Deflection yoke

Details Deflection yoke Deflection yoke

2001-11-16

2004-07-27

Patel, Nimeshkumar D. (Department: 2879)

Electric lamp and discharge devices

Cathode ray tube

Beam deflecting means

C313S403000, C313S456000

Reexamination Certificate

active

06768251

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a deflection yoke, in particular, which can improve an assembly structure of a printed circuit board thereby preventing release thereof while enhancing the productivity.
2. Description of the Prior Art
In general, a Cathode Ray Tube (CRT) in a television or a monitor has a deflection yoke for correctly deflecting RGB beams scanned from an electron gun to a fluorescent screen applied on a screen of the CRT. Such a deflection yoke as one of the most important magnetic components in the CRT serves to deflect the electron beams from the electron gun so that electric signals transmitted in time sequence can be reproduced as images on the screen of the CRT.
In other words, since the electron beams projected from the electron gun directly move onto the screen via a high voltage to light only central phosphors in the screen, the deflection yoke externally deflects the electron beams in the order of scanning. Here, the deflection yoke forms a magnetic field to deflect the electron beams correctly to the fluorescent screen applied on the screen of the CRT based on the fact that the electrons are forced to change the path thereof while passing through the magnetic field.
FIG. 1
is a side elevation view for showing a general CRT. As shown in
FIG. 1
, a deflection yoke
4
is placed in an RGB electron gun section
3
of the CRT
1
to deflect electron beams scanned from an electron gun
3
a
to a fluorescent screen applied on a screen surface
2
.
Such a deflection yoke
4
comprises coil separator
10
constituted by a pair of symmetric upper and lower parts which are coupled into one unit.
The coil separator
10
is provided to insulate a horizontal deflection coils
15
and a vertical deflection coils
16
while assembling the positions thereof in a suitable degree, and comprised of a screen portion
11
a
for being coupled to a screen surface side of the CRT
1
, a rear cover
11
b
and a neck portion
12
integrally extended from a central surface of the rear cover
11
b
for being coupled to the electron gun section
3
of the CRT
1
.
The coil separator
10
is respectively provided in the inner and outer peripheries with the horizontal deflection coils
15
and the vertical deflection coils
16
for forming a horizontal magnetic field and a vertical magnetic field via externally applied power.
Further, a pair of ferrite cores
14
made of a magnetic substance are installed to wrap the vertical deflection coil
16
to strengthen a vertically deflected magnetic field generated from the vertical deflection coil
16
.
The deflection yoke
4
configured like this is installed in the neck portion
12
of the CRT
1
, and when the horizontal deflection coil
15
and the vertical deflection coil
16
are applied with a sawtooth wave pulse, generates the magnetic field based on the Fleming's left hand rule to deflect the RGB electron beams emitted from the electron gun
3
a
of the CRT for determination of scanning positions on the screen through.
Meanwhile, the deflection yoke as shown in
FIG. 1
is classified into a saddle-saddle type deflection yoke as shown in
FIGS. 2 and 3
and a saddle-toroidal type deflection yoke as shown in
FIGS. 4 and 5
according to the winding structure of the coils.
In this case, the saddle-saddle type deflection yoke as shown in
FIGS. 2 and 3
comprises saddle type deflection coils
15
installed in the upper and lower sides of the inner periphery of a screen portion of a substantially conical coil separator and saddle type vertical deflection coils
16
installed in right and left sides of the outer periphery thereof.
In order to strengthen the magnetic field of the vertical deflection coils
16
, the coil separator
10
is provided in the outer periphery of the screen portion
11
a
with a substantially cylindrical ferrite core
14
.
Further, around the outer periphery of the neck portion
12
of the coil separator
10
is provided a coma-free coil (not shown) for compensating coma generated from the vertical deflection coils
16
.
FIGS. 4 and 5
show a general saddle-toroidal type deflection yoke. In the saddle-toroidal type deflection yoke, horizontal deflection coils
15
are installed in the upper and lower sides of the inner periphery of a screen portion
11
a
of a substantially conical coil separator
10
, a substantially cylindrical ferrite core
14
is provided in the outer periphery, and vertical deflection coils
16
are wound along the upper and lower sides of the ferrite core
14
.
Further, around the outer periphery of a neck portion
12
of the coil separator
10
is additionally installed a coma-free coil (not shown) for compensating coma generated from the vertical deflection coils
16
.
Besides, each of the saddle-saddle type and saddle-toroidal type deflection yokes has a printed circuit board installed in one side of the coil separator
10
for supplying power to the foregoing horizontal deflection coils
15
and the vertical deflection coils
16
.
FIGS. 6 and 7
show an assembly structure of a printed circuit board in a deflection yoke of the prior art. As shown in
FIGS. 6 and 7
, a coil separator
10
has a rear cover
11
b
coupled with the printed circuit board
100
for electrically connecting deflection coils and various electric instruments.
The printed circuit board
100
, as shown in
FIG. 6
, comprises slide grooves
110
formed in an upper part with a predetermined interval and through-holes
120
formed at a predetermined interval under the slide groove
110
, in which the slide grooves
110
and the through-holes
120
are typically provided in a pair. Mean while, as shown in
FIG. 6
, each of the slide grooves
110
has a U-shape, and each of the through-holes is provided as a substantially rectangular hole.
Such a printed circuit board
100
is fitted and coupled into a number of hook pieces
200
provided on the rear cover
11
b
, in which the hook pieces
200
are constituted by upper hook pieces
210
and lower hook pieces
220
respectively formed at positions corresponding to the slide grooves
110
and the through-holes
120
.
In this case, the upper and lower hook pieces
210
and
220
are inserted into the slide grooves
110
and the through-holes
120
formed in the printed circuit board
100
to fix the printed circuit board to the rear cover
11
b
. Such upper and lower hook pieces
210
and
220
have ribs r
1
and r
2
and triangular piece-shaped protrusions p
1
and p
2
which are integrally formed at an interval corresponding to the thickness of the printed circuit board
100
for contacting to front and rear sides of the printed circuit board
100
for support thereof.
Meanwhile, the protrusions p
1
and p
2
are projected from the leading ends of the upper and lower hook pieces
210
and
220
in triangular shape and have sizes that allow interference fit into the slide grooves
110
and the through-holes
120
, and in particular, the protrusions p
1
in the upper hook pieces
210
are projected as opposed to the protrusions p
2
in the lower hook pieces
220
. Further, the ribs r
1
and r
2
are projected at positions distanced from the protrusions p
1
and p
2
at an interval corresponding to the thickness of the printed circuit board.
The upper and lower hook pieces
210
and
220
with the foregoing protrusions pl and p
2
and the ribs r
1
and r
2
have an interval that is slightly wider than that of the pair of slide grooves
110
and the pair of through-holes
120
for enabling elastic fastening thereof.
The conventional deflection yoke configured as above can be fixed through insertion of the slide grooves
110
and the through-holes
120
of the printed circuit board
100
into the upper and lower hook pieces
210
and
220
which are integrally projected from the rear cover
11
b.
However, in the convention deflection yoke like this, the printed circuit board
100
and the rear cover
11
are coupled through a fitting structure, in which assembly thereof is extraordinarily difficult due to the str

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