Printing – Processes – Condition responsive
Reexamination Certificate
1999-09-21
2002-08-20
Funk, Stephen R. (Department: 2854)
Printing
Processes
Condition responsive
C101S217000
Reexamination Certificate
active
06435093
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a printing apparatus, and a method for manufacturing a print substrate, an electron source and an image displaying device using such a printing apparatus, and more particularly, it relates to a print substrate, an electron source and an image displaying device using such a printing apparatus, in which poor printing can be prevented when the print substrate such as a color filter and the electron source of the image displaying device are manufactured by printing.
2. Related Background Art
Recently, as image displaying devices for substituting for bulky and heavy Braun tubes, thin flat plate-shaped image displaying devices have been used. Among the flat plate-shaped image displaying devices, although liquid crystal displaying devices have been investigated and developed vigorously, the liquid crystal displaying device still has disadvantages in that an image becomes dark and that an angle of view is narrow. Further, as displays for substituting for the liquid crystal displaying devices, displays of self light emitting type, i.e., plasma displays, and displays using electron emitting elements such as fluorescent display tubes or surface conduction type electron emitting elements have been proposed. In the display of the self light emitting type, a brighter image can be obtained and the angle of view is wider, in comparison with the liquid crystal displaying device. On the other hand, recently, a Braun tube including a picture plane displaying portion having a dimension of 30 inches or more has been proposed, and larger Braun tubes have been requested. However, when the Braun tube is made large-sized, an installation space increases accordingly.
A flat plate-shaped display of self light emitting type is suitable for a large and bright display. The inventors paid attention to image displaying devices using electron emitting elements (among the flat plate-shaped image displaying devices of self light emitting type), particularly, an image displaying device using a surface conduction type electron emitting element proposed by M. I. Elinson et al. (Radio Engineering and Electronic Physics, No. 10, pp. 1290-1296, (1965)), in which emission of electrons could be achieved with a simple arrangement.
In the surface conduction type electron emitting element, electrons are emitted by flowing current through a thin film having a small area formed on a substrate in parallel with a surface of the film. As such surface conduction type electron emitting elements, a type using SnO
2
film proposed by M. I. Elinson et al., a type using Au film proposed by G. Dittmer (Thin Solid Films, No. 9, pp. 317-320 (1972)), a type using In
2
O
3
/SnO
2
film proposed by M. Hartwell & C. G. Fonstad (International Electron Devices Meeting Technical Digest, pp. 519-521 (1975)) and a type using carbon film proposed by Hisashi Araki et al. (Journal of the Vacuum Society of Japan, Vol. 26, page 22 (1983)) have been disclosed.
FIG. 10
is a schematic view showing an element structure proposed by M. Hartwell as a typical example of the surface conduction type electron emitting element. In
FIG. 10
, the reference numeral
1001
denotes a substrate. A conductive thin film
1004
consists of metal oxide film formed by spattering in an H-shaped pattern, and an electron emitting portion
1005
is formed by communication treatment called communication forming (described later). Incidentally, in
FIG. 10
, a distance L between element electrodes
1002
,
1003
is selected, for example, to be 0.5 to 1 mm and a width W′ is selected to be about 1 mm.
U. S. Pat. No. 5,066,883 discloses a surface conduction type electron emitting element in which fine particles for emitting electrons are dispersed and disposed between a pair of element electrodes. This electron emitting element can control an electron emitting position, in comparison with the abovementioned conventional surface conduction type electron emitting elements.
FIGS. 11A and 11B
show typical element structures of this surface conduction type electron emitting element.
FIG. 11A
is a plan view of the element structure and
FIG. 11B
is a sectional view of the element structure. In
FIGS. 11A and 11B
, the reference numeral
1101
denotes an insulation substrate;
1102
,
1103
denote element electrodes for achieving electrical connection; and
1104
denotes a conductive thin film. In this surface conduction type electron emitting element, a distance L between the pair of element electrodes is selected to be 0.01 to 100 &mgr;m, and a gap
1105
is formed in the conductive thin film
1104
. Further, it is desirable that each element electrode has a thickness d of 200 nm or less in order to achieve electrical connection to the conductive thin film.
The inventors have investigated maximizing an area of an image displaying device in which a plurality of such surface conduction type electron emitting elements are disposed on the substrate. Various methods for manufacturing an electron source substrate in which the electron emitting elements and wirings are disposed on the substrate were considered, and, among them is a method for forming element electrodes and parallel wires by photolithography.
On the other hand, a method for forming an electron source substrate including such a surface conduction type electron emitting element by using a printing technique such as screen printing, offset printing or the like was also considered.
The printing method is suitable for forming a pattern having a large area. A number of surface conduction type electron emitting elements can be formed on the substrate by manufacturing the element electrodes of the surface conduction type electron emitting element by the printing method. Further, the manufacturing cost can be reduced. In the formation of the element electrode by using the printing method, the offset printing technique suitable for forming the thin film is advantageous. An example of the offset printing technique being applied to formation of a circuit substrate is disclosed in Japanese Pat. Application Laid-open No. 4-290295.
According to the substrate disclosed in the above Japanese patent document, in order to eliminate poor coupling due to dispersion in dimension of electrode pitches caused by expansion/contraction of the pattern during the printing, angles of a plurality of coupling electrodes to be connected to parts of the circuit are changed. Further, in the above Japanese patent application, a technique in which the electrode pattern is formed by the offset printing is described.
Generally, in the offset printing, after ink is loaded on an intaglio having a desired pattern, a rotating barrel called a blanket contacts the intaglio so that the blanket receives the ink. Thereafter, the rotating blanket contacts a glass substrate, thereby transferring the desired ink pattern onto a surface of the glass substrate.
In this way, in consideration of movement of the ink, one printing cycle is completed by three main stages, i.e., the loading step, receiving step and transferring step.
The printing ink can appropriately be selected on the basis of a function of the pattern to be formed. That is to say, regarding an electrode pattern for a recording thermal head and the like, ink mainly including organic Au metal called an Au resinated paste is used, and, regarding a color filter used in a liquid crystal displaying device, ink in which R (red), G (green) and B (blue) pigments are dispersed or ink including organic coloring matter is used. The solvent for such inks may be an organic solvent such as terpineol or butyl Carbitol.
When the organic solvent is used as the ink solvent in this way, as the ink pattern is transferred from the blanket to the glass substrate, the ink solvent penetrates into the blanket (mainly cylindrical rubber) to enhance a cohesive force of ink and to reduce interfacial tension between the ink pattern and the blanket, with the result that the ink is apt to be transferred to the glass substrate. This fact is described
Midorikawa Satoko
Yamada Shuji
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Funk Stephen R.
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