JPH087789A - Image distortion correction device - Google Patents

Abstract

PURPOSE:To improve substantial magnetic field correction effect so as to correct special image distortion even in the case of using the same volume. CONSTITUTION:Bar magnets 26, 28 for correcting image distortion are attached to aperture parts sides of a cathode-ray tube opposed to the top and the bottom sides of a screen. Both magnetic poles of the bar magnets 26, 28 have such a shape as approaching to CRT tube axis and its cross section is set to a inversed U shape. Both magnetic poles are made to approach to CRT tube axis side so that magnetic field correction effect is improved and even special image distortion can be corrected without enlarging the shape of a magnet or using a plurality of them.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image distortion correction device suitable for application to a wide-angle cathode ray tube, a large-screen cathode ray tube, a horizontally long cathode ray tube, and the like.

[0002]

2. Description of the Related Art A cathode ray tube (CRT) is equipped with a deflecting device to deflect an electron beam horizontally and vertically.
In the screen obtained by scanning with the electron beam, image distortion (upper pincushion distortion) in which the vertical direction is distorted into a pin shape may occur as shown in FIG. 7A. This screen is shown in Figure B.
The image distortion correction device 10 as shown in FIG. 8 is usually used for the correction.

In FIG. 1, for example, a saddle-shaped horizontal deflection coil (not shown) is wound around a coil separator (not shown), and a trumpet-shaped ferrite core 12 as shown is provided outside the coil separator. The ferrite core 12 is attached and the vertical deflection coil 14 is wound around the ferrite core 12. Reference numeral 16 denotes a rear cover body, in which a magnet for color purity correction and the like are housed.

A ring-shaped front cover body 20 as shown in the drawing is mounted on the opening side (CRT phosphor side) of the core 12. The front cover body 20 is a short tubular molded body having a size that covers a front bend portion (not shown) of the coil separator, and has a part of its outer peripheral surface, in this example, upper and lower portions corresponding to the upper and lower screen portions. Magnet mounting parts 22, 2 at the position
4 are integrally formed, and rod-shaped magnets 26 and 28, which are image distortion correcting means, are attached and fixed thereto.

Since the horizontal and vertical deflection magnetic fields are corrected by the correction magnetic fields of the magnets by mounting and fixing the straight bar magnets 26, 28 each having a square cross section at predetermined upper and lower positions, the bar magnets 26, 2 are corrected.
Image distortion as shown in FIG. 7A can be corrected as shown in FIG. 7B by appropriately selecting the magnetization amount of No. 8.

[0006]

By the way, in recent years, as a cathode ray tube used for a monitor of a television receiver or an OA device, a wide angle, a large size, and a lateral length (widening) have been achieved.
There is a strong demand for, and if a cathode ray tube is designed in accordance with it,
This time, image distortion (tonbi distortion) as shown in FIG. 9A has started to occur.

This image distortion is pincushion distortion having a waveform. To correct this image distortion, the rod-shaped magnets 26, 2
The magnetization amount of No. 8 should be increased. But in the normal case,
Since the magnets of the rod-shaped magnets 26, 28 used are often magnetized with the maximum amount of magnetization, the volume of the rod-shaped magnets 26, 28 may be increased to increase the amount of magnetization.
As a result, the magnet itself becomes large, and it is often impossible to correct the special image distortion as shown in FIG. 9A simply by increasing the magnetization amount.

Therefore, in addition to the currently used rod-shaped magnet, another auxiliary magnet is used to correct the image distortion as described above. For example, as shown in FIG. 10, the auxiliary magnets 30, 32 are provided on the rod-shaped magnets 26, 28.
Attaching and fixing, or attaching the auxiliary magnets 34, 36 to the positions shown by the chain line, and further attaching the auxiliary magnets to the peripheral surface a of the front cover body 20 (not shown). It corrects the special image distortion such as 9A. However, even this still cannot fully correct this image distortion.

Therefore, the present invention solves such a conventional problem, and proposes an image distortion correction device capable of simply correcting such a special image distortion.

[0010]

In order to solve the above-mentioned problems, in the invention described in claim 1, a rod-shaped magnet for image distortion correction is attached to the opening side of the cathode ray tube corresponding to the upper and lower screen portions. At the same time, both poles of the rod-shaped magnet are arranged to be close to the tube axis of the cathode ray tube.

[0011]

Operation: Magnets 26, 28 for image distortion correction shown in FIG.
The cross-section of which has an inverted U-shape and both magnetic poles project downward is used. When the magnets 26 and 28 having such a shape are used, both magnetic poles 26a and 26b are
Since (28a, 28b) approaches the tube axis of the CRT, the magnetizing amount is substantially larger than that when a magnet having the same volume and the same magnetizing amount is used.

In particular, the image distortion shown in FIG. 9 has the maximum image distortion to the left and to the right of the central portion, so that the correction magnetic field should be increased near both magnetic poles of the magnets 26 and 28. Good. When the magnets 26 and 28 having the shape as shown in FIG. 1 are used, the magnetic fields in the vicinity of both magnetic poles of the magnet effectively act on the horizontal and vertical deflection magnetic fields. The image distortion as shown in FIG. 4 is corrected and a normal screen as shown in FIG.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a case where an example of the image distortion correcting device according to the present invention is applied to the above-mentioned cathode ray tube will be described in detail with reference to the drawings.

In the present invention, as the bar-shaped magnet used for image distortion correction, a bar-shaped magnet whose both magnetic poles are close to the CRT tube axis is used. A specific example thereof will be described with reference to FIGS.

In the image distortion correction device 10 according to the present invention, the mounting portions 22 and 24 provided on the upper and lower peripheral surfaces of the front cover body 20 have a shape that conforms to the shape of the magnet to be mounted therein, as will be described later. Selected. Magnets 26, 2 for image distortion correction are attached to the mounting portions 22, 24.
8 is attached.

As shown in FIG. 3, the rod-shaped magnets 26 and 28 have a shape in which the respective magnetic poles 26a and 26b are bent downward as shown in FIG. Its length and volume are the same as conventional magnets. It simply differs in shape. Any of the areas and the protruding lengths of the magnetic poles 26a and 26b can be appropriately selected.

Rod-shaped magnets 26, 2 having such a shape
When 8 is attached to the attachment portions 22 and 24, respectively, as shown in FIG. 2, both magnetic poles 26a and 26b (28a, 28a,
Since 28b) is close to the axis of the CRT tube, even if the magnetization amount is the same, the substantial magnetization amount is increased as compared with the case of a straight rod magnet. As a result, the influence on the horizontal and vertical deflection magnetic fields is large, in other words, the magnetic field correction effect is large, and even image distortion as shown in FIG. You can restore the correct screen as shown. In FIG. 2, BR, BG, B
B is an electron beam corresponding to R, G, and B.

In FIGS. 1 and 2, the magnet mounting portions 22 and 24 are selected to have a recess 40 in accordance with the shape of the rod-shaped magnets 26 and 28, but they are simply box-shaped as shown in FIG. It may be a mounting portion configuration.

4 to 6 show other examples of rod-shaped magnets that can be used in the present invention. The example of FIG. 4 shows a bent rod-shaped magnet 26 in which both left and right magnetic poles 26a and 26b are bent inward. This is a specific example. By thus forming the configuration in which both poles are bent, both poles come closer to the tube axis side, so that the magnetic field correction efficiency is improved, and FIG.
Such image distortion can be corrected.

The length and volume of the bar-shaped magnet 26 are the same as the conventional one. As for the attachment portions 22 and 24 of the front cover body 20, those having a shape selected according to this shape can be used. The other bar-shaped magnet 28 having the same structure is used.

A rod-shaped magnet 2 having the structure shown in FIGS.
6 and 28, the magnet having the largest image distortion correction effect is the magnet having the shape shown in FIG. 4, and next is the order of FIG. 6 and FIG.

FIG. 5 shows bar-shaped magnets 26 and 28 formed in an arc shape, and those having substantially the same curvature as the peripheral surface of the front cover body 20 are used. Its length and volume are the same as before. Even with such rod-shaped magnets 26 and 28, since both poles thereof approach the tube axis, the magnetic field correction efficiency is improved and the image distortion in FIG. 9A can be corrected.

Therefore, the rod-shaped magnet used for correcting the image distortion may be any one as long as its magnetic poles are close to the CRT tube axis.
It can also be configured as shown in. The example of FIG. 6 is a case in which they are arranged close to each other in the tube axis direction (z-axis direction), and by doing so, the correction is strengthened in the tube axis direction.

[0024]

As described above, in the image distortion correcting device according to the present invention, the image distortion is corrected by using the rod-shaped magnets whose both magnetic poles are close to each other in the tube axis direction. .

According to this, as compared with the case where a straight rod-shaped magnet having the same length and the same volume is used by bringing both magnetic poles close to the tube axis, even if the magnetizing amount is the same, it acts on the electron beam substantially. Since the correction magnetic field increases more than before, image distortion can be effectively corrected. Therefore, a magnet having the same volume as the conventional one can be used, and a special image distortion such as a tonbi-shaped image can be effectively corrected by using only a single magnet.

Therefore, the present invention is extremely suitable when applied to a television receiver or the like which aims to widen the angle, increase the size, and increase the width as described above.

[Brief description of drawings]

FIG. 1 is a perspective view showing an example of an image distortion correction device according to the present invention.

FIG. 2 is a side view of a part thereof.

FIG. 3 is a perspective view showing an example of a bar-shaped magnet that can be used in the present invention.

FIG. 4 is a diagram showing an example of a bar-shaped magnet that can be used in the present invention.

FIG. 5 is a diagram showing an example of a bar-shaped magnet that can be used in the present invention.

FIG. 6 is a perspective view showing an example of a bar-shaped magnet that can be used in the present invention.

FIG. 7 is an explanatory diagram of image distortion.

FIG. 8 is a perspective view of a conventional image distortion correction device.

FIG. 9 is a diagram showing another example of image distortion.

10 is a diagram showing an example of the image distortion correction means in FIG.

[Explanation of symbols]

 10 Image Distortion Corrector 12 Ferrite Core 14 Vertical Deflection Coil 20 Front Cover 22,22 Mounting Part 26,28 Rod Magnet 26a, 26b Magnetic Pole

Claims (4)

[Claims] 1. A rod-shaped magnet for image distortion correction is attached to the opening side of the cathode ray tube corresponding to the upper and lower screen portions, and both poles of the rod-shaped magnet are arranged close to the tube axis of the cathode ray tube. Characteristic image distortion correction device. 2. The bar-shaped magnet has an inverted U-shaped cross section.
The image distortion correction device according to claim 1, wherein the image distortion correction device is formed in a letter shape. 3. The image distortion correction device according to claim 1, wherein both pole portions of the rod-shaped magnet are bent toward the tube axis side. 4. The image distortion correction device according to claim 1, wherein the rod-shaped magnet has an arc-shaped cross section.