Electric lamp or space discharge component or device manufacturi – Process – With assembly or disassembly
Reexamination Certificate
2001-07-30
2004-07-06
Reichard, Dean A. (Department: 2831)
Electric lamp or space discharge component or device manufacturi
Process
With assembly or disassembly
Reexamination Certificate
active
06758714
ABSTRACT:
FIELD OF THE INDUSTRIAL UTILIZATION
The present invention relates to a gas discharge panel and a method for manufacturing the same.
BACKGROUND OF THE INVENTION
An AC type plasma display panel (hereinafter called the PDP) as shown in
FIG. 7
has been known as an example of gas discharge panel.
Panel configuration and operation of the conventional PDP will be described below with reference to the accompanying drawing.
FIG. 20
is a perspective sectional view schematically showing the PDP of the prior art.
In this drawing, reference numeral
4
denotes a front substrate (also called the upper panel substrate), and
8
denotes a back substrate (also called the lower panel substrate). An outer casing
10
has such a configuration that the front substrate
4
and the back substrate
8
are disposed to oppose each other with the gap between the peripheries thereof being filled with a sealing member
9
(refer to
FIG. 21
) made of glass having a low melting point thereby to form a gas discharge space which is sealed to be airtight and is filled with a rare gas (a mixture of helium and xenon gases) with a pressure from 300 to 500 Torr.
The front substrate
4
comprises a front panel glass
201
, display electrodes
1
formed in a pattern on the front panel glass
201
, a dielectric film
2
formed to cover the display electrodes
1
and an MgO protective film
3
formed on the dielectric film
2
.
The back substrate
8
comprises a back panel glass
202
, address electrodes
5
(also called the data electrode) formed in a pattern on the surface of the back panel glass
202
, a dielectric film
6
formed to cover the address electrodes, division walls
7
comprising a plurality of ribs, and RGB fluorescent substances
11
a
through
11
c
applied between the ribs. The division wall
7
is means for dividing the gas discharge space. Compartment
12
thus divided serve as light emitting regions, while the fluorescent substance
11
is coated separately in each of these light emitting regions. The ribs of the division walls
7
and the address electrodes
5
are formed in parallel with each other and the display electrodes
1
and the address electrodes
5
cross at right angles with each other.
In the casing
10
configured as described above, when voltages are applied to the address electrodes
5
and the display electrodes
1
at a proper timing, discharge occurs in the compartment
12
divided by the division walls
7
corresponding to display pixels so that ultraviolet rays are emitted and excite the RGB fluorescent substances
11
a
through
11
c
that in turn emit visible light which constitutes an image.
The front panel glass and the back panel glass are sealed to form a space delimited thereby that is filled with the discharge gas. Because pressure of the discharge gas filling the space is usually lower than the atmospheric pressure, however, the front panel glass and the back panel glass are pressed inward by the atmospheric pressure so that ridges of the division walls
7
, or top portions of the ribs, make contact with the inner surface of the front panel glass
201
, thereby keeping the clearance between the front panel glass
201
and the back panel glass
202
. As a consequence, it is not necessary to bond the ridges of the division walls
7
and the inner surface of the front panel glass
201
, which are merely brought into contact with each other.
Now a method for manufacturing the PDP of the prior art will be described below with reference to the accompanying drawings.
FIG. 21
is a partially cutaway perspective view schematically showing the same PDP of the prior art as shown in FIG.
20
.
As shown in
FIG. 21
, the front substrate
4
is made by forming the electrodes
1
on the glass substrate
201
, forming the dielectric film
2
to cover the electrodes
1
, firing the dielectric film
2
and forming the protective film (MgO)
3
thereon by EB vapor deposition.
As for the back substrate
8
, the electrodes
5
are s formed on a glass substrate
202
and is then covered the dielectric film
6
formed thereon and fired. Then after forming a layer of a material to make the division walls all over the surface by printing process, the division wall material is removed by sand blast from portions where the division wall is not to be formed thereby to form the division walls
7
in linear configuration through a firing process. Then the space between the ribs of the division walls
7
is filled with the fluorescent substance
11
by a printing process or the like, dried and fired to complete the back substrate
8
.
The front substrate
4
and the back substrate
8
completed as described above are fired after applying glass of low melting point that makes the sealing member
9
to the peripheries thereof, thereby sealing the space therebetween. After evacuating the inner space through a chip tube (also called the piping member)
13
, the space is filled with a rare gas and the tube is chipped off, thereby completing the PDP.
Operations of filling the inner space with the rare gas using the chip tube
13
and chipping off will be described in more detail below with reference to
FIGS. 21
,
22
.
As shown in
FIG. 21
, when manufacturing the PDP (container filled with the gas) of the prior art, the lower panel substrate
8
is fitted on an external position thereof with the piping member
13
that communicates with the gas discharge space in the casing
10
via a through hole
8
a
formed in the lower panel substrate
8
. Then after purging the air from the inside of the casing (the container before being filled with the gas)
10
and filling the inner space with the discharge gas, the piping member
13
is closed thereby sealing the inner space of the casing
10
.
Closing of the piping member
13
is carried out as shown in FIG.
22
(
a
) by heating and melting the closing portion
13
a
of the piping member
13
with a gas burner
14
or the like applied from the outside. After causing the piping member
13
to contract by moving the lower portion of the closing portion
13
a
which has melted away from the casing
10
as shown in FIG.
22
(
b
), the piping member
13
is cut off by melting as shown in FIG.
22
(
c
). Thus in the prior art, since the atmospheric pressure is higher than the inner pressure of the casing
10
, the closing portion
13
a
of the piping member
13
which has contracted is completely closed due to contraction of the inner wall of the piping.
The lower panel substrate
8
bears the piping member
13
, that was used when purging air from the inner space of the casing
10
and filling it with the discharge gas, remaining thereon as bonded by using the same material as the sealing member
9
.
In the PDP configuration of the prior art as described above, however, the front substrate
4
and the back substrate
8
are bonded to each other on the peripheries thereof by frit glass (sealing member
9
) used for sealing but mostly secured by the differential pressure between the atmospheric pressure acting thereon from the outside and the inner pressure which is below one atmosphere of the gas filing the space between the front substrate and the back substrate, that causes the front substrate to be pressed against the division walls thereby to maintain the configuration.
Pressure of the filling gas is generally from 300 Torr to 500 Torr, which is not significantly different from the atmospheric pressure of 760 Torr.
As a consequence, there has been such a problem that, when the PDP of the prior art is used onboard an airplane, for example, such a flight condition as the pressure in the airplane drops significantly below the normal atmospheric pressure causes the inner surface of the front substrate comes off the ridges of the division walls at the middle of the PDP, thus resulting in cross talk.
Even at the normal atmospheric pressure, there has been such a problem that, when the PDP is subject to vibration, the front substrate temporarily comes off the division walls thus resulting in cross talk leading to disturbed image.
Thus the PDP of the prior art
Aoki Masaki
Hibino Junichi
Higashino Hidetaka
Kudoh Masatoshi
Murai Ryuichi
Matsushita Electric - Industrial Co., Ltd.
Nino Adolfo
RatnerPrestia
Reichard Dean A.
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