Electric lamp and discharge devices: systems – Plural power supplies – Plural cathode and/or anode load device
Reexamination Certificate
2000-01-19
2001-09-25
Wong, Don (Department: 2821)
Electric lamp and discharge devices: systems
Plural power supplies
Plural cathode and/or anode load device
C315S169300, C315S169400, C315S169200, C345S060000, C345S182000
Reexamination Certificate
active
06294875
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method of driving an AC plasma display panel used for image display in a television receiver, a computer monitor, or the like.
BACKGROUND OF THE INVENTION
A partial perspective view of an AC plasma display panel (hereinafter referred to as a “panel”) is shown in FIG.
4
. As shown in
FIG. 4
, a scanning electrode
4
and a sustain electrode
5
that are covered with a dielectric layer
2
and a protective film
3
are provided on a first glass substrate
1
in parallel with each other as a pair. On a second glass substrate
6
, a plurality of data electrodes
8
covered with an insulator layer
7
are provided. Separation walls
9
are provided in parallel to the data electrodes
8
on the insulator layer
7
between every two of the data electrodes
8
. Phosphors
10
are formed on the surface of the insulator layer
7
and on both side faces of each separation wall
9
. The first glass substrate
1
and the second glass substrate
6
are positioned opposing each other with discharge spaces
11
being sandwiched therebetween so that the scanning electrodes
4
and the sustain electrodes
5
are orthogonal to the data electrodes
8
. In the discharge spaces
11
, xenon and at least one selected from helium, neon, and argon are filled as discharge gases. The discharge spaces at the intersections of the data electrodes
8
and pairs of scanning electrode
4
and sustain electrode
5
form respective discharge cells
12
.
FIG. 5
is a diagram showing the electrode array in this panel. As shown in
FIG. 5
, this electrode array has a matrix structure formed of m columns×n rows. In the column direction, m columns of data electrodes D
1
-D
m
are arranged, and n rows of scanning electrodes SCN
1
-SCN
n
and sustain electrodes SUS
1
-SUS
n
are arranged in the row direction. The discharge cell
12
shown in
FIG. 4
corresponds to the region shown in FIG.
5
.
FIG. 6
is a diagram showing the timing chart of an operation driving waveform in a conventional driving method for driving this panel. This driving method is used for displaying 256 shades of gray. One field consists of eight subfields. This driving method is described with reference to
FIGS. 4
to
6
as follows.
As shown in
FIG. 6
, each of first to eighth subfields includes an initialization period, a write period, a sustain period, and an erase period. First, the description is directed to the operation in the first subfield.
As shown in
FIG. 6
, all the data electrodes D
1
-D
m
and all the sustain electrodes SUS
1
-SUS
n
are maintained at a voltage of 0 in an initialization operation in a first part of the initialization period. To all the scanning electrodes SCN
1
-SCN
n
, a lamp voltage is applied, which increases gradually from a voltage of VP toward a voltage of Vr. The voltages of Vp and Vr provide the scanning electrodes SCN
1
-SCN
n
with voltages below and beyond the discharge starting voltage with respect to the sustain electrodes SUS
1
-SUS
n
, respectively. During the lamp voltage increases, a first weak initialization discharge occurs in all the discharge cells
12
from the scanning electrodes SCN
1
-SCN
n
to the data electrodes D
1
-D
m
and the sustain electrodes SUS
1
-D
n
, respectively. Due to the first weak initialization discharge, a negative wall voltage is stored in the regions of the protective film
3
surface that are positioned on the scanning electrodes SCN
1
-SCN
n
(hereinafter this terminology is described simply as “at the surface of the protective film
3
on the scanning electrodes SCN
1
-SCN
n
”). At the same time, a positive wall voltage is stored at the surface of insulator layer
7
on the data electrodes D
1
-D
m
and at the surface of the protective film
3
on the sustain electrodes SUS
1
-SUS
n.
In the initialization operation in a second part of the initialization period, all the sustain electrodes SUS
1
-SUS
n
are maintained at a positive voltage of Vh. To all the scanning electrodes SCN
1
-SCN
n
, a lamp voltage is applied, which decreases gradually from a voltage of Vq toward a voltage of 0. The voltages of Vq and 0 provide the scanning electrodes SCN
1
-SCN
n
with voltages below and beyond the discharge starting voltage with respect to the sustain electrodes SUS
1
-SUS
n
, respectively. During the lamp voltage decreases, a second weak initialization discharge occurs again in all the discharge cells
12
from the sustain electrodes SUS
1
-SUS
n
to the scanning electrodes SCN
1
-SCN
n
. The second weak initialization discharge weakens the negative wall voltage at the surface of the protective film
3
on the scanning electrodes SCN
1
-SCN
n
and the positive wall voltage at the surface of the protective film
3
on the sustain electrodes SUS
1
-SUS
n
. A weak discharge also occurs between the data electrodes D
1
-D
m
and the scanning electrodes SCN
1
-SCN
n
. Consequently, the positive wall voltage at the surface of the insulator layer
7
on the data electrodes D
1
-D
m
is adjusted to a value suitable for a write operation.
Thus, the initialization operation in the initialization period is completed.
In the write operation in the subsequent write period, initially all the scanning electrodes SCN
1
-SCN
n
are maintained at a voltage of Vs. Then, a positive write pulse voltage of +Vw is applied to a designated data electrode D
j
(j indicates one or more integers of 1 to m) that is selected from the data electrodes D
1
-D
m
and corresponds to a discharge cell
12
to be operated so as to emit light in the first line and at the same time a scan pulse voltage of 0 is applied to the scanning electrode SCN
1
of the first line. In this state, the voltage between the surface of the insulator layer
7
and the surface of the protective film
3
on the scanning electrode SCN
1
at the intersection of the designated data electrode D
j
and the scanning electrode SCN
1
is calculated by adding the positive wall voltage at the surface of the insulator layer
7
on the data electrodes D
1
-D
m
to the write pulse voltage of +Vw. Therefore, at this intersection, a write discharge occurs be tween the designated data electrode D
j
and the scanning electrode SCN
1
and between the sustain electrode SUS
1
and the scanning electrode SCN
1
. Thus, at this intersection, a positive wall voltage is stored at the surface of the protective film
3
on the scanning electrode SCN
1
, a negative wall voltage at the surface of the protective film
3
on the sustain electrode SUS
1
, and a negative wall voltage at the surface of the insulator layer
7
on the data electrode D
j.
Then, a positive write pulse voltage of +Vw is applied to a designated data electrode D
j
that is selected from the data electrodes D
1
-D
m
and corresponds to a discharge cell
12
to be operated so as to emit light in the second line. At the same time, a scan pulse voltage of 0 is applied to the scanning electrode SCN
2
of the second line. In this state, the voltage between the surface of the insulator layer
7
and the surface of the protective film
3
on the scanning electrode SCN
2
at the intersection of the designated data electrode D
j
and the scanning electrode SCN
2
is calculated by adding the positive wall voltage stored at the surface of the insulator layer
7
on the designated data electrode D
j
to the write pulse voltage of +Vw. Therefore, at this intersection, a write discharge occurs between the designated data electrode D
j
and the scanning electrode SCN
2
and between the sustain electrode SUS
2
and the scanning electrode SCN
2
. As a result, at this intersection, a positive wall voltage is stored at the surface of the protective film
3
on the scanning electrode SCN
2
, a negative wall voltage at the surface of the protective film
3
on the sustain electrode SUS
2
, and a negative wall voltage at the surface of the insulator layer
7
on the data electrode D
j.
Successively, the same operation is carried out for all remaining lines. Finally, a positive write pulse voltage of +Vw is applied to a d
Ito Yukiharu
Kawachi Makoto
Kurata Takatsugu
Masuda Shinji
Wakitani Takao
Matsushita Electric - Industrial Co., Ltd.
Merchant & Gould P.C.
Vu Jimmy
Wong Don
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