Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
2000-11-01
2003-10-21
Mengistu, Amare (Department: 2673)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S068000, C313S584000
Reexamination Certificate
active
06636188
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method of driving a plasma display panel and a plasma display apparatus employing the method. More particularly, the present invention relates to a method of driving a plasma display panel of an Alternate Lighting of Surfaces (referred to as ALIS hereinafter) type, in which plural first and second electrodes are arranged adjacently and each of plural display lines is formed between a respective pair of adjacent electrodes, and a plasma display apparatus employing the same.
A plasma display panel (PDP) has good visibility because it generates its own light, is thin and can be made with a large and high-speed display; therefore, it is attracting interest as a replacement for a CRT display. A general PDP has n (equal to 512, here) Y electrodes
11
and X electrodes
12
arranged adjacently by turns, making up n pairs of Y electrode
11
and X electrode
12
, and emits light for display between Y electrode
11
and X electrode
12
of each pair. The Y electrodes and X electrodes are called display electrodes (also called sustaining electrodes), and address electrodes are actually provided in the direction that runs at a right angle to the aforementioned electrodes, though they are omitted here. As a result, 2n display electrodes (Y electrodes and X electrodes) are required to make up n display lines.
On the other.hand, a method of emitting light, in which light emission is caused to occur between every two adjacent display electrodes, has been disclosed in Japanese Patent No.2801893 corres. to EP 0 762 373 A2, as shown in FIG.
1
B. This is called the ALIS system. As the detailed structure of the ALIS system has been disclosed in Japanese Patent No. 2801893, only points relating to the present invention will be briefly described here. As shown in
FIG. 1B
, a PDP employing the ALIS system has n (equal to 512, here) Y electrodes (first electrodes) 15-O and 15-E, and n+1 X electrodes (second electrodes) 16-O and 16-E, arranged adjacently by turns, and light emission is caused to occur for display between every pair of adjacent display electrodes (Y electrodes and X electrodes). As a result, 2n+1 display electrodes make up 2n display lines. This means that the ALIS system can double the precision with the same number of display electrodes as that of the structure shown in FIG.
1
A. The ALIS system is also characterized by a high luminance because the discharge space can be used efficiently without any waste and a high opening ratio can be obtained due to a small loss of light due to electrodes or the like.
FIG. 2
illustrates the display method employing the ALIS system. Every pair of two adjacent display electrodes is used to cause discharge for display, but it is impossible to cause discharge between all display lines at the same time. Therefore, so-called interlaced scanning, in which odd-numbered lines and even-numbered lines are used in a time-shared manner for display, is performed. As shown in
FIG. 2
, odd-numbered display lines are used for display in the odd field and even-numbered display lines are used for display in the even field, and the display combining the odd field and the even field can be obtained as a total field.
FIG. 3
shows the principle of operation during the sustaining discharge period in the ALIS system,
FIG.3A
shows the operation in the odd field, and
FIG.3B
shows that in the even field. In the odd field, a voltage Vs is applied to electrodes Y
1
and X
2
, X
1
and Y
2
are connected to the ground level, and discharge is caused to occur between X
1
and Y
1
, and X
2
and Y
2
, that is, in the odd-numbered display lines. At this time, the voltage difference between Y
1
and X
2
of the even-numbered display line is equal to zero, and no discharge is caused to occur. Similarly in the even field, a voltage Vs is applied to electrodes X
1
and Y
1
, Y
2
and X
2
are grounded, and discharge is caused to occur between. Y
1
and X
2
, and Y
2
and X
1
, that is, in the even-numbered display lines.
FIG. 4
shows a drive circuit of a PDP employing the ALIS system. X electrodes and Y electrodes are arranged in parallel, alternately, and address electrodes
19
are arranged in the direction that runs at a right angle to the aforementioned electrodes. Reference number 15-O refers to an odd-numbered Y electrode, 15-E to an even-numbered Y electrode, 16-O to an odd-numbered. X electrode, and 16-E to an even-numbered X electrode. Y electrodes are connected to a scan driver
23
. The scan driver
23
is equipped with switches
24
, being designed to switch so that scan pulses are applied sequentially during the address period, and the odd-numbered Y electrode 15-O is connected to a first Y sustaining pulse generation circuit
25
, and the even-numbered Y electrode 15-E is connected to a second Y sustaining pulse generation circuit
26
during the sustaining discharge period. Similarly, the switches
24
are switched so that the odd-numbered X electrode 16-O is connected to a first X sustain pulse generation circuit
21
and the even-numbered X electrode 16-E is connected to a second X sustain pulse generation circuit
22
. The address electrode
19
is connected to an address driver
27
.
FIGS. 5 and 6
show drive waveforms of a PDP employing the ALIS system.
FIG. 5
shows drive waveforms in the odd field and
FIG. 6
shows those in the even field. As shown in
FIG. 5
, a voltage pulse is applied between every pair of adjacent X electrode and Y electrode to perform the initialization discharge in every display line during the reset period. The address period is divided into the first half and the second half. In the odd field, scan pulses are applied to an odd-numbered Y electrode (Y
1
) sequentially during the first half of the address period. At this time, a positive voltage is applied to the odd-numbered X electrodes (X
1
, X
3
), the even-numbered X electrode (X
2
) is grounded, and a small negative voltage is applied to the even-numbered Y electrode (Y
2
), therefore, address discharge is caused to occur only in the address lines to which an address pulse is applied between the odd-numbered X electrode and the odd-numbered Y electrode, and as a result, wall-charge accumulates. During the second half of the address period in the odd field, scan pulses are applied to the .even-numbered Y electrode (Y
2
) sequentially, a positive voltage is applied to the even-numbered X electrode (X
2
), the odd-numbered X electrodes (X
1
, X
3
) are grounded, and a small negative voltage is applied to the odd-numbered Y electrode (Y
1
), therefore, address discharge is caused to occur only between the even-numbered X electrodes and the even-numbered Y electrodes. As a result, charges corresponding to the display data accumulates in the odd-numbered display lines. Moreover, during the sustaining discharge period, sustaining pulses with opposite phases are applied between the odd-numbered X electrode and the odd-numbered Y electrode, and between the even-numbered X electrode and the even-numbered Y electrode, and sustaining discharge, which is light emission for display, is caused to occur in the odd-numbered display lines. The luminance of the field is determined by the times sustaining discharge is caused to occur (number of sustaining pulses).
As shown in
FIG. 6
, during the first half of the address period in the even field, address discharge is caused to occur between the odd-numbered Y electrode and the even-numbered X electrode, and during the second half, address discharge is caused to occur between the even-numbered Y electrode and the odd-numbered X electrode, sustaining pulses with opposite phase are applied between the odd-numbered Y electrode and the even-numbered X electrode, and between the even-numbered electrode and the odd-numbered X electrode, and as a result, light emission for display is caused to occur in the even display lines.
In a PDP, a display field is divided into plural subfields and representation of a gray scale is realized by combining lit subfields according to the gra
Asao Shigeharu
Kanazawa Yoshikazu
Kishi Tomokatsu
Dharia Prabodh
Fujitsu Hitachi Plasma Display Limited
Mengistu Amare
Staas & Halsey , LLP
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