Deflection yoke for color cathode ray tube

Details Deflection yoke for color cathode ray tube Deflection yoke for color cathode ray tube

2000-09-12

2003-01-21

Patel, Vip (Department: 2879)

Electric lamp and discharge devices

Cathode ray tube

Beam deflecting means

C335S213000

Reexamination Certificate

active

06509681

ABSTRACT:

BACKGROUND OF THE INVENTION
(a) Field of the Invention
The present invention relates to a deflection yoke for a color cathode ray tube, and more particularly, to a deflection yoke which is capable of improved assembling of a ferrite core and a separator in a color cathode ray tube.
(b) Description of the Related Art
In a well-known cathode ray tube, electron beams emitted from an electron gun assembly are deflected to a phosphor screen in horizontal and vertical directions. The electron beams impinge on a corresponding phosphor pixel, resulting in emission of light to form images or characters.
Cathode ray tubes are mainly installed in color televisions and computer monitors to be provided to consumers. Cathode ray tubes have also been enhanced to be installed in High-Definition televisions (HDTV).
Rectangular cathode ray tube cones on which the deflection yoke is mounted have recently been under development, and a ferrite core having a rectangular configuration similar to that of the cone is also being developed so that misconvergence can be minimized.
Color cathode ray tubes of the prior art are illustrated in
FIGS. 1-4
. A color cathode ray tube shown in
FIG. 1
is formed with a vacuum envelope having a substantially rectangular panel
104
, a funnel
106
formed contiguous to the panel
104
, a cylindrical neck
110
formed contiguous to the funnel
106
, and a deflection yoke DY mounted on a cone
106
a
of the funnel
106
near the neck
110
. An electron gun
108
is mounted on the inside of the neck
110
.
The interior cross section of the cone
106
a
of the funnel
106
is made to have a circular shaped cross-section at the neck
110
, and becomes a substantially non-circular shape such as a rectangle towards the panel
104
.
The deflection yoke as shown in
FIG. 4
, which is mounted on the cone
106
a
, comprises a separator
112
made of resin, a horizontal deflection coil
114
and a vertical deflection coil
116
mounted at the inside and outside of the separator
112
, respectively, and a ferrite core
118
mounted at the exterior of the separator
112
.
The separator
112
as shown in
FIG. 2
is formed with a cone shape having a small diameter section
112
a
positioned at a neck of the cathode ray tube and a large diameter section
112
b
positioned at a funnel of the cathode ray tube, so that the interior cross section of the separator
112
is made in substantially a circular shape at the small diameter section
112
a,
then becomes a substantially non-circular shape such as a rectangle towards the large diameter section
112
b
. The separator
112
is formed with separated bodies which are joined to each other in an integrated form.
The ferrite core
118
, as shown in
FIG. 3
, has a small diameter part
118
a
positioned at the neck of the cathode ray tube, and a large diameter part
118
b
positioned at the funnel of the cathode ray tube, so that the cross section of the ferrite core
118
is made to be a substantially circular shape at the small diameter part
118
a
, then becomes a substantially non-circular shape such as a rectangle towards the large diameter part
118
.
It is possible to form the ferrite core
118
as an integrated form of one piece, or as a separated form where the ferrite core
118
is formed by two or more pieces to be clamped by core clamps
120
.
Since the color cathode ray tube of the prior art has a substantially rectangular shape of the cone
106
a
and the separator
112
as well as the ferrite core
118
, it is possible to effectively approximate the deflection coils
114
and
116
to the trajectories of the electrons emitted from the electron gun
108
, resulting in the reduction of deflection power.
However, the color cathode ray tube of the prior art has some drawbacks. The ferrite core has desirable dimensions in order to allow for manufacturing tolerance of the vertical deflection coil, as well as to be easily mounted on the exterior of the separator on which the vertical deflection coil is already mounted. Therefore, a gap of 0.5-2 mm long occurs between the ferrite core and the separator when assembled. Due to the gap, the ferrite core may rotate around the separator, resulting in misalignment of the position and direction of the ferrite core. The misalignment of the position and direction is associated with an increase of the misconvergence, thereby reducing the deflection power efficiency.
Therefore, in order to avoid misalignment or rotation of the ferrite core, the prior art assembling process uses adhesives to fix the ferrite core on the separator after the ferrite core is disposed on the separator and adjusted to the correct position.
However, the prior art assembling process needs an additional fixing process, resulting in an increase of process time. Easy assemble of the ferrite core is required in the manufacturing process.
SUMMARY OF THE INVENTION
In view of the prior art described above, it is an object of the present invention to provide a deflection yoke for a color cathode ray tube capable of easily assembling a ferrite core on a separator.
To achieve this object, as embodied and broadly described herein, the invention comprises:
a separator having a small diameter section positioned at a neck of the cathode ray tube and a large diameter section positioned at a funnel of the cathode ray tube, wherein a horizontal deflection coil and a vertical deflection coil are mounted on the inner surface and outer surface of the separator, respectively;
a ferrite core mounted on the exterior of the separator, having a small diameter part positioned at the neck of the cathode ray tube, and a large diameter part positioned at the funnel of the cathode ray tube; and
a position holding unit provided to the separator and the ferrite core, for holding the ferrite core in a predetermined position and direction with respect to the separator.
In an aspect of the present invention, the position holding unit comprises at least one pair consisting of a raised portion and a depressed portion, the raised portion and depressed portion being provided on the ferrite core and the separator, respectively, and being joined to each other.
In another aspect of the present invention, the position holding unit comprises a pin hole formed on the ferrite core and the separator, and a pin adapted for the pin hole.
Both the foregoing general description and the following Detailed Description are exemplary and are intended to provide further explanation of the invention as claimed.

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