Compositions: coating or plastic – Coating or plastic compositions – O-containing organic compound
Reexamination Certificate
2000-05-15
2002-02-05
Brunsman, David (Department: 1755)
Compositions: coating or plastic
Coating or plastic compositions
O-containing organic compound
C106S316000
Reexamination Certificate
active
06344080
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a plasma display panel, and more particularly, to protection film composition for a plasma display panel.
2. Background of the Related Art
Having all the advantages of the clear picture and the variety of screen sizes of cathode ray tubes, and the light and thin liquid display panel, the plasma display panel is considered as the next generation display. In general, the plasma display panel has a weight approx. ⅓ of the cathode ray tube of the same screen size, and a thickness below 10 cm even for a large sized panel of 40 to 60″. Moreover, though the cathode ray tube and the liquid crystal display have problems coming from a limitation on a size in displaying a digital data picture and a full motion on the same time, the plasma display panel has no such problems. And, while the cathode ray tube is influenced from a magnetic force, the plasma display panel is not influenced from the magnetic force, permitting to provide a stable picture to the watchers. And, since the pixels are controlled in a digital fashion, with no distortion of images at corners of the screen, the plasma display panel can provide a picture quality better than the cathode ray tube. The plasma display panel is provided with two glass substrates having electrodes coated thereon perpendicular, and opposite to each other. There are pixels at portions the electrodes are crossed. The operation of the plasma display panel is almost identical to the operation principle ofa domestic fluorescent lamp.
Referring to
FIG. 1A
, a related art triode surface discharge type plasma display panel has an upper substrate
10
and a lower substrate
20
bonded together to face each other.
FIG. 1B
illustrates a section of the plasma display panel shown in
FIG. 1A
, wherein a surface of the lower substrate
20
is rotated by 90° for convenience of explanation. The upper substrate
10
has scan electrodes
16
and
16
′ and sustain electrodes
17
and
17
′ formed parallel to each other, a dielectric layer
11
coated on the scan electrodes
16
and
16
′ and the sustain electrodes
17
and
17
′, and a protection film
12
. The lower substrate
20
has address electrodes
22
, a dielectric film
21
on an entire surface of the substrate including the address electrodes
22
, partition walls on the dielectric film
21
between the address electrodes
22
, and a fluorescent material coating
24
on surfaces of the partition wall
23
and the dielectric film
21
in each discharge cell. A space between the upper and lower substrates
10
and
20
is filled with a mixture of inert gas, such as helium He and xenon Xe, to a pressure in a range of 400~500 Torr, to form a discharge space. In general, the inert gas filled in the discharge space of a D.C. plasma display panel is a mixture of helium and xenon (He—Xe), and the inert gas filled in the discharge space of an A.C. plasma display panel is a mixture of neon and xenon (Ne—Xe).
Referring to
FIG. 2A and 2B
, the scan electrodes
16
and
16
′ and the sustain electrodes
17
and
17
′ are provided with transparent electrodes
16
and
17
and bus electrodes
16
′ and
17
′ of a metal for enhancing light transmission of each discharge cell.
FIG. 2A
illustrates a plan view of the sustain electrode
17
and
17
′ and the scan electrode
16
and
16
′, and
FIG. 2B
illustrates a section of the sustain electrode
17
and
17
′ and the scan electrode
16
and
16
′. The bus electrodes
16
′ and
17
′ are provided with a discharge voltage from a driving IC fitted outside of the panel, and the transparent electrodes
16
and
17
are provided with the discharge voltage to the bus electrodes
16
′ and
17
′, to cause a discharge between adjacent transparent electrodes
16
and
17
. The transparent electrode
16
and
17
has a total width of approx. 300 &mgr;m of indium oxide or tin oxide, and the bus electrode
16
′ and
17
′ is a thin film having three layers of chrome-copper-chrome. A width of the bus electrode
16
′ and
17
′ line has approx. ⅓ of a width of the transparent electrode
16
and
17
line.
FIG. 3
illustrates wiring of the scan electrodes Sm−1, Sm, Sm+1, - - - , Sn−1, Sn, Sn+1 and the sustain electrodes Cm−1, Cm, Cm+1, - - - , Cn−1, Cn, Cn+1 arranged on the upper substrate, wherein, while the scan electrodes are discontinuous between each other, all the sustain electrodes are connected in parallel. In
FIG. 3
, the section enclosed by the dashed line represents an effective surface a picture is displayed thereon, and the other section represents a non-effective surface no picture is displayed thereon. The scan electrodes on the non-effective surface are in general called dummy electrodes
26
, a number of which are not particularly limited.
The operation of the aforementioned triode surface discharge type A.C. plasma display panel will be explained with reference to FIGS.
4
A~
4
D.
Referring to
FIG. 4A
, when a driving voltage is applied between the address electrode and the scan electrode, an opposed discharge is occurred between the address electrode and the scan electrode. The opposed discharge excites the inert gas in the discharge cell momentarily, to generate ions as the inert gas transits to a ground state, again. As shown in
FIG. 4B
, a portion of the ions, or atoms in quasi-excited states collide onto a surface of the protection film, which causes emission of secondary electrons from the surface of the protection film. The secondary electrons collide with the gas in a plasma state, to spread the discharge. As shown in
FIG. 4C
, when the opposed discharge between the address electrode and the scan electrode ends, wall charges with opposite polarities are generated on surfaces of the protection film over the sustain electrode and the scan electrode, respectively. And, as shown in
FIG. 4D
, when the driving voltage provided to the address electrode is cut off during the wall charges with opposite polarities build up at the scan electrode and the sustain electrode continuously, there is a surface discharge occurred in a discharge region on a surface of the dielectric layer and the protection layer due to a potential difference between the scan electrode and the sustain electrode. These opposed discharge and the surface discharge cause electrons in the discharge cell to collide onto the inert gas in the discharge cell, to generate an UV ray of 147 nm wavelength in the discharge cell as the inert gas is excited. The UV ray collide onto the fluorescent material coated on the address electrode and the partition wall, to excite the fluorescent material, which generates a visible light, that permits to implement a picture on the screen.
In order to make the plasma display panel to have a high commercial preference as a wall mounting type large sized display in view of technology, the plasma display panel should have a luminance and a lifetime, not inferior to the CRT. Particularly, the AC type plasma display panel is provided with a magnesium oxide MgO thin film for preventing damage to the dielectric layer and emitting the secondary electrons that drops the discharge voltage. In general, though the magnesium oxide is deposited on the dielectric layer by PVD, the PVD has a slow rate and costs high. Other than the PVD, there are a few methods for forming the magnesium oxide thin film in the plasma display panel, such as a method disclosed in the Society of Japanese Television IDY94-14, PP1-6, wherein formation of the protection film by screen printing a paste including magnesium oxide powder is suggested. However, the magnesium oxide protection film formed by this method has problems in that application to a front panel is not possible because the protection film is not transparent, and the pin holes formed in the protection film during coating shortens a lifetime. In order to prevent the formation
Chae Hee Kwon
Kim Jeong Jun
Park Chang Woo
Woo Sung Ho
Brunsman David
Fleshner & Kim LLP
LG Electronics Inc.
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