Electric lamp and discharge devices – With luminescent solid or liquid material – Vacuum-type tube
Reexamination Certificate
1998-10-01
2001-04-17
Patel, Nimeshkumar D. (Department: 2879)
Electric lamp and discharge devices
With luminescent solid or liquid material
Vacuum-type tube
C313S309000, C313S336000, C313S051000
Reexamination Certificate
active
06218778
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a field emission device, and more particularly to a field emission device suitable for use for a field emission display (FED) or the like.
2. Discussion of the Background
An FED generally includes an envelope which is formed by sealedly joining a cathode substrate-side structure and an anode substrate-side structure to each other while being spaced from each other at a predetermined interval and is then evacuated to a high vacuum. The FED includes a field emission cathode (FEC), which may be constructed into a Spindt-type cold cathode structure. In the FEC of this type, application of a draw-out voltage to a gate electrode permits a conical emitter arranged in each of holes formed through the gate electrode to field-emit electrons, resulting in a phosphor of an anode electrode which has a positive voltage applied thereto emitting light, leading to display operation.
An FED of the high-voltage type exhibits increased luminance as compared with that of the low-voltage type, because in the former, a phosphor for a high voltage is increased in luminance. The FED of the high-voltage type is adapted to apply a voltage of several kV between an anode and a gate, so that it is needed to increase a gap between the anode and the gate. Thus, in the FED of the high-voltage type, it is required to focus electron beams emitted. In general, the FED has an FEC of the two-stage gate type incorporated therein. The FEC of the two-stage gate type is constructed so that a layer of a focusing electrode is provided separately from that of a gate electrode to provide a two-stage layer structure. This increases the number of layers, to thereby render manufacturing of the FEC costly and troublesome. In view of the problem, an FEC of the plane focusing type wherein a focusing electrode and a gate electrode are arranged in the same plane is proposed to simplify a process of manufacturing.
Such a plane focusing type FEC is generally constructed in such a manner as shown in
FIGS. 5 and 6
, wherein reference numeral
31
designates a focusing electrode,
32
is a gate electrode,
32
a
is holes,
11
is a conical emitter arranged in each of the holes
32
a
,
12
is an insulating layer,
13
is a cathode substrate,
33
is a resistive layer, and
34
is a cathode electrode line.
The plane focusing type FEC fails to fully surround the gate electrode
32
with the focusing electrode
31
. Thus, the focusing electrode
31
and gate electrode
32
, as shown in
FIG. 5
, each are formed into a pectinate configuration and arranged on the same plane on the insulating layer
12
while alternating with each other. The gate electrode
32
is formed at each of projections thereof with a plurality of holes
32
a
in a row in a longitudinal direction of the projection.
The cathode substrate
13
, as shown in
FIG. 6
, is formed thereon with the cathode electrode line
34
, on which the resistive layer
33
is arranged. Then, the insulating layer
12
is arranged on the resistive layer
33
, followed by arrangement of the above-described focusing electrode
31
and gate electrode
32
on the insulating layer
12
. The holes
32
a
are formed through the gate electrode
32
and insulating layer in a manner to commonly extend therethrough and the conical emitter
11
is arranged in each of the holes
32
a
while being placed on the resistive layer
33
. The gate electrode
32
and focusing electrode
31
have a gate electrode voltage and a focusing electrode voltage applied thereto, respectively.
As described above, the plane focusing type FEC essentially fails to fully surround the gate electrode
32
with the focusing electrode
31
. This causes electron beams emitted from the conical emitters
11
to leak through an opening of the focusing electrode
31
as indicated at an arrow in
FIG. 5
, resulting in failing to provide a desired spot diameter of electron beams.
Such a problem is due to the fact that the conventional plane focusing type FEC fails to arrange any electrode or structure between the gate electrode and a line for feeding a voltage to the gate electrode in a manner to surround the gate electrode. Thus, the problem is not restricted to only the focusing electrode. Also, the conventional plane focusing type FEC, even when the focusing electrode or structure is arranged so as not to fully surround the gate electrode, causes relationship in arrangement between the line for feeding a voltage to the gate electrode and the focusing electrode or structure to be subject to restriction.
SUMMARY OF THE INVENTION
The present invention has been made in view of the foregoing disadvantage of the prior art.
Accordingly, it is an object of the present invention to provide a field emission device which is capable of permitting any desired electrode or structure to be arranged around a gate electrode without any restriction.
It is another object of the present invention to provide a field emission device which is capable of permitting a focusing electrode to be arranged around a gate electrode, to thereby simplify a process of manufacturing thereof and substantially reducing a spot diameter of electron beams.
In accordance with the present invention, a field emission device is provided. The field emission device generally includes an insulating layer having an upper surface and a lower surface, a gate electrode arranged on the upper surface of the insulating layer, holes formed through the insulating layer and gate electrode in a manner to commonly extend through both, emitters arranged in the holes, respectively, a gate electrode line, and a cathode electrode line. The gate electrode line is arranged on the upper surface of the insulating layer. A connection line is arranged on the lower surface of the insulating layer. A first interlayer connection is arranged so as to electrically connect the gate electrode to the connection line therethrough and a second interlayer connection is arranged so as to electrically connect the gate electrode line to the connection line therethrough.
Also, in accordance with the present invention, a field emission device is provided. The field emission device generally includes an insulating layer having an upper surface and a lower surface, a gate electrode arranged on the upper surface of the insulating layer, holes formed through the insulating layer and gate electrode in a manner to commonly extend through both, emitters arranged in the holes, respectively, a gate electrode line, and a cathode electrode line. The cathode electrode line is arranged on the upper surface of the insulating layer and the gate electrode line is arranged on the lower surface of the insulating layer. A first interlayer connection is arranged so as to electrically connect the gate electrode to the gate electrode line therethrough and a second interlayer connection is arranged so as to electrically connect the emitters to the cathode electrode line therethrough.
In a preferred embodiment of the present invention, a focusing electrode is arranged on the upper surface of the insulating layer so as to surround the gate electrode.
REFERENCES:
patent: 5075595 (1991-12-01), Kane
patent: 5528103 (1996-06-01), Spindt et al.
patent: 5760810 (1998-06-01), Onodaka
patent: 5903098 (1999-05-01), Jones
Itoh Shigeo
Tomita Masaharu
Tsuburaya Kazuhiko
Yano Kazuyuki
Futaba Denshi Kogyo Kabushiki Kaisha
Guharay Karabi
Oblon, Spivak, McClelland, Maier & Nuestadt, P.C.
Patel Nimeshkumar D.
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