Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
1999-07-16
2003-04-15
Mengistu, Amare (Department: 2673)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S075100, C345S076000, C345S087000, C345S100000, C345S103000, C345S075200, C313S310000, C313S336000
Reexamination Certificate
active
06549181
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an image display apparatus which uses a multi-electron beam source having a plurality of electron emission elements in a matrix layout, and a fluorescent screen having R, G, and B phosphors corresponding to these electron emission elements, and its driving method.
In recent years, flat-panel type, large-screen display apparatuses have been studied and developed extensively. The present inventors have been studying flat-panel type, large-screen display apparatuses using cold cathodes as electron emission elements.
Conventionally, as electron emission elements, two different types of elements, i.e., thermionic cathode elements and cold cathode elements, are known. Of these elements, as cold cathode elements, for example, a field emission element (to be referred to as an FE type element hereinafter), a metal/insulating layer/metal emission element (to be referred to as an MIM type element hereinafter), and the like are known.
Surface conduction type emission elements include, for example, elements described in M. I. Elinson,
Radio Eng. Electron Phys.,
10, 1290 (1965) and other elements to be described later.
The surface conduction type emission element utilizes a phenomenon in that electron emission occurs when currents are flowed in a direction parallel to the surface of a small-area thin film formed on a substrate. As surface conduction type emission elements, in addition to the above-mentioned element using an SnO
2
thin film by Elinson et al., an element using an Au thin film [G. Dittmer: “Thin Solid Films”, 9, 317 (1972)], an element using an In
2
O
3
/SnO
2
thin film [M. Hartwell and C. G. Fondtad: “IEEE Trans. ED Conf.”, 519 (1975)], an element using a carbon thin film [Hisashi Araki et al.:
Vacuum
, Vol. 26, No. 1, 22 (1983)], and the like have been reported.
FIG. 18A
is a plan view of the above-mentioned element by M. Hartwell et al, as a typical example of the element structure of such surface conduction type emission element. In
FIG. 18A
, reference numeral
3001
denotes a substrate; and
3004
, a conductive thin film consisting of a metal oxide formed by sputtering. The conductive thin film
3004
is formed into an H-shaped flat pattern, as shown in FIG.
18
A. An electron emission portion
3005
is formed by performing an energization process called energization forming (to be described later) on the conductive thin film
3004
. The interval L in
FIG. 18A
is set to fall within the range from 0.5 to 1 [mm], and the width W is set to be 0.1 [mm]. Note that
FIG. 18A
illustrates the electron emission portion
3005
as a rectangular portion formed at the center of the conductive thin film
3004
for the sake of illustrative convenience, but it does not necessarily faithfully express the position or shape of the actual electron emission portion.
In the above-mentioned surface conduction type emission elements such as the element by M. Hartwell et al., it is a common practice to form the electron emission portion
3005
by performing an energization process called energization forming on the conductive thin film
3004
before electron emission. More specifically, in the energization forming the electron emission portion
3005
is formed in an electrically high-resistance state in such a manner that the conductive thin film
3004
is locally destroyed, deformed, or denatured by applying a constant DC voltage or a DC voltage that increases at a very slow rate (e.g., about 1 V/min) across the two ends of the conductive thin film
3004
. Note that a fissure is formed on a portion of the locally destroyed, deformed, or denatured conductive thin film. When an appropriate voltage is applied to the conductive thin film after the energization forming, electron emission occurs in the neighborhood of the fissure.
On the other hand, as the FE type elements, for example, an element by W. P. Dyke & W. W. Dolan, “Field emission”,
Advance in Electron Physics,
8, 89 (1956), an element by C. A. Spindt, “Physical properties of thin-film field emission cathodes with molybdenum cones”,
J. Appl. Phys.,
47, 5248 (1976), and the like are known.
FIG. 18B
is a sectional view of the above-mentioned element by C. A. Spindt et al., as an example of the typical element arrangement of the FE type element. Referring to
FIG. 18B
, reference numeral
3010
denotes a substrate;
3011
, an emitter wiring layer or interconnect consisting of a conductive material;
3012
, an emitter cone;
3013
, an insulating layer; and
3014
, a gate electrode. This element causes electron emission from the distal end portion of the emitter cone
3012
by applying an appropriate voltage across the emitter cone
3012
and the gate electrode
3014
.
In another element arrangement of the FE type element, the emitter and the gate electrode are juxtaposed on the substrate to be nearly parallel to the substrate surface in place of the stacked structure shown in FIG.
18
B.
As an example of the MIM type element, an element by C. A. Mead, “Operation of Tunnel-emission Devices,
J. Appl. Phys.,
32, 646 (1961), or the like is known.
FIG. 19
shows a typical example of the element structure of the MIM type element.
FIG. 19
is a sectional view. Referring to
FIG. 19
, reference numeral
3020
denotes a substrate;
3021
, a metal lower electrode;
3022
, a thin insulating layer having a thickness of about 100 Å; and
3023
, a metal upper electrode having a thickness of about 80 to 300 Å. The MIM type element causes electron emission from the surface of the upper electrode
3023
upon application of an appropriate voltage across the upper and lower electrodes
3023
and
3021
.
The above-mentioned cold cathode elements do not require any heaters since they can obtain electron emission at relatively low temperatures as compared to the thermionic cathode elements. Therefore, the cold cathode element has a simpler structure than the thermionic cathode element, and a very small element can be formed. Even when a large number of elements are arranged on a substrate at a high density, the problem of, e.g., melting of the substrate by heat hardly occurs. The thermionic cathode element has a low response speed since it operates upon heating of a heater, while the cold cathode element has a high response speed.
For these reasons, extensive studies have been made to explore effective applications of the cold cathode element. For example, since the surface conduction type emission element has a simplest structure and allows easiest fabrication among the cold cathode elements, a large number of elements can be formed over a large area. Hence, the method of driving an array of a large number of elements has been studied, as disclosed in Japanese Patent Laid-Open No. 64-31332 by the present applicant.
As for applications of the surface conduction type emission element, for example, image forming apparatuses such as an image display apparatus, an image recording apparatus, and the like, a charged beam source, and the like have been studied. In particular, as an application to the image display apparatus, as disclosed in U.S. Pat. No. 5,066,883 and Japanese Patent Laid-Open Nos. 2-257551 and 4-28137 by the present applicant, an image display apparatus which uses a combination of the surface conduction type emission element and a phosphor that emits light upon irradiation of an electron beam has been studied. The image display apparatus which uses a combination of the surface conduction type emission element and the phosphor is expected to have higher characteristics than conventional image display apparatuses. For example, the image display apparatus of this type is superior to liquid crystal display apparatuses that have become popular in recent years, since it is of spontaneous emission type and requires no backlight, and has a wide viewing angle.
The method of driving an array of a large number of FE type elements is disclosed in, e.g., U.S. Pat. No. 4,904,895 by the present applicant. As an example of an app
Sakai Kunihiro
Suzuki Hidetoshi
Mengistu Amare
Nguyen Jimmy H.
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