Electric lamp and discharge devices – Cathode ray tube – Envelope
Reexamination Certificate
2001-04-24
2003-01-21
Patel, Ashok (Department: 2879)
Electric lamp and discharge devices
Cathode ray tube
Envelope
C220S00210A
Reexamination Certificate
active
06509683
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a panel in a cathode ray tube, and more particularly, to a panel structure, which can secure an implosion proof characteristic by suppressing implosion caused by increased stress concentration at an upper portion of a panel coming from making the panel flatter during or after fabrication of the cathode ray tube.
2. Background of the Related Art
The cathode ray tube is a major component for displaying a picture in a display, such as a TV receiver or a computer monitor.
FIG. 1
illustrates a side view with a partial cut away view of a related art color cathode ray tube.
Referring to
FIG. 1
, there is a fluorescent material screen
2
having red, green, and blue fluorescent materials coated thereon on an inside surface of the panel
1
fitted to a front face of the cathode ray tube, and a funnel
3
at a rear of the panel
1
welded to the panel
1
, and an electron gun
4
in a neck portion
3
a
of the funnel
3
. There is a shadow mask
6
fixed to a frame
7
near to the fluorescent material screen
2
inside of the panel
1
for selecting colors of electron beams
5
emitted from the electron gun
4
. The frame
7
is hung from a sidewall of the panel
1
as support springs
8
fixed to the frame
7
are inserted in stud pins
9
fixed to the sidewall of the panel
1
. There is an inner shield
10
fixed to one side of the frame
7
by fastening springs
11
for protecting the electron beams
5
traveling toward the fluorescent material screen
2
from external geomagnetism. There is a magnet
13
having a plurality of poles on an outer circumference of the neck portion
3
a
for correcting a traveling path of the electron beams
5
to hit onto a required fluorescent material exactly, and a reinforcing band
12
strapped around an outer circumference of the cathode ray tube for preventing implosion of the cathode ray tube caused by external impact during operation of the cathode ray tube. A structure of the panel
1
will be explained with reference to
FIGS. 2 and 3
. The panel
1
forms a front face of a vacuum container to maintain an inside space of the cathode ray tube in a vacuum for smooth traveling of the electron beams.
FIG. 2
illustrates a section of key parts of a related art panel, showing a skirt part
28
bent backward from an effective surface portion
20
.
Referring to
FIG. 2
, the panel
1
with the skirt part
28
has a fixed total height
27
, with reference to which the skirt part
28
is divided into an upper part
22
inclusive of the effective surface part
20
having a radius of outward curvature divided by a mold match line
21
, an intermediate part
24
from the mold match line
21
to a break line
23
, and a lower part
26
from the break line
23
to the seal edge line
25
. An edge of the effective surface part
20
in the upper part
22
transits to the skirt part
28
through curvatures R and R′, bland curvatures, wherein the outside bland curvature R′ is connected to the mold match line
21
at an upper part angle ‘a’ of approx. 5° to a vertical line, the intermediate part
24
has an intermediate part angle ‘b’ of approx. 1.5° to the vertical line from the mold match line
21
to a break line
23
, and the lower part
26
has a lower part angle ‘c’ of approx. 3°~4° to a vertical line. Because the outward curved effective surface part of the related art panel, with a consequential curved fluorescent screen on the effective surface, distorts a picture on the fluorescent screen and provides a sensing quality, it is a trend that the effective surface of the panel is formed flatter, to increase a ratio of the height of the upper part greater.
In the meantime, referring to
FIG. 3
, the reinforcing band
32
strapped on an outside of the panel skirt part
28
is in general positioned starting from a boundary point of the bland curvature R′ and the straight section of the upper part
22
of the skirt to entire intermediate part
24
. The reinforcing band
32
has a section similar to a section of the panel skirt part
28
, i.e., the reinforcing band
32
has a band body part
30
positioned at a lower part of the panel and a bent part
31
at the upper part
22
of the panel with reference to the mold match line
21
of the panel
1
. The bent part
31
is bent at an angle identical to the angle ‘a’ of the upper part of the panel, and the band body part
30
is parallel to a cathode ray tube axis. The reinforcing band compresses the panel
1
to act against expansion acting outward during evacuation of the cathode ray tube in fabrication, to reduce a stress on the panel, which makes the structure stable.
However, while the related art cathode ray tube with the curved screen surface exhibits a maximum tension at a periphery of the effective surface part of the panel as stress concentrates thereto, since the flat cathode ray tube with a thickness of the effective surface relatively greater than the related art cathode ray tube exhibits a tension stress concentrated to the skirt part of the panel which is relatively thin, that makes the flat cathode ray tube weak for the stress, such that the suggested panel form and the reinforcing band have a problem of lacking for an actual implosion proof requirement.
The problem can be described in detail as follows.
In the strapping of the reinforcing band, with an inner circumferential length shorter than an outer circumferential length on the mold match line of the panel, on the skirt part of the panel, to exert a contract force to the panel, that generates a tension on the reinforcing band in return, it is required to strap the reinforcing band more tightly on the skirt part for utilizing the tension fixed by a thickness, a width, and a yielding strength of the reinforcing band itself. However, the increased gap between the reinforcing band and the upper part of the skirt of the panel caused by the increased length of the bent part in the upper part of the reinforcing band coming from the increased ratio of the upper part of the panel in the course of making the effective surface flatter makes the tight contact difficult. That is, the increased panel upper part in the panel skirt part makes the contact between the panel upper part and the reinforcing band poor, to deteriorate implosion proof design efficiency. Moreover, the shifting of a tension center on the reinforcing band to front according to the increased panel upper part may cause slip when the reinforcing band slips off the panel.
SUMMARY OF THE INVENTION
Accordingly, the present invention is directed to an implosion proof panel in a cathode ray tube 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 an implosion proof panel in a cathode ray tube, which can enhance an implosion proof characteristic.
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 implosion proof panel in a cathode ray tube, the cathode ray tube includes an effective surface part of a fluorescent screen formed on the panel, the panel with a substantially flat outside surface including, a skirt part starting from a periphery of the effective surface part to a seal edge line of the panel having an upper part, an intermediate part, and a lower part, the upper part and the intermediate part being divided by a mold match line, and a reinforcing band strapped around an outer circumference of the panel for preventing implosion of the cathode ray tube, wherein the panel meets the followi
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