KR20000014267U - Electromagnetic shielding device of deflection yoke - Google Patents

Abstract

The present invention relates to an electromagnetic wave shielding device of a deflection yoke, and more particularly, to obtain a shielding device for shielding electromagnetic waves emitted from a deflection yoke mounted on a CRT.

Cylindrical electromagnetic wave blocking device having a predetermined permeability is provided by a cylindrical tube into which the deflection yoke of the CRT can be inserted and having a predetermined thickness and a ground part made of a material having a predetermined permeability, such as mu-metal or ferromagnetic material. It is installed as the central axis of the deflection yoke to shield the electromagnetic waves leaking out of the deflection yoke, which blocks the electromagnetic waves harmful to the human body and has the excellent stability and reliability of the product.

Description

Electromagnetic shielding device of deflection yoke

The present invention relates to an electromagnetic wave shielding device of a deflection yoke, and more particularly, to a shielding device for shielding electromagnetic waves emitted from a deflection yoke mounted on a CRT.

Conventional deflection yoke electromagnetic shielding device is divided into two. First, when installing around the deflection yoke using iron-based material (Korea Patent Publication No. 96-002415), electromagnetic waves leaking from the deflection yoke by installing at least one annular plate on the neck of the CRT coaxial with the center axis of the deflection yoke. In the form of blocking the annular plate is characterized in that it is bent at a predetermined angle with respect to the central axis of the deflection yoke, secondly, in the case of attaching the electromagnetic wave canceling circuit (Korea Patent Publication No. 94-027031) radiated from the deflection yoke There was a feature to offset the leakage of electromagnetic waves by installing the offset coil in the deflection yoke so that electromagnetic waves are generated in the reverse direction to the electromagnetic waves.

However, in the case of the conventional electromagnetic wave shielding device of the deflection yoke, in case of installing one or more annular plates on the deflection yoke, the attenuation effect of the electromagnetic wave is closely related to the spacing between the installed plates, the thickness of the plate, and the size of the plate Therefore, it is not easy to configure the device to obtain the optimum shielding effect. The annular plate is limited in increasing the diameter because it must be installed in a narrow space. In addition, since the annular plate installed coaxially to the deflection yoke is directly or directly attached to the deflection yoke, there is a problem that a bad effect on the image quality of the screen is inevitable.

Second, in case of installing the electromagnetic offset coil directly on the deflection yoke, it has to go through complicated assembly process, and the path of the reverse electromagnetic wave generated by the offset coil is highly dependent on the deflection coil's design and installation angle. Cost increase and productivity decrease by designing and manufacturing each detailed coil according to the type of. In addition, since the electromagnetic offset coil is directly attached to the deflection yoke, there is a problem of significantly lowering the image quality of the screen.

Accordingly, the present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to mount a cylindrical electromagnetic wave blocking device having a predetermined permeability with a deflection yoke as a central axis to shield electromagnetic waves leaking out of the deflection yoke. It is to provide an electromagnetic shielding device of the deflection yoke that can block the electromagnetic waves harmful to the human body and increase the stability and reliability of the product.

1 is a state in which the electromagnetic wave shielding device of the deflection yoke of the embodiment of the present invention is mounted on the CRT deflection yoke;

2 is a perspective view showing an electromagnetic wave shielding device of the present invention,

Figure 3 is a graph showing the results of the experiment after mounting the present invention CRT deflection yoke,

Figure 4 is a perspective view showing an electromagnetic wave shielding device of the deflection yoke of another embodiment of the present invention.

* Description of the symbols for the main parts of the drawings *

10: CRT 20: electromagnetic wave shielding device

30: deflection yoke 40: ground portion

The electromagnetic wave shielding device of the deflection yoke of the present invention for achieving the above object is a cylinder into which the deflection yoke of the CRT can be inserted, and is made of mu-metal or ferromagnetic material having a predetermined permeability. It is characterized by having a ground portion.

EMBODIMENT OF THE INVENTION Hereinafter, the electromagnetic wave shielding device of the deflection yoke of the Example of this invention is demonstrated in detail based on an accompanying drawing.

1 is a state diagram in which the electromagnetic wave shielding device of the deflection yoke of the embodiment of the present invention is mounted on the CRT deflection yoke, FIG. 2 is a perspective view showing the electromagnetic wave shielding device of the present invention, and FIG. Graph showing the results of the experiment after mounting on the part,

Figure 4 is a perspective view showing an electromagnetic wave shielding device of the deflection yoke of another embodiment of the present invention.

First, the deflection yoke is a pair of horizontal coils and vertical coils installed in the neck portion of the cathode ray tube, and when a current flows through the deflection yoke, an electromagnetic field is generated to change the direction of the electron beam emitted from the cathode ray tube. Therefore, deflection yoke is a device that allows electron beams to be scanned in a certain direction on the screen by periodic changes of electromagnetic fields. Since the deflection yoke generates electromagnetic waves harmful to the human body to the outside, it is important to reduce the level of the electromagnetic waves to below a predetermined regulation value. In order to prevent the electromagnetic wave from leaking outside the deflection yoke, a shielding device is required to surround the outside of the deflection yoke.

1 to 2, the electromagnetic wave shielding device of the deflection yoke of the present invention wraps the deflection yoke 30 of the CRT 10 and has a cylindrical structure having a good heat dissipation structure and a high permeability and magnetic field shielding effect And a shielding device 20 having a constant thickness and having a grounding portion.

The shielding device 20 has a structure that can be mounted so as to be coaxial with each other when the front and rear opening is inserted into the cylinder so that the deflection yoke 30 of the CRT 10 is inserted.

The material part of the shielding device 20 should be a material having a high permeability to shield the effect of the strong magnetic field generated in the deflection yoke when the electromagnetic wave is divided into an electric field and an electric field component. (The permeability here is the ratio of magnetic flux density in the material to the magnetic field, ie the density of magnetic flux that the material can absorb per unit magnetic field, and is the physical quantity that shows the degree of magnetization of the material for a given magnetic field from the outside.) The greater the permeability, the greater the shielding effect of the magnetic field. The well-known metals with high permeability use alloys such as nickel, iron, copper, and chromium, called mu-metal. Mumetals are particularly good at shielding low-frequency magnetic fields from components such as deflection yokes. (These metals are conductors, so if there is a grounding means for grounding the electric field, shielding of electrical waves is possible.)

When mounted on the deflection yoke of the CRT, the cylindrical shielding device 20 is mounted to be coaxial with the deflection coil and grounds the electric field generated in the deflection yoke using the grounding 40 means. The shielding device 20 mounted as described above may absorb the electromagnetic waves generated from the deflection coil and minimize the amount of leakage to the outside. Electromagnetic waves radiated from the deflection yoke 30 are reflected and absorbed back at the surface of the shield, so to maximize the shielding effect without affecting the deflection yoke, the reflection should be minimized and the absorption performance should be increased. As it is proportional to thickness, permeability, and permittivity, the material and size of the shield should be considered together to obtain the required shielding performance. In general, when the gap between the deflection yoke 30 and the shielding device 20 is too close, electromagnetic waves reflected or scattered from the shielding device may affect the electron beam in the deflection yoke, which may cause color bleeding or screen distortion on the screen. It is to be used to reduce the reflectance of the device and to maintain a certain distance from the deflection yoke.

Figure 3 is an embodiment by the electromagnetic shielding device according to the present invention in the case of 14-inch computer monitors compared with the case of shielding the ELF (5Hz-2kHz) magnetic field measurement value according to the radiation angle of the electromagnetic wave leaked and not plotted It is. The results of this test are described graphically; In the case of 14-inch computer monitor, it can be seen that there is a significant electromagnetic attenuation effect when the deflection yoke is not shielded and when the shielding device is installed. Restrictions of representative MPR-II and TCO are 250nT and 200nT, respectively, so that the test according to the present invention shows sufficient performance for electromagnetic shielding.

4 is another embodiment of the shielding device surrounding the deflection yoke is a conical structure (a), a square or angled structure (b), a structure made of a combination of several pieces, in the form of a mesh or grid It has a structure (c) is made of a material capable of absorbing and shielding the electromagnetic waves radiated from the deflection yoke, and the structure surrounding the deflection yoke is included in the scope of the present invention.

In addition, it is possible to mount the shock absorbing material to the outside close to the deflection yoke of the CRT to prevent the impact from the outside, and also to be mounted in the case of the rear so that the deflection yoke is inserted into the assembly. The mounting method can be installed in various ways depending on the usage and shape.

As described above, according to the electromagnetic wave shielding device of the deflection yoke of the present invention,

By blocking electromagnetic waves harmful to the human body radiated from the deflection yoke, it increases the stability and reliability of the product. Cylindrical shielding device is a very useful design because it is easy to manufacture and install, the cost is reduced, and the productivity is improved by the structure in which the heat from both sides of the deflection yoke and the cathode ray tube is easily released.

Claims (8)

Electromagnetic shielding device of the deflection yoke, characterized in that the through-hole structure surrounding the deflection yoke portion of the CRT, shielding device having a predetermined permeability and magnetic field and having a predetermined thickness, and a grounding portion (40). 2. The deflection yoke of claim 1, wherein the shielding device 10 is made of an iron-based alloy alloyed by combining at least one of nickel, iron, silicon, molybdenum, manganese, and aluminum as the shielding material. Electromagnetic shielding device. 2. The electromagnetic shielding device for deflection yoke according to claim 1, wherein the shielding device (10) is formed by coating a ferromagnetic material in the form of a thin film on a general metal as the shielding material. According to any one of claims 1 to 3, wherein the shielding device 10 is characterized in that the structure of the shielding device has a columnar structure having an angle so that the deflection yoke 30 can be inserted into. Electromagnetic shielding device of deflection yoke. The shielding device according to any one of claims 1 to 3, wherein the shielding device has a conical or funnel-like structure and a deflection yoke (30) can be inserted therein. 4. The electromagnetic shielding device of claim 1, wherein the shielding device has a structure in which the structure covers only a part of the deflection yoke so that the deflection yoke can be inserted into the shielding device. The electromagnetic wave shielding device of the deflection yoke according to any one of claims 1 to 3, wherein the shielding device has a mesh or lattice structure. The electromagnetic wave shielding device for deflection yokes according to any one of claims 1 to 3, wherein the shielding device has a cylindrical structure.