a distance between the radio frequency electrode
12
and the scanning electrode
22
is sufficiently assured for the sake of a smooth radio frequency discharge, the barrier ribs
24
are provided at a higher level than those in the existent AC surface-discharge PDP. Alternately, the barrier ribs
28
may be formed into a lattice structure closed on every side for each discharge cell so as to isolate the discharge space. This is because it is difficult to isolate plasma for each cell unlike the existent surface discharge due to the opposite discharge generated between the radio frequency electrodes
12
and the scanning electrodes
22
. A fluorescent material
30
is coated on the surface of the barrier rib
28
to emit a visible light with an inherent color by a vacuum ultraviolet ray generated during the radio frequency discharge. The discharge space defined by the upper substrate
10
, the lower substrate
16
and the barrier ribs
28
is filled with a discharge gas.
The radio frequency PDP having the configuration as described above is driven with a drive waveform as shown in
FIG. 2. A
radio frequency signal RFS is continuously applied to the radio frequency electrode
12
. When charged particles exist in the discharge space
32
, a discharge is not generated even though the radio frequency signal RFS is applied to the radio frequency electrode
12
. A data signal DS is applied to the data electrode
18
in an address interval AP and a scanning signal SS is applied to the scanning electrode
22
, thereby generating an address discharge. Electrons having a relatively high mobility in the charged particles make an oscillation motion between the radio frequency electrode
12
and the scanning electrode
22
during a discharge-sustaining interval SP by virtue of the radio frequency signal RFS. The oscillating electrons excite a discharge gas to generate a vacuum ultraviolet ray, which radiates the fluorescent material
30
to generate a visible light. After such a radio frequency discharge was sustained in the discharge-sustaining interval SP, it is interrupted by an erasing signal ES applied to any one of the data electrode
18
and the scanning electrode
22
in an erasure interval EP. In other words, the oscillating electrons are drawn into an electrode coupled with the erasing signal ES to be extinct, thereby stopping the radio frequency discharge.
The conventional radio frequency PDP driven in accordance with such a discharge mechanism has several problems in view of it structure.
First, in order to sustain the radio frequency discharge smoothly, a distance between the radio frequency electrode
12
and the scanning electrode
22
, that is, a height of the barrier rib must be sufficiently assured. This is because an oscillation width of the electrons making an oscillation motion within the discharge space
32
depends on a frequency of the radio frequency signal RFS. More specifically, as a frequency of the radio frequency signal RFS goes lower, an oscillation width of the electrons is more and more increased. For this reason, when a frequency of the radio frequency signal RFS is not sufficiently high or when a distance between the radio frequency electrode
12
and the scanning electrode
22
is not sufficiently assured, the electrons within the discharge space
32
collide with the upper and lower substrates to be extinct, thereby no longer sustaining a discharge. Accordingly, in order to improve discharge efficiency, it is necessary to raise a frequency of the radio frequency signal RFS or to sufficiently assure a distance between two electrodes
12
and
22
used for the radio frequency discharge. For instance, when a frequency of the radio frequency signal RFS is 200 MHz, an optimal discharge efficiency can not be obtain until a distance between the radio frequency electrode
12
and the scanning electrode
22
becomes about 2 mm. Herein, to raise a frequency of the radio frequency signal RFS requires a driving circuit and a driving method that is capable of treating a high frequency of radio frequency signal RFS. It is difficult to apply this scheme in view of the current technical state and the cost. Accordingly, it is necessary to sufficiently assure a distance between the radio frequency electrode
12
and the scanning electrode
22
so as to obtain desired discharge efficiency with lowering a frequency of the radio frequency signal RFS. However, since a scheme of assuring a distance between the radio frequency electrode
12
and the scanning electrode
20
is determined depending on a height of the barrier rib
28
shown in
FIG. 1
, it has a burden in that the barrier rib
28
must be provided to have a large height. This is because it is difficult to implement a barrier rib having a large height of more than 0.5 mm by the conventional barrier rib fabricating methods such as the screen printing method and the sand blast method, etc. Also, when a height of the barrier rib
28
is more than 1 mm, it is difficult to uniformly coating the fluorescent material
30
on the inner surface of the barrier rib
28
and a transmissivity of a visible light generated from the fluorescent material
30
is reduced.
Second, the conventional radio frequency PDP has a problem in that, since the scanning electrode
22
is commonly used for an address discharge and a radio fre
Kang Jung Won
Park Myung Ho
Yoo Eun Ho
Fleshner & Kim LLP
LG Electronics Inc.
Moyer Michael J.
Saras Steven
LandOfFree
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