Electric lamp and discharge devices – With gas or vapor – Three or more electrode discharge device
Reexamination Certificate
2000-07-21
2003-09-30
Patel, Vip (Department: 2879)
Electric lamp and discharge devices
With gas or vapor
Three or more electrode discharge device
C313S582000, C313S491000, C313S583000
Reexamination Certificate
active
06628075
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a plasma display panel which displays picture using gas discharge between glass substrates, and more particularly, to a structure of a discharge electrode for a plasma display panel.
2. Discussion of the Related Art
Generally, a plasma display panel has high definition of a cathode ray tube(CRT), and various sized screens, and a thin thickness such as a liquid crystal display device. In this respect, the plasma display panel has lately attracted considerable attention as the most practical next generation display of flat panel displays. Also, since the plasma display panel has a weight of ⅓ of a CRT having the same sized screen, a large sized panel of 40 inch to 60 inch can thinly be fabricated at a thickness of 10 cm or below.
The CRT and the liquid crystal display device are limited by their sizes when digital data and full motion are displayed at the same time. However, the plasma display panel does not have such a problem. Furthermore, the CRT may be affected by magnetic force but the plasma display panel is not susceptible to magnetic force, thereby providing stable image to viewers. Moreover, since each pixel of the plasma display panel is digitally controlled, image distortion of corners on a screen does not occur. Thus, the plasma display panel can provide higher picture quality than the CRT.
The plasma display panel displays picture using its internal gas discharge. Since active devices are not required for each cell, the fabrication process is simple. Also, a large sized screen and high response speed can be obtained. For these reasons, the plasma display panel is widely used as a picture display device having a large sized screen, particularly a picture display device for high definition televisions, monitors, and indoor and outdoor advertizement.
The plasma display panel includes two glass substrates coated with electrodes, and a gas sealed between the glass substrates. The electrodes formed in the glass substrates oppose each other in vertical direction, and pixels are formed in crossing portions of the electrodes. A voltage of 100V or more is applied across the electrodes to produce glow discharge within minute cells around the electrodes to emit light from each cell, thereby displaying picture information.
Such a plasma display panel is classified into three types, a two-electrode type, a three-electrode type, and a four-electrode type in accordance with the number of electrodes assigned to each cell. Of them, the two-electrode type is intended that an address voltage and a sustain voltage are applied to two electrodes. The three-electrode type is generally called an area discharge type and is intended that a discharge cell is switched or sustained by a voltage applied to an electrode disposed at a side of the discharge cell.
Such a related art plasma display panel of three-electrode area discharge type will be described with reference to the accompanying drawings.
FIG. 1
is an exploded perspective view of upper and lower substrates of a general plasma display panel, and
FIG. 2
is a sectional view of a related art plasma display panel.
As shown in
FIGS. 1 and 2
, the plasma display panel of three-electrode area discharge type includes an upper substrate
10
and a lower substrate
20
which are bonded to each other with a certain space and sealed.
The upper substrate
10
includes scan electrodes
16
and
16
′, sustain electrodes
17
and
17
′, a dielectric layer
11
, and a protection layer
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 of the dielectric film
21
. The upper substrate and the lower substrate
20
are joined together by a frit glass. 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 filled in a discharge area of a DC type plasma display panel. A mixing gas of Ne—Xe is filled in a discharge area of an AC type plasma display panel.
The scan electrodes
16
and
16
′ and the sustain electrodes
17
and
17
′ are of transparent electrodes and metals so as to increase optical transmitivity of each discharge cell, as shown in
FIGS. 3 and 4
. That is to say, the electrodes
16
and
17
are of transparent electrodes while the electrodes
16
′ and
17
′ are of metals.
A discharge voltage from an externally provided driving integrated circuit(IC) is applied to the metal scan and sustain electrodes
16
′ and
17
′. The discharge voltage applied to the metal 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 metal 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
.
FIG. 5
is a wiring diagram of scan electrodes (S
m−1
, S
m
, S
m+1
, . . . , S
n−1
, S
n
, S
n+1
) and sustain electrodes (C
m−1
, C
m
, C
m+1
, . . . , C
n−1
, C
n
, C
n+1
) arranged on the upper substrate. In
FIG. 5
, 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. 5
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 type plasma display panel of three-electrode area discharge type will be described with reference to
FIGS. 6
a
to
6
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. 6
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 protection layer as shown in
FIG. 6
b
. The collision of the electrons secondarily discharges electrons from the surface of the protection layer. 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 protection layer 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 protection layer due to potential difference between the scan electrodes and the sustain electrodes as shown in
FIG. 6
d
. The electrons in the discharge cell come into collision with the inert gas
Fleshner & Kim LLP
LG Electronics Inc.
Patel Vip
Quarterman Kevin
LandOfFree
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