KR100341058B1 - Shield for protecting magnetic field of monitor and the method of manufacturing thereof - Google Patents

Abstract

PURPOSE: A magnetic field shield of a monitor and a method for fabricating the same are provided to shield effectively external magnetic field by using a triple structure of a frame, a magnetic layer, and a conductive material layer. CONSTITUTION: A magnetic field shield is used for covering the remaining portion except for a front portion of a monitor. A steel frame(10) has mechanical intensity and is used for covering the monitor. A magnetic layer(20) for shielding magnetic field is located on an inner surface of the frame(10). The magnetic layer(20) is formed with a magnetic substance. A conductive material layer(30) is located on an inner surface of the magnetic layer(20). The conductive material layer(30) is formed with a conductive material. The magnetic layer(20) is formed with Ni alloy.

Description

Shield for protecting magnetic field of monitor and the method of manufacturing Technical Field

The present invention relates to a magnetic field shielding shield of a monitor for protecting the monitor so that the image of the monitor screen such as TV, CRT, etc. is not distorted due to the influence of the magnetic field, or a phenomenon such as vibration or color tone change does not occur. It is about.

In general, the sites of smelting factories, such as steelmaking and non-ferrous smelting factories, are provided with cameras installed on-site for the purpose of preventing accidents by properly grasping the progress of the operation and taking appropriate measures to cope with it. Connected eye TVs and operation control motors are usually mounted in control rooms located indoors.

In particular, the monitor-type devices may vibrate, distort or change color due to the influence of a magnetic field generated by an electric furnace using a large amount of electric power.As a result of this phenomenon, it is difficult for an operator to accurately understand the operation progress. As a result, it is difficult to deal with sudden accidents or the like immediately. In general, in the field of operation such as steel mill, the screen transmitted from the surveillance camera is not clear due to the dust, and the wide field must be captured by the camera so as to be in a narrow angle so that all objects are lightly reflected on the screen. Since it is not easy to distinguish the objects, it is necessary to provide a high quality monitor screen in order to thoroughly control the field monitoring function and operation control in the control room.

Recently, a shielding shield is mainly used to shield the monitor from magnetic fields in response to such a request so that the image of the monitor screen is not distorted, or a phenomenon such as vibration or color tone change does not occur. It consists of a shape surrounding the monitor.

However, due to its characteristics, a large amount of heat is generated from itself, and if this heat is maintained inside the monitor, it causes not only an accident such as a fire, but also adversely affects the performance of the monitor. In order to achieve this, a shield is provided with a hole for mounting the fan and also serving as an outlet for the heat discharged by the fan, and such a fan mounting hole greatly reduces the magnetic shielding performance of the shield shield. In particular, the fan mounting hole formed in the large monitor has a problem that the magnetic field shielding can not be performed to an appropriate degree because the size of the fan mounting hole is very large compared to the fan mounting hole of the small monitor.

Accordingly, an object of the present invention is to provide a magnetic field shielding shield of a monitor excellent in shielding performance by having a triple structure consisting of a frame, a magnetic layer, and a conductive material layer, to improve the conventional problems as described above.

It is also an object of the present invention to provide a magnetic field shielding shield of a monitor which is configured to improve the rear magnetic field shielding efficiency by forming a plurality of heat sinks having a small diameter for dissipating heat generated from the monitor.

It is also an object of the present invention to provide a magnetic field shielding shield of a monitor which is designed to improve shielding efficiency by tilting the upper and rear shielding walls for shielding the magnetic field to have a proper inclination from the horizontal and vertical states.

It is another object of the present invention to provide a magnetic field shielding shield manufacturing method of a monitor having excellent shielding performance by manufacturing a magnetic shielding shield having a triple structure consisting of a frame, a magnetic layer and a conductive material layer.

1 is a front schematic view showing a magnetic shielding shield of a monitor according to the present invention;

Figure 2 is a right cross-sectional schematic view showing the cut off the shield of the present invention

Figure 3 is a schematic configuration diagram showing a shield shield of the present invention from the rear side

4 is a graph showing test results for the relationship between the magnetic field strength and the shielding efficiency with respect to the size of the heat dissipation hole formed in the rear shielding wall.

Explanation of symbols on the main parts of the drawings

10 ... frame

20 ... magnetic layer

30 ... conductive frame

40 ... heatsink

50 ... upper shielding wall

60 ... rear shielding wall

70 ... side shielding

90 ... lower shielding wall

As a technical configuration for achieving the above object, the present invention, in the magnetic field shielding shield of the monitor configured to surround the magnetic field except the front portion of the monitor, to shield the magnetic field, having a mechanical strength to surround the monitor It has a triple structure consisting of a frame, a magnetic shielding magnetic layer made of magnetic material on the inner surface of the frame, and a magnetic shielding conductive material layer of high frequency band made of a conductive material on the inner surface of the magnetic layer. The magnetic field shielding shield of the monitor shall be provided.

In addition, the present invention is configured to surround the periphery except the front of the monitor to shield the magnetic field, the rear shielding wall in the magnetic field shielding shield of the monitor to form a heat dissipation opening to discharge the heat generated from the monitor to the outside by the fan The magnetic shielding shield of the monitor is characterized in that the plurality of heat dissipation openings of the rear shielding wall are formed in a plurality of areas having a smaller diameter than that of the fan.

In addition, the present invention is a magnetic field shielding shield of the monitor configured to surround the periphery except for the front portion of the monitor to shield the magnetic field, the upper shielding wall and the rear shielding wall has an inclination angle with respect to the horizontal reference plane and the vertical reference plane, respectively The magnetic field shielding shield of the monitor, characterized by the inclination so as to.

In addition, the present invention is a magnetic field shielding shield manufacturing method of the monitor to shield the magnetic field by covering the periphery except the front portion of the monitor, the plate-shaped magnetic layer consisting of a steel plate-shaped frame and magnetic material by spot welding Manufacturing to overlap two layers; Manufacturing a shielding shield body so that the monitor is accommodated therein by bending and welding the frame and the magnetic layer manufactured by the above step into an approximately box shape with one side open; A heat treatment step of imparting magnetic properties to the magnetic layer by maintaining the shielding body at a high temperature in a hydrogen atmosphere for a predetermined time after fabrication; And attaching a conductive material layer made of a conductive material to an inner surface of the magnetic layer by using an adhesive after the heat treatment step.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

In general, inside monitors such as home color picture tube (CPT) and color display tube (CDT) for display, the electron beam injected from the electron gun passes through the opening of the shadow mask and lands on the surface of the fluorescent surface (brown tube). It is designed to be. However, since the electron beam is greatly affected by the geomagnetic field and other external magnetic fields, an inner shield is installed on both sides of the CRT to reduce deflection of the beam due to the external magnetic field, thereby minimizing landing miss. It is configured to provide clear picture quality. The inner shield is usually manufactured by being made of ultra low carbon steel, but the development of a material having better shielding performance is desired, and the inner shield has a structural design problem that cannot partially shield the external magnetic field. That is, even if a material with excellent shielding performance is developed, the CRT cannot be shielded to be a closed curved surface, so a monitor shield shield that blocks a magnetic field is essential, especially in an operation site with a large external magnetic field.

The present invention monitor shielding shield (1) is to use a combination of low-frequency and high-frequency magnetic shielding (electromagnetic shielding) in order to increase the shielding effect for the purpose of the shielding shield, as shown in FIG. It is provided to surround the monitor while having a frame 10, the magnetic layer 20, which is provided on the inner surface of the frame 10 and serves as a magnetic shield, and is located on the inner surface of the magnetic layer 20 It is composed of a triple structure consisting of a conductive material layer 30 that plays a shielding role in a high frequency band, and will be described by dividing it into a material side and a shape side.

First, in terms of material, the magnetic layer 20 formed in the center is preferably made of a magnetic material to improve the shielding effect in the low frequency band. In general, the magnetic shielding effect S using the magnetic material is the following regardless of the shape of the shielding body. It is expressed as Equation 1 (最新 磁 氣 解析. 遮蔽 設計 と 磁性 應用 技術, (株) 總 合 技術 セ ン タ-, 1986.p210).

Where μ and t represent the magnetic permeability and the thickness of the magnetic body, and γ represents the diameter of the shield (in the case of a cylinder or a sphere).

Therefore, in order to enhance the shielding effect in the low frequency band, the magnetic material of the shielding shield should be made of a material having a high permeability as much as possible. In the present invention, a plate-shaped member made of high Ni alloy (super Ni alloy) is adopted to form a magnetic layer 20).

As shown in Equation 1, the thickness of the magnetic layer 20 is better, but should be determined in consideration of the processing side and manufacturing cost (for example, 1mm).

The frame 10 overlapping the surface of one side of the magnetic layer 20 has an appropriate permeability (about 200) and can maintain the strength so that stress is not applied to the shield responsible for shielding and is easy to process. After overlapping the magnetic layer 20 with each other by spot welding using a common cold rolled steel sheet having a thickness of about 1.2 mm, the front side, that is, the side where the monitor is installed, is opened by bending and welding at the same time. The overall shape in the box shape of the to make it possible to reduce the man-hours of production, and the frame 10 to be on the outer surface side. Of course, since the elongation of the frame 10 and the magnetic layer 20 are different from each other, the frame 10 and the magnetic layer 20 should be processed in consideration of the thickness ratio of the material forming the frame and the magnetic layer so as not to cause cracking or fracture.

In particular, the high Ni alloy plate material constituting the magnetic layer 20, the magnetic properties are dependent on the heat treatment, this heat treatment is the approximate box shape with the front side open so that the frame 10 and the magnetic layer 20 overlap each other. After the manufacturing process and processing is completed in the hydrogen atmosphere finally maintained at about 1100 ℃ for 30 minutes and then cooled to have a proper magnetic properties.

In addition, the operation site should also consider the effect on the electromagnetic wave, which is an undesired wave of the MHz band generated from large cranes (50-150 tons), the shielding performance in the high frequency band on the inner surface side of the magnetic layer (20) The conductive material layer is formed.

및

(σ는 전기전도도)에 의존하므로(最新 磁氣解析. 遮蔽設計と磁性應用技術, (株)總合技術センタ-,1986.p208) 이들 정수의 값이 되도록 큰 재료를 선택하는 것이 유리하다. 예로써 투자율이 큰 Ni 합금은 특히

가 10^-3정도로 매우 작으며 일반강 또한 10^-2정도로 매우 작은 값을 갖는다.In the high frequency band, the absorption loss and reflection loss of the shield must be considered at the same time.

And

Since σ depends on the electrical conductivity, it is advantageous to select a large material so that the value of these integers is the value of these constants (最新 磁 解析, 遮蔽 設計 と 磁性 應用 技術, (株) Ni alloys with high permeability, for example,

Is very small, such as 10 ^-3, and ordinary steel is also very small, such as 10 ^-2 .

Materials with large values of these constants include silver (1.05), copper (1.0), and aluminum (0.61). Silver is expensive, while copper is inexpensive and its reflection loss constant is large and easy to process. And adopted in the present invention. In consideration of the skin depth, the conductive material layer is formed by bonding a copper foil having an appropriate thickness (for example, 36 μm) to the inner surface of the magnetic layer 20 by using an adhesive such as epoxy resin. 30).

Next, when the features of the present invention are described in terms of shape, the magnetic layer 20 made of high Ni alloy is located in the center portion, and the frame 10 made of a general cold rolled steel sheet located on the outer surface of the magnetic layer 20; The shielding body is formed on the inner surface of the magnetic layer 20 and has a substantially box shape in which the front side is opened in a triple structure made of a conductive material layer 30 made of copper foil. In the case where the monitor is accommodated therein, a heat dissipation hole, which is a means for dissipating heat generated therefrom, is usually equipped. In the related art, the present invention is shown in FIG. As described above, a plurality of heat dissipation holes 40 having a diameter of several mm are formed in the region A to which the fan is attached. As will be described later, the shielding efficiency is superior to that of forming a single hole having a large diameter, and in the following examples, the optimum size with better shielding efficiency is derived.

In addition, although the overall shape of the shielding shield is merely a rectangular shape according to the related art, the overall shape of the shielding shield body is substantially similar to that of the conventional art, but the upper shielding wall 50 as shown in FIG. And the rear shielding wall 60 is inclined so as to have an appropriate inclination angle with respect to each of the reference surfaces R1 and R2 corresponding to the upper and rear surfaces of the conventional rectangle. That is, the upper shielding wall 50 is formed to be inclined so as to have an appropriate inclination angle θ1 (for example, about 2.8 °) raised to the front side opened with respect to the horizontal reference plane R1, and the rear shielding wall 60 is vertical. It is formed to be inclined so as to have an appropriate inclination angle θ2 in which the lower portion is inclined toward the front side more than the upper portion with respect to one reference plane R2, thereby improving the shielding effect (absorption and reflection loss) of the magnetic field.

And, more preferably, the upper shielding wall 50 has an open end side end portion extending a predetermined length further to the outside, and in response to this, the open side end portion of the side shielding wall 70 further protrudes outward toward the upper side. As a result, the open side of the shielding shield body is formed in a shade to improve the shielding effect (absorption and reflection loss) of the magnetic field.

In addition, in consideration of appearance and durability, the powder-like paint is coated on the outer surface of the frame 10 to a thickness of about 60 μm, and then fired at 160-170 ° C. for about 40 minutes.

Reference numeral (2) is a leg that is fixed to the bottom surface of the lower shielding wall 90 a plurality of legs, and (3) is a leg fixed to the lower surface of the lower shielding wall 90 a plurality of legs. (4) is a door supported by a spring or the like not shown so as to be able to be restored to a vertical state rotatable to the upper surface of the open side end of the lower shielding wall 90.

Hereinafter, the present invention will be described in detail through examples.

Example 1

One of the features of the present invention is to form a plurality of heat dissipation holes 40 formed in the rear shielding wall 60 having a small diameter, 120mm x 120mm to verify the magnetic shielding effect by this structure Heat sinks having diameters of 1.0, 3.0, 5.0, and 7.0 mm were formed at equal intervals on the x0.5 mm magnetic sheet, respectively, and the strength of the magnetic field leaked was measured.

Helmholtz coils (maximum magnetic field 720G) with an outer diameter x inner diameter x width of 12 cm x 3.2 cm x 6 cm were fabricated to increase the magnetic field from 5G to 100G at a position 10mm away from the coil. Measured.

4 shows the result of examining the effect of the size of the heat radiation hole on the shielding efficiency. As can be seen from the figure, the shielding efficiency decreases with or without the size of the heat radiation hole as the intensity of the external magnetic field increases. have.

Since the shielding of monitors is intended for shielding in the low magnetic field environment, it is appropriate to compare the shielding efficiency when the external magnetic field is less than 20G.

As shown in the figure, the case where the heat radiation holes are formed is sharply reduced in terms of shielding efficiency as compared with the case where the heat radiation holes are not formed, and as the diameter of the heat radiation holes is increased at the boundary of 3 mm, the shielding efficiency is greatly increased. It turns out that it is falling. That is, when the 1 mm and 3 mm heat sinks are formed, the shielding efficiency does not show a large change, whereas when the size is 5 mm or more, the shielding efficiency is greatly reduced and the size of the heat sink is about 3 mm. It was found that the optimal size to improve the shielding efficiency while increasing the.

Example 2

In order to compare the shielding performance of the present inventors shielding shield with the conventional shielding shield, a shielding shield having a size of 530 (W) x 610 (L) x 520 (H) mm is manufactured to have a triple structure by the above-described process, and the prior art. The comparative example is manufactured to have a double structure of a magnetic body and an aluminum sheet.

In the shielding performance test, the magnetic field inside the shielding shield was measured with a model HI-3604 power survey meter manufactured by HOLADAY under the condition of generating an alternating magnetic field of 50-80mG. The results are shown in Table 1.

Shield size (mm) Shield structure Shield Shield Shield Internal Magnetic Field (mG) Shield effect The present invention 530 (W) x610 (L) x520 (H) Triple structure (rolled steel sheet / magnetic material / copper foil) 0.5 to 1.2 40 dB Comparative example 590 (W) x650 (L) x600 (H) Double structure (magnetic material / aluminum sheet) 4 to 5 24 dB

As can be seen in Table 1, the shielding shield of the present invention is very superior in terms of shielding effect compared to the shielding shield of the comparative example, and accordingly, when the monitor is shielded from the magnetic field using the shielding shield according to the present invention, the monitor screen It was confirmed that no distortion and vibration were detected at all.

As described above, according to the magnetic field shielding shield of the monitor according to the present invention, the triple magnetic structure of the frame, the magnetic layer and the conductive material layer effectively blocks the external magnetic field as well as the rear of the monitor by a plurality of heat radiation holes having a small diameter. It also has the effect of effectively blocking the electromagnetic waves generated from the negative, in particular, it is also suitable for shielding home TVs and computer monitors, which can block electromagnetic waves in the low frequency and high frequency bands to generate electromagnetic waves of several hundred mG.

In addition, the present invention can be applied to shielding devices using electron beams such as CRT (Cathode-ray Tube), that is, oscilloscope, radar scope, display of CAD device, electron microscope, electron exposure device, electron beam analyzer.

Claims (10)

In the magnetic field shielding shield of the monitor configured to surround the magnetic field except for the front portion of the monitor, On the inner surface of the magnetic layer 20 and the magnetic shielding magnetic layer 20 made of a magnetic material located on the inner surface of the frame 10, the steel frame 10 to surround the monitor while having mechanical strength The magnetic field shielding shield of the monitor, characterized in that it has a triple structure consisting of a conductive material layer 30 for magnetic shielding of the high frequency band made of a conductive material. The shield of claim 1, wherein the magnetic layer is made of a high Ni alloy. The magnetic field shielding shield of a monitor according to claim 1, wherein the conductive material layer (30) is formed of a highly conductive material in the form of a foil. (Correction) The magnetic field shielding shield of a monitor according to claim 1, wherein said conductive material layer (30) comprises a material having high conductivity in powder form. In the magnetic field shielding shield of the monitor so as to surround the magnetic field, and to surround the magnetic field, and the rear shielding wall to form a heat dissipation hole to discharge heat generated from the monitor to the outside by the fan, The heat shield 40 of the rear shielding wall 60 is a magnetic field shielding shield of the monitor, characterized in that formed in a plurality having a diameter smaller than the area (A) in the area (A) on which the fan is mounted. 6. The magnetic shielding shield of a monitor according to claim 5, wherein the diameter of the heat dissipation port (40) is 1 to 5 mm. In the magnetic field shielding shield of the monitor configured to surround the magnetic field except for the front portion of the monitor, Magnetic shielding shield of the monitor, characterized in that the upper shielding wall 50 and the rear shielding wall 60 are inclined so as to have inclination angles θ1 and θ2 with respect to the horizontal reference plane R1 and the vertical reference plane R2, respectively. . 8. The magnetic field shielding shield of claim 7, wherein the open side of the upper shielding wall (50) and the side shielding wall (70) is formed in a sunshade projecting outwardly toward the top. In the method of manufacturing a magnetic shield shield shield of the monitor to shield the magnetic field by surrounding the periphery except the front of the monitor, Manufacturing a plate-shaped magnetic layer 20 made of steel and a plate-shaped magnetic layer 20 made of a magnetic material so as to overlap two layers by spot welding; Manufacturing a shielding shield body so that the monitor can be accommodated by bending and welding the frame 10 and the magnetic layer 20 manufactured by the above step into an approximately box shape with one side open; A heat treatment step of providing a magnetic property to the magnetic layer 20 by maintaining the shielding body at a high temperature in a hydrogen atmosphere for a predetermined time after fabrication; And And attaching a conductive material layer (30) made of a conductive material to the inner surface of the magnetic layer (20) using an adhesive after the heat treatment step. 10. The method of claim 9, further comprising firing the powder coating on the outer surface of the frame (10) for about 40 minutes at 160-170 ° C.

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