Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
2000-04-14
2001-09-11
Shalwala, Bipin (Department: 2673)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S066000, C345S067000, C345S068000, C315S169100, C315S169200, C315S169300, C315S169400, 30
Reexamination Certificate
active
06288691
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a plasma display panel and the driving method thereof, and more particularly, to a plasma display panel, one of flat panel display devices, having improved electrical connections and the driving method thereof.
2. Description of the Related Art
Generally, to display an image on a flat panel display device, a matrix driving method is utilized. In this method, a pair of electrodes are sequentially selected among a plurality of scan electrodes arranged in the same horizontal direction as the scanning direction of a video signal and a plurality of address electrodes arranged in the vertical direction, and on the cross point of the pair of the electrodes, a video signal of a pixel can be displayed. In addition, two types of steps are required to display images on a flat panel display device. One step is an addressing step to sequentially address each one of pixels of the display panel, and the other one is a sustaining discharge step to display a video signal for a certain period of time at the corresponding pixel. In the plasma display panel, the two types of steps are carried out by selecting a pair of horizontal and vertical electrodes, and by establishing a negative glow discharge within a discharge space filled with a gas between the two electrodes. In other words, after a pair of scan electrodes and an address electrode are selected according to the sync pulses of a video signal, and a pulse voltage is impressed at least one of the electrodes to establish a gas discharge at the selected pixel, a pulse voltage is impressed across the scan electrodes to achieve a sustaining discharge, and therefore the video signal is transformed to a light signal and is displayed at the selected pixel.
The structural types of the plasma display panels are classified into a facing discharge type and a surface discharge type according to arrangement configurations of discharge electrodes, the driving types of the plasma display panels are classified into an AC driving type and a DC type according to whether the polarity of the voltage impressed for sustaining discharges is varying with the passage of time or not.
FIG. 1
a
shows a basic structure of a general DC type facing discharge plasma display panel, and
FIG. 1
b
shows a basic structure of a general AC type surface discharge plasma display panel. As shown in
FIGS. 1
a
and
1
b
, the DC type facing discharge plasma display panel, and the AC type surface discharge plasma display panel are respectively provided with discharge spaces
5
and
15
between front glass substrates
1
and
11
and back glass substrates
7
and
17
. In the DC type plasma display panel, since a scan electrode
2
and an address electrode
6
are directly exposed to the discharge space
5
, the flow of electrons supplied by a cathode is the energy source sustaining a discharge. In the AC type plasma display panel, since the scan electrodes
12
are embedded in a dielectric layer
13
, they are electrically isolated from the discharge space
15
. In this case, the discharge is sustained by the well-known wall charge effect. In addition, the AC type plasma display panels are classified into a facing discharge type and a surface discharge type according to the disposition of electrodes establishing discharges.
In the facing discharge plasma display panel, a pixel is addressed by the address electrode
6
on the back substrate
7
and the scan electrode
2
on the front substrate
1
which are disposed to face each other and to be orthogonal to each other and are addressed according to sync pulses of the video signal, and the discharge occurs and is sustained in the discharge space between the electrodes
2
and
6
. In the surface discharge plasma display panel, a pair of the scan electrodes
12
formed on the front substrate
11
to be parallel to each other and the address electrode
16
formed on the back substrate
17
to be orthogonal with respect to the electrodes
2
and
6
are provided. In this panel, an address discharge occurs between the address electrode
16
and the scan electrodes
12
, and then a sustaining discharge to display a video signal occurs between two scan electrodes
12
, namely, an X electrodes
12
a
and an Y electrodes
12
b
. Further, each type may employ 3 electrode structure, 4 electrode structure and so on including a plurality of scan electrodes and/or address electrodes in order to easily establish the discharge.
FIG. 2
shows a schematic exploded perspective view of an AC type
3
electrode surface discharge plasma display panel which is commercially available. An address electrode
16
and a pair of scan electrodes
12
to be orthogonal with respect to the address electrode
16
are disposed at both sides of a corresponding point of a discharge space
15
. Partition walls
18
have roles to define discharge spaces
15
and to prevent cross talks between neighbor pixels from occurring by blocking space charges created during a discharge period and ultraviolet rays. To make a plasma display panel capable of displaying color images as a color display device, fluorescent materials
19
which can be excited by ultraviolet rays radiated during a discharge period and respectively emit visible light rays of red, blue, and green colors are respectively coated on the inside surfaces of the discharge spaces sequentially and repeatedly.
Such a plasma display panel coated with the fluorescent materials has to exhibit gray scale to achieve a preferable performance of a color image display device, and a gray scale exhibition method in which a image frame is divided into a plurality of subfields and the panel is driven in a time-division manner is currently utilized.
FIG. 3
shows a diagram to explain a gray scale exhibition method of a general AC type plasma display panel. As shown in
FIG. 3
, the gray scale exhibition method of the AC type plasma display panel employs a method in which a image frame is divided into 4 subfields operated in a time-division manner and 2
4
=16 gray scale can be displayed. The operation period of each subfield consist of respective one of address periods A
1
to A
4
and respective one of sustaining discharge periods S
1
to S
4
, the fact that the brightness perceived by human eyes is directly proportional to the relative duration of the sustaining discharge period is utilized to exhibit the gray scale. In other words, since the sustaining discharge periods S
1
to S
4
of a first subfield SF
1
to a fourth subfield SF
4
are in the ratio 1:2:4:8, combinational periods of each sustaining discharge period such as 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) are possible and therefore 16 level gray scale can be displayed. For example, in order to display level 6 of the gray scale in a certain pixel, the second subfield 2T and the third subfield 4T have to be addressed, and in order to display level
15
of the gray scale, all of the first, second, third and fourth subfields have to be addressed.
FIG. 4
shows a diagram of an electrode connection scheme of an AC type 3 electrode surface discharge plasma display panel to realize the gray scale exhibition method as described above. As shown in
FIG. 4
, X electrodes
12
a
of scan electrodes
12
are connected to a common line, and accordingly a voltage signal of the same waveform including a sustaining discharge pulse is impressed to all the X electrodes
12
a
. Therefore, as a scan signal of the scan electrodes
12
is impressed to an Y electrode, an address discharge occurs between the Y electrode
12
b
and an address electrode
6
, and then as a sustaining discharge pulse is impressed across the Y electrode
12
b
and the X electrodes, the display discharge is sustained. The waveforms of driving signals respectively impressed to the electrodes connected as desc
Mikoshiba Shigeo
Ryeom Jeong-duk
Lowe Hauptman & Gilman & Berner LLP
Nguyen Jimmy H.
Samsung Display Devices, Ltd.
Shalwala Bipin
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