Electric lamp and discharge devices – With gas or vapor – Three or more electrode discharge device
Reexamination Certificate
1998-11-09
2001-09-11
Patel, Nimeshkumar D. (Department: 2879)
Electric lamp and discharge devices
With gas or vapor
Three or more electrode discharge device
Reexamination Certificate
active
06288488
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a plasma display panel, in particular to a surface discharge type plasma display panel.
Recently, there has been a demand that a surface discharge type plasma display panel be put into actual use, i.e., for use as a color display device which is large in size but small in thickness.
FIG. 6
is a plane view schematically illustrating the structure of a conventional surface discharge type plasma display panel.
FIG. 7
is a cross sectional view schematically indicating the internal structure of the plasma display panel of FIG.
6
.
Referring to
FIG. 6
, the conventional plasma display panel has a plurality of row electrode pairs
2
,
2
, each arranged along a display line L of a matrix array on the panel, in a manner such that each electrode pair
2
,
2
has a discharge gap
11
formed therebetween. Further, along each display line L, there are formed several unit luminescent areas, each of which forms a picture element cells (discharge sell).
FIG. 7
is a cross sectional view taken along a line V—V in
FIG. 6
, illustrating some important portions of the conventional display panel of FIG.
6
. As shown in
FIG. 7
, formed on the inner side of a front glass substrate
1
(serving as a front display plate), are a plurality of color filter layers
41
R,
41
G,
41
B each consisting of an inorganic pigment material, a transparent overcoat
42
covering the color filter layers
41
, a plurality of row electrode pairs
2
,
2
, a dielectric layer
3
covering the row electrode pairs
2
,
2
, a protection layer
4
consisting of MgO for covering the dielectric layer
3
.
Each row electrode
2
includes a transparent electrode
2
a
consisting of a belt-like transparent conductive film of ITO having a relatively large width, and a metal electrode (bus electrode)
2
b
consisting of a metal film having a relatively small width. The metal electrode
2
b
is used to supplement the conductivity of the transparent electrode
2
.
On the other hand, a rear glass substrate
5
is positioned spaced apart from the front glass substrate
1
so that a discharge space
8
is formed between the two substrates. As shown in
FIG. 7
, a plurality of column electrodes
6
are provided on the inner surface of the rear glass substrate
5
in a manner such that they are all orthogonal to the row electrode pairs
2
,
2
. In fact, each intersection of the row electrode pairs
2
,
2
with a column electrode
6
forms a picture element cell. Further, a plurality of belt-like partitions
9
are provided between the column electrodes
6
, so that the discharge space
8
is divided into several sections. In addition, a plurality of fluorescent layers (
7
R,
7
G,
7
B) are disposed in the discharge space
8
to cover the column electrode
6
and the partitions
9
. Finally, after a noble gas is sealed into the discharge space
8
, a plasma display panel is thus formed.
In use of the surface discharge type plasma display panel constructed in the above prior art, at first, an addressing process is performed by selected discharges between the column electrodes
6
and the row electrodes
2
, so as to select lighting cells (in which wall charges are formed) and not-lighting cells (in which wall charges are not formed). After the addressing process, by alternatively applying discharge maintaining pulses to the row electrode pairs
2
,
2
on all the display lines L, a surface discharge will occur every time the discharge maintaining pulses are applied to the lighting cells. Then, with the effect of the surface discharge, an ultraviolet light will occur, so that the fluorescent layer
7
is excited, thereby producing a visible light.
Conventionally, in order to improve a contrast and a color fineness of a surface discharge type plasma display panel, color filter layers
41
R,
41
G,
41
B are usually provided on the inner surface of the front glass substrate
1
, as shown in FIG.
7
. However, if several color filter layers
41
R,
41
G,
41
B are disposed on the inner surface of a front glass substrate
1
, these color filters
41
are difficult to be made uniform in their thickness, because different color filter layers are usually manufactured with different requirements and have different optical characteristics. As a result, some irregularities will occur on the inner surface of the front glass substrate
1
. To eliminate such irregularities, an overcoat layer
42
is often formed to cover up these color filters
41
, but still fails to obtain a smooth and flat surface, unavoidably producing some shouldered portions of several microns. Consequently, as shown in
FIG. 7
, some undesired gaps
50
will be formed, resulting in a problem that a discharge in one cell will undesirably spread to an adjacent cell through such gap
50
, hence causing a wrong discharge.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an improved plasma display panel which involves the use of color filters for improving a contrast and a color fineness but is capable of preventing a wrong discharge and further has an enlarged display margin, so as to solve the above-mentioned problems peculiar to the above-mentioned prior art;
According to the present invention, there is provided a plasma display panel comprising: a front substrate plate providing a display surface; a plurality of row electrode pairs formed on an inner surface of the front substrate plate, each row electrode pair including a pair of elongated main body portions extending in a horizontal direction, a plurality of projection pairs, each projection pair being formed in a unit luminescent area and protruding toward each other in a vertical direction with a discharge gap formed therebetween; a dielectric layer formed on the plurality of row electrode pairs; a protection layer formed on the dielectric layer; a rear substrate plate spaced apart from the front substrate plate with a discharge space formed therebetween; a plurality of column electrodes formed on an inner surface of the rear substrate layer, said column electrodes being arranged in a direction orthogonal to the row electrode pairs; a plurality of elongated partitions disposed between the plurality of column electrodes; a fluorescent layer of various colors, covering the column electrodes and elongated partitions; a plurality of color filter layers formed on the inner surface of the front substrate layer, said color filter layers corresponding to the fluorescent layer of various colors. In particular, each projection pair is formed by a transparent conductive film and is isolated in one unit luminescent area, while each elongated main body portion is formed by a metal film and is overlapped on an edge of the transparent conductive film opposite to a discharge gap.
In one aspect of the present invention, each projection of a projection pair is formed into a T-shape element including a large-width portion and a narrow-width portion.
In another aspect of the present invention, some surface areas of the dielectric layer formed corresponding to the elongated main body portions of the row electrode pairs are projected with respect to other portions of the dielectric layer.
In one more aspect of the present invention, the protection layer is formed by a secondary electron emission material, covering most surface areas of the dielectric layer except those formed corresponding to the elongated main body portions of the row electrode pairs.
In one more aspect of the present invention, the protection layer is formed by a secondary electron emission material, covering most surface areas of the dielectric layer except those formed corresponding to the elongated partitions.
In one more aspect of the present invention, some surface areas of the dielectric layer formed corresponding to the elongated partitions are projected with respect to other portions of the dielectric layer.
The above objects and features of the present invention will become better understood from the following description with reference to the accompanying drawings.
Arent Fox Kintner & Plotkin & Kahn, PLLC
Guharay Karabi
Patel Nimeshkumar D.
Pioneer Electronic Corporation
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