Electric lamp and discharge devices: systems – Plural power supplies – Plural cathode and/or anode load device
Reexamination Certificate
2001-08-28
2003-01-28
Wong, Don (Department: 2821)
Electric lamp and discharge devices: systems
Plural power supplies
Plural cathode and/or anode load device
C315S169100, C345S055000, C345S060000, C345S063000, C313S494000, C313S498000
Reexamination Certificate
active
06512337
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an alternating current plane discharge type plasma display panel and, more particularly, it relates to an alternating current plane discharge type plasma display panel having structurally improved plane electrodes.
2. Description of the Related Art
Plasma display panels (to be referred to as PDPs hereinafter) are known and designed to display images by causing electrons accelerated by an electric field to collide with and excite discharge gas and transforming ultraviolet rays emitted by way of a relaxation process into rays of visible light. Such PDPs are normally provided as flat surface image display devices having a large display screen and a large capacity. Particularly, alternating current (to be referred to as AC hereinafter) discharge type PDPs are advantageous in comparison with direct current (to be referred to as DC hereinafter) discharge type PDPs in terms of luminance of emitted light, efficiency of light emission and service life.
Japanese Patent Laid-Open Publication No. Hei. 8-22772 discloses an AC plane discharge type PDP of the type under consideration.
FIG. 1
of the accompanying drawings is a partly cut out schematic perspective view of a PDP similar to the one illustrated in
FIG. 1
of the above cited publication.
FIG. 2A
is a schematic plan view of plane electrodes of the PDP similar to those illustrated in
FIG. 2
of the above cited publication.
FIG. 2B
is a schematic cross sectional view of one of the plane electrodes.
FIG. 3A
is a schematic plan view of plane electrodes similar to those illustrated in
FIG. 8
of the above cited publication.
FIG. 3B
is a schematic cross sectional view of one of the plane electrodes.
FIG. 4A
is a schematic plan view of plane electrodes similar to those illustrated in
FIG. 11
of the above cited publication.
FIG. 4B
is a schematic cross sectional view of one of the plane electrodes. The structure of the known PDP will be described below with reference to these drawings.
As far as this specification is concerned, a “vertical direction” and a “horizontal direction” correspond to the column direction and the row direction respectively of the plane electrodes of the plasma display device that is typically fitted to a wall surface for use, respectively. The expressions of “longitudinal direction” and “transversal direction” may sometimes be used in place of “vertical direction” and “horizontal direction”, respectively, in the following description. The expressions of “upward” and “downward” refer to those directions viewed along the thickness of the glass substrate and along the layers thereon, respectively. More specifically, “upward” refers to the direction in which layers are formed sequentially on the glass substrate in the manufacturing process. A common electrode may also be referred to as a sustenance electrode. A line electrode may also be referred to as a bus electrode or trace electrode.
A plurality of data electrodes
2
typically made of silver (Ag) are formed longitudinally (in the column direction) to run along the longitudinal central axes of the cells on a back substrate
1
typically made of soda-lime glass. A white dielectric layer
3
made of PbO (lead oxide), SiO
2
(silicon oxide), B
2
O
3
(boron oxide), TiO
2
(titanium oxide) or ZrO
2
(zirconium oxide) is arranged on the data electrodes
2
. Then, a plurality of partition walls
4
a
typically made of PbO, SiO
2
, B
2
O
3
, TiO
2
, ZrO
2
or Al
2
O
3
are formed on the white dielectric layer
3
and run longitudinally in parallel with the data electrodes
2
. Fluorescent layers
5
that are adapted to emit visible rays of light of red, green and blue (fluorescent layers
5
a
for red cells, fluorescent layers
5
b
for green cells, fluorescent layers
5
c
for blue cells) are arranged alternately on the white dielectric layer
3
including the lateral surfaces of the partition walls
4
a.
A plurality of plane electrodes
7
a
typically made of SnO2 (tin oxide) or ITO (indium tin oxide) are formed on the bottom surface of a front substrate
6
typically made of soda-lime glass so that each one crosses the corresponding transversal central axes of the cells. More specifically, plane electrodes
7
a
are arranged in the transversal direction (in rows) and in the longitudinal direction (in columns). Narrow strip-shaped trace electrodes
8
a
typically made of silver (Ag) are formed under the plane electrodes
7
a
and run transversally in a direction perpendicular to the data electrodes
2
. The trace electrodes
8
a
are provided in pairs. The plane electrodes
7
a
corresponding to each pair of trace electrodes
8
a
are electrically connected to the latter to form a scan electrode
9
a
and a common electrode
10
a
that run transversally (in the row direction). The resulting scan electrodes group and the common electrodes group are arranged alternately in the longitudinal direction (column direction). A transparent dielectric layer
11
typically made of PbO, SiO2 or B2O3 is formed under the scan electrodes
9
a
and the common electrodes
10
a
and then a protection layer
12
typically made of MgO (magnesium oxide) is formed under the transparent dielectric layer
11
.
Then, the back substrate
1
and the front substrate
6
are bonded to each other with the layered structures facing each other and the entire device is air-tightly sealed by means of frit glass arranged along the peripheral edges of the substrates. The device contains therein a discharge gas such as He (helium), Ne (neon), Ar (argon), Kr (krypton) or Xe (xenon) for generating ultraviolet rays to show a predetermined internal pressure level.
A visible light reflecting layer containing TiO
2
, ZrO
2
or the like may be arranged under the fluorescent layer
5
on the back substrate
1
in order to improve the luminance of emitted light. Similarly, colored layers corresponding to the red cells, the green cells and the blue cells may be arranged in the transparent dielectric layer
11
in order to improve the color temperature and the color purity.
Now, the operation of the PDP having the above described configuration will be described below. The data electrodes
2
to which a signal voltage pulse is applied independently on a line by line basis and the scan electrodes
9
a
to which a scan voltage pulse is applied sequentially on a line by line basis are made to electrically discharge oppositely for writing discharges. This is done in order to generate wall charges and priming particles (electrons, ions, meta-stable particles, etc.) and select cells. Then, the scan electrodes
9
a
to which a sustained voltage pulse is applied after the application of the scan voltage pulse and the common electrodes
10
a
are made to give rise to sustaining discharges that are plane discharges. This is done in order to cause the fluorescent layer
5
to emit visible light and make the cells operate for displaying an image.
The known arrangement of electrodes described above and illustrated in
FIGS. 2A and 2B
is adapted to provide each cell (unitary light emitting pixel) with a plane electrode
7
a
to reduce the surface area of the plane electrodes
7
a
as a whole and also with a sustaining discharge current. The light emitting efficiency of the panel is maximized while the sustained voltage is reduced to by turn lower the power consumption rate by optimizing a length L
1
and a width W
1
of the plane electrode. As a result, the temperature rise of the panel in operation is suppressed to improve the reliability of operation of the panel.
Referring to
FIGS. 3A and 3B
, or
FIGS. 4A and 4B
showing alternative known arrangements of electrodes, the plane electrodes
7
b
and
7
c
are provided with narrow sections
13
a
and
13
b
respectively to further reduce the surface area of the plane electrodes
7
b
and
7
c
as a whole and lower the sustaining discharge current. As a result, the power consumption rate of either arrangement of
FIGS. 3A and 3B
or
FIGS. 4A and 4B
is reduced from that of t
Aibara Nobumitsu
Hasegawa Hiroshi
Hirano Naoto
NEC Corporation
Sughrue & Mion, PLLC
Vo Tuyet T.
Wong Don
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