Electric lamp or space discharge component or device manufacturi – Process – With assembly or disassembly
Reexamination Certificate
2000-01-11
2002-05-07
Ramsey, Kenneth J. (Department: 2879)
Electric lamp or space discharge component or device manufacturi
Process
With assembly or disassembly
C445S024000
Reexamination Certificate
active
06383050
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of producing an image forming apparatus provided with an electron source and an image forming member (for example, fluorescent substance) for forming an image by irradiation with an electron beam emitted from the electron source, in a vacuum container, and to a process for forming a getter for use in such image forming apparatus.
2. Related Background Art
In an apparatus for displaying an image by irradiating a fluorescent substance constituting an image display member with an electron beam emitted from an electron source to cause light emission of the fluorescent substance, the interior of the vacuum container containing the electron source and the image forming member has to be maintained at high vacuum. This is because, if the pressure in the vacuum container is elevated by gas generation, although the effect extent of the gas is different depending to the kind of the gas, such gas disadvantageously affects the electron source to lower the amount of emitted electrons, whereby bright image display cannot be attained. Also the generated gas may be ionized by an electron beam to generate ions and the ions are accelerated by the electric field for accelerating electrons to collide with the electron source, thereby leading to the destruction of the apparatus.
The vacuum container of the image display apparatus is generally formed by combining glass members and adhering the joint portions thereof with frit glass or the like, and once the adhesion is completed, the internal pressure is maintained by a getter provided in the vacuum container.
In the ordinary cathode ray tube (CRT), an alloy composed of Ba as a main component is heated by supplying an electric current or a high frequency wave in the vacuum container to form an deposited film on the inside wall of the container, and high vacuum state is maintained by absorbing the internally generated gas with the deposited film.
On the other hand, there is being developed a plat panel display employing an electron source and a plurality of electron emitting devices arranged on a plat substrate. In such apparatus, the volume of the vacuum container becomes smaller in comparison with that of the CRT while the area of the gas-emitting wall does not decrease, so that the gas generation of a similar level results in a larger rise in the pressure in the container, thereby causing a severer influence.
Also in case of CRT, the vacuum container is provided therein with sufficient wall portions where the electron source or the image display member is absent, and the above-mentioned getter material can be deposited on such wall portions. On the other hand, in case of the flat panel display, the internal wall of the vacuum container is mostly occupied by the electron source and the image forming member. When the deposited-type getter film is attached on the occupied area to cause disadvantageous effects such as short-circuit of the wirings, so that the location of the getter film to be formed is limited.
For this reason, there has been considered utilizing the corner or the like of the vacuum container as the area for forming the getter film, thereby avoiding the deposition of the getter material on the portion constituted by the image forming member and the electron source (hereinafter, referred to as “image display area”). But, if the flat panel display exceeds a certain size, there cannot be secured a sufficient area of the deposited getter film in comparison with the gas discharge amount.
In order to solve the above drawbacks and to secure a sufficient area of the getter, there has been proposed a method (Japanese Patent Application Laid-Open No. 5-151916) of providing, as shown in a cross-sectional view of
FIG. 3
showing a portion concerning the getter treatment of a conventional flat image display apparatus, a wire getter
1008
on an outside, for example, along the external peripheral portions, of the image display area between a fluorescent substance
1006
and a field emittion device
1007
provided opposite to each other in an external container
1005
, thereby depositing and forming a getter film
1009
on the side surface of the external peripheral portion, a method (Japanese Patent Application Laid-Open No. 4-289640) of attaching, as shown in a cross-sectional view of
FIG. 4
showing a portion concerning a getter treatment of a conventional flat image display apparatus, a getter chamber
1015
containing a getter material
1018
for forming the getter film, at a side of a space formed by a face plate
1014
and a rear plate
1012
, and a method (Japanese Patent Application Laid-Open No. 1-235152) of providing a space between an electron source substrate and a rear plate of a vacuum container and forming the getter material therein.
In addition to the aforementioned drawbacks, the gas generation in the vacuum container of the flat image display apparatus causes a drawback that a pressure easily increases in a local position. In the image display apparatus having the electron source and the image display member, the gas generation in the vacuum container principally takes place in the image display area irradiated with the electron beam.
In the conventional CRT, since the image display member and the electron source are mutually separated and the getter film formed on the internal wall of the vacuum container is positioned therebetween, the gas generated in the image display member widely diffuses until is reaches the electron source, and a part of the gas is adsorbed by the getter film, so that the pressure does not rise extremely at the position of the electron source. Also an extreme local pressure rise is not caused by the gas discharged from the electron source itself, since the getter film is also provided around the electron source.
In the flat image display apparatus, however, the image display member and the electron source are closely positioned, so that the gas generated from the image display member reaches the electron source before diffusing sufficiently, thereby inducing a local pressure rise. Particularly in the central portion of the image display area, the local pressure rise tends to appear larger in comparison with the peripheral portion, because the gas cannot diffuse to the area of the getter film. The generated gas is ionized by the electrons emitted from the electron source, thereby causing damage between the electron source and the image display member or inducing a discharge to destroy the electron source.
In consideration of the foregoing, there is already disclosed a constitution of the flat image display apparatus having a specified structure, which comprises positioning a getter material in the image display area and immediately absorbing the generated gas. For example, Japanese Patent Application Laid-Open No. 4-12436 discloses a method, in an electron source having a gate electrode for taking out the electron beam, of forming the getter electrode with a getter material, and illustrates an electron source of field emission type having a conical projection as the cathode and a semiconductor electron source having a pn junction. Also, Japanese Patent Application Laid-Open No. 63-181248 discloses a method, in a plat panel display provided with an electrode (for example, grid) for controlling the electron beam between a group of cathodes and a face plate of the vacuum container, of forming a film of getter material on such control electrode.
Also, U.S. Pat. No. 5,453,659, entitled by “Anode plate for flat panel display having integrated getter”, issued on Sep. 26, 1995 to Wallace et al. discloses a structure of forming a getter member in the gap between the fluorescent substances on the stripes formed on the image display member (anode plate). In this example, the getter material is electrically separated from the fluorescent substance and the conductive member electrically connected thereto, and the getter is activated by giving a suitable potential to the getter and irradiating and heating the getter with t
Gofuku Ihachiro
Hasegawa Mitsutoshi
Ishikura Junri
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