Electric lamp and discharge devices – With luminescent solid or liquid material – Solid-state type
Reexamination Certificate
1999-06-17
2003-02-25
Patel, Vip (Department: 2879)
Electric lamp and discharge devices
With luminescent solid or liquid material
Solid-state type
C313S496000, C313S502000, C313S495000, C252S502000, C252S508000, C252S512000
Reexamination Certificate
active
06525468
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a fluorescent display device, and more particularly to an aluminum paste used for a fluorescent display device constructed so as to permit a phosphor to emit light due to impingement of electrons thereon, a fluorescent display device including a conductive layer using such an aluminum paste and a method for manufacturing such a fluorescent display device.
Now, a conventional fluorescent display device which has been typically known in the art will be described with reference to
FIGS. 6 and 7
.
A conventional fluorescent display device generally designated at reference numeral
1
in
FIG. 6
includes a box-like vacuum envelope
2
of which an interior is evacuated at a high vacuum and kept airtight. The vacuum envelope
2
includes an anode substrate
3
made of an insulating material, as well as a lid-like casing
6
formed of a front cover
4
made of an insulating and light-permeable material and a frame-like side plate
5
made of an insulating material.
The anode substrate
3
, as shown in
FIG. 7
, is formed on an inner surface thereof positioned in the vacuum envelope
2
with a wiring
7
in a predetermined pattern corresponding to a display pattern
8
. The wiring
7
is made of a thin aluminum film. The wiring
7
is then laminatedly formed thereon with an insulating layer
9
. The insulating layer
9
is made of an insulating glass paste and deposited in the form of a thick film by printing. The insulating glass paste may be constituted of a powder of, for example, lead silicate glass, a powder of an inorganic material such as a heat-resistant pigment or the like, and a vehicle. The insulating layer
9
is formed at a portion thereof corresponding to each of segments
10
of the display pattern
8
with a through-hole
11
, through which the wiring
7
is exposed. The through-holes
11
through which the wiring
7
is exposed each are filled with a conductive layer
12
, which is formed of a conductive paste mainly consisting of Ag by printing.
The insulating layer
9
, as shown in
FIG. 7
, is discretely formed thereon with an anode conductor
13
for every segment
10
of the display pattern
8
so that it may be electrically connected through the conductive layer
12
to the wiring
7
. The anode conductors
13
thus discretely arranged each are provided thereon with a phosphor layer
14
so as to correspond in configuration to each of the segments
10
of the display pattern
8
. The phosphor layer
14
is made of a phosphor paste consisting of a phosphor powder and a vehicle by printing. This permits an anode
15
to be provided for every segment
10
of the display pattern
8
. A grid electrode
16
is arranged above the anodes
15
and filamentary cathodes
17
are then stretchedly arranged above the grid electrode
16
.
In manufacturing of the conventional fluorescent display device
1
constructed as described above, an Ag—PbO glass paste prepared by mixing an Ag powder, a glass powder and a vehicle with each other at predetermined ratios is typically used as the paste for the conductive layer
12
for filling the through-hole
11
of the insulating layer
9
. The paste may have a composition of 80 to 97% by weight in Ag powder and 3 to 20% by weight in PbO glass frit.
Manufacturing of the fluorescent display device
1
is started by forming the anodes
15
defining the display pattern
8
divided into a predetermined shape on the anode substrate
3
. More particularly, an thin Al film is deposited on the anode substrate
15
and then subject to patterning by photolithography, so that the wiring
7
may be formed in correspondence to the display pattern
8
.
Then, the insulating layer
9
provided with the through-holes
11
is formed on the Al wiring
7
by printing and then subject to calcination at a temperature of, for example, 550 to 600° C. Then, the through-holes
11
of the insulating layer
11
each are filled with the Ag—PbO glass paste described above, resulting in the conductive layer
12
being formed therein. Subsequently, a graphite paste is printed on the conductive layer
12
, to thereby form the anode conductors
13
, which are then subject to calcination at a temperature of, for example, 550 to 600° C. Then, the phosphor layer
14
is formed on each of the anode conductors
13
by printing and then subject to calcination at a temperature of 500° C. or below.
Thereafter, the anode substrate
3
on which the anodes
15
are thus formed is coated on an outer periphery thereof with a low-melting glass paste, which is then subject to calcination at 500° C. or below. Then, a mounting paste for fixing the mesh-like grid electrode
16
on the anode substrate
3
is coated on the anode substrate
3
. Subsequently, the grid electrode
16
is arranged on the mounting paste, resulting in being fixed on the anode substrate
3
.
Separately from the above-described operation, a frame which has the filamentary cathodes
17
stretched arranged thereon is assembled. The side plate
5
of the casing
6
is positioned at a bottom peripheral surface thereof on an outer periphery of the anode substrate
3
which is coated thereon with a low-melting paste. The anode substrate
3
and casing
6
are vertically pressed against each other and then subject to calcination at 500° C. or below, so that the outer periphery of the anode substrate
3
and the casing
6
may be sealed to each other, so that the vacuum envelope
2
may be assembled. Finally, the envelope
2
thus formed is evacuated at a high vacuum and then sealed, so that the fluorescent display device
1
may be completed.
In manufacturing of the fluorescent display device
1
, as described above, the insulating layer
9
provided with the through-holes
11
is formed on the wiring
7
made of the thin Al film by printing. Formation of only one such insulating layer
9
causes pin holes to be formed in the insulating layer
9
due to intrusion of dust or the like thereinto during printing, so that the wiring
7
and anode conductor
13
are connected to each other through the pin holes, leading to deterioration in insulation. In order to avoid such a problem, printing of the insulating paste on the wiring is carried out twice, to thereby construct the insulating layer
9
into a two-layer structure, resulting in eliminating the above-described deterioration in insulation.
Now, a conventional fluorescent display device equipped with three-dimensional grids or stereogrids will be described hereinafter with reference to
FIGS. 8 and 9
by way of example, wherein
FIG. 8
generally shows the fluorescent display device and
FIG. 9
shows an electrode structure incorporated in the fluorescent display device. The stereogrid-equipped fluorescent display device generally designated at reference numeral
100
, as shown in
FIG. 8
, includes a vacuum envelope
200
of a box-like shape kept airtightly and at a high vacuum. The vacuum envelope
200
includes an anode substrate
300
and a lid-like casing
600
. The lid-like casing
600
is formed of an anode substrate
300
made of an insulating material, a flat plate or front cover
400
made of an insulating and light-permeable material and a frame-like side plate
500
made of an insulating material. The substrates
300
,
400
and
500
of the vacuum envelope
200
each are made of glass. The anode substrate
300
is sealedly mounted on an outer periphery thereof with the casing
600
by means of a sealing substance, resulting in the vacuum envelope being provided, which is then evacuated at a high vacuum.
The anode substrate
300
, as shown in
FIG. 9
, is formed on an inner surface thereof with a wiring
700
in a predetermined pattern. The wiring
700
is made of a thin film of a conductive material such as Al or the like. The anode substrate
300
is formed thereon with an insulating layer
900
so as to cover the wiring
700
. The insulating layer
900
is formed with through-holes
800
, each of which is filled with a conductive material
110
such as, for example, Ag or the like.
Also, the fluorescen
Itakura Kazuhiko
Kato Masahiro
Kogure Junichiro
Namiki Akio
Okamoto Yoshinari
Futaba Corporation
Patel Vip
Quarterman Kevin
LandOfFree
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