Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
2001-11-06
2004-09-14
Vo, Tuyet T. (Department: 2821)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S078000, C345S077000, C315S169300
Reexamination Certificate
active
06791517
ABSTRACT:
This application claims the benefit of the Korean Application No. P2000-65959 filed on Nov. 7, 2000, which is herein incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a plasma display panel (PDP) and a driving method thereof, and more particularly, to a PDP and a driving method thereof that can improve luminous efficiency.
2. Discussion of the Stated Art
A PDP is a display device using visible rays generated from a phosphor when vacuum ultraviolet rays gene-rated by gas discharge excite the phosphor. The PDP is thinner and lighter in weight than a cathode ray tube (CRT) that has been mainly used as a display device. The PDP also enables a large sized screen with high definition.
Such a PDP includes a plurality of discharge cells, each cell having one pixel on a screen.
FIG. 1
is a perspective view illustrating a discharge cell of a related art three-electrode alternating current area discharge type PDP.
Referring to
FIG. 1
, the discharge cell of the related art three-electrode alternating current area discharge type PDP includes a scan/sustain electrode
12
Y, a common sustain electrode
12
Z, and an address electrode
20
X. The scan/sustain electrode
12
Y and the common sustain electrode
12
Z are formed on an upper substrate
10
, and the address electrode
20
X is formed on a lower substrate
18
.
On the upper substrate
10
on which the scan/sustain electrode
12
Y and the common sustain electrode
12
Z are formed in parallel, an upper dielectric layer
14
and a passivation film
16
are layered. Wall charges generated by a plasma discharge are accumulated in the upper dielectric layer
14
. The passivation film
16
prevents the upper dielectric layer
14
from being damaged due to sputtering generated by the plasma discharge and increases secondary electron emission. MgO is generally used as the passivation film
16
.
A lower dielectric layer
22
and a sidewall
24
are formed on the lower substrate
18
on which the address electrode
20
X is formed. A phosphor layer
26
is deposited on surfaces of the lower dielectric layer
22
and the sidewall
24
.
The address electrode
20
X is formed to cross the scan/sustain electrode
12
Y and the common sustain electrode
12
Z. The sidewall
24
is formed in parallel with the address electrode
20
X, so that ultraviolet rays and visible rays generated by a discharge are prevented from leaking out to an adjacent discharge cell. The phosphor layer
26
is excited by the ultraviolet rays generated by the plasma discharge and generates one of red, green, or blue visible rays.
Also, an inert gas for a gas discharge is injected into a discharge space between the upper substrate
10
or the lower substrate
18
and the sidewall
24
.
The aforementioned alternating current area discharge type PDP divides one frame into a plurality of sub-fields having different discharge number of times to display gray level of a picture image. Each sub-field includes a reset period for uniformly generating a discharge, an address period for selecting a discharge cell, and a sustain period for displaying gray level in accordance with discharge number of times. For example, if a picture image is displayed in 256 gray levels, a frame period (16.67 ms) corresponding to {fraction (1/60)} sec. is divided into eight sub-fields. Each of the eight sub-fields is divided into a reset period, an address period, and a sustain period. The reset period has the same value in each sub-field. Likewise, the address period has the same value in each sub-field. However, the sustain period is increased at a rate of 2
n
(n=0, 1, 2, 3, 4, 5, 6, 7) in each sub-field. Since the sustain period is varied in each sub-field, gray level of the picture image can be displayed.
A reset pulse is supplied to the scan/sustain electrode
12
Y during the reset period, so that a reset discharge occurs. During the address period, a scan pulse is supplied to the scan/sustain electrode
12
Y and a data pulse is supplied to the address electrode
20
X so that an address discharge occurs between the electrodes
12
Y and
20
X. Wall charges are generated in the upper and lower dielectric layers
14
and
22
during the address discharge. During the sustain period, an alternating current signal is alternately supplied to the scan/sustain electrode
12
Y and the common sustain electrode
12
Z so that a sustain discharge occurs between the electrodes
12
Y and
12
Z.
However, in the related art alternating current area discharge type PDP, a sustain discharge space is concentrated on the center of the upper substrate
10
, thereby reducing applicability of the discharge space. That is, as shown in
FIG. 2
, since the sustain discharge occurs between the scan/sustain electrode
12
Y and the common sustain electrode
12
Z formed on the upper substrate
10
at a narrow distance, a discharge area is reduced, thereby reducing luminous efficiency. At this time, if the scan/sustain electrode
12
Y and the common sustain electrode
12
Z are formed at a widen distance to increase the discharge area, a high driving voltage should be applied to the scan/sustain electrode
12
Y and the common sustain electrode
12
Z. That is, power consumption is increased for the sustain discharge, thereby reducing driving efficiency of the PDP.
To solve such a problem, a five-electrode alternating current area discharge type PDP as shown in
FIG. 3
has been proposed.
FIG. 3
is a perspective view illustrating a discharge cell of another related art five-electrode alternating current area discharge type PDP.
Referring to
FIG. 3
, the related art five-electrode alternating current area discharge type PDP includes first and second trigger electrodes
34
Y and
34
Z formed at the center of a discharge cell on an upper substrate
30
, a scan/sustain electrode
32
Y and a common sustain electrode
32
Z formed at a peripheral portion of the discharge cell on the upper substrate
30
, and an address electrode
42
X formed at the center of the lower substrate
40
to be orthogonal to the trigger electrodes
34
Y and
34
Z, the scan/sustain electrodes
32
Y, and the common sustain electrode
32
Z. On the upper substrate
30
on which the scan/sustain electrode
32
Y, the first trigger electrode
34
Y, the second trigger electrode
34
Z, and the common sustain electrode
32
Z are formed in parallel, an upper dielectric layer
36
and a passivation film
38
are layered. On the lower substrate
40
on which the address electrode
42
X is formed, a lower dielectric layer
44
and a sidewall
46
are formed. A phosphor layer
48
is deposited on surfaces of the lower dielectric layer
44
and the sidewall
46
.
An alternating current pulse is supplied to the trigger electrodes
34
Y and
34
Z formed at the center of the discharge cell at a narrow distance during the sustain period. The trigger electrodes
34
Y and
34
Z are used to start a sustain discharge. The alternating current pulse is also supplied to the scan/sustain electrode
32
Y and the common sustain electrode
32
Z formed at a widen distance at the peripheral portion of the discharge cell during the sustain period. The scan/sustain electrode
32
Y and the common sustain electrode
32
Z are used to start a plasma discharge between the trigger electrodes
34
Y and
34
Z and to maintain the plasma discharge. To drive the five-electrode alternating current area discharge type PDP, a waveform shown in
FIG. 4
is applied.
Referring to
FIG. 4
, in the related art five-electrode alternating current area discharge type PDP, one frame is divided into various sub-field having different discharge number of times to display gray level of a picture image. Each sub-field includes a reset period for uniformly generating a discharge, an address period for selecting a discharge cell, and a sustain period for displaying gray level in accordance with discharge number of times.
During the reset period, a reset pulse is supplied to the second trigger electrode Tz so that a reset discharge for initiating the discharge
Fleshner & Kim LLP
Vo Tuyet T.
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