Electric lamp and discharge devices: systems – Plural power supplies – Plural cathode and/or anode load device
Reexamination Certificate
2001-08-31
2002-11-26
Philogene, Haissa (Department: 2821)
Electric lamp and discharge devices: systems
Plural power supplies
Plural cathode and/or anode load device
C315S169100, C313S495000, C313S496000, C313S497000
Reexamination Certificate
active
06486610
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electron-beam generation device, and an image forming apparatus utilizing the electron-beam generation device.
2. Description of the Related Art
Two types of electron emitting devices, i.e., thermionic-cathode devices and cold-cathode devices, have been known. For example, surface-conduction-type emitting devices, field-emission-type (hereinafter abbreviated as “FE-type”) devices, and metal/insulator-metal-type (hereinafter abbreviated as “MIM-type”) emitting devices have been known as the cold-cathode-type devices.
For example, a device described in “M. I. Elinson, Radio Eng. Electron Phys., 10, 1290 (1965)” or other devices to be described below have been known as the surface-conduction-type emitting devices.
The surface-conduction-type emitting devices utilize the phenomenon that electron emission occurs by causing a current to flow in a direction parallel to the surface of a small-area thin film formed on a substrate. In addition to the device described by M. I. Elinson which utilizes a SnO
2
thin film, a device utilizing an Au thin film (G. Dittmer: “Thin Solid Films”, 9, 317 (1972)), a device utilizing an In
2
O
3
/SnO
2
thin film (M. Hartwell and C. G. Fonstad: “IEEE Trans. ED Conf.”, 519 (1975)), and a device utilizing a carbon thin film (H. Araki et al.: Shinku (J. Vac. Soc. Japan), vol. 26, no. 1, 22 (1983)) have been reported as the surface-conduction-type emitting devices.
FIG. 18
is a plan view of the above-described device by M. Hartwell et al., serving as a typical example of the configuration of a surface-conduction-type emitting device.
In
FIG. 18
, reference numeral
3001
represents a substrate. A conductive thin film
3004
is made of a metal oxide formed by sputtering.
As shown in
FIG. 18
, the conductive thin film
3004
is provided in the form of an H-shaped plane. By performing current-supply processing, called current-supply forming, on the conductive thin film
3004
, an electron emitting portion
3005
is formed. In
FIG. 18
, a distance L is set to 0.5-1 mm, and a width W is set to 0.1 mm.
In order to facilitate understanding, the electron emitting portion
3005
is shown in the shape of a rectangle at the center of the conductive thin film
3004
. However, this is a schematic diagram, which does not faithfully represent the position and the shape of the actual electron emitting portion.
In the above-described surface-conduction-type emitting devices inclusive of the device by M. Hartwell et al., the electron emitting portion
3005
is generally formed by performing current-supply processing called current-supply forming on the conductive thin film
3004
before performing electron emission.
That is, in the current-supply forming, current is supplied by applying a constant DC voltage or a DC voltage that increases at a very slow rate, such as about 1V/min, between both ends of the conductive thin film
3004
, to locally destruct, deform or alter the conductive thin film
3004
in order to form the electron emitting portion
3005
that has a high electric resistance.
Cracks are generated at locally destructed, deformed or altered portions of the conductive thin film
3004
.
When an appropriate voltage is applied to the conductive thin film
3004
after the current-supply forming, electron emission occurs at portions near the cracks.
For example, a device described in “W. P. Dyke & W. W. Dolan, “Field emission”, Advance in Electron Physics, 8, 89 (1956)”, and a device described in “C. A. Spindt, “Physical properties of thin-film field emission cathodes with molybdenum cones”, J. Appl. Phys., 47, 5248 (1976)” have been known as the FE-type devices.
FIG. 19
is a cross-sectional view of the above-described device by C. A. Spindt et al., serving as a typical example of the configuration of a FE-type device.
In
FIG. 19
, there are shown a substrate
3010
, an emitter wire
3011
made of a conductive material, an emitter cone
3012
, an insulating layer
3013
, and a gate electrode
3104
.
In this device, by applying an appropriate voltage between the emitter cone
3012
and the gate electrode
3014
, field emission occurs from the distal end of the emitter cone
3012
.
In another FE-type device, an emitter and a gate electrode are disposed on a substrate so as to be substantially parallel to the plane of the substrate, in contrast to the laminated structure shown in FIG.
19
.
For example, a device described in “C. A. Mead, “Operation of tunnel-emission devices”, J. Appl. Phys., 32, 646 (1961)”, and the like have been known as the MIM-type devices.
FIG. 20
is a cross-sectional view illustrating a typical example of the configuration of an MIM-type device. In
FIG. 20
, there are shown a substrate
3020
, a lower electrode
3021
made of a metal, a thin insulating film having a thickness of about
100
angstroms, and an upper electrode
3023
made of a metal having a thickness of about 80-300 angstroms. In this MIM-type device, by applying an appropriate voltage between the upper electrode
3023
and the lower electrode
3021
, electron emission occurs from the surface of the upper electrode
3023
.
In the above-described cold-cathode devices, since electron emission can be obtained at a lower temperature than in the thermionic-cathode devices, heaters are unnecessary.
Accordingly, the cold-cathode devices have simpler structures than the thermionic-cathode devices, and therefore small devices can be formed. In addition, even if a large number of devices are disposed on a substrate at high density, problems, such as thermal melt of a substrate, and the like, will hardly arise. Furthermore, in contrast to a slow response speed of the thermionic-cathode devices operating by being heated, a high response speed is obtained for the cold-cathode devices.
Accordingly, applications of the cold-cathode devices are widely being studied. For example, the surface-conduction-type emitting devices are advantageous when forming a large number of devices on a large area, since they have simpler structures and can be more easily manufactured than other types of surface-conduction-type emitting devices.
Hence, as disclosed, for example, in Japanese Patent Application Laid-Open (Kokai) No. 64-31332 (1989) by the assignee of the present application, methods for arranging and driving a large number of devices have been studied.
As for applications of the surface-conduction-type emitting devices, for example, image forming apparatuses, image recording apparatuses and charged beam sources are being studied.
Particularly, as for applications to image forming apparatuses, as disclosed, for example, in U.S. Pat. No. 5,066,883, and Japanese Patent Application Laid-Open (Kokai) Nos. 2-257551 (1990) and 4-28137 (1992) by the assignee of the present application, image forming apparatuses in which surface-conduction-type emitting devices and phosphors emitting light by collision with electrons are combined have been studied.
Image forming apparatuses combining surface-conduction-type emitting devices and phosphors are expected to have better properties than other conventional image forming apparatuses.
For example, these image forming apparatuses are superior to liquid-crystal displays which have recently been widely spread in that a backlight is not required and the angle of visibility is wide because these apparatuses emit light by themselves.
Methods for arranging and driving a large number of FE-type devices are disclosed, for example, in U.S. Pat. No. 4,904,895 by the assignee of the present application, and the like.
As an example of application of FE-type devices to an image forming apparatus, a flat display device reported by R. Mayer et al. (R. Meyer: “Recent Development on Microtips Display at LETI”, Tech. Digest of 4th Int. Vacuum Microelectronics Conf., Nagahama, pp. 6-9 (1991)) has been known.
An example of application of a large number of MIM-type devices to an image forming apparatus is disclosed, for example, in Japanese Patent Application Laid-Open (Kokai) No. 3-55738 (1991
Kojima Shinsuke
Onishi Tomoya
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