Electric lamp and discharge devices – Cathode ray tube – Beam deflecting means
Reexamination Certificate
2001-04-25
2004-04-13
Krishnan, Sumati (Department: 2875)
Electric lamp and discharge devices
Cathode ray tube
Beam deflecting means
Reexamination Certificate
active
06720724
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a deflection yoke used with an in-line type cathode ray tube (CRT), and particularly relates to a deflection yoke for adjusting a characteristic of a magnetic field, such as convergence or purity, by rotating a multipolar magnetic ring mounted on a cylindrical neck portion of such deflection yoke.
2. Description of the Related Art
Generally, a deflection yoke used with an in-line type CRT, has a multipolar, for example, dipole or quadrupole magnetic ring. The multipolar magnetic ring is used for adjustment of a magnetic field characteristic such as convergence or purity of a CRT by tuning a position of such the multipolar magnetic ring.
FIG. 8
is a perspective view for explaining an example of a deflection yoke for a CRT. In
FIG. 8
, the deflection yoke comprises a pair of separators
1
a
and
1
b
made by an insulating material, a pair of horizontal deflection coils (not shown) in inside of the deflection yoke, a pair of vertical deflection coils
7
on the outside of the deflection yoke, and a pair of cores
2
on the outer side of the vertical deflection coil
7
. A flange if is formed in a narrower diameter side of the first separator
1
a
and the second separator
1
b
, and a cylindrical neck portion
103
is formed in the flange
1
f
. A clamp band
5
with a screw
6
is loaded on the upper portion of the neck portion
103
to stabilize deflection yoke on to CRT.
FIG. 9
is a partial perspective view for explaining the example of the deflection yoke shown in FIG.
8
. In
FIG. 9
, the cylindrical neck portion
103
having tongues
103
a
through
103
f
, is formed on a flange
1
f
with the first and second separators
1
a
and
1
b.
The cylindrical neck portion
103
is inwardly flexible as it has slits
104
a
through
104
f
. A clamp band
5
for fixing the deflection yoke to a neck of the CRT is provided on the upper side of the neck portion
103
. The screw
6
is screwed to the clamp band
5
, and fastens the deflection yoke to the neck of the CRT by tightening the clamp band
5
about the neck portion
103
. A prominence
14
is formed on the upper portion of tongues
103
c
and
103
f
to fit with a pair of hole
5
a
and
5
b
formed in the clamp band
5
. The prominence
14
has a slope in downward direction for leading the holes
5
a
and
5
b
to make the clamp band
5
easily fit with the neck portion
103
. The clamp band
5
with a screw
6
is loaded on the upper portion of the neck portion
103
to stabilize the deflection yoke on to the CRT.
A magnetic ring
10
and a magnetic ring
11
having a multipolar magnet respectively are provided between the clamp band
5
and the flange
1
f
of the first and second separators
1
a
and
1
b
.
FIG. 9
shows the clamp band
5
and the magnetic rings
10
and
11
being removed from the neck portion
103
. Generally, the magnetic rings
10
and
11
comprise material dispersed with magnetic powder such as barium ferrite or the Alnico alloy substance evenly on a nylon plastic. As the magnetic ring has variety in size at manufacturing, the inner diameter of the magnetic rings
10
and
11
is 0.4 mm wider at maximum than the outer diameter of the neck portion
103
, in order to avoid the magnetic ring being tightfitting with the neck portion
103
.
More precisely, protrusions
12
a
and
12
b
are provided at the bottom of the neck portion
103
, and are flexible in the longitudinal direction of the neck of the CRT (i.e. the direction of a Z axis). A hook
13
having a claw
13
a
of triangular shape at their distal ends are formed in the tongues
103
c
and
103
f
of the neck portion
103
. The magnetic rings
10
and
11
are inserted from the rear side of the deflection yoke, about the neck portion
103
between the protrusions
12
a
and
12
b
, and the claw
13
a.
FIG. 10
is a cross-sectional view of the neck portion
103
along with the direction of the Z axis. An edge side
13
a
1
of the claw
13
a
is almost orthogonal with the Z axis and a sloped side
13
a
2
of the claw
13
a
stick out with length d
1
which is about 1.3 mm long enough to hold the magnetic ring being attached between the protrusions
12
a
and
12
b
, and the claw
13
a
. An outer side
13
a
3
of the claw
13
a
is provided to maintain the strength of metal mold for molding the separators
1
a
and
1
b
. The outer side
13
a
3
is almost parallel to the Z axis and has length of approximately 0.3 mm.
Recently, there has been a need for small display monitor using CRT in the market. In order to provide such a small display, the length of CRT and the deflection yoke is required to be shorter. For this reason, the distance between the bottom side of the clamp band
5
and the bottom side of magnetic rings attached to the neck portion
103
is required to be shorter, and the length of the claw
13
a
in the direction of Z axis is required to be 1.3 mm at maximum. Under circumstance, the length of each side of the claw
13
a
should be set to make slope angle &thgr; of the slope side
13
a
2
bigger so that the magnetic rings can be easily attached to the neck portion
103
.
A slope side
13
a
2
s
is a start position of the slope for the slope side
13
a
2
. The slope side
13
a
2
s
is not set to the position coming out of the outer diameter side of the neck portion
103
but contiguous the outer diameter portion of the neck portion
103
. The slope angle &thgr;, for example, is 32 degrees. The reason why the slope side
13
a
2
s
does not start from the inner diameter side of the neck portion
103
(and the reason why the claw
13
a
has the edge side
13
a
1
) is because the slope angle &thgr; will be maximum at this position.
As the magnetic rings
10
and
11
are inserted to the neck portion
103
from the narrower diameter side of the deflection yoke, the magnetic rings
10
and
11
contact the prominence
14
and the neck portion
103
flex inwardly to let the magnetic rings
10
and
11
pass through the prominence
14
. Then the magnetic rings
10
and
11
contact the slope side
13
a
2
and the tongue
13
flex inwardly. Eventually, the magnetic rings
10
and
11
are held between the protrusions
12
a
and
12
b
, and the claw
13
a
. The distance between the protrusions
12
a
and
12
b
, and the claw
13
a
is lesser than the thickness of the magnetic rings
10
and
11
so that the bounce force of the protrusion
12
a
and
12
b
holds the magnetic rings
10
and
11
.
The adjustment of a characteristic of a magnetic field of CRT can be accomplished by putting a deflection yoke on the CRT and rotating the magnetic rings
10
and
11
. The magnetic rings can be rotate at an appropriate torque (not too tight or not too loose) by the protrusions
12
a
and
12
b
, and the claw
13
a
holding the magnetic rings
10
and
11
so that the magnetic rings
10
and
11
can not easily rotate before they are being fixed with a glue after the adjustment. This torque is also caused by the bounce force of the protrusions
12
a
and
12
b
in the direction of the Z axis.
FIG. 11
is a cross-sectional view of the tongues
103
f
and
103
c
of the neck portion
103
along with the direction of the Z axis where the magnetic ring
11
is being inserted. When the magnetic rings
10
and
11
is inserted in the neck portion
103
by hands, the magnetic ring
11
will occasionally be pushed to the direction shown as an arrow A in
FIG. 11
which is the direction orthogonal to the Z axis. Then the tongue
103
f
flexes inwardly from the position shown in a dotted line. At this position, the inner circumference side of the magnetic ring
11
contacts the edge side
13
a
1
of the claw
13
a.
This will cause the insertion of magnetic ring
11
to the neck portion
103
difficult. Too much strength to insert the magnetic ring
11
in the neck portion
103
at this position may break the magnetic rings
10
and
11
. As explained above, the magnetic rings
10
and
11
may break in the way of inserting.
SUMMARY OF THE INVENTION
Accordingly, in con
Chonan Yusuke
Morimoto Keiji
Connolly Bove & Lodge & Hutz LLP
Krishnan Sumati
Victor Company of Japan Ltd.
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