Electric lamp and discharge devices – Cathode ray tube – Envelope
Reexamination Certificate
2000-04-14
2003-09-30
Patel, Vip (Department: 2879)
Electric lamp and discharge devices
Cathode ray tube
Envelope
C313S461000, C220S00210R, C220S00210A
Reexamination Certificate
active
06628062
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a color CRT Cathode Ray Tube), and more particularly, to a color CRT panel which forms a front surface of a CRT for displaying an image.
2. Background of the Related Art
The CRT forms an important part for displaying an image thereon in a display, such as a TV receiver or a computer monitor.
FIG. 1
illustrates a side view inclusive of a partial section of a color CRT.
Referring to
FIG. 1
, there is a fluorescent film
1
a
on an inside surface of a panel
1
which forms a front surface of the CRT having red, green and blue fluorescent materials coated thereon, a funnel
2
at rear of the panel
1
frit glass welded to the panel
1
, and an electron gun
4
provided in a neck portion
2
a
of the funnel
2
. And, there is a shadow mask
5
fastened to a frame
6
close to the fluorescent film
1
a
on an inner side of the panel
1
for selecting a color of electron beams
3
. The frame
6
is hung from the sidewall of the panel
1
by a support spring
8
having one end fastened thereto and the other end inserted to a stud pin
1
b
fastened to a sidewall of the panel
1
. And, there is an inner shield
7
fastened to the frame
6
by a fastening spring on one side of the frame
6
for protecting the electron beams
3
traveling toward the fluorescent film
1
a
from an external geomagnetic field. There is a deflection yoke
10
attached to an outer circumferential surface of the neck portion
2
a
having a plurality of poles for correcting a locus of travel of the electron beams
3
so that the electron beams
3
exactly hit a desired fluorescent material, and a reinforcing band
9
on an outer circumferential surface of the CRT for preventing breakage of the CRT from an external impact during operation of the CRT. Within a basic structure of the CRT, the shadow mask
5
, formed to have a required curvature and disposed to have a required space from the panel
1
, forms a panel assembly with the panel, so that the three electron beams
3
emitted from the electron gun
4
exactly hit onto the fluorescent material on an inside surface of the panel through the shadow mask
5
, to reproduce an image. Accordingly, an accurate curvature design of the shadow mask
6
is required for implementing an exact image, for which an inner curvature of the panel
1
is considered as a precondition of the curvature design.
FIG. 2
illustrates a cross section of a panel assembly, referring to which a relation between a panel inside surface curvature and a curvature of the shadow mask will be explained.
Referring to
FIG. 2
, the panel
1
has an inside/an outside curved surfaces, radius Ro of the outside surface and radius Ri of the inside surface have Ro>Ri relation, for withstanding a force caused by a pressure difference between the atmospheric pressure and a high vacuum in a Braun tube. The inside surface curvature Ri of the panel
1
is considered to be the most important factor for determining a curvature of the shadow mask
5
, and the curvature of the shadow mask
5
determined herein has close relations with a structural strength, and thermal deformation characteristics of the shadow mask
5
. As shown in
FIG. 3
, the inside surface curvature Ri of the panel
1
has an arc curvature shown in a solid line and a super arc curvature shown in dashed line. The super arc curvature exhibits a height displacement of the shadow mask less than the arc curvature, according to which the super arc curvature is effective to a thermal deformation of the shadow mask
5
. Accordingly, through the arc curvature and the super arc curvature are applied to the related art CRT without any particular distinction, the super arc curvature is used more when a thermal deformation characteristic is taken into consideration. Currently, the outside surface curvature Ro is designed to be greater than 40,000 mm for forming the outside surface of the panel
1
to be flat perfectly or close to the perfect flat, which causes the inside surface curvature Ri dependent on the outside surface curvature Ro of the panel
1
, together with an increase a curvature of the shadow mask
5
which is dependent on the inside surface curvature Ri. As explained, the greater the curvature of the shadow mask
5
, though the more effective to a thermal deformation, the worse to a strength of the shadow mask
5
. Accordingly, howling is occurred, in which an image is shaken by an impact, or speaker sound, and a poor color reproducibility is caused, in which a color of the image is changed partially. Currently, since the thermal deformation is solved, not by a method of the curvature of the shadow mask
5
, but by other method, i.e., by a method in which a reflection film (not shown) is coated on a surface the electron beams
3
hit thereon for reflecting thermal ions, a method for reinforcing the structural strength of the shadow mask is required.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to a color 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 color CRT panel which has a structure of an inside surface curvature that can reinforce a structural strength of the shadow mask.
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 color CRT panel includes an outside surface substantially flat, and an inside surface with a desired curvature, wherein an inside surface curvature structure of the panel consists of arc curvatures having a long axis direction radius R
x
of curvature and a short axis direction radius R
y
of curvature different from each other.
T
c
+
(
R
y
-
R
y
2
-
L
ye
2
)
T
c
is within a range greater than 1.5 and smaller than 2.5, where,
R
y
=
L
ye
2
+
Z
ye
2
2
×
Z
ye
Tc denotes a thickness of a center portion of the panel,
L
ye
denotes a distance from the center portion of the panel to an end of an effective surface in a short axis direction, and
Zye denotes a height at the end of the effective surface in the short axis direction.
R
x
/R
y
is preferably within a range of 2.2-2.8.
F′(r)=(a+b·R+c·R
2
)·r±(d+e·L
e
+f·L
e2
), and F′(r)=(a+b·R
x
+c·R
x
2)·r±(d+e·L
xe
+f·L
xe
2
), when ‘r’ is on the long axis (X-axis), and F′(r)=(a+b·R
y
+c·R
y
2
)·r±(d+e·L
ye
+f·L
ye
2
), when ‘r’ is on the short axis (Y-axis), wherein the constants “a, b, c, d, e, and f” in both of F′(r) for the long axis and the short axis have the following values.
a=1.17146E−03,
b=−4.11994E−07,
c=4.53728E−11,
d=4.82475E−02,
e=−2.36837E−04, and
f=3.78612E−07
The panel inside surface curvature meets a range of dispersion of the primary derivative F′(r) dependent on the constants “a, b, c, d, e, and f”, a radius of curvature R
x
or R
y
, and a distance L
xe
or L
ye
.
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: 4537322 (1985-08-01), Okada et al.
patent: 5155410 (1992-10-01), Wakasono et al.
patent: 5506470 (1996-04-01), Inoue et al.
patent: 6121723 (2000-09-01), Sugawara et al.
patent: 6160344 (2000-12-01), Cho et al.
patent: 6232712 (2001-05-01), Pyun et al.
patent: 6268690 (20
Nah Keon Soo
Park Hyoung Guen
LG Electronics Inc.
Patel Vip
Williams Joseph
LandOfFree
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