Electric lamp and discharge devices: systems – Plural power supplies – Plural cathode and/or anode load device
Reexamination Certificate
2001-01-08
2003-12-02
Wong, Don (Department: 2821)
Electric lamp and discharge devices: systems
Plural power supplies
Plural cathode and/or anode load device
C315S169300, C313S584000
Reexamination Certificate
active
06657396
ABSTRACT:
BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT
The present invention relates to an alternating current driven type plasma display device having a characteristic feature in a dielectric material layer and a method for the production thereof.
As an image display device that can be substituted for a currently mainstream cathode ray tube (CRT), flat-screen (flat-panel) display devices are studied in various ways. Such fat-panel display devices include a liquid crystal display (LCD), an electroluminescence display (ELD) and a plasma display device (PDP). Of these, the plasma display device has advantages that it is relatively easy to form a larger screen and attain a wider viewing angle, that it has excellent durability against environmental factors such as temperatures, magnetism, vibrations, etc., and that it has a long lifetime. The plasma display device is therefore expected to be applicable not only to a home-use wall-hung television set but also to a large-sized public information terminal.
In the plasma display device, a voltage is applied to discharge cells having discharge spaces charged with a discharge gas composed of a rare gas, and a fluorescence layer in each discharge cell is excited with ultraviolet ray generated by glow discharge in the discharge gas, to give light emission. That is, each discharge cell is driven according to a principle similar to that of a fluorescent lamp, and generally, the discharge cells are put together on the order of hundreds of thousands to constitute a display screen. The plasma display device is largely classified either as a direct-current driven type (DC type) or an alternating current driven type (to be abbreviated as “AC type” hereinafter) according to methods of applying a voltage to the discharge cells. Each type has advantages and disadvantages. The AC plasma display device is suitable for attaining a higher fineness, since separation walls which work to separate the individual discharge cells within a display screen can be formed, for example, in the form of stripes. Further, it has an advantage that electrodes for discharge are less worn out and have a long lifetime since surfaces of the electrodes are covered with a dielectric material layer.
FIG. 7
shows an exploded perspective of part of a typical constitution of an AC plasma display device. This AC plasma display device comes under a so-called tri-electrode type, and glow discharge takes place mainly between a pair of sustain electrodes
12
A and
12
B. In the AC plasma display device shown in
FIG. 7
, a first panel (front panel)
10
and a second panel (rear panel)
20
are bonded to each other in their circumferential portions. Light emission from fluorescence layers
24
in the second panel
20
is viewed through the first panel
10
.
The first panel
10
comprises a transparent first substrate
11
; pairs of the sustain electrodes (first sustain electrodes
12
A and second sustain electrodes
12
B) composed of a transparent electrically conductive material and formed on the first substrate
11
in the form of stripes; bus electrodes (first bus electrodes
13
A and second bus electrodes
13
B) composed of a material having a lower electric resistivity than the sustain electrodes
12
A and
12
B and provided for decreasing the impedance of the sustain electrodes
12
A and
12
B; a dielectric material layer
14
formed on the first substrate
11
, the sustain electrodes
12
A and
12
B and the bus electrodes
13
A and
13
B; and a protective layer
115
formed on the dielectric material layer
14
. Generally, the dielectric material layer
14
is composed, for example, of a calcined product of a low-melting glass paste, and the protective layer
115
is composed of magnesium oxide (MgO).
The second panel
20
comprises a second substrate
21
; second electrodes (also called address electrodes or data electrodes)
22
formed on the second substrate
21
in the form of stripes; a dielectric substance layer
23
formed on the second substrate
21
and the second electrodes
22
; insulating separation walls
25
which are formed in regions on the dielectric substance layer
23
and between neighboring second electrodes
22
and which extend in parallel with the second electrodes
22
; and fluorescence layers
24
which are formed on, and extend from, upper surfaces of the dielectric substance layer
23
and which are also formed on side walls of the separation walls
25
. Each fluorescence layer
24
is constituted of a red fluorescence layer
24
R, a green fluorescence layer
24
G and a blue fluorescence layer
24
B, and the fluorescence layers
24
R,
24
G and
24
B of these colors are formed in a predetermined order.
FIG. 7
is an exploded perspective view, and in an actual embodiment, top portions of the separation walls
25
on the second panel side are in contact with the protective layer
115
on the first panel side. A region where a pair of the sustain electrodes
12
A and
12
B and the second electrode
22
positioned between two separation walls
25
overlap corresponds to a discharge cell. A rare gas is sealed in each space surrounded by neighboring two separation walls
25
, the fluorescence layer
24
and the protective layer
115
. The first panel
10
and the second panel
20
are bonded to each other in their circumferential portions.
The extending direction of projection image of the bus electrodes
13
A and
13
B and the extending direction of projection image of the second electrodes
22
make an angle of 90°, and a region where a pair of the sustain electrodes
12
A and
12
B and one set of the fluorescence layers
24
R,
24
G and
24
B for emitting light of three primary colors overlap corresponds to one pixel. Since glow discharge takes place between a pair of the sustain electrodes
12
A and
12
B, a plasma display device of this type is called “surface discharge type”. In each discharge cell, the fluorescence layer excited by irradiation with vacuum ultraviolet ray generated by glow discharge in the rare gas emits light of colors characteristic of kinds of fluorescence materials. Vacuum ultraviolet ray having a wavelength depending upon the kind of the sealed rare gas is generated.
FIG. 6
shows a layout of the sustain electrodes
12
A and
12
B, the bus electrodes
13
A and
13
B and the separation walls
25
in the plasma display device shown in
FIG. 7. A
region surrounded by dotted lines corresponds to one pixel. For clearly showing each component, slanting lines are added to FIG.
6
. One pixel generally has the form of a square. One pixel is divided into three sections (discharge cells) with the separation walls
25
, and light in one of three primary colors (R, G, B) is emitted from one section.
FIG. 23
shows a schematic partial end view of the first panel
10
having the above structure when the first panel
10
is cut along an arrow B—B in FIG.
6
.
FIG. 14
schematically shows a variant in which the layout of the sustain electrodes
12
A and
12
B, the bus electrodes
13
A and
13
B and the separation walls
25
in the plasma display device is varied. JP-A-9-167565 discloses this variant, which has a structure in which the sustain electrodes
12
A and
12
B extend from a pair of the bus electrodes
13
A and
13
B toward the bus electrodes
13
B and
13
A. When cut in the same direction as the direction of the arrow B—B in
FIG. 6
, the first panel
10
having the above structure gives a schematic partial end view as shown in FIG.
23
.
Generally, the discharge gas charged in the discharge space consists of a gas mixture of an inert gas such as a neon (Ne) gas, a helium (He) gas or an argon (Ar) gas with approximately 4% by volume of a xenon (Xe) gas, and the gas mixture has a total pressure of approximately 6×10
4
Pa to 7×10
4
Pa, and the xenon (Xe) gas has a partial pressure of approximately 3×10
3
Pa. Further, a pair of the sustain electrodes
12
A and
12
B has a distance of approximately 100 &mgr;m from each other.
The problem with presently commercialized AC plasma display devices is that that the brigh
Kimura Tomohiro
Mori Hiroshi
Nakada Satoshi
Oniki Kazunao
Shirozu Shinichiro
Kananen Ronald P.
Rader & Fishman & Grauer, PLLC
Sony Corporation
Vu Jimmy F.
Wong Don
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