Electricity: magnetically operated switches – magnets – and electr – Magnets and electromagnets – Electron or ion beam deflecting type
Reexamination Certificate
2000-04-07
2002-09-17
Barrera, Ramon M. (Department: 2879)
Electricity: magnetically operated switches, magnets, and electr
Magnets and electromagnets
Electron or ion beam deflecting type
C335S212000
Reexamination Certificate
active
06452471
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a color purity and convergence magnet for adjusting the static characteristics of the color purity and convergence of a color cathode ray tube and, more particularly to a color purity and convergence magnet capable of fine-adjusting the running paths of the electron beams irrespective of the position of the axial direction of the tube, reducing the influence of its adjusting magnetic field on the electron beams and improving the workability when manufacturing the color cathode ray tube.
2. Description of the Background Art
Generally, in a color cathode ray tube having an electron gun with a structure of in-line arrangement, a color purity and convergence magnet (PCM) is composed of two-pole, four-pole and six-pole magnets. The two-pole magnet adjusts the color purity, the four-pole magnet adjusts the mutual position of two outer electron beams, that is, R/B electron beams, and the six-pole magnet adjusts the mutual position of a central electron beam and two outer electron beams, that is, R/G and B/G electron beams, thereby adjusting the static characteristics of the color purity and convergence of the color cathode ray tube. Each of these magnets is formed in a pair in order to adjust finely the color purity and convergence.
A four-pole magnet widely utilized in the conventional art is illustrated in FIG.
1
and
FIGS. 2
a
through
2
b
. As illustrated therein, the four-pole magnet consists of a pair of front and rear rings
11
and
12
having a predetermined width. As illustrated in
FIG. 1
, the front and rear rings
11
and
12
are mounted on the neck portion
1
of the tube in a longitudinal direction of the cathode ray tube. The rear ring
12
is formed to have a magnetic field about 1.1~1.3 times stronger than that of the front ring
11
. The two-pole and six-pole magnets are formed in the same manner. This difference between the magnetic fields formed at the front and rear rings
11
and
12
is obtained by considering components of velocity acquired when electrons are accelerated in the electron gun.
However, such configuration is disadvantageous for the following reasons. Firstly, since a pair of magnets on which a certain magnetic field is formed influence the electron beams differently depending on their position, an optimum adjustment may be made only at a position corresponding to the difference between the magnetic fields formed at the front and rear rings
11
and
12
.
Secondly, since a certain magnetic field was already formed in each of the front and rear rings, it influences the electron beams even in the case that adjustment is not required.
In other words, at any random position at which a composite magnetic field in front-rear arrangement is accelerated from the axial direction of the tube to the screen direction, the magnetic field cannot be close to zero and thus this adjustment becomes difficult. Generally, two-pole, four-pole and six-pole magnetic fields or electric fields have a problem of distorting the shape of electron beams. Among them, the four-pole magnetic field is most fatal. Moreover, there is another problem that it is difficult to achieve the fine adjustment required in an ITC process of combining a cathode ray tube and a deflection yoke.
In order to solve the above problems, Japanese patent application laid-open publication No. Sho 51-65830 (Jun. 7, 1976) discloses a magnetic beam adjusting device for use in a cathode ray tube that is not arranged forward and backward in a longitudinal direction of the tube, but arranged to overlap in a radial direction as illustrated in
FIGS. 3 and 4
.
In the conventional beam adjusting device as illustrated in
FIGS. 3 and 4
, two four-pole ring-shaped magnets
1
A and
1
B in a pair are formed, for example, by using a binder made of rubber and synthetic resin and injecting powdered magnet material such as barium ferrite into the binder. The pair of magnets have different inner diameters and are combined in a state in which they are double-sided in and out, with one direction at the inner side and the other direction at the outer side, and relative rotation is freely performed. To ensure this combination, a flange
2
is formed at one end of the inner ring-shaped magnet
1
A, and the outer ring-shaped magnet
1
B is fixedly fitted to a step portion formed along the outer circumferential surface of the flange
2
.
This pair of ring-shaped magnets
1
A and
1
B are mounted on the neck portion of the picture tube, and both magnets
1
A and
1
B are positioned at the same surface orthogonal to the tube axis. Both ring-shaped magnets
1
A and
1
B have four magnetic poles arranged at the same interval from each other in a circumferential direction, with alternating polarity. These magnetic fields are installed at the outer surface of the inner ring-shaped magnet
1
A and at the inner surface of the outer ring-shaped magnet
1
B, so that they are opposed to the surface of contact between the inner and outer ring-shaped magnets
1
A and
1
B. Herein, the reference numerals
3
and
4
indicate hand levers for rotation control of the ring-shaped magnets
1
A and
1
B, respectively.
By this construction, the magnetic field in the tube can be remained in a zero state, thereby an accurate adjustment becomes possible, leakage flux minimally influences on the interior of the picture tube, and, further, the length in the axial line direction can be decreased.
In addition, as an example of an another conventional art, Japanese patent application laid-open publication No. Hei 4-181638 (Jun. 29, 1992) discloses a convergence purity correction apparatus as illustrated in
FIGS. 5
a
-
5
c
and FIG.
6
.
In
FIGS. 5
a
and
5
b
, a two-pole magnet
40
A and a four-pole magnet
40
B are combined on the same surface. For this reason, the axial length for a pair of ring magnets is decreased, and the back space for a deflection yoke can be set as large as the decreased length as compared to the conventional art. Thus, it is possible to sufficiently back the deflection yoke toward the electron gun assembly during color purity adjustment for the cathode ray tube, and it is easy to perform the color purity adjustment.
Also, in a composite ring magnet
40
A as illustrated in
FIG. 6
, a two-pole magnet
40
A
1
having an inner diameter larger than that of a ring type four-pole magnet
40
B having almost the same inner and outer diameters as in the conventional art is co-axially attached to the same surface as the four-pole magnet
40
B, with a rotary ring
40
D
1
intercalated to the outer diameter of the four-pole magnet
40
B, and another two-pole magnet
40
A
2
is co-axially attached to the same surface as the four-pole magnet
40
B and the two-pole magnet
40
A
1
, with a rotary ring
40
D
2
intercalated to the outer diameter of the two-pole magnet
40
A
1
.
In this structure, the rotary rings
40
D
1
and
40
D
2
are constructed in such a manner that they can rotate freely, independently and smoothly, being interlocked with an H-type sphere at the inner and outer diameter portions of the rotary rings
40
D
1
and
40
D
2
and a protruding portion formed at the inner and outer diameter portions of the four-pole magnet
40
B and the two-pole magnets
40
A
1
and
40
A
2
. In a ring portion at the outer diameter of the two-pole magnets
40
A
1
and
40
A
2
and four-pole magnet
40
B, respective hand levers are constructed such that they are formed as a single body to thereby perform rotation adjustment conveniently.
By the construction as above described in which the two-pole magnets and the four-pole magnet are combined and the two-pole magnets are arranged at the outer sides of the four-pole magnet, a back space for the deflection yoke can be obtained, and the axial length of the magnetic correcting device can be reduced. Moreover, by enlarging the inner diameter of the two-pole magnet, a parallel uniform magnetic field can be obtained in a region where electron beams exist, thereby eliminating the deformation of a section of an e
Byun Soo Ryong
Lee Kwang Jun
Barrera Ramon M.
Notaro $ Michalos PC
Orion Electric Co. Ltd.
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