Electric lamp and discharge devices – With gas or vapor – Three or more electrode discharge device
Reexamination Certificate
2001-01-26
2003-01-28
Patel, Vip (Department: 2879)
Electric lamp and discharge devices
With gas or vapor
Three or more electrode discharge device
Reexamination Certificate
active
06512330
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 plasma display panel of a surface discharge scheme AC type as an oversized and slim display for color screen has been received attention, which is becoming widely available.
FIG. 7
is a schematically plane view of a conventional plasma display panel of a surface discharge scheme AC type.
FIG. 8
is a sectional view taken along the V
3
—V
3
line of FIG.
7
.
FIG. 9
is a sectional view taken along the W
4
—W
4
line of FIG.
7
.
FIG. 10
is a sectional view taken along the W
5
—W
5
line of FIG.
7
.
In
FIG. 7
to
FIG. 10
, 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 of which is formed of a transparent conductive film made of ITO (Indium Tin Oxide) or the like, and narrower bus electrodes Xb′ and Yb′ each of which is 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′ in between, and alternate in the column direction to form display lines (row) L on a matrix display screen.
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 DI 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
comprised of a red phosphor layer
6
(R), green phosphor layer
6
(G) and blue phosphor layer
6
(B) which individually overlay 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 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. 8 and 9
, on the :backside of the dielectric layer
2
and at a portion opposing to the back-to-back bus electrodes Xb′ and Yb′ extending in parallel to each other, 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
toward the inside of the discharge space S′. The additional dielectric layer
2
A has a function of suppressing the spread of a surface discharge d, caused between the opposite transparent electrodes Xa′ and Ya′, toward the respective bus electrodes Xb′ and Yb′ in the discharge space S′, in order 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 address 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′) inunison. 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 adjoined to each other sandwiching the lighted cell. The surface discharge generates ultraviolet radiation, to excite the red phosphor layer
6
(R) and/or the green phosphor layer
6
(G) and/or the blue phosphor layer
6
(B), formed in the discharge space S′, for light emission, resulting in forming the display image.
As explained above, the conventional plasma display panel (PDP) is configured such that the additional dielectric layer,
2
A which is formed at a position opposing to the bus electrodes Xb′ and Yb′ to extend in the row direction, limit's the spread of the discharge in the column direction to present interference between the discharges caused in the discharge cells C′ adjacent to each other in the column direction.
However, as shown in
FIG. 10
, 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. 7
, the surface discharge d in one discharge cell may spread via the clearance r′ to 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 across 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 with a discharge space in between; 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 a first additional dielectric layer protruding from a backside of the dielectric layer toward the inside of the discharge space and extending along an edge of the unit; light emitting area extending parallel to the row direction; and a second additional dielectric layer formed to protrude from a portion of the backside of the dielectric layer opposing the vertical wall of the partition wall toward the inside of the discharge space, and extend in the column direction to shield the adjacent unit light e
Ebe Masaomi
Nakajima Yoshihiro
Arent Fox Kintner Plotkin and Kahn
Patel Vip
Pioneer Corporation
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