Electric lamp and discharge devices – Discharge devices having a thermionic or emissive cathode
Reexamination Certificate
2000-11-28
2003-12-02
Patel, Nimeshkumar D. (Department: 2879)
Electric lamp and discharge devices
Discharge devices having a thermionic or emissive cathode
C313S495000, C313S292000
Reexamination Certificate
active
06657368
ABSTRACT:
This application is a continuation of International Application No. PCT/JP99/04872, filed on Sep. 8, 1999, which claims the benefit of Japanese Patent Applications No. 10-254343, filed on Sep. 8, 1998 and No. 10-285763, filed on Oct. 7, 1998.
TECHNICAL FIELD
The present invention relates to an electron beam device and, more particularly, to an electron beam device having a spacer for maintaining the interval between an electron source and a member to be irradiated with electrons, a method for producing a charging-suppressing member used in the electron beam device, and an image forming apparatus.
BACKGROUND ART
Conventionally, electron-emitting elements are mainly classified into two types of elements: a thermionic cathode element and cold cathode element. Of these elements, the thermionic cathode element is used in a cathode ray tube and the like. Known examples of the cold cathode element are surface-conduction type electron-emitting elements, field emission type electron-emitting elements (to be referred to as FE type electron-emitting elements hereinafter), and metal/insulator/metal type electron-emitting elements (to be referred to as MIM type electron-emitting elements hereinafter).
The surface-conduction type electron-emitting element utilizes the phenomenon that electrons are emitted from a small-area thin film formed on a substrate by flowing a current parallel through the film surface. The surface-conduction type electron-emitting element includes an electron-emitting element using an SnO
2
thin film by Elinson [M. I. Elinson, Radio Eng. Electron Phys., 10, 1290, (1965)], an electron-emitting element using an Au thin film [G. D Mitter, “Thin Solid Films”, 9,317 (1972)], an electron-emitting element using an In
2
O
3
/SnO
2
thin film [M. Hartwell and C. G. Fonstad, “IEEE Trans. ED Conf.”, 519 (1975)], and an electron-emitting element using a carbon thin film [Hisashi Araki et al., Vacuum, Vol. 26, No. 1, 22 (1983)].
FIG. 24
is a plan view showing an element by M. Hartwell et al. described above as a typical example of the element structures of these surface-conduction type electron-emitting elements. In
FIG. 24
, reference numeral
1
denotes a substrate; and
2
, a conductive thin film made of a metal oxide formed by sputtering. This conductive thin film
2
has an H-shaped pattern, as shown in FIG.
24
. The conductive thin film
2
undergoes electrification processing called electrification forming to form an electron-emitting portion
3
.
In electrification forming, a constant DC voltage or a DC voltage which rises at a very low rate of, e.g., 1 V/min is applied between the two ends of the conductive thin film
2
to partially destroy or deform the conductive thin film
2
, thereby forming the electron-emitting portion
3
with an electrically high resistance. Note that the destroyed or deformed part of the conductive thin film
2
forms a fissure. When an appropriate voltage is applied to the conductive thin film
2
after electrification forming, electrons are emitted by the electron-emitting portion
3
near the fissure.
After electrification forming processing, a voltage pulse is periodically applied in a vacuum atmosphere as electrification activation processing, thereby depositing on the electron-emitting portion
3
carbon or a carbon compound derived from an organic compound present in the vacuum atmosphere. This electrification activation processing enhances a stable electron emission effect.
Known examples of the FE type electron-emitting element are described in W. P. Dyke & W. W. Dolan, “Field Emission”, Advance in Electron Physics, 8, 89 (1956) and C. A. Spindt, “Physical Properties of Thin-Film Field Emission cathodes with molybdenium Cones”, J. Appl. Phys., 47, 5248 (1976).
FIG. 24
is a sectional view showing an element by C. A. Spindt et al. described above as a typical example of the element structure of the FE type electron-emitting element. In
FIG. 24
, reference numeral
4
denotes a substrate;
5
, an emitter wiring line made of a conductive material;
6
, an emitter cone made of molybdenum or the like;
7
, an insulating layer; and
8
, a gate electrode. This electron-emitting element emits electrons toward a high-voltage electrode arranged above the element by applying a proper voltage between the emitter cone
6
and the gate electrode
8
, and emitting a field from the distal end of the emitter cone
6
.
As another element structure of the FE type electron-emitting element, in addition to the stacked structure having a conical shape as shown in
FIG. 24
, an emitter and gate electrode are arranged on a substrate to be almost parallel to the substrate plane.
A known example of the MIM type electron-emitting element is described in C. A. Mead, “Operation of Tunnel-Emission Devices, J. Appl. Phys., 32,646 (1961).
FIG. 25
shows a typical example of the element structure of the MIM type electron-emitting element.
FIG. 25
is a sectional view. In
FIG. 25
, reference numeral
9
denotes a substrate;
10
, a lower electrode made of a metal;
11
, an insulating layer as thin as about 100 Å; and
12
, an upper electrode made of a metal with a thickness of about 80 to 300 Å. The MIM type electron-emitting element emits electrons from the surface of the upper electrode
12
by applying a proper voltage between the upper electrode
12
and the lower electrode
10
.
Compared to a thermionic cathode element, various cold cathode elements described above can emit electrons at a low temperature, and does not require any heater. Thus, the cold cathode element has a simpler structure than the thermionic cathode element, and can form a small element. Even if many elements are arranged on a substrate at a high density, problems such as thermal melting of the substrate hardly arise. In addition, the response speed of the thermionic cathode element is low because it operates upon heating by a heater, whereas the response speed of the cold cathode element is high.
As applications of cold cathode elements, there are image forming apparatuses such as an image display apparatus and image recording apparatus, charge beam sources, and the like.
Particularly as applications of cold cathode elements to an image display apparatus, as disclosed in U.S. Pat. No. 5,066,883 by the present applicant and Japanese Patent Application Laid-Open Nos. 2-257551 and 4-28137, an image display apparatus using a combination of a surface-conduction type electron-emitting element and a fluorescent substance which is irradiated with an electron beam to emit light has been studied. That is, there is an image display apparatus using a combination of a surface-conduction type electron-emitting element and a fluorescent substance which is irradiated with an electron beam to emit light has been studied.
A known application of FE type electron-emitting elements to an image display apparatus is a flat display apparatus reported by R. Meyer et al. [R. Meyer: “Recent Development on Microtips Display at LETI”, Tech. Digest of 4th Int. Vacuum Micro-electronics Conf., Nagahama, pp. 6 to 9 (1991)].
An application of many MIM type electron-emitting elements arranged side by side to an image display apparatus is disclosed in Japanese Patent Application Laid-Open No. 3-55738 by the present applicant.
Of these electron-emitting elements, the surface-conduction type electron-emitting element has a simple structure and can be easily manufactured, and many elements can be easily formed in a wide area.
An image display apparatus using a combination of a surface-conduction type electron-emitting element and fluorescent substance is superior to a liquid crystal display apparatus in that the image display apparatus does not require any backlight because of self-emission type and that the view angle is wide.
In a flat image display apparatus, many electron-emitting elements are arranged on a flat substrate, and fluorescent substances for emitting light by electrons are arranged to face the electron-emitting elements. The electron-emitting ele
Fushimi Masahiro
Kosaka Yoko
Mitsutake Hideaki
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Patel Nimeshkumar D.
Santiago Mariceli
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