Electric lamp and discharge devices – Cathode ray tube – Beam deflecting means
Reexamination Certificate
2000-05-08
2002-12-17
Patel, Nimeshkumar D. (Department: 2879)
Electric lamp and discharge devices
Cathode ray tube
Beam deflecting means
C313S47700R, C313S47700R, C335S210000, C335S213000, C220S00210A
Reexamination Certificate
active
06495951
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a cathode-ray tube for color picture tube, color monitor and the like, and more particularly, to a cathode-ray tube having a yoke mounting part in the form of a pyramid to raise a degree of freedom in rotation during an ITC process and enhanced productivity, with the radii of inner and outer curvatures of the funnel and the thickness being optimized to enhance atmospheric pressure resistance and deflection sensitivity.
2. Background of the Related Art
In general, a color cathode-ray tube, for example, has an outer vacuum tube made of glass that comprises a panel having an approximately rectangular screen, a funnel joined to the panel, and a cylindrical neck joined to the funnel. The neck is internally provided with electron guns emitting three electron beams, and a deflection yoke is provided around the circumference of the funnel to control deflection of the electron beams. A portion of the funnel in which the deflection yoke is mounted is referred to as “yoke mounting part”.
The above-structured cathode-ray tube has the electron guns arranged in a line for emitting three electron beams on the same horizontal plane and scans the electron beams over the whole screen in such a manner that the electron beams are deflected with a pincushion-shaped horizontal deflection magnetic field and a barrel-shaped vertical deflection magnetic field generated from the deflection yoke.
Such a general cathode-ray tube has the deflection yoke usually designed based on the funnel. However, in a pyramidal funnel and deflection yoke structure, the cone of the funnel, i.e., the yoke mounting part has to be designed to have an optimal inside profile as determined in consideration of the explosion characteristic and the beam strike neck (BSN) to the beam trajectory, the funnel being designed based on the deflection yoke in the order of deflection yoke profile modeling, beam trajectory calculation, vacuum stress calculation at the funnel bulb, and deflection yoke shape modeling considering deflection sensitivity. This constraint on designing the yoke mounting part requires optimization in designing the outside profile of the funnel so as to enhance atmospheric pressure resistance in consideration of deflection sensitivity and explosion characteristic in a situation that the values related to the inside profile of the funnel are almost fixed.
A color cathode-ray tube is illustrated in
FIGS. 1 and 2
as an example of the above-constructed conventional cathode-ray tube.
The color cathode-ray tube has an outer vacuum tube
10
made of glass.
The outer vacuum tube
10
comprises a face panel
3
having an approximately rectangular effective part
1
and a skirt part
2
provided in the periphery of the effective part
1
, a funnel
4
joined to the skirt part
2
, and a cylindrical neck
7
extending from the funnel
4
.
The effective part
1
of the face panel
3
has an approximately rectangular form with horizontal and vertical axes H and V perpendicular to each other through a tubular axis Z of the cathode-ray tube.
And, a deflection yoke
6
is externally provided over an area ranging from the neck
7
to the funnel
4
. The funnel
4
has a small-diameter region, so-called yoke mounting part
12
extending from the joint with the neck
7
to the mount position of the deflection yoke
6
., i.e., extending to the side of the face panel
3
.
On the inner surface of the effective part
1
of the face panel
3
are provided a fluorescent screen S comprising three dot or stripe type fluorescent layers emitting blue, green and red lights, and a stripe type light-shielding layer interposed between the fluorescent layers.
The outer vacuum tube
10
is internally provided with a shadow mask
11
as a dichroic electrode opposite to the fluorescent screen
5
.
And, electron guns
9
emitting three electron beams
8
are provided in the neck
7
. The three electron beams
8
emitted from the electron guns
9
are deflected by the horizontal and vertical magnetic fields generated from the deflection yoke
6
, thus horizontally and vertically scanning the fluorescent screen
5
via the shadow mask
11
to form a color image on the screen
5
.
The yoke mounting part
12
of the funnel
4
in which the deflection yoke
6
is mounted in the color cathode-ray tube has an approximately pyramidal form. Here, the deflection yoke
6
is of a saddle shape with less leakage magnetic field and comprises a cylindrical frame made of a synthetic resin for fixing horizontal and vertical deflecting coils and a core. More specially, the pyramidal yoke mounting part
12
has a circular cross section perpendicular to the tubular axis Z as the neck
7
around the joint with the neck
7
and an approximately rectangular cross section in conformity with the profile of the effective part
1
of the face panel
3
, as shown in
FIGS. 3 and 4
, around the central portion along the tubular axis Z and the end portion on the side of the fluorescent screen
5
.
As illustrated in
FIG. 4
, the cross section of the yoke mounting part
12
has the outside profile in an approximately rectangular form constituted by the continuity of a pair of circular arcs
20
for a horizontal radius Roh having a center on the horizontal (major) axis H with respect to the effective part
1
, a pair of circular arcs
21
for a vertical radius Rov having a center on the vertical (minor) axis V, and a pair of circular arcs
22
for a diagonal radius Rod having a center on the diagonal axis D.
That is, as shown in
FIG. 3
, the cross section of the yoke mounting part
12
has the inside profile with inner diameters La, Sa and da in the directions of horizontal (major), vertical (minor) and diagonal axes H, V and D, respectively, extending from the joint with the neck
7
to the end of the deflection yoke
6
.
The yoke mounting part has, as also shown in
FIG. 3
, outer diameters DA, LA and SA in the directions of diagonal, horizontal (major) and vertical (minor) axes D, H and V, respectively, extending from the joint with the neck
7
to the screen side of the deflection yoke
6
, i.e., the end of the deflection yoke
6
.
As such, the cross section of the yoke mounting part
12
perpendicular to the tubular axis Z has the outside profile almost in the same circular form as the neck
7
around the joint with the neck
7
, and in an approximately rectangular form on the side of the fluorescent screen
5
with a gradual decrease in the outer diameters LA and SA in the directions of the major and minor axes, respectively, with respect to the outer diameter DA in the direction of the diagonal axis D.
While on the other, the yoke mounting part
12
has the inside profile not in a perfect plane but in a pincushion form protruding in the direction of the tubular axis Z, as illustrated in FIG.
3
. That is, the cross section perpendicular to the tubular axis Z of the yoke mounting part
12
has the inside profile not in a perfect rectangular form but in an imperfect rectangular form of which the sides form a convex curve protruding in the direction of the tubular axis Z.
Each short side
24
for the inside profile of the yoke mounting part
12
is in the form of a convex curve having an apical part on the horizontal axis H, each long side
25
being in the form of a convex curve having an apical part on the vertical axis V.
In a case where the long and short sides
25
and
24
for the inside profile are in the form of a convex curve, the individual corners are all formed with arc curves, i.e., arcs
22
and
26
in both inside and outside profiles so as to prevent an abrupt decrease in the diagonal thicknesses due to a difference between inner and outer diameters La and LA in the direction of the horizontal (major) axis, and a difference between inner and outer diameters Sa and SA in the direction of the minor axis.
The long and short sides perpendicular to the tubular axis Z with respect to the inside profile of the yoke mounting part
12
have thicknesses Th and Tv as determined based
Bak Jin-Mok
Kim Ki-Tae
Fleshner & Kim LLP
LG Electronics Inc.
Patel Nimeshkumar D.
Roy Sikhar
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