JPH0594780A - External magnetism shielding method for crt - Google Patents

Abstract

(57) [Summary] [Purpose] In recent years, high-definition large CRTs are increasingly used in environments where external magnetic fields are present. Along with that, we will implement measures that are not affected by magnetic fields from all directions. [Structure] A CRT consisting of a shield box 1 made of a high-permeability magnetic material that can be attached so as to cover the circumference of a CRT 4 and a part of which is open, and a mirror 2 attached inside the shield box 1. Magnetic shielding device. [Effect] The applied DC magnetism is absorbed in the shield box material made of a high permeability magnetic material and released into the air in the opposite direction, and the external DC magnetic field does not affect the CRT inside the shield box. Absent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for shielding external magnetism of a CRT, and more particularly, when the CRT is exposed to external magnetism applied from multiple directions and is affected by color misregistration and display movement. The present invention relates to an external magnetic shielding method for preventing the influence.

[0002]

2. Description of the Related Art Generally, as a measure against color misregistration due to direct current magnetism applied to a CRT from outside, simply cover the CRT with a shield box made of a high-permeability magnetic material whose portion corresponding to the CRT display image is open. Things,
As described in JP-A-63-208386, only the shield box is combined with a coil.

[0003]

A CRT which is simply covered with a shield box made of a high-permeability magnetic material with the portion corresponding to the CRT display image being opened is completely prevented from entering the magnet through the opening portion of the shield box. The magnetism that leaks inside the shield box without being able to do so causes color shift. In addition, the method of combining the coil with the shield box requires a sensor to detect the magnetism, but since it can detect only the magnetic field of a part of the place where the sensor is installed, it cannot correct the color misregistration over the entire screen. There was a problem.

An object of the present invention is to completely eliminate the influence of DC magnetism applied to the CRT from the outside, and prevent color shift and display movement of the CRT.

[0005]

The above-mentioned object is to provide a CRT
Inside the shield box made of high permeability magnetic material, part of which is open, it is installed so that it cannot be seen directly from the open part, and the external magnetic field leaked from the open part of the shield box is directly applied to the CRT. Achieved by not reaching.

[0006]

The CRT is installed in a shield box, which is made of a high-permeability magnetic material and is partially open, so that it cannot be directly seen from the open portion. It is absorbed in the shield box material created in, passes through it, and is released into the air in the opposite direction. In this way, the direct current magnetism entering from the open part of the shield box is not directly reached to the CRT but is gradually absorbed in the high permeability magnetic material of the shield box and is released to the outside without affecting the CRT. It

Further, the CRT display image is reflected by the mirror and can be seen from the open portion of the shield box.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 shows a perspective view, in which a CRT 4 is installed in a shield box 1 made of a high-permeability magnetic material having an opening 5 in the direction of the figure, and two mirrors 2, 3 are provided.
Is attached at the angle shown.

According to this embodiment, the external direct current magnetic field applied from above and below is absorbed in the high permeability magnetic material without entering the inside of the shield box, passes through the material and is emitted outside the shield box. To be done. Similarly, with respect to the magnetism applied from the left and right directions, no magnetism from the outside penetrates inside the shield box. On the other hand, the magnetism applied from the front-back direction partially penetrates into the shield box through the open portion of the shield box. However, it does not reach the bottom with the CRT, is absorbed in the high magnetic permeability magnetic material, passes through the material, and is emitted to the outside of the shield box. Therefore, magnetism does not penetrate into the bottom of the shield box where the CRT is installed, and is not affected by the magnetism.

Further, in the display of the CRT screen, the image reflected in the order of the mirrors 2 and 3 can be seen from the opening 5. CRT
The image flowing in the order of 4 → mirror 2 → mirror 3 → opening 5 is light and is not affected by magnetism.

[0011]

According to the present invention, the portion affected by the external magnetism is only the inside of the CRT, and the CRT allows the external magnetism from any direction to pass through the high magnetic permeability magnetic material to be emitted to the outside. Since the shield box is installed so as not to be directly exposed to DC magnetism from the outside, color shift of an image does not occur. From the CRT display image, the path of light reflected by the mirror and reaching the open portion is a flow of light, and therefore refraction does not occur even when passing through magnetism. Therefore, the CRT seen from the open part of the shield box
The image does not cause color misregistration or the like even when externally applied DC magnetism.

[Brief description of drawings]

FIG. 1 is a perspective view of a shield box according to an embodiment of the present invention,

FIG. 2 is a sectional view taken along the line II-II of FIG.

[Explanation of Codes] 1 ... Shield box made of high-permeability magnetic material, 2 ... Mirror, 3 ... Mirror, 4 ... CRT, 5 ... Open part, 6 ... External magnetic field application direction, 7 ... CRT display image flow ..

Claims (1)

[Claims] 1. An external magnetic field of a CRT comprising a shield box made of a high-permeability magnetic material which can be mounted so as to cover the periphery of the CRT and which is partially open, and a mirror mounted inside the shield box. In the shielding device, the CRT is installed inside so that it cannot be seen from the opening of the shield box, and the image is reflected by a mirror so that the image can be seen from the opening of the shield box. Shield the magnetic field,
An external magnetic shield method for a CRT, characterized in that the influence thereof is not exerted on the display image of the CRT.