Electric lamp or space discharge component or device manufacturi – Process – With start up – flashing or aging
Reexamination Certificate
1999-04-15
2001-04-10
Ramsey, Kenneth J. (Department: 2879)
Electric lamp or space discharge component or device manufacturi
Process
With start up, flashing or aging
C445S024000
Reexamination Certificate
active
06213834
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to methods for making an electron emission device and an image forming apparatus, and to an apparatus for making the same.
2. Description of the Related Art
Conventional electron emission devices are classified into thermal electron source devices and cold cathode electron source devices. The cold cathode electron source devices include field emission (hereinafter referred to as FE) types, metal-insulator-metal (hereinafter referred to as MIM) types, and surface conduction types.
FE type devices are disclosed by, for example, W. P. Dyke & W. W. Dolan (“Field Emission”, Advances in Electron Physics, Vol. 8, 89 (1956)), and by C. A. Spindt (“Physical Properties of Thin-Film Field Emission Cathodes with Molybdenum Cones”, J. Appl. Phys., Vol. 47, 5248 (1976)). MIM type devices are disclosed by, for example, C. A. Mead % (“The Tunnel-Emission Amplifier”, J. Appl. Phys., Vol. 32, 646 (1961)). Surface conduction type devices are disclosed by, for example, M. I. Elinson (Radio Eng. Electron Phys., Vol. 10, 1290 (1965)).
In surface conduction electron emission devices, when a current flows along the plane of a thin film with a small area formed on a substrate, electrons are emitted. Examples of thin films disclosed as surface conduction electron emission devices include an SnO
2
thin film by Elinson as described above, a gold thin film by G. Dittmer (Thin Solid Films, Vol. 9, 317-328 (1972)), an In
2
O
3
/SnO
2
thin film by M. Hartwell and C. G. Fonstad (IEEE Trans. ED Conf., p. 519 (1975)), and a carbon thin film by H. Araki et al. (Sinku (Vacuum), Vol. 26, No. 1, 22 (1983)).
FIG. 25
shows a configuration of the above device by M. Hartwell as a typical example of a surface conduction electron emission device. A conductive film
4
having an H shape is formed on a substrate
1
. The conductive film
4
is composed of the above-described composite metal oxide. The conductive film
4
is subjected to an electrifying process generally called “electrifying forming” to form an electron emitting section
5
. In the drawing, two device electrodes have a total length L in the range of 0.5 to 1.0 mm, and a width W′ of approximately 0.1 mm.
In the surface conduction electron emission device, the electron emitting section
5
is generally formed by the “electrifying forming” process of the conductive film
4
prior to electron emission. In the electrifying forming, a voltage is applied to two ends of the conductive film
4
to locally destruct, deform or modify the conductive film
4
. As a result, the electron emitting section
5
having high electrical resistance is formed. The electron emitting section
5
includes cracks and electrons are emitted near the cracks.
Examples of arrays of many surface conduction electron emission devices are ladder-type electron sources disclosed in, for example, Japanese Patent Application Laid-Open Nos. 64-31332, 1-283749, and 2-257552, in which many lines of surface conduction electron emission devices are arranged, and two ends (electrodes) of each devices are connected to lead lines (common lead lines).
An array of surface conduction electron emission devices enables production of a planar display device similar to a liquid crystal display device. U.S. Pat. No. 5,066,883 discloses such a display device which comprises a combination of an electron source including many surface conduction electron emission devices and a fluorescent coating which is irradiated with electrons from the electron source to emit visible light.
Preferably, a voltage is applied to the electron emission device subjected to electrifying forming in an atmosphere containing an organic substance in order to improve electron emission characteristics (hereinafter referred to as an activation step). The voltage applied in the activation step is substantially equal to the voltage applied in the forming step. Carbon and/or carbonaceous materials are deposited on and near the electron emitting section
5
during the activation step, as disclosed, for example, in European Patent Application Laid-Open No. 0660357.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a method for making an electron emission device having superior electron emission characteristics.
It is another object of the present invention to provide a method for making an image forming apparatus using such electron emission devices.
It is still another object of the present invention to provide an apparatus for making electron emission devices.
It is a further object of the present invention to provide a method and an apparatus for making an image forming apparatus capable of forming higher quality images.
A method for making an electron emission device including a conductive film having an electron emitting section disposed between a pair of electrodes, includes a removal step for removing impurities in an organic substance, and a voltage-applying step for applying an voltage to the conductive film through the electrodes in an atmosphere containing the organic substance.
In an embodiment of the method, the removal step may include removing atmospheric components, such as oxygen and nitrogen, contained in the organic substance when the organic substance is introduced from a supply source of the organic substance into a treating unit for performing the voltage-applying step.
Preferably, the atmospheric components contained in the organic substance are removed by a freeze and thawing method. Preferably, the organic substance is introduced to the treating unit without contact with air after the atmospheric components contained in the organic substance are removed.
Another aspect of the present invention is a method for making an image forming apparatus including at least one electron emission device and an image forming member for forming an image by electrons emitted from the electron emission device, wherein the electron emission device is made by the above-described method.
Another aspect of the present invention is an apparatus for making an electron emission device including a pair of electrodes and a conductive film having an electron emitting section disposed between the electrodes. The apparatus includes a container for containing a substrate including a pair of electrodes and a conductive film disposed between the electrodes, a first evacuating means for evacuating the container, a voltage applying means for applying an voltage between the electrodes, a gas supply means for supplying a vaporized organic substance from a supply source to the vessel, and a second evacuating means for evacuating the interior of the supply source.
Another aspect of the present invention is an apparatus for making an electron emission device including a pair of electrodes and a conductive film having an electron emitting section disposed between the electrodes. The apparatus includes a container for containing a substrate including a pair of electrodes and a conductive film disposed between the electrodes, an evacuating means for evacuating the container, a voltage applying means for applying an voltage between the electrodes, a gas supply means for supplying a vaporized organic substance from a supply source to the vessel, and a gas exhausting line for evacuating the interior of the supply source from the evacuating means without through the container.
Further objects, features and advantages of the present invention will become apparent from the following description of the preferred embodiments with reference to the attached drawings.
REFERENCES:
patent: 5066883 (1991-11-01), Yoshioka et al.
patent: 5853310 (1998-12-01), Nishimura et al.
patent: 0 660 357 (1995-06-01), None
patent: 0788130 (1997-08-01), None
patent: 0803892 (1997-10-01), None
patent: 1-031332 (1989-02-01), None
patent: 1-283749 (1989-11-01), None
patent: 2-257552 (1990-10-01), None
Dyke, W.P., et al., “Field Emission,” Advances in Electronics and Electron Physics, New York: Academic Press, Inc. (1956), pp. 89-185.*
Elinson, M.I., et al., “The Emission of
Mitome Masanori
Ohnishi Toshikazu
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Ramsey Kenneth J.
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