Electric lamp or space discharge component or device manufacturi – Process – With assembly or disassembly
Reexamination Certificate
1999-02-09
2001-04-24
Ramsey, Kenneth J. (Department: 2879)
Electric lamp or space discharge component or device manufacturi
Process
With assembly or disassembly
Reexamination Certificate
active
06220913
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an automatic support pillar transfer mechanism that arranges pressure-resistant support pillars within an envelope used for a display device which contains field emission cathodes acting as electron sources and to a support pillar transferring method.
In flat display devices such as field emission displays (FEDs) where field emission cathodes are used as electron sources, an envelope formed of thin glass plates is maintained in a high-evacuated state. In order to sufficiently withstand the external pressure, supports called as support pillars are needed between an anode substrate on which display sections are formed with fine pitches and a cathode substrate on which cathode electrodes are formed. In order to support the substrates without disturbing the display, glass fibers, for example, short fibers of an outer diameter of several tens &mgr;m are used as the support pillar.
Glass fibers with a smooth cut cross section and a uniform length must be used as support pillars to be erected within an envelope for the field emission display. A conventional process of fabricating support pillars satisfying the above-mentioned requirements will be explained below by referring to FIGS.
3
(
a
) to
3
(
g
).
Plural glass fibers
51
are arranged on the flat glass substrate
52
. In concrete, a continuous glass fiber is cut into glass fiber pieces with a predetermined length. The plural cut glass fibers
51
are closely arranged in parallel on the glass substrate
52
(refer to FIG.
3
(
a
)). In this case, the glass fibers
51
are damped with an organic solvent to prevent static electricity.
A bonding agent is applied on the glass fibers
51
. Thus, the glass fibers
51
are temporarily fixed on the glass substrate
52
. With the bonding agent solidified on the glass fibers
51
, the glass fibers
51
are cut at constant intervals using, for example, a cutter with a diamond blade (FIG.
3
(
b
)). Thereafter, the bonding agent coated on the glass fibers
51
is dissolved to remove the cut glass fibers
51
from the glass substrate
52
. Thus, a plurality of support pillars
15
of a predetermined length are fabricated (FIG.
3
(
c
)).
The support pillars
15
thus fabricated are arranged using the special jig
53
shown in FIG.
3
(
d
). The jig
53
consists of a positioning plate
54
, a cushioning material
55
, a porous material
56
and a suction apparatus
57
. The positioning plate
54
has through holes
54
a
corresponding to the arranging positions of the support pillars
15
to be inserted into the substrate. The cushioning material
55
is closely placed on the lower portion of the positioning plate
54
and is formed of a resilient Teflon sheet. The porous material
56
is closely placed on the lower surface of the cushioning material
55
and is formed of a metal such as a stainless steel plate with enormous porosities (e.g. of a diameter of 100 to 300 &mgr;m). The suction apparatus
57
sucks and holds the support pillars
15
inserted into the through holes
54
a
of the positioning plate
54
via both the cushioning material
55
and the porous material
56
.
In order to arrange the support pillars within an envelope, one end surfaces of the support pillars
15
are sucked using the suction apparatus
57
to insert them into the through holes
54
a.
Thus, the one end surfaces of the support pillars
15
are closely held on the surface of the cushioning material
55
by suction while plural support pillars
15
are being inserted into the through holes
54
a
in an arranged state (FIG.
3
(
d
)). Next, the bonding agent coated substrate
59
, over which a bonding agent is coated, is forcibly placed on the one end surfaces of the support pillars
15
in parallel to the positioning plate
54
, so that the bonding agent is coated on the one end surfaces of the support pillars
15
(FIG.
3
(
e
)).
The anode substrate
60
used for constructing an envelope is placed under pressure and securely fixed on the ends of the support pillars
15
thus arranged on which the bonding agent
58
are coated (FIGS.
3
(
f
) and (
g
)). Thereafter, the anode substrate
60
, on which the support pillars
15
are securely fixed, is removed from the jig
53
. Then a bonding agent is applied to the other end surfaces of the support pillars
15
and the outer fringe portion of the anode substrate
60
. An envelope is formed by securely fixing the other end surfaces of the support pillars
15
to the anode substrate and by sealing the spaces between the outer fringe of the cathode substrate and the outer fringe of the anode substrate.
Since the support pillars
15
are evenly transferred onto the entire surface of the substrate forming an envelope for a field emission display (the anode substrate
60
in FIG.
3
), it is needed to control the contact height (transfer height) between the ends of the support pillars and the substrate to a suitable value of ±10 &mgr;m.
Conventionally, as shown in
FIG. 3
, the support pillars
15
are transferred to the substrate while the condition where the substrate makes contact with the support pillar
15
at the nearest position from the side surface of the substrate is being observed under the microscope
61
. At this time, the allowable range of heights of the support pillars
15
to be transferred depends on the cushioning material
55
inserted between the positioning plate
54
and the porous material
56
. In concrete, a porous Teflon sheet of an average opening diameter of 3 &mgr;m is used to support the support pillars of a diameter of 50 &mgr;m. The resilient deformation range of 20 &mgr;m of the Teflon sheet provides a transfer allowable range.
However, the above-mentioned art has the following disadvantages.
Since the transfer height of the support pillar
15
is visually controlled under the microscope
61
, it is difficult to realize an automatic support transfer operation. In some cases, some support pillars
15
may be transferred to the substrate so that a production failure may occur. It is difficult that the image recognition management using a CCD (Charge Coupled Device) or a computer, evolved from the above-mentioned method, provides a sufficient accuracy and leads to reduced production costs.
Moreover, plural jigs
53
are required for mass-production of display panels. However, because it is difficult to uniformly orient the respective upper surfaces of jigs
53
, a variation of about 40 &mgr;m is assumed in consideration of the machining accuracy. The gradient of the plane orientation of the substrate is within a tolerance of about 20 &mgr;m. The transfer height is out of the allowable range by considering other mechanical accuracy so that a transfer failure may occur. Even when a single jig is used, the above-mentioned error factors limit the transfer range of the support pillar
15
to at most about 12 cm in diagonal line of a screen.
SUMMARY OF THE INVENTION
The present invention is made to solve the above-mentioned problems. The objective of the present invention is to provide an automatic support pillar transfer mechanism that realizes mass-production, enlarged transfer ranges and reduced product failure.
Another objective of the present invention is to provide an automatic support pillar transferring method that realizes mass-production, enlarged transfer ranges and reduced product failure.
The objective of the present invention is achieved by an automatic support pillar transfer mechanism comprising a jig for sucking and holding plural support pillars at predetermined intervals; measuring means for measuring a variation in plane orientation of a surface of the jig and a variation in plane orientation of a surface of a substrate onto which the support pillar is transferred; jig adjusting section for positioning and holding the jig and for adjusting the parallelism of the plane orientation of the jig surface based on measurement results from the measuring means; a moving section for vertically moving a substrate on which a bonding agent is applied or a substrate
Itakura Masayuki
Makita Yoshio
Ozawa Katsunosuke
Takashima Nobuhiko
Yamaura Tatsuo
Futaba Denshi Kogyo Kabushiki Kaisha
Hopper Todd Redd
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Ramsey Kenneth J.
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