Electric lamp or space discharge component or device manufacturi – Process – With assembly or disassembly
Reexamination Certificate
2000-05-31
2001-08-07
Ramsey, Kenneth J. (Department: 2879)
Electric lamp or space discharge component or device manufacturi
Process
With assembly or disassembly
C445S021000
Reexamination Certificate
active
06270389
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a metal-containing composition that can be used effectively for manufacturing an electron-emitting device comprising an electroconductive film containing therein an electron-emitting region and arranged between a pair of device electrodes and it also relates to an electron-emitting device formed by using such a composition, an electron source comprising a number of such devices and an image-forming apparatus realized by using such an electron source.
2. Related Background Art
The use of surface conduction electron-emitting devices in a cold cathode type electron source is known. A surface conduction electron-emitting device is realized by utilizing the phenomenon that electrons are emitted out of a small thin film formed on a substrate when an electric current is forced to flow therethrough in parallel with the film surface. While Elinson proposes the use of SnO
2
thin film for a device of this type, the use of Au thin film is proposed in [G. Dittmer: “Thin Solid Films”, 9, 317 (1972)] whereas the use of In
2
O
3
/SnO
2
and that of carbon thin film are discussed respectively in [M. Hartwell and C. G. Fonstad: “IEEE Trans. ED Conf.”, 519 (1975)] and [H. Araki et al.: “Vacuum”, Vol. 26, No. 1, p. 22 (1983)].
FIG. 17
of the accompanying drawings schematically illustrates a typical surface conduction electron-emitting device proposed by M. Hartwell. In
FIG. 17
, reference numeral
171
denotes a substrate. Reference numeral
174
denotes an electroconductive film, part of which eventually makes an electron-emitting region
173
when it is subjected to an electrically energizing process referred to as “energization forming” as will be described hereinafter. In
FIG. 17
, the device electrode has a length L of 0.5 to 1 mm and a width W of 0.1 mm.
Conventionally, an electron emitting region
173
is produced in a surface conduction electron-emitting device by subjecting the electroconductive film for forming an electron-emitting region of the device to a current conduction treatment, which is referred to as “energization forming”. In an energization forming process, a voltage is applied to the opposite ends of the electroconductive thin film for forming an electron-emitting region by way of the device electrodes to partly destroy, deform or transform the film and produce an electron-emitting region
173
which is electrically highly resistive. A fissure or fissures may be produced in the electroconductive film
174
as a result energization forming to make an electron-emitting region
173
of fissure so that electrons may be emitted from the fissure itself or from an area surrounding the fissure.
Note that, once subjected to an energization forming process, a surface conduction electron-emitting device comes to emit electrons from its electron emitting region
173
whenever an appropriate voltage is applied to the electroconductive film
124
to make an electric current run through the device.
Since a surface conduction electron-emitting device having a configuration as described above is structurally simple, a large number of such devices can advantageously be arranged over a large area. Efforts have been made to exploit this advantage and the devices proposed to exploit this characteristic feature of surface conduction electron-emitting device include charged beam sources and display apparatuses. Japanese Patent Applications Laid-Open Nos. 64-31332, 1-283749 and 2-257552 proposes an electron source comprising a large number of surface conduction electron-emitting devices arranged in parallel rows, where the devices of each row are commonly wired in a ladder-like arrangement. While flat-type displays using liquid crystal have come into the mainstream of image-forming apparatuses to push out, at least partly, CRT displays, the liquid crystal display has a drawback of requiring the use of a back light because it is not of emission type and does not beam unless irradiated with light. Therefore, there is a consistent demand for emission type displays. The U.S. Pat. No. 5,066,883 discloses an image-forming apparatus realized by combining an electron source comprising a large number of surface conduction electron-emitting devices and an fluorescent body that emits visible light when irradiated with electrons emitted from the electron source.
An electroconductive film for forming an electron-emitting region is typically produced by depositing an electroconductive material on an insulating substrate directly by means of an appropriate deposition technique such evaporation or sputtering. An electroconductive film for forming an electron-emitting region may also be produced by applying, drying and baking a solution of a metal compound to remove the non-metal components of the solution by pyrolysis and form a thin film of metal or metal oxide. The latter technique is advantageous for producing a large number of devices on a substrate having a large surface area because it does not involve the use of a vacuum apparatus.
Materials that can be used for forming an electroconductive film of metal or a metal compound by way of an liquid applying, drying and baking process include a liquid containing a metal resinate or a compound of precious metal such as gold and resin and a solution prepared by dissolving an organic complex of organic amine and transition metal into an organic solvent. In short, electron-emitting devices can be manufactured from various different solutions.
It is well known, on the other hand, that many halides and oxyacid salts of transition metals are water soluble and produce corresponding metals or metal oxides by pyrolysis when heated to high temperature.
However, known metal compositions that can be used for manufacturing electron-emitting devices comprising an electroconductive film that contains an electron-emitting region such as surface conduction electron-emitting devices are accompanied by a number of problems as will be described hereinafter.
While it is true that many halides and oxyacid salts of transition metals are water soluble and produce corresponding metals or metal oxides by pyrolysis when heated to high temperature, the temperature for pyrolyzing such compounds is typically higher than 800° C., although it is not desirable to prepare electroconductive films for surface conduction electron-emitting devices by pyrolysis involving such high temperature. A number of surface conduction electron-emitting devices are formed on the surface of an appropriate substrate that carries a pattern of wires for wiring the devices. In other words, if such a pattern of wires is prepared on the substrate along with the electrodes of surface conduction electron-emitting devices before the electroconductive films of the devices are formed, the conditions for producing the electroconductive films by baking have to be carefully selected in order to avoid damages that may be given rise to the patterned wires and/or the electrodes by heat. More specifically, if the substrate is a silicon wafer or a glass substrate, the heating and baking process for producing electroconductive films on the substrate has to be conducted at temperature lower than 600° C., preferably at about 500° C., where the material of the wires such as copper or silver is not thermally degraded. Thus, any materials that have to be heated to temperature higher than 500° C. for producing electroconductive films may not suitably be used for manufacturing surface conduction electron-emitting devices. Aqueous solutions of halides or oxyacid salts of transition metals that require high baking temperature may not be used for preparing electroconductive films in the manufacture of surface conduction electron-emitting devices if such compounds are easily soluble to water.
Meanwhile, a number of organic metal complexes of a metal resinate or organic amine and a transition metal that may be easily decomposed at relatively low temperature lower than 500° C. are known. Since most of the organic metal compounds that
Furuse Tsuyoshi
Iwaki Takashi
Kobayashi Shin
Miura Naoko
Tomida Yasuko
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Hopper Todd Reed
Ramsey Kenneth J.
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