Electric lamp or space discharge component or device manufacturi – Process – With assembly or disassembly
Reexamination Certificate
2000-11-16
2003-03-25
Ramsey, Kenneth J. (Department: 2879)
Electric lamp or space discharge component or device manufacturi
Process
With assembly or disassembly
C445S025000, C313S292000, C313S582000, C313S495000
Reexamination Certificate
active
06537120
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of manufacturing barrier ribs of a plasma display panel, and more particularly, to a method of manufacturing barrier ribs of a plasma display panel by which the upper surface of barrier ribs can be effectively made planar during a baking process.
2. Description of the Related Art
A typical plasma display panel displays an image by using a gas discharge phenomenon and is well known as a display device capable of replacing a CRT since it has superior display features in display capacity, brightness, contrast, and a viewing angle. In the plasma display panel, a discharge is generated in a gas between electrodes by applying a DC or AC voltage applied to the electrodes and ultraviolet rays are radiated and excite a fluorescent substance so that light is emitted.
The plasma display panel can be divided into an AC type and a DC type according to a discharge mechanism. The DC type plasma display panel has a structure in which electrodes are directly exposed to a discharge gas in a sealed discharge cell. In the DC type plasma display panel, charged particles directly move between the corresponding electrodes. In the AC type plasma display panel, electrodes are embedded in a dielectric layer. Here, charged particles do not directly move between the corresponding electrodes. Instead, the discharge is performed by wall charges.
FIG. 1
shows the structure of a typical AC type plasma display panel. Referring to the drawing, a first electrode
13
a
, which is a transparent display electrode, and a second electrode
13
b
, which is an address electrode, are located between a front substrate
11
and a rear substrate
12
. The first and second electrodes
13
a
and
13
b
are formed in stripes on the inner surfaces of the front and rear substrates
11
and
12
, respectively. When the front and rear substrates
11
and
12
are coupled to each other, the first electrode
13
a
and the second electrode
13
b
perpendicularly cross each other. A first dielectric layer
14
and a protective film
15
are deposited in order on the inner surface of the front substrate
11
. A second dielectric layer
16
is formed on the rear substrate
12
and a plurality of barrier ribs
17
are formed on the upper surface of the second dielectric layer
16
. A discharge cell
19
is defined by the barrier ribs
17
and the discharge cell
19
is filled with a discharge gas. Also, phosphor
18
coats the surfaces of the barrier ribs
17
forming the discharge cell and the upper surface of the second dielectric layer
16
.
In the operation of a plasma display panel having the above structure, a high voltage, which is called a trigger voltage, is applied to the electrodes
13
a
and
13
b
in order to generate a discharge between the electrodes
13
a
and
13
b
. When the trigger voltage exceeds a threshold voltage, the discharge gas inside the discharge cell
19
turns to a plasma state due to the discharge and a stable discharge state is maintained between the electrodes
13
a
and
13
b
. In the stable discharge state, ultraviolet rays are generated to and irradiate the phosphor
18
and accordingly the phosphor
18
emits light. Consequentially, pixels of each of the discharge cells
19
can display an image.
As described above, the barrier ribs
17
provide space where the phosphor
18
is present and have a function of sectioning the discharge space. The barrier ribs
17
can be manufactured in a screen printing method, a sandblasting method, or a photolithography method.
In the screen printing method, barrier ribs are formed by repeatedly printing and drying paste which is a material for the barrier ribs in a screen print process on a rear substrate formed of glass material. Then, the barrier ribs are completed by a baking process.
In the sandblast method which is widely used, material for the barrier ribs is applied to the glass rear substrate in a predetermined thickness, and dried. Then, after a protective film having the shape of desired barrier ribs is formed thereon, or after a mask for sand blasting is inserted, sand is injected at a high pressure so that unnecessary portions are removed, thus forming the barrier ribs. The barrier ribs are completed by a baking process.
FIGS. 2A through 2F
show steps of manufacturing the barrier ribs of the plasma display panel according to the sand blasting. Referring to the drawings, paste
30
, which is material for the barrier ribs, uniformly coats a glass substrate
20
(FIG.
2
A). The paste
30
is covered with photoresist
40
exhibiting great resistance with respect to the sandblast (FIG.
2
B). When the photoresist
40
is exposed to ultraviolet light using a photo mask
45
(FIG.
2
C), portions exposed to the ultraviolet light become chemically stable. By developing the exposed photoresist, resist
50
having the same pattern as the barrier ribs is formed (FIG.
2
D). Next, when abrasive grains are injected at a high pressure, the material for the barrier ribs where the resist
50
is not attached is removed (FIG.
2
E). Finally, after the remaining resist
50
is detached, the material for the barrier ribs is baked and a barrier rib
37
is completed (FIG.
2
F).
In the photolithography method, photosensitive glass paste, which will be barrier ribs is uniformly printed on a glass substrate and the printed paste is exposed and patterned to form the barrier ribs. Then, the barrier ribs, are completed by a baking process.
The barrier ribs formed by these methods should have flat upper surfaces and the heights of the barrier ribs should be uniform throughout the entire barrier ribs. If the upper surfaces of the barrier ribs are not planar or the heights thereof are not uniform, when the front substrate and the rear substrate are coupled to each other forming a seal, gaps may be generated between the upper surfaces of the barrier ribs and the lower surface of the front substrate. Thus, cross talk is generated between discharge cells formed by the barrier ribs, so that brightness and contrast of a plasma display panel are deteriorated.
As a method for making the barrier ribs plane, a method for baking barrier ribs and polishing them has been used. However, according to this method, the barrier ribs may be damaged during a polishing process. To solve the above problem, U.S. Pat. Nos. 5,526,151 and 5,810,634 disclose methods of filling spaces between the barrier ribs and removing the reinforcing material after a polishing process, which makes the process complicated. Thus, a method of manufacturing the barrier ribs while securing the planar upper surfaces in a simplified process, is needed.
SUMMARY OF THE INVENTION
To solve the above problems, it is an object of the present invention to provide a method of manufacturing the barrier ribs of a plasma display panel by which the upper surfaces of the barrier ribs are made planar.
Accordingly, to achieve the above object, there is provided a method of manufacturing barrier ribs of a plasma display panel which comprises the steps of a) forming barrier ribs having predetermined thicknesses on a substrate where electrodes are formed, b) heating the barrier ribs to a maximum baking temperature to bake the barrier ribs, c) cooling the barrier ribs to an intermediate temperature lower than the maximum baking temperature, d) pressing upper portions of the barrier ribs by using a planarization roller at the intermediate temperature so as to make upper surfaces of the barrier ribs plane, and e) cooling the barrier ribs to a room temperature.
It is preferred in the present invention that, in the step (d), the barrier ribs are moved in a lengthwise direction of the barrier ribs to perform planarization, and that, when material for the barrier ribs includes aluminum oxide by 60through 70%, an appropriate temperature for planarization is in a range of 500 through 600° C., which is about 20 through 30° C. lower than the maximum baking temperature of the barrier ribs.
To achieve the above object, there is provided a method of manufactu
Leydig , Voit & Mayer, Ltd.
Ramsey Kenneth J.
Samsung SDI & Co., Ltd.
Santiago Mariceli
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