Electric lamp and discharge devices: systems – Plural power supplies – Plural cathode and/or anode load device
Reexamination Certificate
2000-07-24
2002-01-22
Wong, Don (Department: 2821)
Electric lamp and discharge devices: systems
Plural power supplies
Plural cathode and/or anode load device
C345S047000, C345S060000
Reexamination Certificate
active
06340867
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a plasma display panel, and more particularly to a plasma display panel that can be driven by an active matrix system with an analog image signal. The present invention also is directed to a method and apparatus for driving the PDP.
2. Description of the Related Art
Generally, a plasma display panel (PDP) radiates a fluorescent body by an ultraviolet with a wavelength of 147 nm generated during a discharge of He+Xe or Ne+Xe gas to thereby display a picture. Such a PDP is easy to be made into a thin-film and large-dimension type. Moreover, the PDP provides a very improved picture quality owing to a recent technical development. Such a PDP typically includes a surface-discharge and alternating current (AC) type PDP that has three electrodes as shown in FIG.
1
and is driven with an alternating current voltage.
FIG. 1
is a perspective view of a discharge cell of a conventional three-electrode and AC-type PDP. Referring to
FIG. 1
, the discharge cell includes an upper substrate
10
provided with a sustaining electrode pair
12
and
14
, and a lower substrate
20
provided with an address electrode
22
. The upper substrate
10
and the lower substrate
20
are spaced, in parallel to each other, with having a barrier rib
26
therebetween. A mixture gas such as Ne—Xe or He—Xe, etc. is injected into a discharge space defined by the upper substrate
10
and the lower substrate
20
and the barrier rib
26
. Any one electrode
12
of the sustaining electrode pair
12
and
14
is used as a scanning/sustaining electrode that responds to a scanning pulse applied in the address interval to cause an opposite discharge along with the address electrode
22
, and responds to a sustaining pulse applied in the sustaining interval to cause a surface discharge along with the adjacent sustaining electrode
14
. The sustaining electrodes
14
adjacent to the sustaining electrode
12
used as the scanning/sustaining electrode are used as a common sustaining electrode to which a sustaining pulse is applied commonly. On an upper substrate
10
provided with the sustaining electrode pair
12
and
14
, an upper dielectric layer
16
and a protective film
18
are disposed. The upper dielectric layer
16
is responsible for limiting a plasma discharge current as well as accumulating a wall charge during the discharge. The protective film
18
prevents a damage of the upper dielectric layer
16
caused by a sputtering generated during the plasma discharge and improves an emission efficiency of secondary electrons. This protective film
18
is usually made from MgO. The address electrode
22
crosses the sustaining electrode pair
12
and
14
and is supplied with a data signal for selecting cell to be displayed. A lower dielectric layer
24
is formed on the lower substrate
20
provided with the address electrode
22
. The barrier ribs
26
for dividing the discharge space are extended perpendicularly on the lower dielectric layer
24
. The surfaces of the lower dielectric layer
24
and the barrier rib
26
is coated with a fluorescent material
28
excited by a vacuum ultraviolet ray to generate a red, green or blue visible light.
The PDP discharge cell having the structure as described above sustains a discharge by a surface discharge between the sustaining electrode pair
12
and
14
after being selected by an opposite discharge between the address electrode
22
and the scanning/sustaining electrode
12
. The fluorescent material
28
is radiated by an ultraviolet ray generated during the sustaining discharge to emit a visible light into the exterior of the cell. In this case, a discharge sustaining interval, that is, a sustaining discharge frequency of the cell is controlled to realize a gray scale required for an image display.
Such a PDP driving method typically includes a sub-field driving method in which the address interval and the discharge sustaining interval are separated. In the sub-field driving method as shown in
FIG. 2
, one frame is divided into n sub-fields SF
1
to SFn corresponding to each bit of an n-bit image data. Each of which is again divided into a reset interval RP, an address interval AP and a discharge sustaining interval SP. The reset interval RP is an interval for initializing a discharge cell, the address interval AP is an interval for generating a selective address discharge in accordance with a logical value of a video data, and the sustaining interval SP is an interval for sustaining interval a discharge at the discharge cell
12
having generated the address discharge. The reset interval RP and the address interval AP are equally allocated in each sub-field interval. A weighting value with a ratio of
2
0
:
2
1
:
2
2
: . . . :
2
n−1
is given to the discharge sustaining interval SP to express a gray scale by a combination of the discharge sustaining intervals SP.
FIG. 3
is waveform diagrams of driving signals applied to the PDP during a certain one sub-field interval SFi. In the reset interval RP, a priming pulse Pp is applied to the common sustaining electrode. By this priming pulse Pp, a reset discharge is generated between each common sustaining electrode and each scanning/sustaining electrodes of the entire discharge cells to initialize the discharge cells. At this time, a voltage pulse lower than the priming pulse Pp is applied to the address electrode so as to prevent a discharge between the address electrode and the common sustaining electrode. By the reset discharge, a large amount of wall charges are formed at the common sustaining electrode and the scanning/sustaining electrode of each discharge cell. Subsequently, a self-erasure discharge is generated at the discharge cells by the large amount of wall charges to eliminate the wall charges and leave a small amount of charged particles. These small amount of charged particles help an address discharge in the following address interval. In the address interval AP, a scanning voltage pulse SCp is applied line-sequentially to the first to mth scanning/sustaining electrodes. At the same time, a data pulse Dp according to a logical value of a data is applied to the address electrodes. Thus, an address discharge is generated at discharge cells to which the scanning voltage pulse SCp and the data pulse Dp are simultaneously applied. Wall charges are formed at the discharge cells in which the address discharge has been generated. During this address interval, a desired constant voltage is applied to the common sustaining electrodes to prevent a discharge between each address electrode and each common sustaining electrode. In the sustaining interval SP, a sustaining pulse Sp is alternately applied to the first to mth scanning/sustaining electrodes and the common sustaining electrodes. Accordingly, a sustaining discharge is generated continuously only at the discharge cells formed with the wall charges by the address discharge to emit a visible light.
In such a sub-field driving method, the reset interval RP is set for each sub-field to initialize the discharge cells in the same state. Due to the reset interval RP, however, a spurious light-emission that does contribute to the brightness is generated at the rising and falling edges of the reset voltage pulse Pp every sub-field SF
1
to SFn. A brightness of a black level rises from such a spurious emission to lower the contrast. In order to overcome this contrast deterioration, a scheme of including one reset interval per frame or a reset interval having a lower frequency than the prior art, that is, a full writing period FWP as shown in
FIG. 4
has been disclosed in Japanese Laid-open Patent Gazette No. Pyung 5-313598.
In the PDP adopting the sub-field driving method, the brightness is determined by the display interval, that is, the discharge sustaining interval. Since a relatively long time is wasted due to the address interval allocated equally for each sub-field SF
1
to SFn, however, a time allocated for the discharge sustaining interval determining the bri
Fleshner & Kim LLP
LG Electronics Inc.
Tran Thuy Vinh
Wong Don
LandOfFree
Plasma display panel driving method and apparatus thereof does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Plasma display panel driving method and apparatus thereof, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Plasma display panel driving method and apparatus thereof will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2875053