Electric lamp and discharge devices – With support and/or spacing structure for electrode and/or... – Supporting and/or spacing elements
Reexamination Certificate
1999-06-25
2002-03-05
Day, Michael H. (Department: 2879)
Electric lamp and discharge devices
With support and/or spacing structure for electrode and/or...
Supporting and/or spacing elements
C313S495000, C313S422000
Reexamination Certificate
active
06353280
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a spacer provided in a container including an electron-emitting device, an image-forming apparatus comprising an electron-emitting device, an image-forming member, and a spacer, in a container, and a manufacturing method thereof.
2. Related Background Art
As an image-forming apparatus using an electron-emitting device, an electron beam display panel of a flat type has been conventionally known in which an electron source substrate on which a number of cold cathode electron emitting devices are formed is opposed in parallel to an anode substrate comprising a transparent electrode and a fluorescent member and which is exhausted to be in a vacuum.
Among image-forming apparatuses of this kind, an image-forming apparatus using a field emission electron-emitting device is, for example, disclosed in I. Brodie, “Advanced technology: flat cold-cathode CRTs”, Information Display, 1/89, 17(1989). Another image-forming apparatus using a surface conduction electron-emitting device is, for example, disclosed in Japanese Patent Application Laid-open No. 7-45221.
An electron beam display panel of a flat surface type can realize a lighter weight and a larger screen in comparison with a cathode ray tube (CRT) display apparatus which is widely used at present, and can provide an image with a higher luminance and a higher quality in comparison with a flat type display panel including, for example, a plasma display or a liquid crystal display.
FIGS. 14 and 15
are views schematically showing a structure of a conventional flat type electron beam display panel, as an example of an image-forming apparatus using an electron-emitting device. See Japanese Patent Application Laid-open No. 8-180821.
FIG. 15
is a cross-section cut along line
15
—
15
in FIG.
14
.
The structure of the conventional flat type electron beam display panel shown in
FIGS. 14 and 15
will now be explained in details below. In these figures, reference
141
denotes a rear plate on which an electron source substrate
144
is provided, and reference
142
denotes a face plate as an anode substrate. These substrates are connected with each other and also with a supporting frame (or outer frame)
143
by a connecting portion made of frit glass or the like, thereby forming a vacuum envelope. Reference
145
denotes an electron-emitting element. Reference
146
a
(e.g., a scanning electrode) and reference
146
b
(e.g., a signal electrode) are electrode wires and are connected to the electron-emitting device
145
. References
147
a
and
147
b
denote a scanning line and a signal line, respectively. Reference
148
is a glass substrate as a base member of the face plate. Reference
149
denotes a fluorescent member, and reference
150
denotes a metal back. Reference
151
is a spacer which maintains the rear plate
141
and the face plate
142
with a predetermined distance inserted therebetween, and is provided as a support member against an air pressure.
To form an image by the electron beam display panel, scanning lines
147
a
and signal lines
147
b
arranged in a matrix are sequentially applied with a predetermined voltage, to selectively drive predetermined electron-emitting devices
145
positioned at cross points of the matrix. Electrons emitted therefrom are irradiated onto a fluorescent member
149
to obtain a luminance point at a predetermined position. Note that a metal back (anode)
150
is applied with a high electric potential such that a positive potential is obtained with respect to devices
145
, in order to accelerate emitted electrons to obtain a luminance point with a higher luminance.
The image-forming apparatus constructed in the structure as described above, particularly, uses a fluorescent member of a low price having a high light-emission efficiency, which is used in a current CRT display, and an acceleration voltage of several kV to several tens kV is applied to obtain a high luminance and to improve color performance. However, a distance d between the rear plate
141
and the face plate
142
must be set to 1 mm or more in consideration of an insulating break-down in a vacuum (i.e., a discharge).
Meanwhile, in the case of using a field emission electron-emitting device as an electron-emitting device as described above, a convergence electrode may be provided or the distance d between the rear plate
141
and the face plate
142
may be reduced, to form an image, in response to a problem of convergence of an electron beam. The voltage applied in this case falls within a range from several hundreds V to several kV although the voltage depends on the performance of a fluorescent member, the presence or absence of a metal back, and the distance between the face plate and the rear place. Therefore, the distance d between the rear plate
141
and the face plate
142
(or the distance between the wire
147
b
and the metal back
150
, more specifically) is generally set to one hundred &mgr;m to several mm, so that a insulating break-down in a vacuum (i.e., a discharge) might not take place.
In order to reduce deformation of substrates caused by a pressure difference between the vacuum inside an envelope and the external air pressure, the rear plate substrate
141
and the face plate substrate
148
must be thickened as the display area of a display panel increases. An increase in thickness of the substrates causes an increase in weight of the display panel and deformation viewed from an oblique direction. Therefore, by providing a spacer
151
, loads to the strength of the substrates
141
and
148
can be reduced, and a weight reduction, a low cost, and a large screen can be achieved, so that advantage of a flat type electron beam display panel can be sufficiently performed.
Material used for the spacer
151
requires the following conditions. A sufficient air pressure strength (or compressive strength) is ensured and a high aspect ratio (i.e., the ratio between the height of the spacer and the cross-sectional area) is obtained so that the spacer can be arranged in an image-forming apparatus, i.e., the material is strong against a break-down, deformation, and bending caused by compression; the material has a heat resistance enough to withstand heating steps in manufacturing steps and high-vacuum formation steps and matches with heat expansion coefficients of the substrates of the display panel, a supporting frame, and the like; the material is highly resistive material or insulating material having a dielectric strength enough to withstand an application of a high voltage; the material has a low gas discharge rate to maintain a high vacuum; and the material can be processed with high size precision and ensures a high mass-productivity. Generally, glass material is used.
On the other hand, spacers which are improved in creeping discharge breakdown voltage by forming irregularity on their surfaces are exemplarily described in Japanese Patent Application Nos. 8-241667, 8-241670 and 8-315726. It is also described that secondary electrons emitted by incident electron beams to such spacers can be captured by a concave surface to further improve the creeping discharge breakdown voltage and that such spacers are manufactured by molding glass, ceramic or polymer materials.
Glass material generally used has relatively excellent mechanical strength, heat characteristics, and disorption gas characteristics. In addition, such glass material has an excellent process ability and an excellent mass-productivity and is therefore generally used as spacer material.
Meanwhile, there is a case in which some electrons emitted from an electron-emitting device enter into the surface of a spacer. As a result, the spacer surface is charged and greatly reduces the creeping discharge breakdown voltage or the potential of the surface changes and distorts the electric field in the vicinity of the surface, so that courses of electrons from the electron source are adversely affected, resulting in a phenomenon such as a color dislocation which degrades t
Ikeda Sotomitsu
Kobayashi Toyoko
Shibata Masaaki
Yamanobe Masato
Canon Kabushiki Kaisha
Day Michael H.
Fitzpatrick ,Cella, Harper & Scinto
Williams Joseph
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