Electric lamp and discharge devices – Cathode ray tube – Envelope
Reexamination Certificate
1999-08-09
2002-06-18
Patel, Vip (Department: 2879)
Electric lamp and discharge devices
Cathode ray tube
Envelope
C313S385000, C313S386000, C313S493000, C252S511000
Reexamination Certificate
active
06407497
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a composition for forming a conductive layer, and more particularly, to a composition for forming a conductive layer having excellent conductivity and contrast characteristics, and a cathode ray tube (CRT) having the conductive layer formed using the above composition.
2. Description of the Related Art
The driving principle of a CRT lies in that electron beam emitted from an electron gun is selectively deflected by a deflection yoke according to landing positions and lands on a phosphor layer formed on the inner surface of a panel to thus excite the phosphor causing it to luminesce, thereby forming an image.
As the panel for a CRT, a curved panel having a predetermined curvature is typically used. Although the curved panel has a disadvantage in view of attainment of a high-quality image, caused by severe glare and image distortion at the peripheral portion thereof, it is still chiefly used as a panel for a CRT due to a technical difficulty in manufacturing flat panels.
However, according to recent advancement of a technology of manufacturing flat panels, existing curved panels are replaced by flat panels having a curvature close to infinity.
A panel having a large curvature, that is, a nearly flat panel, can realize a clean image by suppressing the blaze due to reflection of external light, reduce eye fatigue and avoid distortion of an image.
As an example of a flat panel, a panel shown in
FIG. 1
, whose internal and external surfaces are both completely flat, has been proposed. In a CRT employing such a flat panel, an image formed on the central portion of the panel appears to recede inwardly.
To overcome this problem, as shown in
FIG. 2
, a flat panel having a completely flat external surface and a curved internal surface having a predetermined curvature has been proposed.
However, according to this flat panel, it is difficult to attain a uniform image due to different transmittances between the central portion and the peripheral portion of the panel, which is caused by a difference in thicknesses. Also, in the case of employing a general dark tint panel or a semi-tint panel having a transmittance of about 40~50% as the flat panel, the difference in transmittances between the central portion and the peripheral portion of the panel becomes bigger.
Thus, according to the present invention, there has been proposed a method for overcoming the above-mentioned problems, by which a clear panel having a transmittance of 80% or higher is used as the flat panel, and a conductive layer for adjusting the transmittance and improving contrast characteristics is coated on the external surface thereof.
SUMMARY OF THE INVENTION
To solve the above problems, it is an objective of the present invention to provide a composition for forming a conductive layer having excellent conductivity and contrast characteristics.
It is another objective of the present invention to provide a cathode ray tube employing the conductive layer formed using the composition.
Accordingly, to achieve the first objective, there is provided a composition for forming a conductive layer including 0.01~1.0% by weight of a conductive black pigment, 0.05~10% by weight of a binder, 0.01~50% by weight of a conductive agent, and the remaining amount of a solvent on the basis of the total weight of the composition.
To achieve the second objective, there is provided a cathode ray tube including a panel, and a conductive layer and a protective layer sequentially formed on the outer surface of the panel, wherein the conductive layer is prepared by coating the composition for forming a conductive layer mentioned above on the outer surface of the panel, coating, drying and heating the same.
REFERENCES:
patent: 5523649 (1996-06-01), Tong et al.
patent: 5587835 (1996-12-01), Shimizu et al.
patent: 5908585 (1999-06-01), Shibuta
patent: 6351063 (2002-02-01), Lee et al.
patent: 94-14738 (1994-07-01), None
patent: 95-11564 (1995-05-01), None
Lee Ji-won
Park Jong-whan
Shim Myun-ki
Zang Dong-sik
Leydig , Voit & Mayer, Ltd.
Patel Vip
Quarterman Kevin
Samsung Display Devices Co. Ltd.
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