Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
2002-02-20
2004-03-30
Awad, Amr (Department: 2675)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S063000, C345S068000, C315S169400
Reexamination Certificate
active
06714176
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a plasma display device employing a plasma display panel (hereinafter referred to as a PDP) and a method of driving the PDP, and in particular is effective for improving ultraviolet-light-producing efficiency and thereby improving luminous efficacy.
Recently, quantity production of plasma display devices employing the ac surface-discharge type PDP has been started for use as large-area, thin-profile, color display devices. The ac surface-discharge type PDP is driven by ac voltages for generating surface-discharge.
FIG. 7
is an exploded perspective view of an example of a conventional ac surface-discharge type PDP employing a three-electrode structure.
In the ac surface-discharge type PDP shown
FIG. 7
, a discharge space
33
is formed between a pair of opposing glass substrates, a front substrate
21
and a rear substrate
28
. The discharge space
33
is filled with a discharge gas at several hundreds or more of Torrs. As the discharge gas, usually He, Ne, Xe, and Ar are used either alone or in combination with one or more of the others.
A plurality of pairs of X and Y electrodes for sustaining discharge (hereinafter called discharge-sustaining electrodes or sustain-discharge electrodes) are disposed on the underside of the front substrate
21
serving as a display screen, for discharge-sustaining mainly for light emission for forming a display.
In this specification, “discharge-sustaining” and “sustain-discharge” are used interchangeably.
Usually, each of the X and Y electrodes is made of a combination of a transparent electrode and an opaque electrode for supplementing conductivity of the transparent electrode.
The X electrodes are comprised of transparent X electrodes
22
-
1
,
22
-
2
, . . . and corresponding opaque X bus electrodes
24
-
1
,
24
-
2
, . . . , respectively, and the Y electrodes are comprised of transparent Y electrodes
23
-
1
,
23
-
2
, . . . and corresponding opaque Y bus electrodes
25
-
1
,
25
-
2
, . . . , respectively. It is often that the X electrodes are used as a common electrode and the Y electrodes are used as independent electrodes.
A discharge gap Ldg between the X and Y electrodes in one discharge cell are designed to be small such that a discharge start voltage is not excessively high, and a spacing Lng between two adjacent cells is designed to be large such that unwanted discharge is prevented from occurring between two adjacent cells.
The X and Y sustain-discharge electrodes are covered with a front dielectric substance
26
which, in turn, is covered with a protective film
27
made of material such as magnesium oxide (MgO).
The MgO protects the front dielectric substance
26
and lowers a discharge start voltage because of its high sputtering resistance and high secondary electron emission yield.
Address electrodes
29
for addressing cells and thereby generating address-discharge are arranged on the upper surface of the rear substrate
28
in a direction perpendicular to the X and Y sustain-discharge electrodes.
The address electrodes
29
are covered with a rear dielectric substance
30
, separation walls
31
are disposed between the address electrodes
29
on the rear dielectric substance
30
.
A phosphor
32
is coated in a cavity formed by the surfaces of the separation walls
31
and the upper surface of the rear dielectric substance
30
.
In this configuration, an intersection of a pair of sustain-discharge X, Y electrodes with an address electrode
29
corresponds to one discharge cell, and the discharge cells are arranged in a two-dimensional fashion. In a color PDP, a trio of three discharge cells coated with red, green and blue phosphors, respectively, forms one pixel.
FIG.
8
and
FIG. 9
are cross-sectional views of one discharge cell shown in
FIG. 7
viewed in the directions of the arrows D1 and D2, respectively. In
FIG. 9
, the boundary of the cell is approximately represented by broken lines. In
FIG. 9
, reference numeral denote electrons,
4
is a positive ion,
5
is a positive wall charge, and
6
are negative wall discharges.
Next operation of the PDP of this example will be explained.
The principle of generation of light by the PDP is such that discharge is started by a voltage pulse applied between the X and Y electrodes, and then ultraviolet rays generated by excited discharge gases are converted into visible light by the phosphor.
FIG. 10
is a block diagram illustrating a basic configuration of a plasma display device. The PDP
100
is incorporated into the plasma display device
102
. A driving circuit
101
receives signals for a display image from a video signal source
103
, converts the signals into driving voltages, and then supplies them to respective electrodes of the PDP
100
. Concrete examples of the driving voltages are illustrated in
FIGS. 11A-11C
.
FIG. 11A
is a time chart illustrating a driving voltage during one TV field required for displaying one picture on the PDP shown in FIG.
7
.
FIG. 11B
illustrates waveforms of voltages applied to the address electrode
29
, the X electrode and the Y electrode during the address-discharge period
50
shown in FIG.
11
A.
FIG. 11C
illustrates pulse driving voltages (or voltage pulses) applied to the X and Y electrodes serving to sustain discharge and a driving voltage applied to the address electrode, all at the same time during the light-emission period
51
shown in FIG.
11
A.
Portion I of
FIG. 11A
illustrates that one TV field
40
is divided into sub-fields
41
to
48
having different numbers of light emission more than one from one another. Gray scales are generated by a combination of one or more selected from among the sub-fields.
Suppose the eight sub-fields are provided which have gray scale brightness steps in binary number step increments, then each discharge cell of a three-primary color display device provides 2
8
(=256) gray scales, and as a result the three-primary color display device is capable of displaying about 16.78 millions of different colors.
Portion II of
FIG. 11A
illustrates that each sub-field comprises a reset-discharge period
49
for resetting the discharge cells to an initial state, an address period
50
for addressing discharge cells to be selected and made luminescent, and a light-emission period (also called a sustain-discharge period)
51
.
FIG. 11B
illustrates waveforms of voltages applied to the address electrode
29
, the X electrode and the Y electrode during the address-discharge period
50
shown in
FIG. 11A. A
waveform
52
represents a voltage V0(V) applied to one of the address electrodes
29
during the address-discharge period
50
, a waveform
53
represents a voltage V1(V) applied to the X electrode, and waveforms
54
and
55
represent voltages V21(V) and V22(V) applied to ith and (i+1)st Y electrodes.
As shown in
FIG. 11B
, when a scan pulse
56
is applied to the ith Y electrode, in a cell located at an intersection of the ith Y electrode with the address electrode
29
supplied with the voltage V0, first an address-discharge occurs between the Y electrode and the address electrode, and then between the Y electrode and the X electrode. No address-discharges occur at cells located at intersections of the X and Y electrodes with the address electrode
29
at ground potential.
The above applies to a case where a scan pulse
57
is applied to the (i+1)st Y electrode.
As shown in
FIG. 9
, in the cell where the address-discharge has occurred, charges (wall discharges) are generated by the discharges on the surface of the dielectric substance
26
and the protective film
27
covering the X and Y electrodes, and consequently, a wall voltage Vw(V) occurs between the X and Y electrodes. In
FIG. 9
, reference numeral
3
denote electrons,
4
is a positive ion,
5
is a positive wall charge, and
6
are negative wall charges. Occurrence of sustaining discharge during the succeeding light-emission period
51
depends upon the presence of this wall charge.
FIG. 11C
illustrates pulse driving voltages (or volta
Ho Shirun
Kajiyama Hiroshi
Suzuki Keizo
Yamamoto Ken-ichi
A. Marquez, Esq. Juan Carlos
Fisher Esq. Stanley P.
Hitachi , Ltd.
Reed Smith LLP
LandOfFree
Plasma display device and a method of driving the same 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 device and a method of driving the same, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Plasma display device and a method of driving the same will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3279423