Electric lamp or space discharge component or device manufacturi – Process – With start up – flashing or aging
Reexamination Certificate
2002-01-25
2004-08-31
Williams, Joseph (Department: 2879)
Electric lamp or space discharge component or device manufacturi
Process
With start up, flashing or aging
C445S024000
Reexamination Certificate
active
06783414
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for manufacturing cathodes, and a method for manufacturing electron sources, electron beam generating apparatuses, and image forming apparatuses such as flat-panel displays.
2. Description of the Related Art
There are two types of cathodes (electron-emitting devices) that have been conventionally known; thermionic cathodes, and cold cathodes. Cold cathodes include field-emission types (hereafter referred to as “FE-type”), and metal layer/insulating layer/metal layer types (hereafter referred to as “MIM-type”) and surface conduction type cathodes.
Examples of surface conduction type cathodes are disclosed in Japanese Patent Laid-Open No. 8-55563, Japanese Patent Laid-Open No. 7-235255, Japanese Patent Laid-Open No. 8-007749, Japanese Patent Laid-Open No. 8-321254, Japanese Patent No. 2836015, Japanese Patent Laid-Open No. 9-237571, Japanese Patent Laid-Open No. 7-65704, Japanese Patent Laid-Open No. 10-40807, Japanese Patent Laid-Open No. 8-171850, Japanese Patent Laid-Open No. 9-069334, and so forth.
FIG. 12
schematically illustrates an example of the configuration of a surface conduction type cathode, disclosed in the above Japanese Patent Laid-Open No. 8-321254. In the Figure, reference numeral
1
denotes a substrate,
2
and
3
denote electrodes,
4
denotes an electroconductive film,
5
denotes an electron emission portion, and
10
denotes a carbon film. The area near the electron emission portion
5
is formed of a first gap
6
which defines the gap in the electroconductive film, and a second gap
7
which defines the gap in the carbon film
10
. The gap L shown in the Figure is set at several tens of &mgr;m to several hundred &mgr;m, the width W at several &mgr;m to several hundred &mgr;m, and the thickness d at several tens of &mgr;m to several hundred &mgr;m.
Also,
FIG. 13
illustrates an example of the method of manufacturing a conventional surface conduction type cathode, such-as disclosed in the above Japanese Patent Laid-Open No. 8-321254.
First, electrodes
2
and
3
are positioned on the substrate
1
(FIG.
13
A). Then, an electroconductive film
4
for connecting the electrodes
2
and
3
is positioned (FIG.
13
B). Next, flowing a current through the electroconductive film
4
forms a first gap
6
at a portion of the electroconductive film (FIG.
13
C). The process of forming this first gap
6
in the electroconductive film is called “forming” or “energization forming”. Next, the carbon film
10
is formed by, for example, introducing an organic gas in a vacuum, and applying voltage between the two electrodes
2
and
3
in this atmosphere (FIG.
13
D). Incidentally, the second gap
7
is formed at the same time as forming this carbon film
10
. The process of forming the carbon film
10
and the second gap
7
is called “activation”. The area near the second gap
7
formed by this activation process is called the electron emission portion
5
.
SUMMARY OF THE INVENTION
There have been the following problems with the above-described conventional activation process.
Firstly, in the case of forming the carbon film from organic material gas, there have been the following problems. There is the need to introduce the organic material gas at an optimal gas pressure for the above activation process. Particularly, depending on the type of organic material gas that is to be introduced, there has been problems in pressure controllability in the event that the optimal gas pressure is low. Also, there have been cases wherein the amount of time necessary for the activation process changes or the nature of the formed carbon film differs due to residual water, oxygen, or the like in the vacuum atmosphere. This has caused irregularities in the electron emission properties of electron sources or image forming apparatuses.
Secondly, in the event of using the aforementioned cathodes for image forming apparatuses or electron sources, there have been the following problems. That is following the activation process, the gas used on the activation process, and also water, oxygen, etc., have adhered to the substrate for the electron source, or member comprising the image forming apparatus, e.g., a face plate having fluorescent material. Accordingly, there is the need to remove the gas and the like adhering thereto, to stabilize electron emission properties. To this end, conventional arrangements required a process called “stabilizing”, wherein the substrate on which the electron-emitting devices are arrayed, or the air-tight container enveloping the devices, are baked at high temperatures for long periods of time. With this stabilizing process, the higher the temperature, the better; and the longer the time, the better. However, in practice, the stabilizing process is restricted regarding the heating temperature due to the heat-resistance properties of the members comprising the cathodes, electron sources, and image forming apparatuses, so sufficient heating has not always been able to be performed.
Thirdly, in the sealing process for fabricating image forming apparatuses, there have been the following problems. That is, in the case of fabricating image forming apparatuses, conventional arrangements involved bonding together at high temperatures an electron source substrate comprising wires and the like for driving each device with a face plate having fluorescent material or the like, thereby forming an envelope (referred to as the sealing process). Then, following this sealing process, voltage is applied from the wires, the aforementioned forming and activating processes and the like are performed. In this way, the forming and activating processes are performed after the image forming apparatus (vacuum envelope) is assembled, so in the event that a defect occurs on the electron source substrate due to one reason or another, the entire image forming apparatus becomes defective. Accordingly, an arrangement has been awaited wherein the forming and activating processes are performed, and inspected, following which the electron source substrate which has passed the inspection and the face plate are assembled to manufacture the image forming apparatus.
Fourthly, the above Japanese Patent Laid-Open No. 9-237571 discloses a manufacturing method which is said to solve the above problems, but means for realizing further reductions in costs has been awaited.
Accordingly, the present invention has achieved the above objectives, by the following manufacturing methods.
According to an aspect of the present invention, a method for manufacturing a cathode comprises the steps of:
A) a process for applying onto a substrate a fluid mixture comprising polymers or precursors to the polymers, fine particles of electroconductive material or organic metal compound, and solvent;
B) a process for removing the solvent by heating the fluid mixture applied on the substrate, thereby obtaining an electroconductive organic film comprising the polymers and the electroconductive material; and
C) a process for forming a gap at a portion of the electroconductive organic film by flowing a current through the film.
Now, the process for applying the fluid mixture according to the present invention may be performed by the ink-jet method, and the ink-jet method may involve applying heat to the fluid mixture to the point of boiling so as to generate bubbles, thereby using the pressure of the bubbles to eject droplets of the fluid mixture.
Also, according to the present invention, the ink-jet method may involve applying electric signals to piezoelectric elements so as to cause deformation thereof, thereby ejecting droplets of the fluid mixture.
The polymers may comprise at least one selected from the following group: all-aromatic polymers, and polyacryllo nitryl. Here, the all-aromatic polymer may comprise one of polyimide, polybenzoimidazole, and polyamideimide.
The electroconductive material according to the present invention may comprise at least one selected from the following group: Pd, Ru, Ag, Cu, Tb, Cd, Fe, Pb, Z
Iwaki Takashi
Minami Masato
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Williams Joseph
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