JP2001332189A - Deflection yoke - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a deflection yoke for effectively reducing raster distortion due to making a screen planer or using a plurality of screen systems. SOLUTION: Correcting elements 37 for generating a magnetic field are provided near bent portions 35a of a pair of horizontal deflection coils 35 on the inner face side of a molding 32. Each of the used correcting elements 37 is flat with its thickness being almost the same as that of the horizontal deflection coil 35. The raster distortion of an image on a plane screen is effectively reduced without using a magnet having a great volume.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a deflection yoke with reduced raster distortion.

[0002]

2. Description of the Related Art Generally, a color picture tube for displaying a color image and a monochrome picture tube for displaying a monochrome image are widely used for displaying various kinds of images. I'm advancing. As the screen is flattened in this way, the conventional deflection yoke has a large raster distortion, which cannot be sufficiently corrected.

Further, a system for projecting one image using two or more electron guns and a deflection yoke has been proposed. However, in such a system, the deflection angle in the vertical direction is large, so that distortion is large. It tends to be. In addition, it is necessary to reduce the horizontal line distortion more than before, and the vertical line distortion is also related to the continuity of the screen boundary,
Its control becomes particularly important.

Here, the structure of a conventional general deflection yoke will be described with reference to FIGS.

In general, the deflection yoke 1 scans an electron beam emitted from an electron gun in a horizontal direction and a vertical direction, and has a pair of horizontal deflection coils and a pair of vertical deflection coils provided orthogonally to each other.

As shown in FIGS. 7 and 8, a mold 2 is provided for holding and fixing the horizontal deflection coil and the vertical deflection coil. This mold 2
The mold 2 is formed by injection molding into a funnel shape having a tapered portion whose outer diameter becomes smaller from one end to the other end.
Although not shown, a pair of horizontal deflection coils are provided inside the. As shown in the figure, a ferrite core 3 is provided outside the mold 2 so as to cover the outer surface of the tapered portion.
As shown in the figure, a pair of left and right vertical deflection coils 4 are provided.

[0007] Also, at the front of the outside of the mold 2,
As shown in FIG. 8, magnets 5 as correction elements for correcting raster distortion at the top and bottom of the screen are provided at the top and bottom, respectively. Depending on the model, a small electromagnetic coil 6
Some are provided.

Generally, it is known that a raster distortion as shown in FIG. 9 can occur in a deflection yoke. This raster distortion can be divided into horizontal line distortion, which is vertical distortion, and vertical line distortion, which is horizontal distortion.

Among them, the method of correcting left-right distortion using a deflection circuit is widely used, and it is not necessary to completely correct the distortion using a magnetic field distribution. On the other hand, for vertical distortion,
Correction by the deflection circuit is possible, but the circuit becomes complicated,
In addition to the increase in cost, there is a limit to the amount of correction, and in practice, it is necessary to correct only the magnetic field distribution.

For this purpose, the most basic method is to use a horizontal magnetic field as a pin magnetic field, but there is a limit to this alone, and magnets are widely provided above and below the deflection yoke. This magnet is usually provided outside and above the front of the mold 2 as shown in FIGS. 7 and 8.

The effect of reducing the raster distortion will be described with reference to FIG. A magnetic field 22 generated by the distortion correcting magnet 5 is shown together with the horizontal deflection magnetic field 21, and an electron beam 23 directed to a diagonal of the screen is shown for these. The action of the magnetic field in the third and fourth quadrants is not shown.

Under such a magnetic field, the electron beam 23 directed to the diagonal of the screen receives the Lorentz force FA1.
The Lorentz force FA1 has a vertical component FA1y as shown in the figure because the horizontal deflection magnetic field 21 is pin-shaped. The vertical component FA1y acts to press down the electron beam 23. This is the same in the second quadrant, and the electron beam 23 directed to the diagonal of the screen is pressed down. On the other hand, the electron beam 24 directed to the end point V of the vertical axis of the screen is caused by the Lorentz force due to the magnetic field 22 generated by the distortion correcting magnet 5.
It will be raised by Fm.

As described above, even with the conventional deflection yoke 1, the electron beam 23 directed to the diagonal D is subjected to a Lorentz force that is pressed downward, and near the end point V of the vertical axis, the electron beam 24 is pressed. Raster distortion is reduced by the Lorentz force acting such that is lifted upward.

In recent years, the screen of a color picture tube has been flattened, but the raster distortion becomes larger as the screen becomes flatter. For this reason, in order to perform more corrections, a magnet having a large volume is required, but this increases the cost. In addition, a large volume imposes restrictions on the magnetic field distribution, which is not desirable in terms of characteristics.

In the case of a multi-screen system using a plurality of electron guns and a change yoke, as shown in FIG. 12, the vertical distortion leads to bending at the boundary, so that it is more permissible than in the case of one screen. Becomes smaller. Also, in a multi-screen system, the vertical deflection angle increases,
In the first place, distortion tends to be difficult to correct. However, it has been difficult for the conventional distortion correcting magnet to cope with such correction.

[0016]

As described above, in the conventional deflection yoke 1, a color picture tube having a flat screen is used. In a multi-screen system, the horizontal deflection magnetic field 21 generated by a horizontal deflection coil is used. Magnetic field generated by correction magnet 5
It is difficult to sufficiently correct raster distortion with only 22. In order to sufficiently correct the raster distortion, it is necessary to use the magnet 5 having a large volume, which causes a problem that the size of the apparatus is increased and the cost is increased.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a deflection yoke that can effectively reduce raster distortion caused by flattening a screen and a multiple screen system.

[0018]

The present invention comprises a pair of horizontal deflection coils for deflecting an electron beam in a horizontal direction, a pair of vertical deflection coils for deflecting the electron beam in a vertical direction,
A core formed of a magnetic material, a mold for holding and fixing the horizontal deflection coil and the vertical deflection coil, and a raster distortion generated by generating a magnetic field and located near the pair of horizontal deflection coils inside the outer surface of the mold. Since the correction element is provided near the horizontal deflection coil inside the outer surface of the mold,
Raster distortion generated on a flat screen can be effectively reduced without using a large-volume magnet.

The horizontal deflection coil has a bend, and the correction element is installed near the bend.
Raster distortion generated on a flat screen can be effectively reduced without using a large-volume magnet.

Further, since the correction element is provided on the inner surface side of the mold, raster distortion generated on a flat screen can be effectively reduced without using a large-sized magnet.

Further, the mold has a concave portion on the outer surface side, and the correction element is provided in the concave portion, and can be positioned inside the outer surface of the mold without providing the correction element inside the mold.

Further, since the correction element has a roundness in accordance with the shape of the mold, the correction element can be efficiently attached.

Further, the correction element is a permanent magnet.

Further, since the correction element has a flat shape, the size can be reduced.

The correction element has a thickness substantially the same as that of the horizontal deflection coil, and prevents the adjustment from being impossible when the correction element is mounted on a cathode ray tube, for example.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a deflection yoke according to the present invention will be described below with reference to the drawings. Parts corresponding to those of the conventional example will be described with the same reference numerals.

As shown in FIGS. 1 and 2, a deflection yoke
31 has a mold 32, which is formed in a funnel shape by injection molding so that the outer diameter becomes smaller from one end to the other end.
As shown by, a ferrite core 33 and a pair of left and right vertical deflection coils 34 are provided. In addition, this mold 32
A pair of horizontal deflecting coils 35 are vertically arranged inside, and the bend portion 35a of the horizontal deflecting coil 35 is disposed inside the opening end of the tapered portion of the funnel-shaped mold 32.

A correction element 37 corrects raster distortion and has a thickness of 3 mm and a width of 15 m, for example.
Permanent magnets such as ferrite molded to a size of m and a length of about 40 mm are used. This correction element is 37
The inner side of the outer surface of the mold 32, that is, as shown in FIG.
1, are provided vertically above and below in the horizontal direction as shown in FIG. As shown in FIG. 1, the magnetization direction of the correction element 37 is such that the upper right is the north pole and the left is the south pole, and the lower is the right is the south pole and the left is the north pole.

Here, the thickness of the correction element 37 is set to about 3 mm. However, when the deflection yoke 31 is attached to a cathode ray tube (not shown), the thickness of the correction element 37 is set to be substantially the same as the thickness of the horizontal deflection coil 35. This is to prevent the contact with the cathode-ray tube and the adjustment from being impossible.

This correction element 37 can be formed flat as shown in FIG. 3B, as compared with the conventional rectangular parallelepiped type shown in FIG. 3A. Further, as shown in FIG. 4, the length direction of the correction element 37 may be rounded in accordance with the shape of the tapered portion of the mold 32.

As described above, the correction element 37 is disposed inside the outer surface of the mold 32 and at the bend portions 35a of the pair of horizontal deflection coils 35.
, The Lorentzka Fm shown in FIG. 13 can be increased without increasing the size of the correction element 37, and the vertical distortion correction effect can be increased.

As a result, even in a color picture tube with a flat screen and a multi-screen system, distortion can be sufficiently corrected and a good image can be obtained.

Next, a method of mounting the correction element 37 according to another embodiment will be described with reference to FIG.

First, the correction element 37 may be mounted inside the outer surface of the mold 32, and the mounting position is not limited to the inner surface of the mold 32 as shown in FIG. Then, as shown in FIG. 5, for example, a concave portion 32a is formed on the outer surface of the mold 32, and the correcting element 37 is mounted in the concave portion 32a. Because it is located inside than the outer surface of 32,
An effect equivalent to that of the structure of FIG.

A method of mounting the correction element 37 according to another embodiment will be described with reference to FIG.

The correction element 37 may be mounted near the bend 35a of the horizontal deflection coil 35, and may be mounted at the front of the bend 35a as shown in FIG.

The arrangement of the correction element 37 according to the above embodiment and the conventional configuration shown in FIGS. 7 and 8 will be compared by experiments.

In the conventional example, three pairs of magnets 5 as a conventional correction element having the shape shown in FIG. 3A as a conventional correction element were formed as a pair of upper and lower parts, and raster distortion could not be sufficiently corrected unless a total of six magnets were used. . On the other hand, according to the above embodiment, FIG.
By using only two magnets having the shape and dimensions shown in FIG. 3B as a pair of upper and lower correction elements 37, it is possible to obtain a sufficient raster distortion correction effect equivalent to the case where six conventional magnets are used. did it. Therefore, a sufficient raster distortion correction effect can be obtained by the correction element 37 having a small volume and a small number, so that an image is projected on a flat screen or one image is divided and projected using a plurality of electron guns. Also in such a case, a pincushion-type raster distortion does not occur, and good display quality can be achieved with a low cost and small shape.

Although the thickness of the magnet, which is the correction element 37, is 3 mm, the width is 15 mm, and the length is 40 mm, the dimensions vary depending on the installation location, and are not limited to these dimensions. Absent.

[0040]

According to the present invention, a sufficient raster distortion correction effect can be obtained with a small volume and small number of correction elements.

[Brief description of the drawings]

FIG. 1 is a front view showing an embodiment of a deflection yoke according to the present invention.

FIG. 2 is a side sectional view of FIG.

FIG. 3 is a perspective view showing a magnet shape as a correction element according to the first embodiment; (a) Conventional example (b) One embodiment

FIG. 4 is a perspective view showing a correction element according to another embodiment of the present invention;

FIG. 5 is a sectional view showing another embodiment of the same for a mold.

FIG. 6 is a front view showing still another embodiment of the present invention.

FIG. 7 is a side view showing a conventional deflection yoke.

FIG. 8 is a rear view showing a conventional deflection yoke.

FIG. 9 is a front view showing raster distortion generated in an image by a conventional deflection yoke.

FIG. 10 is a perspective view showing raster distortion generated when one image is divided and displayed by two deflection yokes according to a conventional example.

FIG. 11 is a front view showing raster distortion generated when one image is divided and displayed by two deflection yokes according to a conventional example.

FIG. 12 is a front view showing a state in which one image is divided and displayed by two deflection yokes according to a conventional example, and an overlap occurs at the center of the boundary of the image due to raster distortion.

FIG. 13 is an explanatory diagram illustrating a principle of correcting raster distortion by a correction element.

[Explanation of symbols]

 31 Deflection yoke 32 Mold 35 Horizontal deflection coil 35a Bend 37 Correction element

Claims (8)

[Claims] A pair of horizontal deflection coils for deflecting the electron beam in the horizontal direction; a pair of vertical deflection coils for deflecting the electron beam in the vertical direction; a core formed of a magnetic material; A mold for holding and fixing the vertical deflection coil; and a correction element for generating a magnetic field and installed near the pair of horizontal deflection coils inside the outer surface of the mold and for correcting raster distortion. Deflection yoke. 2. The deflection yoke according to claim 1, wherein the horizontal deflection coil has a bend, and the correction element is installed near the bend. 3. The deflection yoke according to claim 1, wherein the correction element is provided on an inner surface side of the mold. 4. The deflection yoke according to claim 1, wherein the mold has a concave portion on the outer surface side, and the correction element is provided in the concave portion. 5. The deflection yoke according to claim 1, wherein the correction element has a round shape according to a shape of the mold. 6. The deflection yoke according to claim 1, wherein the correction element is a permanent magnet. 7. The deflection yoke according to claim 1, wherein the correction element has a flat shape. 8. The deflection yoke according to claim 1, wherein the correction element has a thickness substantially equal to a thickness of the horizontal deflection coil.