Electric lamp and discharge devices: systems – Plural power supplies – Plural cathode and/or anode load device
Reexamination Certificate
1999-07-27
2002-11-05
Wong, Don (Department: 2821)
Electric lamp and discharge devices: systems
Plural power supplies
Plural cathode and/or anode load device
C315S169300, C313S582000, C345S060000
Reexamination Certificate
active
06476562
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a plasma display device, and more particularly to a plasma display panel that is adapted to make use of a radio frequency discharge.
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 controls a discharge interval of each pixel to display a picture. Such a PDP typically includes a PDP of alternating current(AC) system having three electrodes and driven with an AC voltage as shown in FIG.
1
.
FIG. 1
shows a cell structure arranged in a matrix pattern in the conventional AC system PDP. The PDP cell includes a sustaining electrode pair
12
A and
12
B formed on an upper substrate
10
sequentially, an upper plate having an upper dielectric layer
14
and a protective film
16
, and a lower plate having an address electrode
20
, a lower dielectric layer
22
, a barrier rib
24
and a fluorescent layer
26
. The upper substrate
10
and the lower substrate
18
are spaced, in parallel, by the barrier rib
24
. The sustaining electrode pair
12
A and
12
B consists of a scanning/sustaining electrode and a sustaining electrode.
A scanning signal for a panel scanning and a sustaining signal for a discharge sustaining are applied to the scanning/sustaining electrode
12
A while a sustaining signal is applied to the sustaining electrode
12
B. An electric charge is accumulated into the upper dielectric layer
14
and the lower dielectric layer
22
. The protective film
16
prevents a damage of the upper dielectric layer
14
due to the sputtering, thereby prolonging a life of PDP as well as improving an emissive efficiency of secondary electrons. Usually, MgO is used as the protective film
16
. The address electrode
20
is crossed with the sustaining electrode pair
12
A and
12
B. A data signal for selecting cells to be displayed is applied to the address electrode
20
. The barrier rib
24
is formed in parallel to the address electrode
20
. The barrier
24
prevents an ultraviolet ray produced by a discharge from being leaked into the adjacent cell. The fluorescent layer
26
is coated on the surface of the lower dielectric layer
22
and the barrier rib
24
to generate any one of a red, green, and blue visible lights. An inactive gas for a gas discharge is sealed into an inner discharge space.
The PDP cell having the structure as described above sustains a discharge by a surface discharge between the sustaining electrode pair
12
A and
12
B after being selected by an opposite discharge between the address electrode
20
and the scanning/sustaining electrode
12
A. In the PDP cell, the fluorescent body
26
is radiated by an ultraviolet ray generated during the sustaining discharge to emit a visible light into the exterior of the cell. As a result, the PDP having the cells displays a picture. In this case, the PDP controls a discharge-sustaining interval, that is, a sustaining discharge frequency of the cell to implement a gray scale required for an image display. Accordingly, the sustaining discharge frequency becomes an important factor for determining the brightness and a discharge efficiency of the PDP. For the purpose of performing such a sustaining discharge, a sustaining pulse having a duty ratio of 1, a frequency of 200 to 300 kHz and a width of about 10 to 20 &mgr;s is alternately applied to the sustaining electrode pair
12
A and
12
B. The sustaining discharge is generated only once at an extremely short instant per the sustaining pulse by responding to the sustaining pulse. Charged particles generated by the sustaining discharge are moved along a discharge path formed between the sustaining electrode pair
12
A and
12
B in accordance with the polarity of the sustaining electrode pair
12
A and
12
B to form a wall charge on the surface of the upper dielectric layer
14
. This wall charge cancels a voltage applied between the sustaining electrode pair
12
A and
12
B to reduce a discharge voltage loaded in the discharge space, thereby stopping the sustaining discharge. As described above, the sustaining discharge is generated only once at an extremely shorter instant than a width of the sustaining pulse, and it is consumed for a formation step of wall charge and a preparation step of the next sustaining discharge. Due to this, in the conventional PDP, a real discharge interval becomes very short in comparison to the entire discharge interval to have a low brightness and discharge efficiency.
In order to solve such a problem of low brightness and discharge efficiency, we has suggested a method of utilizing a radio frequency discharge using a radio frequency signal of hundreds of MHz as a display discharge. In the case of the radio frequency discharge, electrons perform an oscillating motion by the radio frequency signal to sustain the display discharge during a time interval when the radio frequency signal is applied. More specifically, when a radio frequency signal having a continuously alternating polarity is applied to any one of the two opposed electrodes, electrons within the discharge space are moved toward one electrode or the other electrode depending on the polarity of the voltage signal. In the case where electrons are moved into any one electrode, if the polarity of a radio frequency voltage signal having been applied to the electrode before the electrons arrive at the electrode is changed, then a movement speed of the electrons is decelerated gradually and hence a movement direction thereof is changed. The polarity of the radio frequency voltage signal applied to the electrode before the electrons within the discharge space arrive at the electrode, so that the electrons do an oscillating motion between the two electrodes. Accordingly, when the radio frequency voltage signal is being applied, ionization, an excitation and a transition of gas particles are continuously generated without an extinction of electrons. The display discharge is sustained during most discharge time, so that the brightness and a discharge efficiency of the PDP can be improved. Such a radio frequency discharge has the same physical characteristic as a positive column in a glow discharge structure.
However, the conventional PDP having the cell structure shown in
FIG. 1
is unsuitable for making use of the above-mentioned radio frequency discharge. In other words, in order to utilize the radio frequency discharge as the display discharge, a distance between the two electrodes must be assured sufficiently. Since there exists a limit in increasing the size of cell when the scanning/sustaining electrode
12
A and the sustaining electrode
12
B formed on the same surface is used for the radio frequency discharge, however, a distance between the electrodes required for the radio frequency discharge can not be assured sufficiently by the conventional AC-system PDP structure. Accordingly, it is necessary to provide a PDP having a structure suitable for making use of the radio frequency discharge.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a plasma display panel that can utilize a radio frequency discharge efficiently.
Further object of the present invention is to provide a PDP driving mechanism and method that can efficiently drive the PDP utilizing a radio frequency.
Still further object of the present invention is to provide a PDP driving apparatus that can efficiently drive the PDP utilizing a radio frequency.
In order to achieve these and other objects of the invention, a radio frequency plasma display panel according to one aspect of the present invention has cells each of which comprises a radio frequency electrode for applying a radio frequency voltage; a data electrode for applying a data voltage; a scanning electrode for applying a scanning voltage; and a discharge space into which discharge gases for causing a gas discharge are injected.
A method of driving a plasma display panel according to another aspect of the present in
Choi Jeong Pil
Kang Jung Won
Yoo Jun Yeong
Yoo Yeun Ho
Fleshner & Kim LLP
LG Electronics Inc.
Vu Jimmy T.
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