Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
2000-06-28
2003-05-06
Lao, Lun-Yi (Department: 2673)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S209000
Reexamination Certificate
active
06559815
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a plasma display panel (PDP) with improved energy recovery efficiency, and a driving method thereof.
2. Description of the Related Art
A PDP is a display device for restoring image data input as an electrical signal by arranging a plurality of discharge tubes in a matrix to selectively emit light. PDPs are largely classified into direct current (DC) type PDPs and alternating current (AC) type PDPs according to whether the polarity of the voltage applied for sustaining a discharge changes or not over time.
FIG. 1
shows the basic structure of a general AC face discharge PDP. Referring to
FIG. 1
, a discharge space
15
is formed between a front glass substrate
11
and a rear glass substrate
17
. In the AC face discharge PDP, a discharge sustaining electrode
12
is covered by a dielectric layer
13
so as to be electrically isolated from the discharge space
15
. In this case, a discharge is sustained by the well-known wall charge effect. The above-described face discharge PDP includes two parallel discharge sustaining electrodes
12
formed on the front substrate
11
and an address electrode
16
formed on the rear substrate
17
so as to be orthogonal to the discharge sustaining electrodes
12
. According to this structure, an address discharge in which a pixel is selected occurs between the address electrode
16
and the discharge sustaining electrodes
12
, and then a sustained discharge in which a video signal is displayed occurs between the two discharge sustaining electrodes
12
, that is, between a common (X) electrode
12
a
and a scanning (Y) electrode
12
b.
FIG. 2
is an exploded perspective view schematically illustrating a generally used AC three-electrode face discharge PDP, in which an address electrode
16
and a pair of discharge sustaining electrodes
12
a
and
12
b
perpendicular to the address electrode
16
are installed for each discharge space
15
which is divided by partitions
18
formed on a rear substrate
17
. The partitions
18
serve to block space charges and ultraviolet rays produced during a discharge, to thus prevent cross talk from being generated at neighboring pixels, as well as to form the discharge spaces
15
. In order for a PDP to operate as a color display device, fluorescent material layers
19
made of a fluorescent material excited by the ultraviolet rays produced during discharge and having red (R), green (G) and blue (B) visible ray emitting characteristics, for displaying R, G and B colors, are sequentially coated in the discharge spaces
15
in order, thereby displaying R, G and B colors.
In order for a fluorescent-material-coated PDP to be capable of operating as a color video display device, a gray scale display must be utilized. Currently, a gray scale display method in which a picture of one frame is divided into a plurality of sub-fields to then be driven in a time-division manner is widely used.
FIG. 3
shows a gray scale display method in a general AC PDP. As shown in
FIG. 3
, in the gray scale display method of a general AC PDP, a picture of one frame is divided into a plurality of sub-fields each consisting of address periods and sustained discharge periods. Here, a 6-bit gray scale implementation method, for example, is explained. A picture of a frame is temporally divided into six sub-fields and 64 (=2
6
) gray scales are displayed. Each sub-field consists of address periods A
1
-A
6
and sustained discharge periods S
1
-S
6
. Gray scales are displayed using a principle in which the comparative lengths of the sustained discharge periods are expressed visually in the brightness ratio. In other words, since the lengths of the sustained discharge periods S
1
to S
6
of the first sub-field (SF
1
) to the sixth sub-field (SF
6
) comply with a ratio of 1:2:4:8:16:32, altogether, 64 types of sustained discharge periods, that is, 0, 1(1T), 2(2T), 3(1T+2T), 4(4T), 5(1T+4T), 6(2T+4T), 7(1T+2T+4T), 8(8T), 9(1T+8T), 10(2T+8T), 11(3T+8T), 12(4T+8T), 13(1T+4T+8T), 14(2T+4T+8T), 15(1T+2T+4T+8T), 16(16T), 17(1T+16T), 18(2T+16T), . . . , 62(2T+4T+8T+16T+32T) and 63(1T+2T+4T+8T+16T+32T) are constituted, thereby displaying 64 gray scale levels. For example, in order to display a gray scale level of 6 at an arbitrary pixel, only the second sub-field (2T) and the third sub-field (4T) have to be addressed. Also, in order to display a gray scale level of 15, all of the first through fourth sub-fields have to be addressed.
FIG. 4
is a layout diagram of electrodes of an AC face discharge PDP constructed for implementation of the gray scale display method shown in FIG.
3
. Here, among the discharge sustaining electrodes
12
, consisting of paired horizontal electrodes, the interconnected electrodes are common electrodes (X-electrodes)
12
a
and the other side electrodes are scanning electrodes (Y-electrodes)
12
b
. The common electrodes (X-electrodes)
12
a
are all connected together, and a voltage signal, including a discharge sustain pulse, is applied thereto. Thus, a scanning signal is applied to the scanning electrodes, that is, the Y-electrodes
12
b
, so that addressing is done between the Y-electrodes
12
b
and the address electrodes
6
, and the discharge sustain pulse is applied between the Y-electrodes
12
b
and the X-electrodes
12
a
so that a display discharge is sustained. Waveforms of the driving signals applied to the respective electrodes connected as above are shown in FIG.
5
.
FIG. 5
is a diagram showing the waveforms of driving signals of a generally used AC PDP, in which a picture display is implemented by an address/display separation (ADS) driving method. In
FIG. 5
, reference mark A denotes a driving signal applied to address electrodes, reference mark X denotes a driving signal applied to the common electrodes (to be also referred to as X-electrodes)
12
a
, and reference marks Y
1
through Y
480
denote driving signals applied to the respective Y-electrodes
12
b
. During a total erase period A
11
a total erase pulse
22
a
is applied to the common (X) electrodes
12
a
for an accurate gray scale display to cause a strong discharge, thereby erasing wall charges generated by a previous discharge to promote the operation of the next sub-field (step
1
). Next, during a total write period A
12
and a total erase period A
13
, in order to reduce an address pulse voltage
21
, a total write pulse
23
is applied to the Y-electrodes
12
b
and a total erase pulse
22
b
is applied to the X-electrodes
12
a
to cause a total write discharge and a total erase discharge, respectively, thereby controlling the amount of wall charges accumulated in the discharge space
15
(steps
2
and
3
). Then, during an address period A
14
, data converted into an electrical signal is written on a selected location on the whole screen of the PDP by a selective discharge using the address pulse (data pulse)
21
and a write pulse
24
between the address electrode
16
and the scanning electrode
12
b
intersecting each other (step
4
). Next, during a sustained discharge period S
1
, a display discharge, which is caused by continuously applying the discharge sustain pulse
25
, is sustained for a given period of time, for the purpose of displaying picture data on the screen.
As shown, as the number of scanning lines increases, the time required for a write operation increases and the number of sub-fields increases so that the time allocated to the sustain discharge is reduced. Thus, a panel having a higher resolution has a lesser overall luminance. That is, for a high-resolution display, luminance degradation cannot be avoided.
FIG. 6
is a schematic perspective plan view illustrating the structure of a conventional three-electrode face discharge PDP. As described above, an address electrode
16
is formed on a rear glass substrate
17
, and the address electrode
16
extends to either the top o
Kang Kyoung-Ho
Lee Seong-charn
Ryeom Jeong-Duk
Lao Lun-Yi
Lowe Hauptman & Gilman & Berner LLP
Samsung SDI & Co., Ltd.
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