JP2002075250A - Deflection yoke - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a deflection yoke that prevents generation of residual four-pole magnetic field and does not bring about configuration deterioration of the electron beam even when a centering magnet of alnico system magnetic material is used. SOLUTION: The deflection yoke having a centering magnet for centering adjustment is provided. To resolve the above problem, the centering magnet is injection molded by having the even number of injection mold gates placed symmetrically for the centering magnet. And each pole is magnetized and set at any of the opposing gate portions of the centering magnet or at any of the opposing weld line portions.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cathode ray tube (CR)
T) relates to a deflection yoke for deflecting the electron beam.

[0002]

2. Description of the Related Art Conventionally, in a deflection yoke, centering adjustment of an electron beam is performed by combining two ring-shaped centering magnets (1) and (1) on the neck side of the deflection yoke (2) as shown in FIG. The two centering magnets (1) are mounted and adjusted by rotating each of them.

The centering magnets (1) and (1) for centering adjustment are two-pole magnets, and as shown in FIG. 6, one side of the rotation adjusting knobs (1a) and (1b) (1b side in FIG. 6). ) Is formed by pouring a resin mixed with a magnetic material powder, molding the resin, and then magnetizing two poles.

As the magnetic material of the centering magnets (1), (1), alnico-based, ferrite-based, or rare-earth-based magnetic materials are used. The system type is generally used.

[0005]

However, since the alnico magnetic powder used for the resin centering magnet has larger particles than the ferrite magnetic powder, the density of the magnetic powder in the centering magnet during resin molding is large. There is a problem that spots (bias) are formed.

More specifically, as shown in FIG. 7, the density of the magnetic powder decreases on the gate opening side where the resin is poured, and the opposite side of the gate opening, that is, the tip where the resin flows and the resin that flows in are formed by a molding die. The density is increased by a weld line formed at a portion where it is merged again after being divided in two directions. Then, when the magnetic force is magnetized on the centering magnet having the density unevenness, a magnetization unevenness is formed in accordance with the density unevenness, and as shown by an arrow in FIG. The poles have a dispersed shape on the side, the poles are concentrated at the high-density tip and weld line, and the polarization point is reduced from the center between the poles. It shifts to the concentrated person.

When two centering magnets whose polarization points are displaced in this way are used in combination for centering adjustment, for example, in order to make the adjustment magnetic force zero, two centering magnets (1) (1) as shown in FIG. ) Is overlapped between different poles, a residual quadrupole magnetic field as shown in FIG. 10 is generated because the synthesized magnetic field lines are not symmetrical. Such a residual quadrupole magnetic field distorts the shape of the electron beam as shown in FIG. 11, and as a result, degrades the focus performance of the image projected on the picture tube and lowers the resolution of the image.

Accordingly, the present invention is applicable to the case where the centering magnet of an alnico magnetic material is used.
An object of the present invention is to provide a deflection yoke that prevents generation of a polar magnetic field and does not cause deterioration of the shape of an electron beam.

[0009]

SUMMARY OF THE INVENTION The present invention is a deflection yoke provided with a centering magnet for adjusting centering. In order to solve the above-mentioned problems, the centering magnet has a resin molded gate opening with respect to the centering magnet. It is characterized in that an even number of the centering magnets are provided and resin-molded so as to be symmetrical, and each pole is magnetized at any of the facing gate opening portions or any of the opposite weld line portions of the centering magnet. And

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a first embodiment of a centering magnet used for a deflection yoke according to the present invention, and the present invention will be described below with reference to the drawings.

In FIG. 1, a centering magnet (1) of the present invention is formed by molding a resin mixed with alnico-based magnetic material powder, and has the same ring shape as the conventional one, and a rotation adjusting knob. (1a) and (1b), and FIG.
As shown in (1), two pieces are combined and mounted on the neck side of the deflection yoke as in the conventional case. What is different from the conventional example of this embodiment is that the resin-molded gate opening for resin-molding the centering magnet (1) is provided with the rotation adjustment knobs (1a) (1b).
In two places and molded.

In the centering magnet (1) of this embodiment, the resin flows as indicated by the arrow in FIG. 1, and the density of the magnetic material powder is substantially at the center between the rotation adjusting knobs (1a) and (1b) which are gate openings. High weld line occurs. On the other hand, the density of the magnetic material powder in the rotation adjustment knobs (1a) (1b) on the gate opening side is low. Further, in this embodiment, the magnetization is performed so that the rotation adjustment knobs (1a) and (1b) become poles.

The centering magnet according to the present embodiment
(1) FIG. 2 shows the shape of the line of magnetic force in (1). That is, in the present embodiment, each pole is magnetized in a portion having a low density, and the density distribution of the magnetic material powder in the centering magnet (1) is symmetric with respect to the center line between the poles. A point is formed between each pole. As a result, the lines of magnetic force are shown in FIG.
As shown in (1), it occurs symmetrically with respect to the center line of each pole.

The two centering magnets (1)
When (1) is overlapped between mutually different poles, the synthesized magnetic lines of force coincide symmetrically as shown in FIG. 3, and as a result, they are canceled as shown in FIG. 4, and no residual quadrupole magnetic field is generated unlike the related art.

FIG. 5 shows a second embodiment of the centering magnet used in the deflection yoke of the present invention. In this embodiment, the gate opening of the resin molding is
The rotation adjustment knobs (1a) and (1b) of (1) are respectively provided at centrally opposed positions. In this case, a weld line having a high density can be formed at the rotation adjustment knobs (1a) and (1b) located between the gate openings. Here, as shown in FIG. 5, when the rotation adjustment knobs (1a) and (1b) are magnetized so as to be at the respective poles, the density distribution of the magnetic material powder in the centering magnet (1) becomes the center between the poles. Since it is symmetrical with respect to the line, the polarization point is formed in the middle of each pole, and the same effect as in the first embodiment can be obtained.

As described above, in the first and second embodiments, the respective poles are formed on the rotation adjustment knobs (1a) and (1b). However, the respective poles are formed at intermediate positions of the rotation adjustment knobs (1a) and (1b). Similar effects can be obtained by forming the poles. The number of gate ports is not limited to two, and an even number is provided so as to be symmetrical with respect to the centering magnet (1), and each pole is provided at any of the opposing gate port portions or at any of the opposing weld line portions. The same effect can be obtained by magnetizing.

[0017]

According to the present invention, since the magnetic field lines of the centering magnet are generated symmetrically with respect to the center line of each pole, a four-pole magnetic field is generated in a festival in which two centering magnets are overlapped by different poles. Since the lines of magnetic force are ideally canceled without performing, the deterioration of the shape of the electron beam can be prevented.

[Brief description of the drawings]

FIG. 1 is a diagram showing a first embodiment of a centering magnet used in a deflection yoke according to the present invention.

FIG. 2 is a diagram showing lines of magnetic force in the first embodiment of the present invention.

FIG. 3 is a diagram showing lines of magnetic force synthesized in the first embodiment of the present invention.

FIG. 4 is a view showing a result of synthesizing magnetic lines of force in the first embodiment of the present invention.

FIG. 5 is a view showing a second embodiment of the centering magnet used in the deflection yoke according to the present invention.

FIG. 6 is a view showing a deflection yoke using a centering magnet.

FIG. 7 is a view showing a conventional centering magnet.

FIG. 8 is a diagram showing lines of magnetic force in a conventional example.

FIG. 9 is a diagram showing magnetic lines of force synthesized in a conventional example.

FIG. 10 is a diagram showing a result of synthesizing magnetic lines of force in a conventional example.

FIG. 11 is a diagram showing deformation of an electron beam in a conventional example.

[Explanation of symbols]

 1. Centering magnet 1a, 1b. Rotation adjustment knob 2. Deflection yoke

Claims (3)

[Claims] 1. A deflection yoke provided with a centering magnet for adjusting centering, wherein the centering magnet is resin-molded by providing an even number of resin-molded gate openings so as to be symmetrical with respect to the centering magnet. A deflection yoke, wherein each pole is magnetized at any of the opposed gate openings of the centering magnet. 2. A deflection yoke provided with a centering magnet for adjusting centering, wherein the centering magnet is resin-molded by providing an even number of resin-molded gate openings so as to be symmetrical with respect to the centering magnet. A deflection yoke characterized in that each pole is magnetized at one of opposite weld line portions of a centering magnet. 3. The deflection yoke according to claim 1, wherein the centering magnet is made of an alnico-based magnetic material.