Plasma display device including overlapping electrodes

Details Plasma display device including overlapping electrodes Plasma display device including overlapping electrodes

2001-07-18

2003-07-15

Philogene, Haissa (Department: 2821)

Electric lamp and discharge devices: systems

Plural power supplies

Plural cathode and/or anode load device

C315S169400, C313S584000, C313S585000, C313S521000

Reexamination Certificate

active

06593702

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 improving discharge efficiency.
2. Description of the Related Art
Generally, a plasma display panel (PDP) is a display device utilizing a visible light emitted from a fluorescent layer when an ultraviolet ray generated by a gas discharge excites the fluorescent layer. The PDP has an advantage in that it has a thinner thickness and a lighter weight in comparison to the existent cathode ray tube (CRT) and is capable of realizing a high resolution and a large-scale screen. The PDP includes a plurality of discharge cells arranged in a matrix pattern, each of which makes one pixel of a field.
FIG. 1
is a perspective view showing a discharge cell structure of a conventional three-electrode, alternating current (AC) surface-discharge PDP.
Referring to
FIG. 1
, a discharge cell of the conventional three-electrode, AC surface-discharge PDP includes a scanning/sustaining electrode
12
Y and a common sustaining electrode
12
Z provided on an upper substrate
10
, and an address electrode
20
X provided on a lower substrate
18
.
On the upper substrate
10
provided with the scanning/sustaining electrode
12
Y and the common sustaining electrode
12
Z in parallel, an upper dielectric layer
14
and a protective film
16
are disposed. Wall charges generated upon plasma discharge are accumulated into the upper dielectric layer
14
. The protective film
16
prevents a damage of the upper dielectric layer
14
caused by a sputtering during the plasma discharge and improves the emission efficiency of secondary electrons. This protective film
16
is usually made from magnesium oxide (MgO).
A lower dielectric layer
22
, barrier ribs
24
are formed on the lower substrate
18
provided with the address electrode
20
X. The surfaces of the lower dielectric layer
22
and the barrier ribs
24
are coated with a fluorescent layer
26
. 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 rib
24
is formed in parallel to the address electrode
20
X to prevent an ultraviolet ray and a visible light generated by a discharge from being leaked to the adjacent discharge cells. The fluorescent layer
26
is excited by an ultraviolet ray generated during the plasma discharge to generate any one of red, green and blue visible light rays. An inactive gas for a gas discharge is injected into a discharge space defined between the upper and lower substrate
10
and
18
and the barrier rib
24
.
Such a three-electrode AC surface-discharge PDP drives one frame, which is divided into various sub-fields having a different discharge number, so as to realize gray levels of a picture. Each sub-field is again divided into a reset period for uniformly causing a discharge, an address period for selecting the discharge cell and a sustaining period for realizing the gray levels depending on the discharge number.
For instance, when it is intended to display a picture of 256 gray levels, a frame interval equal to {fraction (1/60)} second (i.e. 16.67 msec) is divided into 8 sub-fields. Each of the 8 sub-fields is again divided into a reset period, an address period and a sustaining period. The reset period and the address period of each sub-field are equal every sub-field, whereas the sustaining period thereof is increased at a ration of 2
n
(wherein n=0, 1, 2, 3, 4, 5, 6 and 7) at each sub-field. Since the sustaining period becomes different at each sub-field as mentioned above, the gray levels of a picture can be expressed.
In the reset period, a reset pulse is applied to the scanning/sustaining electrode
12
Y to cause a reset discharge. In the address period, a scanning pulse is applied to the scanning/sustaining electrode
12
Y and a data pulse is applied to the address electrode
20
X, to thereby cause an address discharge between two electrodes
12
Y and
20
X. During the address discharge, wall charges are formed on the upper and lower dielectric layers
14
and
22
. In the sustaining period, a sustaining discharge is caused between two electrodes
12
Y and
12
Z by an alternating current signal alternately applied to the scanning/sustaining electrode
12
Y and the common sustaining electrode
12
Z.
However, the conventional AC surface-discharge PDP has a sustaining discharge space concentrated at the center of the upper substrate
10
to reduce a utility of the discharge space. Thus, it has a problem that the reduced discharge area deteriorate a light emission efficiency.
In order to solve this problem, there has been suggested a five-electrode, AC surface-discharge PDP as shown in FIG.
2
.
Referring to
FIG. 2
, the conventional five-electrode, AC surface-discharge PDP includes first and second trigger electrodes
34
Y and
34
Z provided on an upper substrate
30
in such a manner to be positioned at the center of a discharge cell, first and second sustaining electrodes
32
Y and
32
Z provided on the upper substrate
30
in such a manner to be positioned at the edge of the discharge cell, and an address electrode
42
X provided at a lower substrate in a direction crossing the trigger electrodes
34
Y and
34
Z and the first and second sustaining electrodes
32
Y and
32
Z.
On the upper substrate
30
provided with the first sustaining electrode
32
Y, the first trigger electrode
34
Y, the second trigger electrode
34
Z and the second sustaining electrode
32
Z in parallel, an upper dielectric layer
36
and a protective layer
38
are disposed. On the other hand, a lower dielectric layer
44
and a barrier rib
46
are formed on a lower substrate
40
provided with the address electrode
42
X, and a fluorescent layer
48
is coated on the surfaces of the lower dielectric layer
44
and the barrier ribs
46
.
The trigger electrodes
34
Y and
34
Z spaced at a narrow distance Ni at the center of the discharge cell are supplied with a sustaining pulse in the sustaining period to initiate a sustaining discharge. The first and second sustaining electrodes
32
Y and
32
Z spaced at a wide distance Wi at the edge of the discharge cell maintain a plasma discharge after the discharge between the trigger electrodes
34
Y and
34
Z was initiated by an application of a sustaining pulse in the sustaining period.
FIG. 3
is a section view representing a state of rotating the upper substrate by 90° with respect to the lower substrate so as to show up the overall electrode structure within one discharge cell.
An operation process of the five-electrode AC surface-discharge PDP will be described in detail with reference to FIG.
3
and
FIG. 4
below.
The five-electrode AC surface-discharge PDP drives one frame, which is divided into various sub-fields having a different discharge number, so as to realize gray levels of a picture. Each sub-field is again divided into a reset period for uniformly causing a discharge, an address period for selecting the discharge cell and a sustaining period for expressing the gray levels depending on the discharge number.
First, in the reset period, a reset pulse is applied to the second trigger electrode Tz of the discharge cell to generate a reset discharge for initializing the discharge cell. At this time, the address electrode X is supplied with a direct current voltage for preventing an erroneous discharge.
In the address period, a scanning pulse C is sequentially applied to the first trigger electrode Ty and a data pulse Va synchronized with the scanning pulse C is applied to the address electrode X. At this time, an address discharge is generated at the discharge cells supplied with the data pulse Va.
In the sustaining period, a sustaining pulse is alternately applied to the first trigger electrode Ty and a first sustaining electrode Sy and the second trigger electrode Tz and a second sustaining electrode Sz. In this case, a voltage Vt applied to the trigger electrodes Ty and Tz has a lower level than a v

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