Electric lamp or space discharge component or device manufacturi – Process – With assembly or disassembly
Reexamination Certificate
1999-04-29
2003-01-14
Ramsey, Kenneth J. (Department: 2879)
Electric lamp or space discharge component or device manufacturi
Process
With assembly or disassembly
C445S025000, C313S292000, C313S495000, C313S496000, C313S238000
Reexamination Certificate
active
06506087
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of manufacturing an image forming apparatus having an image forming means and a spacer in an envelope, the spacer maintaining a space in the envelope.
2. Related Background Art
Two types of electron emitting elements are known, a hot cathode element and a cold cathode element. As the cold cathode element, a surface conduction type electron emitting element (hereinafter described as a surface conduction type emitting element), a field emission type electron emitting element (hereinafter described as FE type element), a metal/insulating layer/metal type electron emitting element (hereinafter described as MIM type element) or the like are known.
The surface conduction type emitting element is described, for example, in “Radio Eng. Electron Phys.” by M. I. Elinson, 10, 1290, (1965) and other examples to be later described are known.
The surface conduction type emitting element utilizes the phenomenon that electrons are emitted when current flows through a thin film having a small area formed on a substrate in parallel to the film surface. Surface conduction type emitting elements heretofore reported include an element, for example, using an SnO
2
thin film by Elinson or others, an element using an Au thin film (“Thin Solid Films” by G. Dittmer, 9, 317 (1972), an element using an In
2
O
3
/SnO
2
thin film (“IEEE Trans. ED Conf.”, by M. Hartwell and C. G. Fonstad, 519 (1975)), an element using a carbon thin film (“Vacuum”, by Hisashi ARAKI, et al., Vol. 26, No. 1, 22 (1983)), and the like.
A typical example of the structure of a surface conduction type emitting element proposed by M.
Hartwell is shown in the plan view of FIG.
37
. In
FIG. 37
, reference numeral
3001
represents a substrate, and reference numeral
3004
represents a conductive thin film made of sputtered metal oxide. The conductive thin film
3004
is of an H-character shape. The conductive thin film
2004
is subject to an electric energization process called an electric energization forming process to be described later, to thereby form an electron emission area
3005
. A distance L is 0.5 to 1 mm, and a width W is 0.1 mm. In
FIGS. 27A and 27B
, although the electron emission area
3005
is schematically shown as a rectangle at the center of the conductive thin film
3004
for the purpose of simplicity, this does not reflect the actual shape and position of the electron emission area, with high fidelity.
The electron emission area
3005
of the element proposed by M. Hartwell or the other elements described above are generally formed by subjecting the conductive thin film
3004
to an electric energization process called an electric energization forming process to emit electrons. With the electric energization, a constant d.c. voltage or a d.c. voltage rising at a very slow rate, e.g., at 1 V/min, is applied across opposite ends of the conductive film
3004
to locally destroy, deform or decompose the conductive thin film
3004
and form the electron emission area having an electrically high resistance. Cracks are formed in the conductive thin film
3004
where it is locally destroyed, deformed or decomposed. If a proper voltage is applied to the conductive thin film
3004
after this electric energization, electrons are emitted form an area near the cracks.
As the FE type element, those elements are known which are described, for example, in “Field emission”, Advance in Electron Physics, by W. P. Dyke and W. W. Dolan, 8, 89 (1956) or in “Physical properties of thin-film field emission cathodes with molybdenum cones”, J. Appl. Phys. by C. A. Spindt, 47, 5248 (1976).
A typical example of the structure of an FE type element proposed by C. A. Spindt is shown in the cross sectional view of FIG.
38
. In
FIG. 38
, reference numeral
3010
represents a substrate, reference numeral
3011
represents an emitter layer made of conductive material, reference numeral
3012
represents an emitter cone, reference numeral
3013
represents an insulating layer, and reference numeral
3014
represents a gate electrode
3014
. Electrons are emitted from the tip of the emitter cone
3012
of this element through an electric field emission by applying a proper voltage between the emitter cone
3012
and gate electrode
3014
.
Instead of the lamination structure shown in
FIG. 38
, the FE type element having a different structure is also known in which an emitter and a gate electrode are formed on a substrate generally in parallel to the substrate surface.
As an example of the MIM type element, an element described in “Operation of tunnel-emission Devices”, by C. A Mead, J. Appl. Phys., 32, 646 (1961) and other elements are known. A typical example of the structure of an MIM type element is shown in the cross sectional view of FIG.
39
. In
FIG. 39
, reference numeral
3020
represents a substrate, reference numeral
3021
represents a lower electrode made of metal, reference numeral
3022
represents a thin insulating layer of about 100 angstroms in thickness, and reference numeral
3023
represents an upper electrode made of metal and having a thickness of about 80 to 300 angstroms. Electrons are emitted from the surface of the upper electrode
3023
of the MIM type element by applying a proper voltage between the upper electrode
3023
and lower electrode
3021
.
The cold cathode elements described above can emit electrons at a temperature lower than hot cathode elements, and do not require a heater. Therefore, the structure is simpler than that of a hot cathode element and a fine element can be manufactured. Also, even if a number of elements are formed on a substrate at a high density, thermal melting of a substrate is not likely to occur. Although a response speed of a hot cathode element is low because of heating the heater, a response speed of a cold cathode element is high.
From the above reasons, applications of cold cathode elements have been studied vigorously.
For example, since a surface conduction type emitting element among cold cathode elements is simple in structure and easy to manufacture, it has the advantage that a number of elements can be formed in a large area. As disclosed in JP-A-64-31332 by the same assignee as the present assignee, a method of driving a number of elements has been studied. As the applications of surface conduction type emitting elements, an image forming apparatus for an image display device, an image recording device, a charge beam source, and the like have been'studied.
As the application to an image display apparatus, an image display apparatus utilizing a combination of surface conduction type emitting elements and a fluorescent member which emits light upon application of an electron beam, has been studied as disclosed in U.S. Pat. No. 5,066,883, JP-A-2-257551, JP-A-4-28137 by the same assignee as the present assignee. An image display apparatus utilizing a combination of surface conduction type emitting elements and a fluorescent member is expected to have more excellent characteristics than a conventional image display apparatus of other types. For example, as compared to a recently prevailing liquid crystal display apparatus, the image display apparatus of this type does not require back light because of self light emission and has a broad angle of view.
A method of driving a number of FE type elements is disclosed in U.S. Pat. No. 4,904,895 by the same assignee as the present assignee. An example of the application of FE type elements to an image display apparatus is a flat panel type display apparatus reported by R. Meyer in “Recent Development on Microtips Display st LETI”, Tech. Digest of 4th int. Vacuum Microelectronics Conf., Nagahama, pp. 6-9 (1991).
An example of the application of a number of MIM type elements to an image display apparatus is disclosed in JP-A-3-55738 by the same assignee as the present assignee.
Of image forming apparatuses utilizing the above-described electron emitting elements, a flat panel type display apparatus having a thin depth requires less
Fushimi Masahiro
Sakai Kunihiro
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Ramsey Kenneth J.
Santiago Mariceli
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