Electric lamp and discharge devices – With gas or vapor – Three or more electrode discharge device
Reexamination Certificate
2001-02-02
2003-03-18
Ngo, Hoang (Department: 2852)
Electric lamp and discharge devices
With gas or vapor
Three or more electrode discharge device
C313S582000, C313S584000
Reexamination Certificate
active
06534914
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 oversize and slim display for color screen has been received attention, which is becoming widely available.
FIG. 8
is a schematically front view illustrating a conventional surface discharge scheme AC type plasma display panel.
FIG. 9
is a sectional view taken along the V
3
—V
3
line of FIG.
8
.
FIG. 10
is a sectional view taken along the W
3
—W
3
line of FIG.
8
.
FIG. 11
is a sectional view taken along the W
4
—W
4
line of FIG.
8
.
In
FIGS. 8
to
11
, 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 electrode X′ consists of a T-shaped transparent electrode Xa′ which is composed of a widened distal end Xa
1
′ formed of a transparent conductive film made of ITO or the like and a narrowed linking portion Xa
2
′, and a bus electrode Xb′ formed of a metal film, extending in the row direction and connected to the linking portions Xa
2
′ of the transparent electrode Xa′.
The row electrode Y′, similarly, consists of a T-shaped transparent electrode Ya′ which is composed of a widened distal end Ya
1
′ formed of a transparent conductive film made of ITO or the like and a narrowed linking portion Ya
2
′, and a bus electrode Yb′ formed of a metal film, extending in the row direction and connected to the linking portions Ya
2
′ of the transparent electrode Ya′.
The row electrodes X′ and Y′ are alternated on the front glass substrate
1
in the column direction (in the vertical direction of FIG.
8
). Concerning the transparent electrodes Xa′ and Ya′ of the row electrode pair (X′, Y′) aligned along the respective bus electrodes Xb′ and Yb′, each of the transparent electrodes Xa′ and Ya′ extends toward the pair to the row electrode X′ or Y′. Therefore, the tops of the respective widened distal ends Xa
1
′ and Ya
1
′ oppose each other to interpose a discharge gap g′, having a predetermined width, between them.
Each row electrode pair (X′, Y′) forms a display line (row) L for matrix display.
The front glass substrate
1
faces a back glass substrate
4
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 partition walls
5
divide a discharge space S′ at each intersection of the column electrode D′ and the row electrode pair (X′, Y′) to defines discharge cells C′.
As illustrated in FIG.
9
and
FIG. 10
, in the plasma display panel, on portion of the backside of the dielectric layer
2
which faces the bus electrodes Xb′ and Yb′ oriented back to back and extending in parallel, an additional dielectric layer
2
A is formed to extend in parallel along the bus electrodes Xb′, Yb′.
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′, 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 addressing operation, in all the display lines L, the discharge sustain pulses are applied alternately to the row electrode pairs (X′, Y′) in unison, and thus, in the lighted cell, a surface discharge is caused in a space between a pair of additional dielectric layers
2
A, which are adjacent to each other with the lighted cell in between, on every application of the discharge sustain pulse. 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 discharge cells C′ adjacent to each other in the column direction.
In the above conventional PDP, however, since the additional dielectric layer
2
A is formed in such a manner that a glass paste is screen-printed on the backside of the dielectric layer
2
, and is dried and then further burned, an edge portion
2
A
a
of the additional dielectric layer
2
A is limp to form a gentle slop. Therefore, the edge portion
2
A
a
overlaps end portions Xa
2
″, Ya
2
″ of the respective linking portion Xa
2
′, Ya
2
′ of the transparent electrodes Xa′, Ya′, respectively connected to the bus electrodes Xb′, Yb′ (an area indicated with “n” in FIG.
9
).
For this reason, when an image is formed, the discharge decreases on the end portions Xa
2
″, Ya
2
″ of the linking portions Xa
2
′, Ya
2
′ of the respective transparent electrodes Xa′, Ya′, thereby to decrease the efficiency of light emission in this area.
Hence, there is a problem of the decreased efficiency of light emission in the entire discharge cell C.
The surface discharge caused in the discharge cell C in formation of an image may cross over the gently sloped edge portion
2
A
a
of the additional dielectric layer
2
A to spread out into another adjacent discharge cell C in the column direction. This may produce interference of discharge between the two adjacent discharge cells C in the column direction. In the event of the interfering discharges, lighted and unlighted discharge cells may be reversed to produce an instable and inaccurate image.
SUMMARY OF THE INVENTION
The present invention has been made to solve the disadvantages associated with the conventional plasma display panel as described above.
It is therefore an object of the present invention to provide a plasma display panel which is capable of improving the efficiency of light emission in each discharge cell, and also effectively preventing interference of discharge from occurring between the adjacent discharge cells to display stable images.
To attain the above objects, a
Amemiya Kimio
Torisaki Yasuhiro
Ngo Hoang
Pioneer Corporation
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