Title: Baking system for plasma display panel and layout method for said system
Abstract: A baking system for a plasma display panel which comprises a clean room 1 and a baking furnace having an upper passage 11 for conveying a plasma display panel glass substrate 5 during baking from an inlet 15 of the furnace 3, and a lower passage 13 for conveying the baked substrate 5 in the upper passage 11 towards an outlet of the furnace 3, both of the inlet and the outlet being provided at the same end of the furnace 3, characterized in that only the inlet 15 and the outlet 17 are connected to a clean room 1, while keeping a body thereof outside the clean room 1. Also, there is disclosed a layout method for such a baking system.
Patent Number: 6,998,578 Issued on 02/14/2006 to Tsuji, et al.
| Inventors:
|
Tsuji; Hiroyasu (Sennan-gun, JP);
Morita; Makoto (Nisinomiya, JP);
Suzuki; Masanori (Osaka, JP);
Noiri; Hihuo (Hashima-gun, JP);
Aoki; Michiro (Oobu, JP);
Takeda; Takahiro (Nagoya, JP)
|
| Assignee:
|
NGK Insulators, Ltd. (Nagoya, JP);
Matsushita Electric Industrial Co., Ltd. (Kadoma, JP)
|
| Appl. No.:
|
421729 |
| Filed:
|
April 24, 2003 |
Foreign Application Priority Data
| Apr 30, 2002[JP] | 2002-128082 |
| Current U.S. Class: |
219/388; 219/387; 219/389; 219/390; 219/391; 219/395 |
| Current Intern'l Class: |
F27D 11/00 (20060101) |
| Field of Search: |
219/387-391,395
|
References Cited [Referenced By]
U.S. Patent Documents
Primary Examiner: Fuqua; Shawntina
Attorney, Agent or Firm: Oliff & Berridge, PLC
Claims
What is claimed is:
1. A baking system for plasma display panel comprising a baking furnace for a
plasma display panel; said furnace having an upper passage for conveying a plural
number of plasma display panel glass substrates placed on respective setters while
baking the substrates during conveying and a lower passage for conveying thus baked
plasma display panel glass substrates during conveying in the upper passage in
a direction opposite to the conveying direction of the substrates for baking in
the upper passage, and further being provided with an inlet for introducing the
plasma display panel glass substrates into the upper passage and an outlet for
carrying out the baked plasma display panel glass substrates from the lower passage
at the same end thereof, and a clean room, characterized in that only the inlet
and the outlet are connected to the clean room, but a body of the baking furnace
is disposed outside the clean room.
2. A system according to claim 1, wherein said baking furnace is further provided
with a carry-out carry-in mechanism for conveying a setter in a direction perpendicular
to the conveying direction of a return conveyer so as to carry out a setter on
said return conveyer to the exterior of the baking furnace and carry in a new setter
onto said return conveyer from the exterior of the baking furnace.
3. A layout method for a baking system for a plasma display panel comprising
a baking furnace for a plasma display panel; said furnace having an upper passage
for conveying a plural number of plasma display panel glass substrates placed on
respective setters while baking the substrates during conveying and a lower passage
for conveying thus baked plasma display panel glass substrates during conveying
in the upper passage in a direction opposite to the conveying direction of the
substrates for baking in the upper passage, and further being provided with an
inlet for introducing the plasma display panel glass substrates into the upper
passage and an outlet for carrying out the baked plasma display panel glass substrates
from the lower passage at the same end thereof, and a clean room, characterized
in that said system is arranged so as to connect only said inlet and said outlet
with a clean room, while keeping a body of the baking furnace outside said clean room.
4. A layout method according to claim 3, wherein said baking furnace is further
provided with a carry-out carry-in mechanism for conveying a setter in a direction
perpendicular to the conveying direction of return conveyer so as to carry out
a setter on said return conveyer to the exterior of the baking furnace and carry
in a setter onto said return conveyer from the exterior of the baking furnace.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a baking system for plasma display panel and
a layout method for said system that is used for baking a glass substrate of a
plasma display panel.
2. Description of the Related Art
In recent years, progress has been made steadily to put to practical use large
screen flat panel displays (hereinafter referred to as "FPDs") that can be used
as wall-mounted televisions or multimedia displays. For such a large screen FPD,
a plasma display panel (hereinafter referred to as "PDP") has been nominated as
the most promising candidate, since it has various merits in terms of such a quality
that it is of a self-luminescence type and has a wide visual field angle and its
displaying quality is high, but also in terms of such a production aspect that
its manufacturing process is simple and an increase of size can be easily achieved.
The PDP is produced by forming various components such as electrodes, dielectric
constant, and phosphors in order on the surface of each of large-sized glass substrates
called front glass and rear glass according to a thick film forming method that
repeats processes of printing, drying, and baking a plurality of times, and by
finally sealing a pair of the resultant front glass and the resultant rear glass.
Baking of the PDP glass substrates has been performed according to a method
wherein, for preventing failure or deterioration of products due to adhesion of
foreign matter, baking furnaces
3 are housed within a clean room
1
as shown in FIG. 7, a plural number of PDP glass substrates placed on setters is
conveyed into each baking furnace
3 and, while conveying them in one direction
using conveying means such as rollers, the PDP glass substrates are subjected to
preheating, soaking, and temperature-lowering treatments according to a predetermined
temperature curve.
However, inasmuch as a very large space is required for housing the whole
body of a plural number of baking furnaces
3 within the clean room
1
as described above, initial cost and running cost of the clean room
1 become
enormous. Further, since a maintenance operation of each baking furnace
3
should be performed within the clean room
1, there has been a problem that
dust that is generated upon performing the maintenance operation is scattered in
the clean room
1 to adversely affect other installations arranged in the
clean room
1.
SUMMARY OF THE INVENTION
The present invention has been made under those circumstances and has an object
to provide a baking system for plasma display panel and a layout method for said
system that can largely reduce a space of a clean room necessary for baking PDP
glass substrates, as compared with the conventional system or conventional layout
method as described above, and that can prevent contamination of the clean room
due to dust generated upon performing the maintenance operation of the baking furnace.
According to the present-invention, there is provided a_baking system for
plasma display panel comprising a baking furnace for a plasma display panel; said
furnace having an upper passage for conveying a plural number of plasma display
panel glass substrates placed on respective setters while baking the substrates
during conveying and a lower passage for conveying thus baked plasma display panel
glass substrates during conveying in the upper passage in a direction opposite
to the conveying direction of the substrates for baking in the upper passage, and
further being provided with an inlet for introducing the plasma display panel glass
substrates into the upper passage and an outlet for carrying out the baked plasma
display panel glass substrates from the lower passage at the same end thereof,
and a clean room, characterized in that only the inlet and the outlet are connected
to the clean room, but a body of the baking furnace is disposed outside the clean
room. Further-more, there is provided with a layout method for said baking system
thus constructed.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an explanatory diagram showing a layout method for a baking furnace
for a plasma display panel according to the present invention;
FIG. 2 is an explanatory diagram showing a schematic structure of the baking
furnace that is used in the layout method of the present invention;
FIGS. 3A and 3B are explanatory diagrams showing the state of arrangement of
an exhaust hood and a shutter, wherein FIG. 3A is a plan view and FIG. 3B is a
perspective view;
FIG. 4 is an explanatory diagram schematically showing one example of a carry-out
carry-in mechanism;
FIGS. 5A and 5B are explanatory diagrams showing one example in which a side
wall portion of a thermal shield plate is formed as an open/close door, and a mounting
plate and a control panel are attached to the back side thereof, wherein FIG. 5A
shows the state where the open/close door is closed while FIG. 5B shows the state
where the open/close door is open;
FIG. 6 is an explanatory diagram showing a conventional installation state of
a control panel; and
FIG. 7 is an explanatory diagram showing a conventional layout method for a
baking furnace for a plasma display panel.
DESCRIPTION OF THE PREFERRED EMBODIMENT
FIG. 2 is an explanatory diagram showing a schematic structure of a baking furnace
3 usable for the system for baking plasma display panel glass substrates
and the layout method for said system according to the present invention. The baking
furnace
3 comprises an upper passage
11 in which PDP glass substrates
5 placed on setters
7 are baked while being conveyed therealong,
and a lower passage
13 provided with a conveyer
9 for conveying the
PDP glass substrates
5 baked in the upper passage
11 in a direction
opposite to a conveying direction during baking in the upper passage
11
for taking out from the setter.
An inlet
15 for conveying the PDP glass substrates
5 into the upper
passage
11, and an outlet
17 for taking out the baked PDP glass substrates
5 from the setters on the lower passage
13 are provided at the same
axial end of the baking furnace
3, so that the conveying-in operation and
the taking-out operation can be carried out in substantially the same place.
At front portions of the inlet
15 and the outlet
17, there are
respectively
provided a loader
19 for placing the PDP glass substrates
5 on the
setters
7 before introducing them into the baking furnace
3, and
an unloader
21 for removing the baked PDP glass substrates
5, which
are carried out from the outlet
17, from the setters
7.
In the baking process of the PDP glass substrate
5 using the thus constructed
baking furnace
3, the PDP glass substrate
5 is first placed on the
setter
7 in the loader
19 located in front of the inlet
15,
then conveyed into the upper passage
11 via the inlet
15. In general,
the upper passage
11 comprises a plurality of heating chambers
22
that are defined in the substrate conveying direction (longitudinal direction of
the baking furnace
3), and each heating chamber
22 is kept at a predetermined
temperature by heating means such as an electrical heater
25.
The PDP glass substrate
5 introduced into the upper passage
11
is, while being placed on the setter
7, continuously or intermittently conveyed
by conveying means such as rollers
27 and, while being conveyed, is subjected
to heat treatments (baking) in the order of preheating, soaking, and lowering of
temperature according to a predetermined temperature curve.
Incidentally, "intermittently conveyed" means a conveying method that
repeats an operation such that a PDP glass substrate on placed on one setter in
the upper passage is stopped and subjected to a heat treatment for a predetermined
time in an nth heating chamber from the side of an inlet of a baking furnace, then
the PDP glass substrate is moved into an (n+1)th adjacent heating chamber from
the side of the inlet as quick as possible where the PDP glass substrate is again
stopped and subjected to a heat treatment for a predetermined time.
The PDP glass substrate
5 thus baked in the upper passage
11 is
moved into the lower passage
13 at the other axial end of the baking furnace
3 remote from the inlet
15, then conveyed back in the direction opposite
to the conveying direction during baking in the upper passage
11, then taken
out together with the setter to the exterior of the baking furnace
3 from
the outlet
17 provided at the axial end of the baking furnace
3 where
the inlet
15 is also provided, and finally removed from the setter
7
in the unloader
21 located in front of the outlet
17.
As shown in FIG. 1, the layout method of the present invention is characterized
in that the baking furnace
3 having the foregoing structure is arranged
such that only the inlet
15 and the outlet
17 are connected air-tightly
to the clean room
1, while the body of the baking furnace
3 is placed
outside the clean room
1. In the baking furnace
3 having the structure
above-mentioned, it is rather easy to form the furnace body excluding the inlet
15 and the outlet
17 to have an airtight structure. Therefore, if
only the inlet
15 and the outlet
17 serving as openings leading to
the furnace exterior are connected to the clean room
1, even if the furnace
body is placed outside the clean room
1, the baking process for the PDP
glass substrates can be performed under a clean environment.
By placing the furnace body outside the clean room
1 as described above,
a space of the clean room
1 can be largely reduced and thus the initial
cost and running cost of the clean room
1 can also be largely reduced, as
compared with the conventional system and the conventional layout method for said
system in which the whole bodies of all the baking furnaces
3 are housed
within the clean room
1. Further, since the maintenance operation of the
baking furnace
3 can be performed outside the clean room
1, it is
possible to prevent contamination of the clean room
1 due to dust generated
upon performing the maintenance operation.
On the other hand, for the purpose of preventing invasion of the outside air,
an internal pressure of the clean room
1 is normally set higher than an
external pressure. According to the system for baking plasma display panel and
the layout method for said system of the present invention, inasmuch as the body
of the baking furnace
3 is located outside the clean room
1, air
flows are generated against an opening portion of the inlet
15 and an opening
portion of the outlet
17 from within the clean room
1 and, in particular,
the air flow against the opening portion of the inlet
15 adversely affects
temperature distribution of the heating chambers near the inlet
15 where
preheating is implemented.
In view of this, when applying the present invention, as shown in FIGS. 3A and
3B, it is desirable that an exhaust hood
31 is provided in the neighborhood
of the inlet
15 of the upper passage
11 for exhausting the air entering
from the clean room
1 to the furnace exterior, and that a shutter
33
having an opening portion
35 narrower than the opening portion of the inlet
15 is provided so as to suppress entry of the air into the baking furnace
3 by closing the inlet
15 using the shutter
33 during a time
other than required to make an opening as small as possible.
In the baking of the PDP glass substrates
5 using the baking furnace
3
having the structure above-mentioned, one circuit line is formed by the loader
19 for placing the substrates
5 on the setters
7, the upper
passage
11 for baking the substrates
5, the lower passage
13
for conveying back the baked substrates
5, and the unloader
21 for
removing the substrates
5 from the setters
7. Normally, the foregoing
baking process is repeatedly performed, so that the setters
7 are continuously
moved on such a circuit line.
Then, when such a setter that can not achieve a normal conveyed state due to
deterioration such as warp or deformation thereof is found among the setters moving
on the circuit line, it is necessary to take out that setter to the exterior of
the circuit line, and instead, introduce a new setter on the circuit line.
In general, the setters
7 are assigned individual ID numbers, respectively,
and detection means for detecting the ID numbers is disposed at a specific place
within the circuit line. Conventionally, an ID number of a deteriorated setter
7 is detected and registered by the detection means and, when the setter
7 assigned that ID number moves on the circuit line to reach the inlet
15,
that setter
7 is removed from the circuit line at the inlet
15 and
a substitute setter is introduced on the circuit line.
However, since abrasion powder caused by friction between itself and the
conveying means is adhered to the setter
7 that is removed from the circuit
line, if removal of the deteriorated setter
7 is performed at the inlet
15, the degree of cleanness in the neighborhood of the inlet
15 is
lowered so that the abrasion powder adheres to the PDP glass substrates
5.
Further, since there are provided material handling devices such as the loader
19, the unloader
21, and so on near the inlet
15, there is
substantially no degree of freedom for a space for arranging an apparatus that
removes and introduces the setters
7.
Therefore, for solving such inconveniences, it is desirable that the PDP
baking furnace used in the layout method of the present invention is provided with
a carry-out carry-in mechanism for conveying a setter in a direction perpendicular
to the conveying direction of the return conveyer so as to carry out a setter on
the return conveyer to an exterior space of the furnace within the clean room and
carry in a setter onto the return conveyer from an exterior space of the furnace
within the clean room.
FIG. 4 is an explanatory diagram schematically showing one example of such a
carry-out carry-in mechanism. The carry-out carry-in mechanism of this example
comprises a first conveyer
41 and a second conveyer
43 each of which
can convey a setter in a direction perpendicular to the conveying direction of
the return conveyer
9. The first conveyer
41 is provided with detection
means (not shown) for detecting the ID numbers allocated to the setters
7.
The first conveyer
41 is disposed overlapping part of the return conveyer
9, while the second conveyer
43 is disposed adjacently to the first
conveyer
41 on the side of the return conveyer
9.
The deteriorated setter
7 is first detected by virtue of the ID number
allocated thereto by the detection means of the first conveyer
41 or another
detection means provided in another position on the circuit line, and thus detected
ID Number is registered as an ID number of a setter to be removed from the circuit
line. Then, when the setter
7 allocated this registered ID number moves
on the circuit line to reach the loader
19, the loader
19 conveys
the setter
7 in question into the upper passage
11 as it is, i.e.
without placing a PDP glass substrate
5 thereon.
The setter
7 in question which has passed the upper passage
11
and moved onto the return conveyer
9 in the lower passage
13, is
detected by virtue of thus registered ID number by the detection means of the first
conveyer
41. After confirmation of agreement of the detected ID number with
said registered ID number, the setter
7 in question is conveyed by the first
conveyer
41 in the direction perpendicular to the conveying direction of
the return conveyer
9 and delivered onto the adjacent second conveyer
43
so as to be removed from the circuit line.
On the other hand, those setters whose ID numbers detected by the detection means
of the first conveyer
41 do not agree with the foregoing registered ID number
are conveyed toward the outlet
17 as they are by the return conveyer
9.
A new setter substituting for the setter removed from the circuit line is conveyed
by the second conveyer
43 in a direction opposite to the direction upon
removal, and introduced onto the circuit line at a position at which the return
conveyer
9 overlaps with the first conveyer
41.
A PDP glass substrate can be effectively protected from re-adhesion of abrasion
powder adhered onto the setter, and the layout of the installation of the system
can be effectively attained. This is because the removal of a deteriorated setter
and introduction of a substitute setter can be done at a position outside the clean
room by providing such a carry-out carry-in mechanism.
On the other hand, a control panel
63 comprising a fixed type mounting
plate
61 and various electrical control units having been mounted on the
surface of the mounting plate
61 are often installed on the side of the
return conveyer
9 in the lower passage
13 for the further reduction
in the installation space as shown in FIG. 6, in the case of the conventionally
used PDP baking furnace. However, the mounting plate
61 with the control
panel
63 becomes a hindrance for the maintenance operation when the maintenance
operation of the return conveyer
9 is required within the lower passage
13 due to the occurrence of failure in the return conveyer
9.
Therefore, in the PDP baking furnace used in the baking system and the
layout method thereof according to the present invention, it is desirable that
an open/close hinged door
55 is provided at a side wall portion of a thermal
shield plate covering the whole furnace, and a mounting plate
51 and a control
panel
53 like the mounting plate
61 and the control panel
63
are attached to the back side of the open/close door
55 as shown in FIG.
5A. With this structure, in the state where the open/close door
51 is open
as shown in FIG. 5B, a maintenance operation of the return conveyer
9 can
be easily done within the lower passage
13 without being hindered by the
control panel
53. Further, since the control panel
53 is pulled out
to the exterior of the lower passage
13, a maintenance operation of the
electrical control units mounted on the control panel
53 can also be easily done.
As described above, according to the present invention, a space of the clean
room
necessary for baking the PDP glass substrates can be greatly reduced as compared
with the conventional one and, as a result, the initial and running cost of the
clean room can also be largely reduced. Further, since the maintenance operation
of the furnace can be done outside the clean room, it is possible to prevent contamination
of the clean room due to dust that is generated upon performing the maintenance operation.
*
