Electric lamp or space discharge component or device manufacturi – Process – With start up – flashing or aging
Reexamination Certificate
1998-09-16
2002-07-09
Ramsey, Kenneth J. (Department: 2879)
Electric lamp or space discharge component or device manufacturi
Process
With start up, flashing or aging
C445S024000, C445S059000
Reexamination Certificate
active
06416374
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of manufacturing an electron source with an electron emitting element, a method of manufacturing an image forming apparatus, and apparatuses for manufacturing these electron source and image forming apparatus.
2. Related Background Art
Two types of electron emitting elements are known as roughly classified into a thermal electron emitting element and a cold cathode electron emitting element. The types of a cold cathode electron emitting element include a field emission type (hereinafter called an FE type, a metal/insulator/metal type (hereinafter called an MIM type), a surface conduction type electron emission type, and the like.
Examples of the FE type are disclosed in “Field emission”, by W. P. Dyke & W. W. Dolan, Advance in Electron Physics, 8, 89 (1956), “Physical properties of thin-film field emission cathodes with molybdenum cones”, by C. A. Spindt, J. Appl. Phys., 47, 5248 (1976) and other papers.
Examples of the MIM type are disclosed in “Operation of Tunnel-Emission Devices”, by C. A. Mead, J. Appl., Phys., 32, 646 (1961) and other papers.
Examples of the surface conduction type electron emission element are disclosed in Recio Eng. Electron Phys., by M. I. Elinson, 10, 1290 (1965) and other papers.
The surface conduction type electron emitting element utilizes the phenomenon that when current is flowed in a thin film having a small area formed on a substrate in parallel to the film surface, electron emission occurs. Reported thin films for a surface conduction type electron emitting element include an SnO
2
thin film by Elinson, an Au thin film (“Thin Solid Films”, 9, 317 (1972)), an In
2
O
3
/SnO
2
thin film (“IEEE Trans. ED conf.”, by M. Hartwell and C. G. Fonstad, 519 (1975)), a carbon thin film (“Vacuum”, by Hisashi ARAKI, et al. vol. 26, No. 1. p. 22 (1983)), and the like.
As a typical example of a surface conduction type electron emitting element, the structure of an element proposed by M. Hartwell is schematically shown in FIG.
16
. In
FIG. 16
, reference numeral
1
represents a substrate, and reference numerals
2
and
3
represent element electrodes. Reference numeral
4
represents a conductive thin film which is made of a metal oxide thin film having an H-character shape formed by sputtering. An electron emitting area
5
is formed in the conductive thin film by a power conduction process called a power conduction forming process to be described later. A distance L
1
between the element electrodes is 0.5 to 1 mm, and a width W of the conductive thin film
4
is 0.1 mm.
Conventionally, the electron emitting area
5
of a surface conduction type electron emitting element is generally formed in the conductive thin film
4
by the power conduction process called the power conduction forming process, before electron emission is enabled. With the power conduction forming process, a d.c. voltage or a voltage rising very gently, e.g., at about 1 V/min is applied across the electrodes of the conductive thin film
4
to locally break, deform, or decompose to form the electron emitting area
5
having a high electric resistance.
Cracks or the like are formed in the electron emitting area
5
of the conductive thin film
4
and electrons are emitted from the cracks and nearby areas. When a voltage is applied to the conductive thin film
4
of a surface conduction type electron emitting element subjected to the power conduction forming process and current is flowed therethrough, electrons are emitted from the electron emitting area
5
.
Since the structure of a surface conduction type electron emitting element is simple and the manufacture thereof is easy, a number of elements can be disposed in a large area. By utilizing this advantageous feature, various applications have been studied. For example, the surface conduction type electron emitting element may be used for a charged beam source, a display device, and the like. As will be later described, as an example of disposing a number of surface conduction type electron emitting elements, an electron source is known which has a number of rows disposed in parallel each having a plurality of surface conduction type electron emitting elements each having both terminals being connected by wiring patterns (also called common wiring patterns) (e.g., JP-A-64-031332, JP-A-1-283749, JP-A-2-257552, or the like).
A flat panel type display device using liquid crystal has recently been prevailed as an image forming apparatus in place of a CRT. However, since the flat panel type display device using liquid crystal is not of a self-light emission type so that a back light becomes necessary. Developments on a display device of a self-light emission type have long been desired. As a self-light emission type display device, an image forming apparatus is known which is a combination of an electron source with a number of surface conduction type electron emitting elements and a fluorescent body capable of radiating visible rays upon application of electrons emitted from the electron source (e.g., U.S. Pat. No. 5,066,883).
The present applicant has proposed a surface conduction type electron emitting element having the structure schematically shown in
FIGS. 2A and 2B
and an image forming apparatus using such electron emitting elements. The details of the structure of the electron emitting element and image forming apparatus and the manufacture methods thereof are described, for example, in JP-A-7-235255, JP-A-7-235275, JP-A-8-171849, and the like.
This surface conduction type electron emitting element is constituted of a pair of element electrodes
2
and
3
facing each other on a substrate
1
, and a conductive film
4
having an electron emitting area
5
connected between the element electrodes
2
and
3
. The electron emitting area
5
is a high electric resistance area formed by locally breaking, deforming or decomposing the conductive film
4
. Cracks or the like are formed in the electron emitting area
5
of the conductive thin film
4
. Electrons are emitted from the nearby area of the cracks. The electron emitting area and its nearby area is formed with a deposit film containing at least carbon.
The conductive film is preferably made of conductive fine particles in order to form the electron emitting area of a proper performance by the power conduction process (forming process) to be later described.
The manufacture process will be described briefly with reference to
FIGS. 4A
to
4
C.
First, element electrode
2
and
3
are formed on a substrate
1
by suitable methods such as printing, vacuum deposition, and photolithography techniques (FIG.
4
A).
Next, a conductive film
4
is formed. The conductive film
4
may be deposited by vacuum deposition, sputtering or the like and patterned, or it may be formed by coating liquid which contains source material of the conductive film.
For example, solution of metal organic compound is coated and thermally decomposed to form a metal or metal oxide. In this case, a fine particle film can be formed under the proper film forming conditions.
After the conductive film is formed, it may be patterned to a desired shape. Alternatively, as described in JP-A-9-69334, source material liquid may be coated by an ink jet apparatus or the like to make it have a desired shape, and thereafter it is thermally decomposed to form a conductive film having a desired shape without using a patterning process.
Next, an electron emitting area
5
is formed. This area may be formed by applying a voltage across the element electrodes
2
and
3
and flowing current through the conductive film to locally deform or decompose the conductive film (power conduction forming process). The voltage is preferably a pulse voltage. Waveforms of the pulse voltage may have a constant peak value as shown in
FIG. 5A
, a peak value gradually increasing with time as shown in
FIG. 5B
, or a combination of these. It is desired that while a forming pulse is not applied (during a period between pulses), a pulse having a suffi
Kishi Fumio
Mitome Masanori
Oda Hitoshi
Yamanobe Masato
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Ramsey Kenneth J.
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