Electric lamp and discharge devices – Discharge devices having a thermionic or emissive cathode
Reexamination Certificate
1999-11-10
2001-07-10
Patel, Nimeshkumar D. (Department: 2879)
Electric lamp and discharge devices
Discharge devices having a thermionic or emissive cathode
C313S309000, C313S367000
Reexamination Certificate
active
06259191
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electron source and an image-forming apparatus such as a display apparatus as an application of the electron source and, more particularly, to a surface-conduction electron-emitting device having a new structure, an electron-emitting apparatus or an electron source using the surface-conduction electron-emitting device, and an image-forming apparatus such as a display apparatus as an application of the electron source.
2. Related Background Art
Electron-emitting apparatuses using surface-conduction electron-emitting devices have simple structures, and can be easily manufactured and driven by a driving voltage of several to several tens V. Recently, the electron-emitting apparatuses as flat-type display apparatuses have been developed and researched.
The structures and manufacturing methods for the surface-conduction electron-emitting device and the electron-emitting apparatus using the same have been described in detail in, e.g., Japanese Patent Application Laid-Open No. 7-235255. This prior art will be briefly described below.
FIGS. 1A and 1B
are schematic views of a conventional surface-conduction electron-emitting device.
FIG. 1A
is a plan view of the device, and
FIG. 1B
is a side view of the device. The device includes a substrate
1
, a positive device electrode
2
, and a negative device electrode
3
and is connected to a power supply (not shown). Electroconductive films
5004
and
5005
are-electrically connected to the positive device electrode
2
and the negative device electrode
3
, respectively. The thicknesses of the electrodes
2
and
3
are several tens nm to several &mgr;m. The thicknesses of the electroconductive films
5004
and
5005
are about 1 nm to several tens nm. A fissure
5006
almost electrically disconnects the electroconductive film
5004
from the electroconductive film
5005
. The characteristic features of the fissure will be described together with the manufacturing process. After the device is formed, electrons are scattered and emitted from a portion near the distal end portion of the electroconductive film on the positive device electrode side of the fissure
5006
.
An electron-emitting apparatus using the surface-conduction electron-emitting device will be described below with reference to FIG.
2
.
FIG. 2
is a schematic view showing the electron-emitting apparatus using the surface-conduction electron-emitting device having the structure shown in
FIGS. 1A and 1B
.
This apparatus includes a power supply
10
for applying a device voltage V
f
to the device, an ammeter
11
for measuring a device current I
f
flowing across the device electrodes
2
and
3
, an attracting electrode
12
for capturing electrons emitted from the electron-emitting portion of the device, a high-voltage power supply
13
for applying a voltage V
a
to the attracting electrode
12
, and an ammeter
14
for measuring an emission current I
e
generated by electrons emitted from the surface-conduction electron-emitting device and arriving at the attracting electrode. Additionally, a mesh electrode or phosphor plate is attached to the attracting electrode
12
to measure the distribution of electron arrival positions, as needed. To emit electrons, the power supply
10
is connected to the device electrodes
2
and
3
, and the power supply
13
is connected to the electron-emitting device and the attracting electrode
12
. To measure the device current I
f
and the emission current I
e
, the ammeters
11
and
14
are connected, as shown in FIG.
2
.
The surface-conduction electron-emitting device and the attracting electrode are set in a vacuum vessel
16
, as shown in
FIG. 2
, such that the voltages applied to the device and the electrode can be controlled outside the vacuum vessel. An exhaust pump
15
is constituted by a normal high-vacuum exhaust system comprising a turbo pump and a rotary pump, and an ultra high-vacuum exhaust system comprising an ion pump. The entire vacuum vessel
16
and the electron-emitting device substrate can be heated by a heater (not shown).
The device voltage V
f
can change within the range of about zero to several tens V, and the voltage V
a
of the attracting electrode can change within the range of zero to several kV. A distance H between the attracting electrode and the electron-emitting device is set on the order of several mm.
A method of manufacturing the surface-conduction electron-emitting device will be described below with reference to
FIGS. 3A
to
3
C.
[Step-a]
A silicon oxide film having a thickness of about 0.5 &mgr;m is formed on a cleaned soda-lime glass by sputtering, and a photoresist pattern (negative pattern) of the device electrodes
2
and
3
is formed on the substrate
1
. A Ti film having a thickness of, e.g., 5 nm and an Ni film having a thickness of 100 nm are sequentially deposited on the resultant structure by vacuum deposition. The photoresist pattern is dissolved by an organic solvent. The Ni and Ti deposition films are lifted off to form the device electrodes
2
and
3
(FIG.
3
A).
[Step-b]
A Cr film having a thickness of about 100 nm is deposited by vacuum deposition and patterned by photolithography to form an opening conforming to an electroconductive film. An organic Pd compound (ccp4230, available from Okuno Seiyaku K. K.) is rotatably applied by a spinner, and a heating and baking treatment is performed to form an electroconductive film
7
formed of fine particles whose principal ingredient is palladium oxide. The film of fine particles is a film consisting of a plurality of fine particles. As for the fine structure, the fine particles are not limited to dispersed particles. The film may also be a film comprising fine particles arranged to be adjacent to each other or overlap each other (an island structure is also included).
[Step-c]
The Cr film is etched using an acid etchant and lifted off to form the desired pattern of the electroconductive film
7
(FIG.
3
B).
[Step-d]
The device is set in the apparatus shown in FIG.
2
. The apparatus is evacuated by the vacuum pump to a degree of vacuum of about 2.7×10
−3
Pa (2×10
−5
Torr). The power supply
10
for applying the device voltage V
f
to the device applies the voltage across the device electrodes
2
and
3
to perform electrification process called energization forming. This energization forming process is performed by applying a pulse voltage with a constant or gradually stepping up pulse height. With this energization forming process, the electroconductive film
7
is locally destroyed, deformed, or changed in properties, thus forming the fissure
5006
(FIG.
3
C). Simultaneously, a resistance measurement pulse is inserted between the energization forming pulses at a voltage of, e.g., 0.1 V not to locally destroy or deform the electroconductive film
7
during energization forming, thereby measuring the resistance. When the measured resistance of the electroconductive film
7
becomes about 1 M&OHgr; or more, application of the voltage to the device is stopped to end the energization forming.
[Step-e]
The device which has undergone the energization forming is preferably subjected to processing called activation. With the activation processing, the device current I
f
and the emission current I
e
largely change. The activation processing can be performed by repeating pulse application in an atmosphere containing, e.g., the gas of an organic substance, as in energization forming. This atmosphere can be obtained using an organic gas remaining in the atmosphere in evacuating the vacuum vessel by using, e.g., an oil diffusion pump or rotary pump, or supplying an appropriate gas of an organic substance into the vacuum obtained by sufficiently evacuating the vacuum vessel using an ion pump or the like. The preferable gas pressure of the organic substance changes depending on the application form, the shape of the vacuum vessel, or the type of organic substance, an
Aiba Toshiaki
Asai Akira
Matsutani Shigeki
Mitome Masanori
Okuda Masahiro
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Gerike Matthew T.
Patel Nimeshkumar D.
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