Electric lamp and discharge devices – With luminescent solid or liquid material
Reexamination Certificate
2001-11-27
2004-09-07
Patel, Nimeshkumar D. (Department: 2879)
Electric lamp and discharge devices
With luminescent solid or liquid material
C313S484000, C313S485000, C313S582000, C315S169300, C428S690000
Reexamination Certificate
active
06787978
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to the structure of a plasma display panel (referred to as a PDP hereinafter), and particularly to the structure of an AC surface discharge type PDP and a plasma display device using the PDP.
2. Description of the Background Art
FIG. 20
is a perspective view schematically showing the structure of a conventional PDP
300
. For convenience of explanation,
FIG. 20
shows the front substrate
12
and the back substrate
1
separated from each other, but in practice the front substrate
12
is placed so that the edges of the barrier ribs
2
abut on a protective film
14
described later. Also in
FIG. 20
, a dielectric film
13
, described later, and the protective film
14
formed on the dielectric film
13
are shown with broken lines, so that the configuration of transparent electrodes
6
etc. can be seen.
FIG. 21
is a plan view schematically showing the structure of the PDP
300
; for convenience of explanation,
FIG. 21
does not show the front substrate
12
, dielectric film
13
, protective film
14
, phosphors
3
and address electrodes
7
.
FIG. 22
is a sectional view schematically showing the structure of the PDP
300
taken along the line H—H in
FIG. 21
;
FIG. 22
shows the front substrate
12
, dielectric film
13
, protective film
14
and phosphors
3
which are not shown in FIG.
21
.
FIG. 22
does not show the address electrodes
7
.
The front substrate
12
and the back substrate
1
are disposed in parallel to face each other at a given distance. The space between the front substrate
12
and the back substrate
1
is partitioned into a plurality of independent cell spaces
8
by the grid-like barrier ribs (also referred to as ribs)
2
formed on the back substrate
1
. Such structure of the barrier ribs
2
is called a waffle rib structure.
The front substrate
12
forms the display surface; on the front substrate
12
, bus electrodes
4
X and
5
Y, transparent electrodes
6
and black stripes
16
are formed on the side facing the back substrate
1
. The dielectric film
13
is formed to cover the bus electrodes
4
X and
5
Y, the transparent electrodes
6
and the black stripes
16
, and the protective film
14
is formed thereon. The bus electrodes
4
X and
5
Y are formed of a double-layered structure of black silver and white silver, the transparent electrodes
6
are formed of an ITO film (an alloy oxide film of indium and tin), the protective film
14
is formed of an MgO (magnesium oxide) film, and the black stripes
16
are formed of a black insulating material. The bus electrodes
4
X and
5
Y and the black stripes
16
are disposed so that, when the front substrate
12
and the back substrate
1
are bonded together, they overlap the barrier ribs
2
, seen from the display surface. The black stripes
16
, disposed between the bus electrodes
4
X and
5
Y, are formed after formation of the bus electrodes
4
X and
5
Y. Each transparent electrode
6
is T-shaped, with its one end connected to the bus electrode
4
X or
5
Y. The transparent electrodes
6
protrude over the cell spaces
8
from the connections with the bus electrodes
4
X and
5
Y. The T-shaped electrodes contribute to appropriate control of the discharge spreading to enhance the luminous efficiency. In the PDP
300
, the transparent electrodes
6
extending from the bus electrodes
4
X and the transparent electrodes
6
extending from the bus electrodes
5
Y form pairs to produce given discharges.
The back substrate
1
has address electrodes
7
which three-dimensionally intersect with the bus electrodes
4
X and
5
Y; the address electrodes
7
are disposed approximately in the middle of the cell spaces
8
. A dielectric layer
15
is formed on the back substrate
1
to cover the address electrodes
7
and the grid-like barrier ribs
2
are formed thereon.
A phosphor
3
R for red (R) emission, a phosphor
3
G for green (G) emission, or a phosphor
3
B for blue (B) emission (referred to also as “phosphors
3
” together) is applied in the cell spaces
8
which are formed by the back substrate
1
, the barrier ribs
2
and the front substrate
12
; all cell spaces
8
thus form discharge cells. More specifically, the phosphors
3
are applied on the back substrate
1
and the side surfaces of the barrier ribs
2
forming the cell spaces
8
. When the direction in which the bus electrodes
4
X and
5
Y extend is taken as a row direction and the direction in which the address electrodes
7
extend is taken as a column direction, the phosphors
3
R,
3
G and
3
B are applied in the cell spaces
8
according to a given order among columns.
In the PDP
300
, in order to secure an exhaust path for vacuum evacuation, the dielectric film
13
and the protective film
14
are raised on the bus electrodes
4
X and
5
Y above the remaining area. That is to say, the barrier ribs
2
extending in the row direction abut on the protective film
14
but the barrier ribs
2
extending in the column direction do not abut on the protective film
14
. As a result, the cell spaces
8
are not perfectly closed and an exhaust path is thus ensured. The gap between the barrier ribs
2
and the protective film
14
shown in
FIG. 22
illustrates this exhaust path.
A PDP having the structure shown in
FIG. 20
is described in Video Information Media Society Journal Vol. 54, No.8, pp.1180 to 1184, for example.
In this conventional PDP
300
where all cell spaces
8
form discharge cells which adjoin each other, a discharge in a cell space
8
may induce other cell spaces
8
to cause erroneous discharges. For example, when there is a gap from the first between the edge of a barrier rib
2
and part of the front substrate
12
facing the barrier rib
2
, or when a barrier rib
2
is cut or broken to form a gap during the manufacturing process of the PDP, charged particles under discharge may diffuse through the gap into adjacent cell spaces
8
, possibly causing erroneous discharge over the barrier ribs
2
.
Also, as shown in
FIG. 22
, the light produced in the cell space
8
includes light
21
which travels directly to the display surface and light
22
which penetrates into the barrier ribs
2
toward adjacent cell spaces
8
. While the phosphors
3
have high reflectance and reflects light without loss, the barrier ribs
2
involve large loss of light. Accordingly the light
22
traveling toward adjacent cell spaces
8
is repeatedly reflected in the barrier ribs
2
and attenuated when taken out to the display surface. This causes the problem that, in the light produced in the cell space
8
, the light traveling toward the adjacent cell spaces
8
cannot be effectively taken out onto the display surface.
SUMMARY OF THE INVENTION
A first aspect of the present invention is directed to a plasma display panel comprising: a first substrate forming a display surface; a second substrate placed to face the first substrate at a given distance; and barrier ribs sectioning a space between the first substrate and the second substrate into a plurality of independent cell spaces; wherein the plurality of cell spaces comprise a plurality of discharge cells and a plurality of non-discharge cells, and the plurality of discharge cells and the plurality of non-discharge cells are arranged so that each the discharge cell adjoins at least one the non-discharge cell.
Preferably, according to a second aspect of the present invention, in the plasma display panel of the first aspect, a phosphor is applied in the discharge cells and no phosphor is applied in the non-discharge cells.
Preferably, according to a third aspect of the present invention, the plasma display panel of the first aspect further comprises black insulating films provided on the second substrate in regions corresponding to the non-discharge cells.
Preferably, according to a fourth aspect of the present invention, the plasma display panel of the first aspect further comprises first reflection films provided on sides of the barrier ribs in regions corresponding to the non-disc
Harada Shigeki
Sano Ko
Yura Shinsuke
Leurig Sharlene
Patel Nimeshkumar D.
LandOfFree
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