Electric lamp and discharge devices – Cathode ray tube – Screen
Reexamination Certificate
1999-08-17
2002-05-14
Day, Michael H. (Department: 2879)
Electric lamp and discharge devices
Cathode ray tube
Screen
C313S461000
Reexamination Certificate
active
06388373
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a CRT(Cathode Ray Tube) panel, and more particularly, to a CRT panel which has a curved inside surface and a flat outside surface.
2. Background of the Related Art
FIG. 1
illustrates a side view of a related art CRT having curved inside and outside surfaces, with a partial cut away view,
Referring to
FIG. 1
, the related art CRT is provided with a panel
1
forming a frontal face, a funnel
2
welded to a rear surface of the panel
1
, a neck portion
3
at an end of the funnel
2
, an electron gun
5
disposed inside of the neck portion
3
for emitting electron beams
4
, a fluorescent film (an effective surface of a screen)
6
of read, green and blue fluorescent materials coated inside of the panel
1
a shadow mask
7
fitted between the fluorescent film
6
and the electron gun
5
for selective pass-through of the electron beams, and a deflection yoke
8
mounted on an outer circumference of the neck portion for deflecting the electron beams. Upon application of a current to the electron gun
5
and the deflection yoke
8
, electron beams
4
are emitted from the electron gun
5
, and the deflection yoke
8
forms a deflection magnetic field, so that the electron beams
4
pass-through the shadow mask
7
selectively, to hit onto the fluorescent film
6
and reproduce an image. T.V. watchers can watch the reproduced image on the panel
1
.
FIG. 2
illustrates a section of a related art panel assembly of a color CRT having a panel with curved inside and outside surfaces. In order to sustain a high vacuum inside of the CRT, the inside and outside surfaces of the related art panel
1
are given curvatures having a relation Ri<Ro, where Ri denotes an inside curvature and the Ro denotes an outside curvature.
However, the inside and outside curvatures of the panel
1
causes distortion of an image depending on a direction of users sight to the panel, and a reflection of an external light from alight source
9
at the outside surface of the panel
1
.
FIGS. 3A and 3B
illustrate distortions of images when the panel is seen from the front and side thereof, and
FIG. 4
illustrates that the curvature of the outside surface of the panel
1
acts as a convex mirror, to reflect light incident to the outside surface of the panel
1
at a variety of angles. These image distortions and reflections of the external lights cause the watchers eyes to tire.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to a semi-flat CRT panel that substantially obviates one or more of the problems due to limitations and disadvantages of the related art
An object of the present invention is to provide a semi-flat CRT panel which can prevent reflection of an external light incident to the panel and distortion of image while a strength of the panel is kept the same.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, the semi-flat CRT panel has relations of Ryi<Rdi<Rxi and 2×Ryi<Rxi, where Rxi denotes an inside surface horizontal curvature, Ryi denotes an inside surface vertical curvature, Rdi denotes an inside surface diagonal curvature for a CRT with an aspect ratio of 4:3 and an outside surface diagonal curvature Rd is greater than 30,000 mm.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.
REFERENCES:
patent: 4535907 (1985-08-01), Tokita et al.
patent: 4777401 (1988-10-01), Hosokoshi et al.
patent: 4792722 (1988-12-01), Francis
patent: 5155410 (1992-10-01), Wakasono et al.
patent: 5216321 (1993-06-01), Kawamura et al.
patent: 5552663 (1996-09-01), Iida et al.
patent: 5663610 (1997-09-01), Inoue et al.
patent: 6025676 (2000-02-01), Ohama et al.
patent: 6133681 (2000-10-01), Nakamura et al.
patent: 6160344 (2000-12-01), Cho et al.
patent: 6232712 (2001-05-01), Pyun et al.
Birch & Stewart Kolasch & Birch, LLP
Day Michael H.
LG Electronics Inc.
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