Electric lamp and discharge devices – Discharge devices having a multipointed or serrated edge...
Reexamination Certificate
1999-01-15
2002-12-03
Patel, Vip (Department: 2879)
Electric lamp and discharge devices
Discharge devices having a multipointed or serrated edge...
C313S336000, C313S351000
Reexamination Certificate
active
06489710
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electron emitting apparatus for emitting field electrons from a cathode thereof, a manufacturing method therefor and a method of operating the electron emitting apparatus. More particularly, the present invention relates to a flat electron emitting apparatus having a cathode formed into a flat shape, a manufacturing method therefor and a method of operating the flat electron emitting apparatus.
2. Related Background Art
In recent years, display units have been researched and developed such that the thickness of the display unit is attempted to be reduced. In the foregoing circumstance, a field emission display (hereinafter abbreviated to “FED”) incorporating so-called electron emitting apparatuses has attracted attention.
As shown in
FIG. 1
, the FED has portions each of which corresponds to one pixel, the portion including a spint electron emitting apparatus
100
and a fluorescent surface
101
formed opposite to the spint electron emitting apparatus
100
. A multiplicity of the foregoing pixels are formed into a matrix configuration so that a display unit is constituted.
In the portion corresponding to one pixel, the electron emitting apparatus
100
incorporates a cathode
103
formed on a cathode panel
102
; a gate electrode
105
laminated on the cathode
103
through an insulating layer
104
; and electron emitting portions
107
each of which is formed in each of a plurality of openings
106
formed in the gate electrode
105
and the insulating layer
104
. The FED has the fluorescent surface
101
formed opposite to the electron emitting apparatus
100
. The fluorescent surface
101
is composed of a front panel
108
, an anode
109
and a fluorescent member
110
formed on the front panel
108
. Moreover, the FED is structured such that predetermined voltages are applied to each of the cathode
103
, the gate electrode
105
and the anode
109
, respectively.
Each of the electron emitting portions
107
of the FED is formed into a cone-like shape realized by finely machining a material, such as W, Mo or Ni. The leading end of the electron emitting portion
107
is disposed apart from the gate electrode
105
for a predetermined distance. The electron emitting apparatus
100
is structured such that electrons are emitted from the leading ends of the electron emitting portions
107
. The electron emitting apparatus
10
has a multiplicity of the electron emitting portions
107
.
In the FED structured as described above, a predetermined electric field is generated between the cathode
103
and the gate electrode
105
. As a result, electrons are emitted from the leading ends of the electron emitting portions
107
. Emitted electrons collide with the fluorescent member
110
formed on the anode
109
. As a result, the fluorescent member
110
is excited to emit light. When the quantity of electrons which are emitted from the electron emitting portions
107
of the FED corresponding to the pixels is adjusted, a required image can be displayed on the display unit.
When the spint electron emitting apparatus is manufactured, the openings
106
are formed such that the diameter of each opening
106
is about 1 mm. Then, the electron emitting portions are perpendicularly evaporated in the surfaces of the openings
106
. Specifically, a separation layer is formed on the gate electrode
105
after the openings
106
have been formed. Then, a metal film or the like is formed. As a result, the metal film is formed on the gate electrode
105
and the bottom surfaces of the openings
106
. Then, the film forming operation is continued to grow the metal film so that the cone-line electron emitting portions
107
are formed. Then, the metal film formed on the gate electrode
105
is, together with the separation layer, removed.
However, the cone-like electron emitting portions of the spint type electron emitting apparatus cannot easily be formed. Thus, there arises a problem in that a stable electron emitting characteristic cannot be realized. The reason for this lies in that the electron emitting characteristic of the spint electron emitting apparatus considerably depends on the distance between the leading end of each of the electron emitting portions and the gate electrode. Therefore, the electron emitting portions cannot reliably be formed.
When the electron emitting portions are formed, the process for forming the metal film on the gate electrode having a large area and removal of the metal film and the separation layer from the same must uniformly be performed. If the metal film cannot uniformly be formed or if the metal film and the separation layer cannot uniformly be removed, electrons cannot easily be generated from the electron emitting portions by dint of the electric field generated from the gate electrode.
When electron emitting portions are formed to correspond to a large screen, satisfactory perpendicularity cannot be realized in a film forming direction over the screen. Therefore, uniform electron emitting portions cannot easily be formed on the overall surface of the screen. What is worse, contamination sometimes occur when the metal film and the separation film are removed. Thus, there arises a problem in that satisfactory manufacturing yield cannot be obtained.
To overcome the problems experienced with the spint electron emitting apparatus, a flat electron emitting apparatus has been suggested which has a structure that a high electric field is applied to the edge of a metal electrode so as to emit field electrons.
The flat electron emitting apparatus has a structure that an emitter electrode formed into a plate-like shape is held between a pair of gate electrodes through insulating layers. Thus, an electric field generated between a pair of gate electrodes and an emitter electrode causes electrons to be emitted from the emitter electrode.
The structure of the flat electron emitting apparatus permits the emitter electrode for emitting electrons to be formed into the plate-like shape. Therefore, the flat electron emitting apparatus can easily be manufactured as compared with the above-mentioned spint electron emitting apparatus.
Also the flat electron emitting apparatus must enlarge the electric field which is generated between the emitter electrode and the pair of the gate electrodes in order to improve the electron emitting characteristic. To enlarge the electric field, the emitter electrode must furthermore be fined so as to furthermore reduce the curvature radius of the leading end of the emitter electrode.
However, if the emitter electrode of the flat electron emitting apparatus is simply fined, the mechanical strength of the emitter electrode decreases considerably. Therefore, a great electric field cannot be generated. If a great electric field is applied to the fined emitter electrode, the emitter electrode is sometimes broken. Thus, the foregoing fine emitter electrode cannot be used in a high electric field.
Hitherto, the curvature radius of the leading end of the emitter electrode can be reduced during a process for manufacturing the flat electron emitting apparatus only when exposing, developing and etching conditions for the photoresist are delicately controlled. Therefore, the conventional method cannot easily form an emitter electrode of the type having satisfactory mechanical strength and provided with the leading end having a small curvature radius.
What is worse, the flat electron emitting apparatus suffers from a poor quantity of electrons which reach the anode as compared with the spint electron emitting apparatus. Therefore, the flat electron emitting apparatus cannot cause the fluorescent member disposed on the anode to satisfactorily emit light.
SUMMARY OF THE INVENTION
Accordingly an object of the present invention is to provide an electron emitting apparatus and a manufacturing method therefor which is capable of overcoming the problems experienced with the conventional electron emitting apparatus, which exhibits satisfactory mechanical strength and
Iwase Yuichi
Okita Masami
Yamada Jiro
Kananen, Esq. Ronald P.
Patel Vip
Rader & Fishman & Grauer, PLLC
Sony Corporation
Williams Joseph
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