Electric lamp and discharge devices: systems – Plural power supplies – Plural cathode and/or anode load device
Reexamination Certificate
2001-11-20
2003-11-25
Wong, Don (Department: 2821)
Electric lamp and discharge devices: systems
Plural power supplies
Plural cathode and/or anode load device
C345S055000, C345S076000
Reexamination Certificate
active
06653794
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to an image display device having a display panel in which a plurality of cold cathode devices are arranged in matrix.
Related Background Art
Up to now, there have been known two kinds of electron emitting devices, that is, a hot cathode device and a cold cathode device. In the cold cathode device among them, there have been known, for example, a surface conduction electron emitting device, a field emission device (hereinafter referred to as “FE”), a metal/insulator/metal electron emitting device (hereinafter referred to as “MIM”), and the like.
As the surface conduction electron emitting device, there have been known, for example, M. I. Elinson, Radio Eng. Electron Phys., 10, 1290, (1965), and other examples that will be described later. The surface conduction electron emitting device is so designed as to use a phenomenon in which a current is allowed to flow in parallel with a film surface on a thin film of a small area formed on a substrate to cause electron emission. As the surface conduction electron emitting device, there have been reported the above-mentioned electron emitting device using SnO
2
thin film by Elinson et al., as well as an electron emitting device using an Au thin film (G. Dittmer: “Thin Solid Films”, 9, 317 (1972), an electron emitting device using an In
2
O
3
/SnO
2
thin film (M. Hartwell and C. G. Fonstad: “IEEE Trans. ED Conf.”, 519 (1975)), an electron emitting device using a carbon thin film (Hisashi Araki, et al.: Vacuum, Vol. 26, No. 1, 22 (1983)), and the like.
As a typical example of the device structure of those surface conduction electron emitting devices, a plan view of the above-mentioned device by M. Hartwell, et al. is shown in FIG.
19
. In the figure, reference numeral
3001
denotes a substrate; and
3004
is an electroconductive thin film made of a metal oxide formed through sputtering. The electroconductive thin film
3004
is formed into an H-shaped plane as shown in the figure. The electroconductive film
3004
is subjected to energization called “energization forming” which will be described later, to thereby form an electron emitting portion
3005
. In the figure, an interval L is set to 0.5 to 1 mm, and W is set to 0.1 mm. For convenience of the drawing, the electron emitting portion
3005
is formed into a rectangular shape in the center of the electroconductive thin film
3004
, but this is schematic and does not faithfully represent the position and shape of the actual electron emitting portion.
In the above-mentioned surface conduction electron emitting devices including the device proposed by M. Hartwell et al., it is general that the electron emitting portion
3005
is formed by subjecting the electroconductive thin film
3004
to the energization that is called “energization forming” prior to electron emission. That is, the energization forming is that a constant d.c. voltage, or a d.c. voltage that steps up at a very slow rate of, for example, about 1 V/min is applied between both ends of the electroconductive thin film
3004
to energize the electroconductive thin film
3004
to locally destroy, deform or deteriorate the electroconductive thin film
3004
, thereby forming the electron emitting portion
3005
which is in an electrically high resistant state. Note that a fissure occurs in a part of the electroconductive thin film
3004
that has been locally destroyed, deformed or deteriorated. In the case where an appropriate voltage is applied to the electroconductive thin film
3004
after the energization forming has been made, electron emission is conducted in the vicinity of the fissure.
Also, as the FE type example, there have been known, for example, 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 molybdenum cones”, J. Appl. Phys., 47, 5248 (1976), etc.
As a typical example of the FE type device structure, a cross-sectional view of the above-mentioned device proposed by C. A. Spindt, et al. is shown in FIG.
20
. In the figure, reference numeral
3010
denotes a substrate,
3011
is an emitter wiring made of electroconductive material,
3012
is an emitter cone,
3013
is an insulating layer, and
3014
is a gate electrode. This device conducts the electric field electron emission from a leading portion of the emitter cone
3012
by applying an appropriate voltage between the emitter cone
3012
and the gate electrode
3014
. Also, as another device structure of the FE type, there is an example in which the emitter and the gate electrode are arranged on the substrate substantially in parallel with the substrate plane instead of the laminate structure shown in FIG.
20
.
Also, as the MIM type example, there have been known, for example, C. A. Mead, “Operation of tunnel-emission Devices”, J. Appl. Phys., 32, 646 (1961), and the like. A typical example of the device structure of the MIM type is shown in FIG.
21
. The figure is a cross-sectional view in which reference numeral
3020
denotes a substrate,
3021
denotes a lower electrode made of metal,
3022
denotes a thin insulating layer having a thickness of about 100 Å,
3023
denotes an upper electrode made of metal having a thickness of about 80 to 300 Å. In the MIM type, an appropriate voltage is applied between the upper electrode
3023
and the lower electrode
3021
to conduct the electron emission from the surface of the upper electrode
3023
.
The above-mentioned cold cathode device requires no heater for heating because the electron emission can be obtained at a low temperature as compared with the hot cathode device. Therefore, the cold cathode device is simpler in structure than the hot cathode device, and a fine device can be prepared. Also, it is difficult that a problem such as the heat melting of the substrate occurs even if a large number of devices are arranged on the substrate with a high density. Also, because the hot cathode device operates due to the heat from the heater, there is an advantage in that a response speed is high in case of the cold cathode device which is different from the low response speed. For that reason, a study for applying the cold cathode device has been increasingly conducted.
For example, the surface conduction electron emitting device is advantageous in that a large number of devices can be formed over a large area since the device is particularly simple in structure and easy in manufacture among the cold cathode devices. Therefore, as disclosed in Japanese Patent Application Laid-Open No. 64-31332 made by the present applicant, for example, a method in which a large number of devices are arranged for driving has been studied. Also, in the application of the surface conduction electron emitting device, for example, an image forming apparatus such as an image display device or an image recording device, an electric charge beam source and the like have been studied.
In particular, as the application of the surface conduction electron emitting device to the image display device, there has been studied the image display device using the combination of the surface conduction electron emitting device with a phosphor that emits light upon irradiation of an electron beam thereto as disclosed in, for example, U.S. Pat. No. 5,066,883, Japanese Patent Application Laid-Open No. 2-257551 and Japanese Patent Application Laid-Open No. 4-28137 made by the present applicant. The image display device using the combination of the surface conduction electron emitting device with the phosphor is expected to have the characteristics superior to that of the image display device of other conventional systems. For example, it can be said that such an image display device is superior to a liquid crystal display device that has been spread in recent years in view of the fact that backlight is not required because of a self light emitting type and the fact that an angle of visibility is wide.
Also, a method in which a large number of
Abe Naoto
Sagano Osamu
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