Electric lamp or space discharge component or device manufacturi – Process – With assembly or disassembly
Reexamination Certificate
2000-03-07
2001-10-30
Ramsey, Kenneth J. (Department: 2879)
Electric lamp or space discharge component or device manufacturi
Process
With assembly or disassembly
Reexamination Certificate
active
06309271
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a field emission device and a method for a fabricating the same.
2. Description of the Related Art
FIG. 1
is a sectional view of a conventional field emission device. As shown in
FIG. 1
, a plurality of cathodes
2
are formed on a rear surface substrate
1
in the conventional field emission device. A plurality of microtips
2
′ are formed on the cathodes
2
in an array pattern. The microtips
2
′ are formed in a throughhole
3
a
of an insulating layer
3
formed on the cathodes
2
. Gates
4
having an opening
4
a
corresponding to the throughhole
3
a
are stacked on the insulating layer
3
. A front surface substrate
6
supported by spas
8
spaced from each other by a predetermined distance is provided on the gates
4
. A plurality of anodes
5
are formed on the front surface substrate
6
so as to be opposed to the microtips
2
′. Red, green, and blue fluorescent films
7
are formed on the anodes
5
in strips. The microtip array of the rear surface substrate is a portion (refer to the portion in a circle in the drawing) corresponding to a cathode of an electron gun of a CRT. The portion coated by a fluorescent film of the front surface substrate is a portion corresponding to an anode formed on the front surface glass of a CRT.
When the microtip array of the field emission device is grounded and a uniform voltage is applied between the gates
4
and the anodes
5
, electrons are emitted into a vacuum and arrive at the anodes
5
. At this time, the electrons accelerated by the voltage of the anodes
5
collide with a fluorescent film
7
with a predetermined kinetic energy. The kinetic energy of the electrons is transmitted to the fluorescent film
7
. The fluorescent film
7
receives the kinetic energy of the electrons and is excited. Accordingly, the fluorescent film
7
emits light. However, as shown in
FIG. 1
, since the red, green, and blue fluorescent films
7
are formed in parallel, spaced apart from each other by a predetermined distance, the frequency for driving the gates
4
becomes higher when the device is driven by switching the gates
4
. Accordingly, signal processing becomes more difficult and the red, green, and blue fluorescent films
7
simultaneously emit light or are extinguished. Namely, the red, green, and blue fluorescent films cannot be driven in a way of emitting light individually. Also, the fluorescent films
7
can be fabricated using PVA-slurry or screen printing. A fluorescent material cannot be coated by an electrophoretic method Therefore, it is expensive to fabricate the fluorescent film.
SUMMARY OF THE INVENTION
To solve the above problem(s), it is an objective of the present invention to provide a field emission device in which the frequency of a signal for driving gates is lowered and the cost of coating a fluorescent film is reduced by forming anodes so that each of red, green, and blue fluorescent films emit light individually and driving the anodes and switching the gates at the same time.
It is another objective of the present invention to provide a method for fabricating the above-mentioned field emission device.
Accordingly, to achieve the first objective, there is provided a field emission device, comprising a front surface substrate and a rear surface substrate spaced apart from each other by a predetermined distance and arranged to be opposite each other, cathodes formed on the rear surface substrate in strips, a plurality of microtips formed on the cathodes in an array patter so as to electrically contact the cathodes, an insulating layer formed on the cathodes and the substrate exposing portion so as to have throughhole for holding the plurality of microtips, gates formed on the insulating layer in strips in a direction crossing the cathodes so as to have openings corresponding to the throughholes of the insulating layer anodes formed on the surface of the front surface substrate corresponding to the rear surface substrate in strips, and fluorescent films coated on the anodes wherein the respective pixel cells are formed by sequentially forming the red, green, and blue fluorescent films on the anodes, each of which is comprised of three, external terminals are formed by the anodes on which the fluorescent film of the same color contact each other in the anodes on which the red, green, and blue fluorescent films are formed, and an insulating layer is included in an area in which the anodes cross each other so that a contact wiring for connecting the anodes of an arbitrary color detours the anodes on which a fluorescent film of another color is formed.
In the present invention, a contact line for contacting the external terminals formed on the front surface substrate to the external terminals on the rear surface substrate is further comprised in a vacuum space between the front surface substrate and the rear surface substrate. The contact line is formed of In and Sn in a ratio of 50:50.
To achieve the second objective, there is provided a method for fabricating the field emission device, comprising the steps of (a) forming cathodes, microtips, an insulating layer, and a gate on a rear surface substrate and forming external terminals corresponding to red, green, and blue image signals at one edge, (b) forming anodes in strips on a front surface substrate, contact wirings for contacting anodes to be doped with a fluorescent film of the same color at one edge of anodes, each of which is comprised of three, and external terminals corresponding to the contact wirings. (c) coating red, green, and blue fluorescent films on the anodes by an electrophoretic method, (d) contacting the external terminals of the front surface substrate to the external terminals of the rear surface substrate in a state in which spacers are arranged between the front surface substrate and the rear surface substrate, and (e) sealing the edges of the front surface substrate and the rear surface substrate and vacuumizing the sealed inside.
In the present invention, the step (b) comprises the steps of (b-1) forming an insulating layer on an area in which the anodes cross each other so that a contact line for connecting the anodes on which an fluorescent film of an arbitrary color is to be formed detours anodes on which fluorescent films of other two colors will be formed and (b-2) forming the detouring contact wiring on the insulating layer. The detouring contact wiring is formed by coating the metal paste. In the step (d), the contact lines for contacting the external terminals of the front surface substrate to the external terminals of the rear surface substrate are formed to contain In and Sn in a ratio of 50:50. The step (c) comprises the steps of (c-1) preparing Y
2
O
2
S:Eu:10% In
2
O
3
, ZnS:Cu,Al:10% In
2
O
3
, and ZnS:Ag,Cl,Al:10% In
2
O
3
as the red fluorescent material, the green fluorescent material, and the blue fluorescent material, (c-2) preparing IPA(500 cc) and 7.5 g Al(NO
3
)
3
+9H
2
O (10 cc) as a charger and glycerln(50%)+IPA(50%) as a stabilizer, filling the fluorescent material 50 g+IPA(500 cc)+the charger (10 cc)+the Mobilizer (10 cc)+formic acid(CH
2
O
2
) in a supersonic wave container, and stirring the mixture for 40 minutes. (c-3) installing an Al electrode plate and the front surface plate in the container, controlling the distance between the Al electrode plate and the front surface substrate to be 3-5 cm, applying a bias voltage controlled to be 100-150V to the arbitrary external terminal, and attaching the fluorescent material to the anodes for 3-8 seconds, and (c-4) taking the front surface substrate doped with the fluorescent film from the container and drying the same, wherein the above steps are repeated three times, changing the fluorescent materials in the step (c-2) and the external terminals in the step (c-3). In the step (c-3), the height of the solution in the container is preferably. 3-3.5 cm. The step of controlling the conductivity of a plating solution by putting formic
Ramsey Kenneth J.
Samsung SDI & Co., Ltd.
The Law Offices of Eugene M. Lee, PLLC
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