Electric lamp and discharge devices – Cathode ray tube – Screen
Patent
1996-07-19
1998-12-01
Patel, Nimeshkumar
Electric lamp and discharge devices
Cathode ray tube
Screen
313463, 396546, 396547, 430 23, 430 24, H01J 9227, H01J 2918, H01J 2932
Patent
active
058443550
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a color cathode-ray tube and a method for manufacturing the cathode-ray tube, and more particularly to a high quality of high-definition cathode-ray tube in which a correction lens for formation of a fluorescent dot pattern of the cathode-ray tube for use in a lithography or light exposure step of forming a fluorescent film of the color cathode-ray tube is improved to obtain a high quality of high-definition cathode-ray tube as well as also to a method for manufacturing the cathode-ray tube.
BACKGROUND ART
As a higher definition is demanded for a color cathode-ray tube, a higher accuracy has also been required in the light exposure step of subjecting a fluorescent screen to light exposure and development.
In formation of the fluorescent screen of a black matrix type color cathode-ray tube, a multiplicity of stripe- or dot-like holes are left to form a black body and a stripe- or dot-like fluorescent film is formed for the holes. To this end, the holes should coincide with the fluorescent film in their position, for which reason it becomes vital to accurately position the both with respect to the electronic beam irradiation position.
For the purpose of carrying out the above positioning (registration correction), various types of correction lenses have been used, one of which types have a continuous curved face and another of which have a discontinuous surface. Since the both types are used for the purpose of refracting a light exposure beam to approximate it to the actual orbit of the electronic beam, they have a highly complex surface configuration.
In the case of the color cathode-ray tube having the aforementioned stripe-like fluorescent film, since fluorescent film has a stripe shape elongated in its vertical direction, no color draft will take place even when the electronic beam for its luminescence is projected as deviated in the vertical direction. Accordingly, it is only required to correct a beam deviation to the horizontal direction, the lens design is highly flexible. However, since it is impossible to arrange the fluorescent screen with a high density, it is impossible to obtain a high resolution. For this reason, for a color cathode-ray tube for use in a computer terminal requiring a high resolution, a dot-like fluorescent film is employed.
Upon formation of the above dot-like fluorescent film for the above color cathode-ray tube, correction must be carried out simultaneously both in the horizontal and vertical directions, for which end such various correction lenses as to provide optimum correction have been used.
Explanation will be made by referring to the drawing in connection with a light exposure base having such a discontinuous correction lens built therein as disclosed, e.g., in JP-B-47-40983.
Shown in FIG. 8 is a structure of a light exposure base 84 in which a light source 81, a lens 82 and a correction lens 83 are incorporated, and on which a face panel 85 having a shadow mask 87 is mounted. The correction lens 83, which has a plan shape and cross-sectional shapes tilted in horizontal (X) and vertical (Y) directions, is made up of a plurality of square or rectangular blocks divided in the respective direction, as shown in FIG. 9, (a) to (c). An exposure beam emitted from the light source 81 is passed through the lens 82, refracted by the correction lens 83, and then reaches the inner surface of the face panel 85 through an aperture of the shadow mask 87 for light exposure of a photosensitive film 86. In this case, for the purpose of preventing a latticed dark line pattern of discontinuous boundary faces 83' from being transferred onto the photosensitive film 86, the correction lens 83 is vibrated in the two X and Y directions during the light exposure. However, since the influence of the latticed dark line pattern disables accurater dot formation. To suppress generation of various latticed dark line patterns, many methods have been suggested. One of such suggested methods is a correction lens as disclosed in, e.g., JP-A- 62-154525
REFERENCES:
patent: 4052123 (1977-10-01), Yamazaki et al.
patent: 4866466 (1989-09-01), Van Der Waal
Kobayashi, "Electronic Display (CRT)", Electronic Information Communcations Society, Mar. 10, 1992.
Nishiguchi Takashi
Wang Ying-Fu
Hitachi , Ltd.
Patel Nimeshkumar
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