Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
2001-12-12
2003-07-29
Mengistu, Amare (Department: 2673)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S063000, C345S067000, C313S306000
Reexamination Certificate
active
06600463
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method of driving a plasma display panel and more particularly, to a method of driving an AC-type plasma display panel for displaying a dynamic image without intensity level disturbance and false color contours in a multi-scan driving method within a sustaining pulse period.
BACKGROUND OF THE INVENTION
Recently, a plasma display panel (referred to as “PDP” hereinafter) has advantageous characteristics capable of being utilized as a direct-view large HDTV display apparatus having large screen size but a small thickness and a wide viewing angle compared to other flat display devices.
A PDP is classified into a two-electrode type PDP in which an address discharge and a sustain discharge are performed by two electrodes and a three-electrode type PDP in which an address discharge and a sustain discharge are performed by three electrodes.
FIG. 1
is a schematic sectional view of a discharge cell of a typical PDP and
FIG. 2
is a plan view of a three-electrode type of PDP.
The discharge cell
10
of the three-electrode type PDP
1
comprises two glass plates
12
and
13
arranged to be facing each other. On the first glass plate
13
the first electrode
14
(X electrode) and the second electrode
15
(Y electrode) are formed and arranged parallel to each other. The electrodes function as sustain electrodes. The first and second electrodes
14
and
15
are covered with a dielectric layer
18
. The upper surface of the dielectric layer
18
is covered with a MgO layer
21
, which protects the dielectric layer
18
.
On the second glass plate
12
a third electrode
16
is arranged orthogonal to the first and second electrodes
14
and
15
. The third electrode functions as a data electrode. A barrier rib
17
of a lattice or stripe shape is formed between the two glass plates
12
and
13
to define a discharge cell. A phosphor material
19
is coated on the surface of the third electrode and the inner surface of the barrier rib.
As shown in
FIG. 2
, a PDP display device using such three-electrode type PDP comprises a plurality of X electrodes and Y electrodes arranged parallel to each other and wherein Y electrodes are driven independently by separate Y scan driving circuits
4
- to
4
-n coupled to a Y electrode sustain driving circuit and X electrodes are coupled in common and are driven by a common X electrode driving circuit
5
.
Data electrodes
16
-
1
to
16
-n arranged to be orthogonal to the X and Y electrodes are driven by a data driving circuit
6
. Also, each of separate Y electrode scan driving circuits
4
-
1
to
4
-n is coupled to the Y electrode sustain driving circuit
3
and generates a scan pulse and sustain pulse.
The Y electrode sustain driving circuit
3
generates a sustain discharge pulse and the generated sustain discharging pulse is applied to the Y electrodes
15
-
1
to
15
-n via the separate Y scan driving circuits
4
-
1
to
4
-n.
The common X electrode driving circuit
5
generates a sustaining pulse which is applied to the X electrodes.
The driving circuits
3
,
5
and
6
are controlled by a control circuit (not shown) which is in turn controlled sequentially by a synchronization signal and then a display data signal. In
FIG. 2
, numeral
1
denotes a PDP and numeral
10
denotes a cell constructing the PDP
1
.
There have been proposed several driving methods for a multi-gradation display of such plasma display device. As an example, U.S. Pat. No. 5,541,618 (assigned to Fujitsu Limited.) discloses a driving method in which a frame displaying a single picture is divided into a plurality of subfields and each of the subfields is separated in an addressing period and a sustain period and in each of the subfields, after addressing, a sustaining operation is carried out to all display electrodes at the same time.
FIG. 3
shows a frame structure illustrating a conventional driving method. When scan lines are 480, a frame of a single picture is divided into eight subfields, and a time taken to perform an addressing operation within a frame of a single picture is approximately 11 to 12 microseconds.
Substantially, since a display time (sustaining time) when a viewer can view an image is approximately 5 to 6 microseconds, a display period (sustaining period) that contributes to the brightness of an image is only approximately 30%, resulting in a deterioration of picture brightness. In this case, increasing a frequency of sustain pulse in order to compensate for such deterioration of image brightness can be considered, however, it also causes an increase of the power consumption and a deterioration of driving reliability.
The present applicant has suggested a new driving method capable of solving such problems encountered by the conventional driving method (see PCT/KR98/00204 filed in the name of the present applicant). According to a basic feature of the above-suggested driving method, a frame is divided into a plurality of subfields, and display lines corresponding to the total number of the divided subfields are selected. Then, scan pulses corresponding to the total number of the divided subfields are applied sequentially within a single sustain pulse applied to Y scan sustain electrodes and thereby cells of selected display lines to be displayed are designated. Thereafter, the designated cells of selected display lines are displayed by the following sustain pulse.
Next, after one sustain pulse period, display lines which are downwardly or upwardly shifted from the above selected display lines by one line are selected. Then, scan pulses corresponding to the total number of the divided subfields are applied sequentially within a single sustain pulse applied to Y scan sustain electrodes and thereby cells of selected display lines to be displayed are designated. Thereafter, the designated cells of selected display lines are displayed by following sustain pulse. Continuously, by repeating the display of the subfields for the display lines by shifting one line as a unit one sustain pulse period until each of the subfields for all display lines are completely displayed, the display for a frame is completed.
In this manner, a feature of the above driving method enables scanning of other display lines simultaneously by sustaining them. In order to realize it most suitably, the number of sustain pulses for one frame should be set to be equal to that of the display lines. Also, when selecting display lines, positioning of selected display lines should be determined by considering the number of sustain pulses for each of the subfields.
Now, a feature of the above driving method will be described in detail with reference to
FIGS. 4 and 5
. For convenience of the description, it assumed that a single frame is divided into three subfields (SF
1
, SF
2
, and SF
3
) and display lines are 7 lines (D
1
to D
7
). Accordingly, it is possible to establish sustain periods in subfields SF
1
, SF
2
, and SF
3
to 1, 2 and 4, respectively.
Also, regarding the position of the display line selected firstly, it is possible to select the display lines D
1
, D
3
and D
7
in consideration of the sustain periods set for the subfields SF
1
, SF
2
and SF
3
. In
FIG. 4
, S
1
to S
7
represent sustain periods.
As shown in
FIG. 4
, firstly, display lines D
1
, D
3
and D
7
are selected, and then the display of the subfields SF
1
, SF
2
and SF
3
for display lines D
1
, D
3
and D
7
are executed respectively. Next, selecting display lines D
2
, D
4
and D
1
, which are allocated downwardly by one display line from the above selected display lines D
1
, D
3
and D
7
, and then the display of the subfields SF
1
, SF
2
and SF
3
for display lines D
2
, D
4
and D
1
are executed respectively. Next, selecting display lines D
3
, D
5
and D
2
, which are allocated downwardly by one display line from the above selected display lines D
2
, D
4
and D
1
, and then the display of the subfields SF
1
, SF
2
and SF
3
for display lines D
3
, D
5
and D
2
are executed respectively. Next, selecting display lines D
4
, D
6
and D
Mengistu Amare
Merchant & Gould P.C.
Nguyen Jimmy H.
Orion Electric Co. Ltd.
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