Electric lamp or space discharge component or device manufacturi – Process – With assembly or disassembly
Reexamination Certificate
1999-12-15
2001-12-25
Ramsey, Kenneth J. (Department: 2879)
Electric lamp or space discharge component or device manufacturi
Process
With assembly or disassembly
C445S006000, C445S040000
Reexamination Certificate
active
06332821
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method and an apparatus for fabricating a plasma display device, and more particularly, to a method of evacuating a plasma display device and filling it with a discharge gas and an apparatus for evacuating a plasma display device and filling it with a discharge gas.
2. Description of the Related Art
A plasma display device is a device for displaying images using gas discharge, and is spot-lighted as a display device which can replace a cathode ray tube (CRT) because the former has various excellent display characteristics such as resolution, luminance, contrast, latent image, and a view angle. In such plasma display device, discharge occurs in a discharge gas between electrodes by a DC or AC voltage applied across the electrodes, and a phosphor layer is excited by ultraviolet emission accompanying with the discharge to emit light rays.
FIG. 1
is an exploded perspective view schematically illustrating the structure of a conventional AC type plasma display device.
Referring to
FIG. 1
, transparent first electrodes
13
a
of display electrodes and second electrodes
13
b
of address electrodes are located between a front glass substrate
11
and a rear glass substrate
12
. The first and second electrodes
13
a
and
13
b
are respectively located on the inner surfaces of the front and rear glass substrates
11
and
12
in stripe shapes, and are orthogonal with respect to each other when the substrates
11
and
12
are assembled. An dielectric layer
14
and a protective layer
15
are laminated on the inner surfaces of the front glass substrate
11
in sequence. On the other hand, at the rear glass substrate
12
, partition walls
17
are formed on the upper surface of a dielectric layer
14
′, and cells
19
are formed by the partition walls
17
. In addition, a phosphor layer
18
coats predetermined inside portions of the partition walls
17
forming the respective cells
19
. An inert gas such as argon fills the cells
19
.
The operation of the plasma display device configured as above is described as follows. First, a high voltage a so called trigger voltage is applied across the electrodes
13
a
and
13
b
to cause a discharge. When ions are accumulated in the respective dielectric layers
14
and
14
′, the discharge occurs. When the trigger voltage exceeds a threshold voltage, the discharge gas, such as argon, in the cell
19
goes into a plasma state by the discharge, and a stable discharge can be maintained between the electrodes
13
a
and
13
b
. In the stable discharge state, the rays in the ultraviolet range among rays emitted by the discharge collide with the phosphor layer
18
to emit light rays, and accordingly all pixels formed by the respective cells
19
display an image.
In assembling the plasma display device as above, after the electrodes, dielectric layers, partition walls, etc., are formed and the phosphor layer is applied, the substrates are bonded to each other. Air filled in the cells
19
of the display device right after bonding, and an air exhausting step is performed to remove the air and to fill the cells
19
with a discharge gas of argon. A vent hole is sealed after air exhaustion and filling of discharge gas.
In the conventional art, the air exhausting step is performed by connecting an exhaust pipe to a vent hole formed at a side of the substrate
12
, and the plasma display device is heated simultaneously. That is, the inside of the panel is evacuated by a conventional vacuum pump via the exhaust pipe while the display device is heated. However, since the region of each cell
19
is a micro space whose width and height are in the range from several tens to several hundred micrometers, removing almost all the air contained in the cells
19
only by the vacuum pump is very difficult. Further, since the phosphor layer
18
, partition walls
17
, the protective layer
15
with a magnesium oxide material, etc. which are exposed to the cells
19
have surfaces with very complicated structures, and in particular the protective layer
15
has a characteristic of absorbing moisture, it is not easy to remove all materials absorbed in or combined to such surfaces in the air exhausting step. If the inside of the plasma display device is not evacuated sufficiently, there remains moisture, air, etc., within the panel, and these remaining materials bring a side effect of raising the voltage required for discharge, even though discharge begins within cells subsequently filled with a discharge gas. In addition, discharge in itself is impeded, and even though discharge occurs, sufficient ultraviolet rays cannot be emitted. Accordingly, the number of ultraviolet rays colliding with the phosphor layer decreases to lower the luminance.
SUMMARY OF THE INVENTION
To solve the above problems, it is an objective of the present invention to provide an improved method for fabricating a plasma display device.
It is another objective of the present invention to provide a method of exhausting air and filling a discharge gas in a plasma display device.
It is still another objective of the present invention to provide an apparatus for exhausting air and filling a discharge gas in a plasma display device.
Accordingly, to achieve the first objective, there is provided a method for fabricating a plasma display device comprising the steps of: installing in a heating chamber a plasma display device assembly in which frit glass is coated on the peripheries of substrates; heating the heating chamber while evacuating the plasma display device assembly and the heating chamber via respective exhaust lines; bonding upper and lower substrates of the plasma display device as the frit glass of the plasma display device is melted and spread over portions of the substrates to be bonded; stopping the evacuation and heating of the heating chamber and cooling the heating chamber to a predetermined temperature; filling the heating chamber with a predetermined gas to a normal pressure when the temperature of the heating chamber reaches a predetermined temperature; and filling the discharge gas into the plasma display device when the temperature of the plasma display device reaches room temperature, and closing the plasma display device.
According to one aspect of the present invention, before the step of closing the plasma display device, the method further comprises the steps of: connecting a discharge circuit to the plasma display device, and evacuating the discharge gas after causing the discharge gas within the plasma display device to discharge for a predetermined time; repeating the filling and evacuation of every another charge of the discharge gas in the plasma display device; and filling another charge of the discharge gas into the plasma display device finally, and closing the plasma display device.
According to another aspect of the present invention, the heating chamber is heated to a temperature in the range of 400° C. to 450° C. when heated.
According to still another aspect of the present invention, the step of filling the heating chamber with the predetermined gas to a normal pressure is carried out when the temperature of the heating chamber is 350° C.
According to still another aspect of the present invention, the frit glass is coated thicker than the height of partition walls of the device, and the partition walls contact the facing substrate closely when in the heating step the frit glass is melted and therefore the thickness of the frit glass decreases.
To achieve the second objective, there is provided a method for fabricating a plasma display device comprising the steps of: installing in a heating chamber a plasma display device assembly in which frit glass is coated on the peripheries of substrates; heating the heating chamber while evacuating the plasma display device assembly and the heating chamber; repeating more than twice that every another charge of a discharge gas is filled into, to a predetermined pressure and evacuated from the plasma display device assem
Kim Moo-sung
Park Deuk-il
Rhew Choong-yop
Leydig , Voit & Mayer, Ltd.
Ramsey Kenneth J.
Samsung SDI & Co., Ltd.
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