Electric lamp and discharge devices – With luminescent solid or liquid material – With gaseous discharge medium
Reexamination Certificate
1999-10-27
2002-09-03
Patel, Nimeshkumar D. (Department: 2879)
Electric lamp and discharge devices
With luminescent solid or liquid material
With gaseous discharge medium
C313S581000, C313S582000, C313S584000, C313S586000
Reexamination Certificate
active
06445120
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a plasma display panel, and more particularly, to a structure of a discharge electrode and dielectric layer for a plasma display panel, which reduces discharge current.
2. Background 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 display of panel displays. In particular, the plasma display panel has higher luminance and wider visible 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.
FIG. 1
a
shows a structure of a related art plasma display panel of three-electrode area discharge type. As shown in
FIG. 1
a,
the plasma display panel of three-electrode area discharge type includes an upper substrate
10
and a lower substrate
20
which are bonded opposite to each other.
FIG. 1
b
shows a sectional structure of the plasma display panel of
FIG. 1
a,
in which the lower substrate
20
is rotated by 90°.
The upper substrate
10
includes scan electrodes
16
and
16
′, sustain electrodes
17
and
17
′, a dielectric layer
11
, and a passivation film
12
. The scan electrodes
16
and
16
′ are formed 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 an address electrode
22
, a dielectric film
21
formed on an entire surface of the substrate including the address electrode
22
, an isolation wall
23
formed on the dielectric film
21
between the address electrodes, and a phosphor
24
formed on surfaces of the isolation wall
23
in each discharge cell and 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 is used as a discharge area.
In general, a mixing gas of He—Xe is used as the inert gas filled in a discharge area of a DC plasma display panel while a mixing gas of Ne—Xe is used as the inert gas filled in a discharge area of an AC plasma display panel.
The scan electrodes
16
and
16
′ and the sustain electrodes
17
and
17
′ include discharge electrodes
16
and
17
and bus electrodes
16
′ and
17
′ of metal so as to increase optical transmitivity of each discharge cell, as shown in
FIGS. 2
a
and
2
b.
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 thereof.
A discharge voltage is applied to the bus electrodes
16
′ and
171
from an externally provided driving integrated circuit(IC). The discharge voltage is applied to the discharge electrodes
16
and
17
to generate discharge between the adjacent discharge electrodes
16
and
17
. The discharge 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 three-layered thin film of Cr—Cu—Cr. At this time, the bus electrodes
161
and
171
have a line width of ⅓ of a line width of the discharge electrodes
16
and
17
.
FIG. 3
is a wiring diagram of scan electrodes (S
m−1
, S
m
, S
m+1
, . . . , S
n−1
, S
n
, Sn
n+1
) and sustain electrodes (C
m−1
, C
m
, C
m+1
, . . . , C
n−1
, C
n
, C
+1
) arranged on the upper substrate. In
FIG. 3
, the scan electrodes are insulated from one another while the sustain electrodes are connected in parallel. Particularly, a block indicated by a dotted line in
FIG. 3
shows an active area where an image is displayed and the other blocks show inactive areas where an image is not displayed. The scan electrodes arranged in the inactive areas are generally called dummy electrodes
26
. The number of the dummy electrodes
26
are not specially limited.
The operation of the aforementioned AC plasma display panel of three-electrode area discharge type will be described with reference to
FIGS. 4
a
to
4
d.
If a driving voltage is applied between the address electrodes and the scan electrodes, opposite discharge occurs between the address electrodes and the scan electrodes as shown in
FIG. 4
a.
The inert gas implanted 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. 4
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 electrodes and the scan electrodes ends, wall charges having opposite polarities occur on the surface of the passivation film on the respective address electrodes and the scan electrodes.
If the discharge voltages having opposite polarities are continuously applied to the scan electrodes and the sustain electrodes and at the same time the driving voltage applied to the address electrodes 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 electrodes and the sustain electrodes as shown in
FIG. 4
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 147 nm occur in the discharge cell. The ultraviolet rays come into collision with the phosphors surrounding the address electrodes and the isolation wall so that the phosphors are excited. The excited phosphors generate visible light rays, and the visible light rays display an image on a screen.
One pixel includes a discharge cell having a red phosphor, a discharge cell having a green phosphor, and a discharge cell having a blue phosphor. The plasma display panel displays contrast of an image by controlling the number of discharges in each discharge cell.
The related art plasma display panel has several problems.
Since the distance between the discharge areas is short as compared with a general discharge tube display, ultraviolet rays in a positive column area having good emitting efficiency are not generated. In other words, as shown in
FIG. 9
, since discharge current (
2
) generated in a discharge electrode spaced apart from a field convergence area is remarkably lower than discharge current (
1
) generated in a discharge electrode of the field convergence area, in the related art plasma display panel, discharge time is short. As a result, ultraviolet rays are generated in a negative glow area but are not generated in the positive column area. This reduces emitting efficiency and picture quality as compared with the general discharge tube.
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 in which a structure of a discharge electrode and dielectric layer is provided to generate ultraviolet rays in a positive column area.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the a
Kim Jae Sung
Tamura Masahiko
Fleshner & Kim LLP
Patel Nimeshkumar D.
Roy Sikha
LandOfFree
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