Electric lamp and discharge devices – With gas or vapor – Three or more electrode discharge device
Reexamination Certificate
2001-02-02
2003-03-18
Chen, Sophia S. (Department: 2852)
Electric lamp and discharge devices
With gas or vapor
Three or more electrode discharge device
C313S582000
Reexamination Certificate
active
06534915
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a panel structure of a plasma display panel.
2. Description of the Related Art
Recent years, a surface discharge scheme AC type plasma display panel as an oversized and slim display for color screen has been received attention, which is becoming widely available.
FIG. 10
is a schematic front view of a conventional surface discharge scheme AC type plasma display panel.
FIG. 11
is a sectional view taken along the V
3
—V
3
line of FIG.
10
.
FIG. 12
is a sectional view taken along the W
4
—W
4
line of FIG.
10
.
FIG. 13
is a sectional view taken along the W
5
—W
5
line of FIG.
10
.
In
FIG. 10
to
FIG. 13
, on the backside of a front glass substrate
1
to serve as a display screen of the plasma display panel, there is sequentially provided with a plurality of row electrode pairs (X′, Y′); a dielectric layer
2
overlaying the row electrode pairs (X′, Y′); and a protective layer
3
made of MgO which overlays a backside of the dielectric layer
2
.
The row electrodes X′ and Y′ respectively consist of wider transparent electrodes Xa′ and Ya′ each formed of a transparent conductive film made of ITO (Indium Tin Oxide) or the like, and narrower bus electrodes Xb′ and Yb′ each formed of a metal film, complementary to conductivity of the transparent electrode.
The row electrodes X′ and Y′ are arranged opposing each other with a discharge gap g′ interposed between them, and alternate in the column direction. Each row electrode pair (X′, Y′) forms a display line (row) L for matrix display.
A back glass substrate
4
faces the front glass substrate
1
with a discharge space S′, filled with a discharge gas, in between. The back glass substrate
4
is provided with a plurality of column electrodes D′ arranged to extend in a direction perpendicular to the row electrode pairs X′ and Y′; band-shaped partition walls
5
each extending between the adjacent column electrodes D′ in parallel; and a phosphor layer
6
consisting of a red phosphor layer
6
(R), green phosphor layer
6
(G) and blue phosphor layer
6
(B) and overlaying side faces of the partition walls
5
and the column electrodes D′.
In each display line L, the column electrodes D′ and the row electrode pair (X′, Y′) cross each other and the partition walls
5
divide the discharge space S′, to form a unit light emitting area, and thus a discharge cells C′ is defined therein.
In the plasma display panel, as illustrated in FIGS.
11
and
12
, on the backside of the dielectric layer
2
and at a portion opposing to the bus electrodes Xb′ and Yb′ oriented back to back and extending in parallel, an additional dielectric layer
2
A is formed to extend along the bus electrodes Xb′ and Yb′ in parallel.
The additional dielectric layer
2
A is formed to protrude from the backside of the dielectric layer
2
into the discharge space S′. The additional dielectric layer
2
A has the function of limiting the spread of a surface discharge d caused between the opposite transparent electrodes Xa′ and Ya′ in the discharge space S′ from going toward the bus electrodes Xb′ and Yb′ so as to prevent occurrence of a false discharge between the discharge cells C′ adjacent to each other in the column direction.
In the above surface discharge scheme AC type plasma display panel, an image is displayed as follows:
First, through addressing operation, discharge (opposite discharge) is caused selectively between the row electrode pairs (X′, Y′) and the column electrodes D′ in the respective discharge cells C′, to scatter lighted cells (the discharge cell in which wall charge is formed on the dielectric layer
2
) and nonlighted cells (the discharge cell in which wall charge is not formed on the dielectric layer
2
), over the panel in accordance with the image to be displayed.
After the address operation, in all the display lines L, the discharge sustain pulse is applied alternately to the row electrode pairs (X′, Y′) in unison. In each lighted cell, for every application of the discharge sustaining pulse, surface discharge is produced in each space between a pair of additional dielectric layers
2
A adjacent to each other sandwiching the lighted cell. The above surface discharge generates ultraviolet radiation, and thus the corresponding red(R), green (G) and/or blue (B) phosphor layers
6
in the discharge space S′ are excited to emit light, resulting in forming the display image.
As explained above, in the conventional plasma display panel (PDP), the additional dielectric layer
2
A formed in the portion facing the bus electrodes Xb′, Yb′ to extend in the row direction, limits the spreading of the discharge in the column direction in order to prevent occurrence of interference between discharges in the adjacent discharge cells C′ in the column direction.
However, as shown in
FIG. 13
, the conventional PDP has a clearance r′ which is formed between the partition wall
5
and the dielectric layer
2
and between the adjacent discharge cells C′ in the row direction in order to feed and exhaust a discharge gas into and from the discharge cells C′. For this reason, as illustrated in
FIG. 10
, the surface discharge d in one discharge cell may spread via the clearance r′ into an adjacent discharge cell C′ in the row direction, to possibly cause interfering discharges.
Although the spread of the discharge in the column direction is passably limited by the additional dielectric layer
2
A as explained above, if the surface discharge d develops beyond the additional dielectric layer
2
A, it is impossible to completely prevent the interference between the discharges in the adjacent discharge cells C′ in the column direction.
The possibility of such interference between the discharges in the row direction and the column direction increases, as a pitch between the discharge cells decreases in relation to the high definition of an image. In the event of interfering discharges, lighted and unlighted discharge cells may be reversed producing an instable and inaccurate image.
SUMMARY OF THE INVENTION
The present invention has been made to solve the above problems associated with the conventional plasma display panel.
It is therefore an object of the present invention to provide a plasma display panel which is capable of effectively preventing interference between discharge in adjoining discharge cells to display a stable image.
To attain the above object, a plasma display panel according to a first invention includes a plurality of row electrode pairs extending in a row direction and arranged in a column direction to respectively form display lines and a dielectric layer overlaying the row electrode pairs on a backside of a front substrate, and a plurality of column electrodes extending in the column direction and arranged in the row direction on a back substrate facing the front substrate via a discharge space, and unit light emitting areas formed to be partitioned by a partition wall having at least vertical walls extending in the column direction in a discharge space corresponding to each intersection of the column electrode and the row electrode pair. Such plasma display panel features in that a floating electrode is provided on each portion of at least one of the front substrate and the back substrate facing the vertical wall of the partition wall partitioning the adjacent unit light emitting areas from each other in the row direction.
In the plasma display panel according to the first invention, for forming an image, when a surface discharge is caused between the transparent electrodes of the row electrode pair opposing each other in each unit light emitting area, and then the surface discharge caused around the gap between a pair of the transparent electrodes is
Arent Fox Kintner & Plotkin & Kahn, PLLC
Chen Sophia S.
Pioneer Corporation
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