Electric lamp and discharge devices – Cathode ray tube – Envelope
Reexamination Certificate
1999-03-23
2001-11-27
Day, Michael H. (Department: 2879)
Electric lamp and discharge devices
Cathode ray tube
Envelope
C313S313000, C313S478000, C348S818000, C315S085000
Reexamination Certificate
active
06323592
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a cathode ray tube such as a color television tube equipped with an antireflection film and a method of manufacturing a conductive antireflection film used in a cathode ray tube, etc.
In recent years, a serious problem is pointed out in a cathode ray tube such as a Brawn tube for a color television tube or a CRT for a computer. It is pointed out that an electromagnetic wave generated in the vicinity of the electron gun and deflection yoke within the cathode ray tube leaks to the outside so as to affect electronic equipment arranged around the cathode ray tube. In order to prevent the electromagnetic wave from leaking to the outside, a conductive antireflection film is formed on the surface of the face panel of the cathode ray tube.
Such a conductive antireflection film is disclosed in, for example, U.S. Pat. No. 4,785,217. Specifically, disclosed is a conductive antireflection layer consisting of an antireflection film containing particles of at least one of metals selected from the group consisting of Pd, Sn, Pt, Ag, and Au together with a metal oxide.
The conductive antireflection film is required to be capable of preventing the electromagnetic wave from leaking to the outside and, at the same time, to be capable of achieving a high contrast in order to enable the cathode ray tube to display a clear picture image.
The high contrast can be achieved by improving the light transmittance of the conductive antireflection film. However, if the conductive film is formed thin for improving the light transmittance in the conventional cathode ray tube, the density of the metal fine particles is lowered, resulting in failure to obtain a sufficient electrical conductivity. As a result, it is difficult to prevent the electromagnetic wave from leaking to the outside. On the other hand, if the thickness of the conductive film is increased in an attempt to improve the electrical conductivity, the density of the metal fine particles is increased, leading to a low light transmittance.
It should also be noted that, in the conventional conductive antireflection film, the fine particles of silver, silver-palladium alloy, etc. contained in the film causes the film to strongly absorb light having a wavelength of about 400 nm to 500 nm. It follows that the body color is rendered yellowish and poor in contrast, making it difficult to obtain a clear picture image.
BRIEF SUMMARY OF THE INVENTION
The present invention, which has been achieved for overcoming the above-noted difficulties inherent in the prior art, is intended to provide a cathode ray tube which permits preventing an electromagnetic wave from leaking to the outside and which also permits obtaining a clear image of a high contrast.
The present invention is also intended to provide a method of manufacturing a conductive antireflection film having a high electrical conductivity and excellent in light transmittance.
According to an aspect of the present invention, there is provided a cathode ray tube, comprising:
a faceplate; and
a conductive antireflection film including a conductive layer formed on the faceplate, an insulating covering layer formed on the conductive layer, and a conductive member formed in the insulating covering layer in a manner to extend from the surface of the insulating covering layer into the conductive layer, a part of the conductive member being electrically connected to the conductive layer and another part being exposed to the outside.
According to another aspect of the present invention, there is provided a method of manufacturing a conductive antireflection film, comprising the steps of:
forming a conductive layer on a substrate;
forming an insulating covering layer on the conductive layer;
forming a conductive member in the insulating covering layer such that the conductive member extends from the surface of the insulating covering layer into the conductive layer so as to bring at least a part of the conductive member into electric contact with the conductive layer, with another part of the conductive member exposed to the outside;
bringing an electrolytic solution into contact with the exposed part of the conductive member; and
removing the electrolytic solution.
Further, according to still another aspect of the present invention, there is provided a method of manufacturing a conductive antireflection film, comprising the steps of:
forming a conductive layer on a substrate having a conductive member formed therein in advance such that the conductive layer is brought into contact with a part of the conductive member;
forming an insulating covering layer to cover the conductive layer and the conductive member except another part of the conductive member to permit the another part of the conductive member to be exposed to the outside;
bringing an electrolytic solution into contact with the exposed part of the conductive member; and
removing the electrolytic solution.
In the cathode ray tube of the present invention, the antireflection film includes a conductive member electrically connected to a conductive layer. Since the state of the metal contained in the conductive layer is controlled by the conductive member, the electromagnetic wave is prevented from leaking to the outside and a clear image of a high contrast can be obtained.
According to the method of the present invention for manufacturing a conductive antireflection film, a conductive member connected to a conductive layer is brought into contact with an electrolytic solution so as to control the state of the metal contained in the conductive layer, making it possible to obtain a conductive antireflection film having a high electrical conductivity and excellent in light transmittance.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.
REFERENCES:
patent: 4785217 (1988-11-01), Matsuda et al.
patent: 5025490 (1991-06-01), Tamura
patent: 5246771 (1993-09-01), Kawaguchi
patent: 5757117 (1998-05-01), Hirasawa et al.
patent: 0 554 115 A1 (1993-08-01), None
patent: 9-248935 (1997-09-01), None
patent: WO 95/14289 (1995-05-01), None
Matsuda Hidemi
Oyaizu Tsuyoshi
Takahashi Yoshinori
Day Michael H.
Gerike Matthew J
Kabushiki Kaisha Toshiba
Pillsbury & Winthrop LLP
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