Electric lamp and discharge devices – Cathode ray tube – Beam deflecting means
Reexamination Certificate
1999-11-08
2002-07-30
Ramsey, Kenneth J. (Department: 2879)
Electric lamp and discharge devices
Cathode ray tube
Beam deflecting means
C445S024000, C257S698000
Reexamination Certificate
active
06426588
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for producing an image-forming apparatus while keeping the inside in a pressure-reduced state. Particularly, the invention relates to a method for producing the image-forming apparatus while wires used in the image-forming apparatus are formed by sintering particles of an electric conductor. The invention further concerns the image-forming apparatus produced using the production method.
2. Related Background Art
Cathode-ray tubes (CRTs) are popularly and generally used as the image-forming apparatus at present. Recently, the large cathode-ray tubes with the display screen over 30 inches also came on the market. In order to increase the size of the display screen in the case of the cathode-ray tubes, however, there arise problems that the depth dimension thereof must be increased according to the increase of the screen size and that the weight also becomes greater according to the increase of the screen size.
In order to meet the consumer's desires for images of strong appeal on a larger screen, the cathode-ray tubes thus require a larger placement space and thus are not always suitable for realizing the increase of the screen size.
There are thus expectations for the debut of a flat image display apparatus that is thin enough to be hung on a wall, that is of low power consumption, and that has a thin, lightweight, large screen, in place of the large and heavy cathode-ray tubes (CRTs). Research and development is active on liquid-crystal display devices (LCDs) as such flat image display apparatus.
Since the above LCDs are not of an emissive type, they require a light source called a back light. They thus had a problem that most of the power consumption was due to lighting of the back light. Further, the LCDs still have problems that the image is dark because of low utilization efficiency of light, there is a limit to viewing angles, it is difficult to realize a large screen over 20 inches, and so on.
An emissive type flat image display apparatus is thus drawing attention instead of the LCDs having the above problems. Examples of such display apparatus proposed heretofore are, for example, plasma display panels (PDPs) arranged to emit light by irradiating a fluorescent material with ultraviolet light to excite the fluorescent material, flat panel displays arranged to emit light by irradiating the fluorescent material with electrons emitted from electron-emitting devices to excite the fluorescent material, and so on.
With the displays using the electron-emitting devices, the fluorescent material is made to emit light when the fluorescent material is irradiated with electrons emitted from the devices under reduced pressure. Therefore, the light emission mechanism thereof is thus basically the same as in the case of the CRTs. This permits us to expect high-luminance displays without viewing angle dependence.
Such electron-emitting devices are generally classified into cold cathodes and thermionic cathodes. Further, the cold cathodes include field emission type electron-emitting device (hereinafter referred to as “FE”), electron-emitting device comprised of a stack of metal layer/insulating layer/metal layer (hereinafter referred to as “MIM”), surface conduction electron-emitting device, and so on.
In the image display apparatus using the above electron-emitting devices, the devices need to operate in an airtight vessel maintained, for example, under a pressure lower than 10
−4
Pa.
The image display apparatus using the surface conduction electron-emitting devices among the above cold cathode is disclosed, for example, in Japanese Patent Applications Laid-Open No. 6-342636, No. 7-181901, No. 8-034110, No. 8-045448, No. 9-277586, and so on.
FIG.
5
and
FIG. 6
show the schematic structure of an example of the surface conduction electron-emitting devices disclosed in the above applications.
FIG. 7
is a diagram to show the schematic structure of an example of the image display apparatus using the surface conduction electron-emitting devices disclosed in the above applications.
FIG. 5
is a plan view of the surface conduction electron-emitting device and
FIG. 6
is a cross-sectional view of the surface conduction electron-emitting device. In FIG.
5
and
FIG. 6
, reference numeral
101
designates an insulating substrate,
104
an electroconductive film,
102
and
103
electrodes, and
105
an electron-emitting region. The electron-emitting region
105
has a gap. When a voltage is placed between the electrodes
102
,
103
, the electron-emitting region
105
emits electrons.
In
FIG. 7
numeral
5005
denotes a rear plate,
5006
an outer frame, and
5007
a face plate. Joint (Sealing) portions between the outer frame
5006
, the rear plate
5005
, and the face plate
5007
are joined (or sealed) to each other with a bonding material such as a low-melting-point glass frit or the like not illustrated, thereby composing an airtight vessel
170
for maintaining the inside of the image display apparatus in vacuum. The surface conduction electron-emitting devices
5002
are formed in an array of N×M on the rear plate
5005
(where N and M are positive integers not less than 2 and are properly determined according to the number of display pixels aimed). A fluorescent material is opposed to the electron-emitting devices.
The electron-emitting devices
5002
are wired in a matrix by M column-directional wires
107
and N row-directional wires
106
, as illustrated in FIG.
7
. In the case of this wiring in the matrix, insulating layers, not illustrated, are placed for electrically insulating the two types of wires from each other, at least, at intersecting portions between the row-directional wires and the column-directional wires.
A fluorescent film
5008
comprised of the fluorescent material is formed on the lower surface of the face plate
5007
. A metal back
5009
of Al or the like is formed on the rear-plate-side surface of the fluorescent film
5008
.
In the case of color display, fluorescent materials (not illustrated) of the three primary colors, red (R), green (G), and blue (B), are laid separately. Further, a black material (not illustrated) is laid between the fluorescent materials of the respective colors forming the fluorescent film
5008
.
The inside of the-above airtight vessel is maintained in a vacuum of the pressure lower than 10
−4
Pa. The distance between the rear plate
5005
with the electron-emitting devices formed thereon and the face plate
5007
with the fluorescent film formed thereon, as described above, is usually kept in the range of several hundred &mgr;m to several mm.
A method for driving the image-forming apparatus described above is as follows. A voltage is applied to each electron-emitting device
5002
via terminals Dx
1
to Dxm, Dy
1
to Dyn outside the vessel, and via the wires
106
,
107
, whereby each device
5002
emits electrons. At the same time as it, a high voltage of several hundred V to several kV is applied to the metal back
5009
via a terminal Hv outside the vessel. This accelerates the electrons emitted from each device
5002
to make them collide with the corresponding fluorescent material of each color. On this occasion the fluorescent material is excited to emit light, thus displaying an image.
SUMMARY OF THE INVENTION
In recent years there are needs for further increase of the screen size in the image-forming apparatus. In order to produce the image-forming apparatus of several ten inches at low cost, it is then desirable to form the above wires by a sintering method (for example, a printing method) of applying conductive particles onto a substrate and baking them. Printing methods, particularly screen printing methods, are preferable, because wires of a thick film can be produced at low cost thereby.
Incidentally, in the image-forming apparatus using the electron-emitting devices, the members (the outer frame
5006
, the face plate
5007
, and the rear plate
5005
) forming the airtight vessel
170
are join
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