Electric lamp and discharge devices – With gas or vapor – Three or more electrode discharge device
Reexamination Certificate
2000-03-28
2003-03-25
Patel, Vip (Department: 2879)
Electric lamp and discharge devices
With gas or vapor
Three or more electrode discharge device
C313S584000, C313S485000, C313S505000
Reexamination Certificate
active
06538381
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a plasma-display panel and a method for manufacturing the same, and particularly relates to a surface discharge-type plasma display panel and a method of manufacturing therefor.
2. Background Art
A plasma display panel is a display device utilizing a gas discharge luminescence in inert gases such as neon or xenon. In the conventional plasma display panel, a two counter electrode discharge-type structure has been adopted, in which the image is displayed by selective discharge between intersecting portions of counter electrodes, one of which is a series of line electrodes formed on one panel plate, and the other of which is a series of row electrodes formed on the other panel plate. A typical structure of such a conventional two electrode type plasma display panel is shown in FIG.
12
. In
FIG. 12
, a front plate
100
and a rear plates
102
using two glass plates are arranged so as to face each other. A plurality of line discharge electrodes
104
are formed on the front plate
100
, and a plurality of row discharge electrodes
108
are formed on the back plate
102
, in the direction that crosses the line discharge electrodes
104
at a right angle. A dielectric layer
106
is formed so as to cover the line discharge electrodes
104
.
On the back plate
102
, separating walls
110
are formed in the direction of the line discharge electrodes so as to partition the row discharge electrodes, and fluorescent material layers
112
are formed to cover the side surfaces of the separating walls as well as the row discharge electrodes
108
. A discharge space
114
is filled with the discharge gas such as neon. In the above-described structure, a desired image is displayed by plasma luminescence by selective discharge of the line discharge electrodes
104
or the row discharge electrodes
108
.
The above-described two-electrode-type plasma display panel has been used for monochromatic display. Recently, however, an essential requirement for the color display necessitates conversion of the ultraviolet light generated by the discharge into three visible light and formation of the three fluorescent material coatings in the discharge space. When such coatings are formed in the counter discharge-type panel, the fluorescent material films are likely to be bombarded by charged particles, so that degradation of the fluorescent materials results in short service life.
A new plasma display panel, proposed as a solution to the above-described problem, is a surface discharge-type plasma display panel, in which discharge takes place separated from the fluorescent materials, and the surface discharge-type has recently become the leading plasma display panel. In general, the surface discharge-type plasma display panel uses parallel electrode pairs comprising a scanning electrode and a sustain electrode and as well as a data electrode is disposed in the direction crossing the scanning and sustain electrodes at a right angle, so that this type of plasma display panel is called a three electrode surface discharge-type panel. The schematic structure of the three electrode surface discharge-type plasma display panel is illustrated in FIG.
13
. As illustrated, this type of plasma display panels is constituted by a front insulating glass plate
60
disposed at the front side facing a back insulating glass plate
62
disposed at the back side, leaving a discharge space
80
therebetween.
On the front plate
60
, the surface discharge electrode pairs comprising the scanning electrodes
72
a
and sustain electrodes
72
b
made of transparent films such as ITO or nesa films are formed. In addition, a trace electrode
74
made of metal is formed on the scanning and the sustain electrodes in order to reduce the resistance of those scanning and sustain electrodes. The trace electrode
74
is usually formed by a laminated thin film electrode made of Cr/Cu/Cr or the thick film electrode made of Ag.
Furthermore, these electrodes are covered by a dielectric layer
64
. The dielectric layer
64
is usually formed using a low-melting glass. A protective film made of MgO (not shown) is formed on the dielectric film
64
in order to prevent the damage due to ions or plasma generated by the discharge and to reduce the discharge voltage as well.
On the back plate
62
, the scanning electrode
72
a
and a data electrode
72
b,
made by a thick film of Ag are formed in the direction perpendicular to the sustain electrode
72
b.
Subsequently, on the data electrodes, a white dielectric film
68
is formed by printing and firing a glass paste made by mixing white oxide materials (alumina or titanium oxide) and a low-melting glass powder on the data electrode
78
. This white dielectric layer
68
is used for reflecting visible light from the fluorescent material in order to enhance the efficiency of the emission of visible light. Furthermore, on this white dielectric layer
68
, three types of fluorescent materials
70
are separately coated by thick film technology for converting the ultraviolet light due to the gas discharge into three types of visible light, R (red), G (green) and B (blue).
The front plate
60
and the back plate
62
are disposed facing each other enclosing separating walls (not shown) formed by an insulating material in matrix or stripe forms for forming discharge cells
76
, and a discharge gas, constituted by helium, neon, xenon or a mixture of these gases, is filed in the discharge space
80
. The above separating walls are formed by the thick film technology using a mixture of the low-melting glass with alumina, magnesium oxide, titanium oxide etc.
Hereinafter, the discharge operation of a selected discharge cell
76
will be described with reference to FIG.
14
. First, in the preliminary discharge period, a preliminary discharge pulse PP is applied to the scanning electrodes
72
a
over the entire display surface area for generating discharge between the scanning electrodes
72
a
and the sustain electrodes
72
b.
Subsequently, in the elimination period for eliminating wall charges generated on the scanning electrode
72
a
and the sustain electrode
72
b,
a pulse train PE
1
, PE
2
, and PE
3
is applied to the scanning electrode
72
a
and the sustain electrode
72
b,
respectively. In the writing period, a writing pulse PW is applied so as to scan all scanning electrodes
72
a
in sequence. In synchronism with the writing pulse PW, a data pulse PD in accordance with the desired display data is applied to the data electrode
78
for causing discharge between the scanning electrode and the data electrode.
Next, in the sustain period, the charge generated in the writing period is maintained as the surface discharge by applying a voltage pulse PSUS to both sustain electrodes
72
a
and
72
b
for the display. The above preliminary period and the elimination period play a role to produce reliably the discharge between the scanning electrode
72
a
and the data electrodes
78
corresponding to the display data generated in the writing period succeeding the preliminary period and the elimination period. Accordingly, the strong surface discharge over the entire surface followed by the weak discharge allows eliminating the wall charge on the electrodes forming the discharge cells as well as leaving the space charge due to the ionized particles in the discharge cells.
In the writing period, the discharge caused between the scanning electrode
72
a
and the data electrodes
78
forms the positive wall charge on the scanning electrodes
72
a
and the negative wall charge on the data electrode
78
. When these wall charges are present, since these wall charges overlap with the pulse PSUS applied to the scanning electrode
72
a
and the sustain electrode
72
b,
it becomes possible to generate and maintain the surface discharge in discharge cells corresponding to the display data because the applied voltage exceeds the surface discharge starting voltage.
As described above, the conventional AC memory-type color plasma d
Shiba Hiroshi
Ueoka Mitsuo
NEC Corporation
Patel Vip
Quarterman Kevin
Sughrue & Mion, PLLC
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