Electric lamp and discharge devices – With gas or vapor – Three or more electrode discharge device
Reexamination Certificate
2000-07-20
2003-02-04
Patel, Vip (Department: 2879)
Electric lamp and discharge devices
With gas or vapor
Three or more electrode discharge device
C313S584000, C313S583000
Reexamination Certificate
active
06515419
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a plasma display panel.
2. Discussion of the Related Art
Generally, a plasma display panel and a liquid crystal display (LCD) have lately attracted considerable attention as the most practical next generation display of flat panel displays. In particular, the plasma display panel has higher luminance and a wider viewing angle than the LCD. For this reason, the plasma display panel is widely used as a thin type large display such as an outdoor advertising tower, a wall TV and a theater display.
A related art plasma display panel of three-electrode area discharge type will be described with reference to the accompanying drawings.
As shown in
FIG. 1
a
, the related art plasma display panel of three-electrode area discharge type includes an upper substrate
10
and a lower substrate
20
which face each other. In
FIG. 1
b
, the lower substrate
20
is rotated by 90°.
The upper substrate
10
includes a plurality of scan electrodes
16
and
16
′, a plurality of sustain electrodes
17
and
17
′, a dielectric layer
11
, and a passivation film
12
. The scan electrodes
16
and
16
′ are formed at certain intervals in parallel to the sustain electrodes
17
and
17
′. The dielectric layer
11
is deposited on the scan electrodes
16
and
16
′ and the sustain electrodes
17
and
17
′.
The lower substrate
20
includes a plurality of address electrodes
22
, a dielectric film
21
formed on an entire surface of the substrate including the address electrodes
22
, a plurality of barriers
23
formed on the dielectric film
21
between the respective address electrodes, and a phosphor
24
formed on surfaces of the barriers
23
in each discharge cell and of the dielectric film
21
.
Inert gases such as He and Xe are mixed in a space between the upper substrate
10
and the lower substrate
20
at a pressure of 400 to 500 Torr. The space forms a discharge area.
The scan electrodes
16
and
16
′ and the sustain electrodes
17
and
17
′ are of transparent electrodes and bus electrodes of metals so as to increase optical transmitivity of each discharge cell, as shown in
FIGS. 2
a
and
2
b
. That is to say, the electrodes
16
and
17
are of transparent electrodes while the electrodes
16
′ and
17
′ are of bus electrodes.
FIG. 2
a
is a plane view of the sustain electrodes
17
and
17
′ and the scan electrodes
16
and
16
′, and
FIG. 2
b
is a sectional view of the sustain electrodes
17
and
17
′ and the scan electrodes
6
and
16
′.
A discharge voltage from an externally provided driving integrated circuit (IC) is applied to the bus electrodes
16
′ and
17
′. The discharge voltage applied to the bus electrodes
16
′ and
17
′ is applied to the transparent electrodes
16
and
17
to generate discharge between the adjacent transparent electrodes
16
and
17
. The transparent electrodes
16
and
17
have an overall width of about 300 &mgr;m and are made of indium oxide or tin oxide. The bus electrodes
16
′ and
17
′ are formed of a three-layered thin film of Cr—Cu—Cr. At this time, the bus electrodes
16
′ and
17
′ have a line width of ⅓ of a line width of the transparent electrodes
16
and
17
.
The operation of the aforementioned AC type plasma display panel of three-electrode area discharge type will be described with reference to
FIGS. 3
a
to
3
d.
If a driving voltage is applied between each address electrode and each scan electrode, opposite discharge occurs between the address electrode and the scan electrode as shown in
FIG. 3
a
. The inert gas injected into the discharge cell is instantaneously excited by the opposite discharge. If the inert gas is again transited to the ground state, ions are generated. The generated ions or some electrons of quasi-excited state come into collision with a surface of the passivation film as shown in
FIG. 3
b
. The collision of the electrons secondarily discharges electrons from the surface of the passivation film. The secondarily discharged electrons come into collision with a plasma gas to diffuse the discharge. If the opposite discharge between the address electrode and the scan electrode ends, wall charges having opposite polarities occur on the surface of the passivation film on the respective address electrode and the scan electrode, as shown in
FIG. 3
c.
If the discharge voltages having opposite polarities are continuously applied to the scan electrode and the sustain electrode and at the same time the driving voltage applied to the address electrode is cut off, area discharge occurs in a discharge area on the surfaces of the dielectric layer and the passivation film due to potential difference between the scan electrode and the sustain electrode as shown in
FIG. 3
d
. The electrons in the discharge cell come into collision with the inert gas in the discharge cell due to the opposite discharge and the area discharge. As a result, the inert gas in the discharge cell is excited and ultraviolet rays having a wavelength of 147nm occur in the discharge cell. The ultraviolet rays come into collision with the phosphors surrounding the address electrode and the barrier so that the phosphors are excited. The excited phosphors generate visible light rays, and the visible light rays display an image on a screen. That is, the plasma display panel is operated.
At this time, luminance of the plasma display panel is proportional to discharge current between the scan electrode and the sustain electrode. Accordingly, if the discharge current is great, the screen of the plasma display panel becomes bright. Also, the wider the distance between the scan electrode and the sustain electrode is, the higher luminance of the plasma display panel is. This is because that the discharge distance between the electrodes increases so that ultraviolet rays in a positive column region are generated.
A white colored screen displayed by the plasma display panel is determined by luminance ratio of a red discharge cell, a green discharge cell and a blue discharge cell. At this time, picture quality of the white colored screen becomes clearer if a color temperature is high.
A luminance ratio of phosphors formed in discharge cells of the related art plasma display panel has a value of 2:3:1 in the order of red, green and blue.
Accordingly, if all the discharge cells are discharged to display white color, pure white color is not clear and a color temperature is about 5000°.
However, the plasma display panel has lower luminance than that of a discharge tube such as a fluorescent lamp and a neon lamp, it is not sufficient for a next generation display device to substitute a CRT. This is because that the discharge cell formed in the plasma display panel has a short distance between the discharge electrodes as compared with a discharge tube such as a neon lamp and a fluorescent lamp, thereby resulting in that ultraviolet rays in a positive column region having good light-emitting efficiency are not utilized.
Furthermore, the related art plasma display panel has a problem that picture quality of a white colored screen is poor because the luminance ratio of the discharge cell having a red phosphor, the discharge cell having a blue phosphor and the discharge cell having a green phosphor is different. That is, since light-emitting luminance of the green phosphor is higher than that of the red phosphor and light-emitting luminance of the blue phosphor is lower than that of the red phosphor, purity of white color is lowered.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to a plasma display panel that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide a plasma display panel having higher light-emitting luminance and efficiency.
Another object of the present invention is to provide a plasma display panel in whic
Jeon Chung Huan
Lee Eun Cheol
Fleshner & Kim LLP
LG Electronics Inc.
Patel Vip
Quarterman Kevin
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