Medical magnetic shielding box and demagnetization method thereof

Abstract

The present invention discloses a medical magnetic shielding box, comprising a first shielding plate assembly for providing magnetic shielding. The first shielding plate assembly comprises a first inner Permalloy shielding plate, a first outer Permalloy shielding plate, and a first aluminum-magnesium alloy shielding plate disposed therebetween. Demagnetization coils surround the inner and outer sides of the first shielding plate assembly. The present invention also discloses a demagnetization method for the medical magnetic shielding box, wherein a control circuit outputs a corresponding demagnetization signal to a power supply, causing the power supply to pass a demagnetization current through the demagnetization coil to complete the demagnetization process. The present invention provides a low-remanent magnetism medical magnetic shielding box device through optimized mechanical structure design. Compared to existing technologies, the present invention offers superior magnetic shielding effectiveness and a simpler structure.

Description

Technical Field

[0001] The present invention relates to the field of electromagnetic shielding, and in particular to a medical shielding box and a demagnetization method thereof. Background Art

[0002] Extremely weak magnetic devices have broad and important applications in high-end medical equipment testing, aerospace, resource and energy exploration, national defense, and geological disaster monitoring. As China vigorously develops zero-magnetic science and builds major scientific and technological infrastructure for extremely weak magnetic fields, the future of zero-magnetic medicine, zero-magnetic biology, zero-magnetic chemistry, zero-magnetic basic physics, and materials science will focus on the use of extremely weak magnetic devices. Conducting experiments using medical magnetic shielding boxes is urgent.

[0003] According to the principle of magnetic shielding, the higher the magnetic permeability of the material, the more significant the shielding effect. Therefore, shielding materials generally use materials with high magnetic permeability. Commonly used high magnetic permeability materials include pure iron, electromagnetic steel plates, Permalloy plates, amorphous alloy strips, and microcrystalline alloy strips. Through shielding formulas and simulation software testing, it was found that Permalloy has the best shielding performance against low-frequency magnetic fields compared to other metal materials, and it is easy to purchase and process on the market. Therefore, Permalloy is basically used as the shielding material for shielding boxes in the existing technology. For example, the Chinese patent application number CN201820209018.6 discloses a magnetic field shielding box, which includes an experimental mouse holder, a box body, and a cover plate, wherein the box body and the cover plate are both made of Permalloy, which improves the magnetic field shielding performance while further improving the accuracy of targeted stimulation.

[0004] However, using Permalloy alone as a shielding material cannot effectively shield against high-frequency magnetic fields. Scientific research has shown that when human and animal brain and heart magnetism are stimulated in extremely weak magnetic fields, multi-channel atomic magnetometers and software imaging reveal that normal and cancerous cells present different images. This is of great significance for disease prediction and pathological analysis. Therefore, medical magnetic shielding enclosures suitable for various biological experiments must be able to address the issue of shielding against high-frequency magnetic fields. Furthermore, the stresses experienced by soft magnetic materials during transportation and installation in geomagnetic environments inevitably cause them to become magnetized, generating residual magnetic fields within the material, which significantly reduces the shielding effectiveness of the shielding material. Therefore, it is necessary to eliminate the residual magnetic field in the soft magnetic material to improve the magnetic shielding performance of the shielding enclosure.

[0005] Therefore, further improvements need to be made to the existing technology. Summary of the Invention

[0006] The first technical problem to be solved by the present invention is to propose a medical magnetic shielding box with good magnetic shielding effect and simple structure in response to the above technical status quo.

[0007] The second technical problem to be solved by the present invention is to propose a demagnetization method suitable for medical magnetic shielding boxes to eliminate the residual magnetic field generated in soft magnetic materials in response to the above technical status.

[0008] The technical solution adopted by the present invention to solve the above-mentioned technical problems is: a medical magnetic shielding box, comprising a box body with an opening on one side made of box panels, and a door body connected to the box body for opening and closing the opening, the box panels and the door body are respectively provided with a first shielding layer plate group and a second shielding layer plate group for providing magnetic shielding function, characterized in that the first shielding layer plate group includes a first inner permalloy shielding plate, a first outer permalloy shielding plate and a first aluminum-magnesium alloy shielding plate arranged between the two, the second shielding layer plate group includes a second inner permalloy shielding plate, a second outer permalloy shielding plate and a second aluminum-magnesium alloy shielding plate arranged between the two, and the first shielding layer plate group is surrounded by a demagnetization coil on both sides.

[0009] As an improvement, four degaussing coils are provided, and the four degaussing coils have the same shape. Each of the degaussing coils has an annular U-shaped structure. The outer rings of the four annular U-shaped degaussing coils are attached to the outside of the first outer Permalloy shielding plate, and the inner rings of the four annular U-shaped degaussing coils are attached to the outside of the first inner Permalloy shielding plate, and partially pass through the entire first shielding layer plate group.

[0010] As an improvement, two of the four degaussing coils form a group, and the two groups of degaussing coils are respectively surrounded outside the first shielding layer plate group in a diagonal form.

[0011] As an improvement, the box panels making up the box body include an upper side panel, a left side panel, a lower side panel, a right side panel and a rear side panel, which are connected in sequence to form a box body with an opening on the front side, and the upper side panel, the left side panel, the lower side panel, the right side panel and the rear side panel are all provided with the first shielding layer plate group, and the first shielding layer plate group in the upper side panel and the lower side panel is provided with a winding hole, and four annular U-shaped demagnetization coils pass through the winding hole and surround the inner and outer sides of the first shielding layer plate group.

[0012] As an improvement, the first shielding layer plate group in the upper side plate and the lower side plate are respectively provided with four winding holes, and the four winding holes are distributed around the center of the box plate and are located on the diagonal line of the box plate.

[0013] As an improvement, each of the degaussing coils includes an outer coil segment located outside the first shielding layer plate group, an inner coil segment located inside the first shielding layer plate group, and a connecting coil segment passing through the winding hole and connecting the inner and outer coil segments; the outer coil segment includes a first outer coil segment whose two end points are respectively located at a winding hole of the upper side plate and an upper side plate vertex closest to the upper side plate winding hole, a second outer coil segment whose two end points are respectively located at an upper side plate vertex closest to the upper side plate winding hole and a lower side plate vertex closest to the upper side plate vertex, and a third outer coil segment whose two end points are respectively located at a lower side plate vertex closest to the upper side plate vertex and a lower side plate winding hole closest to the lower side plate vertex; The inner coil segment includes a first inner coil segment with two end points located at a winding hole in the upper plate and the upper plate vertex closest to the winding hole; a second inner coil segment with two end points located at the upper plate vertex closest to the winding hole and the lower plate vertex closest to the winding hole; and a third inner coil segment with two end points located at the lower plate vertex closest to the upper plate vertex and the lower plate winding hole closest to the winding hole; the connecting coil segment includes a first connecting coil segment that passes through the winding hole of the upper plate and the first shielding layer plate group in the upper plate, and a second connecting coil segment that passes through the winding hole of the lower plate and the first shielding layer plate group in the lower plate. Under this structure, the demagnetization magnetic fields generated by the four demagnetization coils independently surround the magnetic shielding box, and no magnetic field conflict occurs due to coil overlap.

[0014] As an improvement, the first inner and outer Permalloy shielding plates are 1.5 mm and 1 mm thick, respectively. Both plates are bent at the opening of the housing to form stepped grooves, allowing them to seal and form surface contact with the second inner and outer Permalloy shielding plates, respectively. The five surfaces of the inner and outer Permalloy shielding plates are completely welded together at the seams using fusion welding, effectively preventing magnetic flux leakage and complicating the mechanical structure of the magnetic shielding box.

[0015] As an improvement, the second inner permalloy shielding plate and the second outer permalloy shielding plate are leveled with the second aluminum-magnesium alloy shielding plate by short and long spacers and then fixed to the door body by fasteners.

[0016] As an improvement, the box panel making up the box body is provided with a first appearance layer group, the first appearance layer group includes a first inner decorative layer, a first outer decorative layer and a decorative strip provided at the opening of the box body respectively provided inside and outside the first shielding layer group; a base load-bearing frame is provided on the bottom side of the first inner decorative layer, the base load-bearing frame is fixed to the first aluminum-magnesium alloy shielding plate together with the first inner permalloy shielding plate through a load-bearing frame partition column; the door body is provided with a second appearance layer group, the second appearance layer group includes a second decorative layer, a nameplate cover and a door handle provided on the outside of the door body, and the nameplate cover and the door handle are fixed to the door body by fasteners.

[0017] A demagnetization method for a medical magnetic shielding box, characterized by comprising the following steps:

[0018] Step 1: Winding the degaussing coil using the above structure;

[0019] Step 2: Connect the degaussing coil to the power supply, insert a high-power resistor in series with the degaussing coil, and connect the output signal of the control circuit to the input terminal of the power supply;

[0020] Step 3: On the host computer, set the demagnetization current parameters to a linear decay sine waveform with a frequency of 10 Hz, a maximum current peak-to-peak value of 10 A, and a 50-cycle current. The current waveform expression is I = (5-t) 5sin(20πt);

[0021] Step 4: Output a corresponding demagnetization signal to the power supply through the control circuit, so that the power supply passes a demagnetization current to the demagnetization coil to complete the demagnetization process.

[0022] Compared with the prior art, the advantages of the present invention are as follows: the medical magnetic shielding box of the present invention is composed of a magnetic shielding door body and a magnetic shielding box body, and relies on inner and outer Permalloy shielding plates, aluminum-magnesium alloy shielding plates and degaussing coils to provide magnetic shielding functions. The Permalloy layer is used to shield the low-frequency magnetic field, the aluminum-magnesium alloy layer is used to shield the high-frequency magnetic field, and the degaussing coil is used to eliminate the magnetic shielding loss caused by the stress generated during the installation of the magnetic shielding box. At the same time, the aluminum-magnesium alloy frame material of the magnetic shielding box body is replaced by aluminum-magnesium alloy, which has higher strength, lower density and lighter weight. Therefore, the design of the present invention can provide a low-residual magnetism medical magnetic shielding box device through mechanical structure design optimization. Compared with the prior art, the magnetic shielding effect of the present invention is good and the structure is simple. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of the structure of an embodiment of the present invention;

[0024] Figure 2 for Figure 1 Schematic diagram from another angle;

[0025] Figure 3 for Figure 1 Schematic diagram of the structure after removing the appearance layer group;

[0026] Figure 4 for Figure 1 A schematic cross-sectional view of the door in a closed state;

[0027] Figure 5 for Figure 3 Schematic diagram of the degaussing coil;

[0028] Figure 6 Schematic diagram of demagnetization current waveform. DETAILED DESCRIPTION

[0029] The present invention will be described in further detail below with reference to the accompanying drawings and embodiments.

[0030] like Figures 1 to 6 FIG. 1 is a preferred embodiment of the present invention.

[0031] As a medical magnetic shielding box of an embodiment of the present invention, Figure 1 and Figure 2 As shown, the device comprises a box body 1 with an opening on one side, made of box panels, and a door body 2 connected to the box body 1 for opening and closing the opening. A first shielding plate group and a second shielding plate group are respectively provided within the box panels and the door body 2 to provide magnetic shielding. The first shielding plate group comprises a first inner permalloy shielding plate 11, a first outer permalloy shielding plate 12, and a first aluminum-magnesium alloy shielding plate 13 disposed therebetween. The second shielding plate group comprises a second inner permalloy shielding plate 21, a second outer permalloy shielding plate 22, and a second aluminum-magnesium alloy shielding plate 23 disposed therebetween.

[0032] Four degaussing coils 3 of the same shape are arranged around the inner and outer sides of the first shielding plate group. Each degaussing coil 3 is a ring-shaped U-shaped structure. Figure 3 and Figure 5 As shown, the outer coil of the degaussing coil 3 is attached to the outside of the first outer permalloy shielding plate 12, while the inner coil is attached to the outside of the first inner permalloy shielding plate 11, and partially passes through the entire first shielding plate set. The four degaussing coils 3 are grouped in pairs, with two groups of degaussing coils 3 each wrapping diagonally around the outside of the first shielding plate set.

[0033] like Figure 3As shown, the box body 1 is made up of a top panel 71, a left side panel 72, a bottom panel 73, a right side panel 74, and a rear panel 75. These top panels 71, 72, 73, 74, and 75 are sequentially connected to form the box body 1, which has an opening at the front. A first shielding layer assembly is provided within each of these top panels 71, 72, 73, 74, and 75. In this embodiment, four winding holes 14 are provided in the first shielding layer assembly within each of the top and bottom panels 71, 73. These four winding holes 14 are distributed around the center of the panel and located on diagonals of the panel. Four annular U-shaped degaussing coils 3 pass through the winding holes 14 and surround the inner and outer sides of the first shielding layer assembly.

[0034] Each degaussing coil 3 includes an outer coil section located outside the first shielding plate group, an inner coil section located inside the first shielding plate group, and a connecting coil section passing through the winding hole 14 and connecting the inner and outer coil sections. Figure 5 As shown. The outer coil segment includes a first outer coil segment 31 whose two end points are respectively located at a winding hole 14 of the upper side plate 71 and a vertex of the upper side plate 71 closest to the winding hole 14 of the upper side plate; a second outer coil segment 32 whose two end points are respectively located at a vertex of the upper side plate 71 closest to the winding hole 14 of the upper side plate and a vertex of the lower side plate 73 closest to the vertex of the upper side plate 71; a third outer coil segment 33 whose two end points are respectively located at a vertex of the lower side plate 73 closest to the vertex of the upper side plate 71 and a vertex of the lower side plate 73 closest to the vertex of the lower side plate 73; the inner coil segment includes a winding hole 14 of the upper side plate 71 and a vertex of the upper side plate closest to the winding hole 14 of the upper side plate. The first inner coil segment 34 is located at the vertex of the side panel 71, and the second inner coil segment 35 has two endpoints located at the vertex of the upper panel 71 closest to the winding hole 14 of the upper panel, and at the vertex of the lower panel 73 closest to the vertex of the upper panel 71. The third inner coil segment 36 has two endpoints located at the vertex of the lower panel 73 closest to the vertex of the upper panel 71, and at the vertex of the lower panel 73 closest to the vertex of the lower panel 73. The connecting coil segments include a first connecting coil segment 37 that passes through the winding hole 14 of the upper panel 71 and through the first shielding layer group within the upper panel 71, and a second connecting coil segment 38 that passes through the winding hole 14 of the lower panel 73 and through the first shielding layer group within the lower panel 73. In this structure, the demagnetization magnetic fields generated by the four demagnetization coils 3 independently surround the first shielding layer group, preventing magnetic field conflicts caused by overlapping demagnetization coils 3.

[0035] In order to ensure the magnetic shielding effect of the magnetic shielding box, the first shielding layer plate group and the second shielding layer plate group need to form a closed shielding barrier when the door body 2 is closed, such as Figure 4As shown. Therefore, the first inner and outer permalloy shielding plates 11 and 12 are made of permalloy materials with thicknesses of 1.5 mm and 1 mm, respectively. The five sides of the material are welded together to form a box-shaped opening. The openings are then bent to form stepped grooves 15, allowing them to form closed surface contact with the second inner and outer permalloy shielding plates 21 and 22. The second inner and outer permalloy shielding plates 21 and 22 are leveled with the second aluminum-magnesium alloy shielding plate 23 using short spacers 27 and long spacers 28, and then secured to the door body 2 using fasteners. The door body 2 is connected to the box body 1 via hinges 4 on one side and latches 5 on the other, forming a closed box structure.

[0036] In addition, the bottom of the box body 1 is provided with feet 62 for the box body 1 to stand, the side of the box body 1 is provided with side handles 63 for conveniently holding the box body 1 and a power interface component 64 for connecting the demagnetization coil 3 to the power supply, and the box body 1 is provided with a magnetic detection hole 16 on the box surface opposite to the door body 2.

[0037] The present invention uses an aluminum-magnesium alloy instead of aluminum alloy, resulting in higher strength, lower density, and lighter weight. Furthermore, the five surfaces of the first aluminum-magnesium alloy shielding plate 12 are grooved to reduce weight. The five surfaces are secured together by screws, and each surface has threaded holes for securing the frame. The back surface has a magnetic detection hole 16, while the top and bottom surfaces have winding holes 14, light and air holes, and threaded holes for adjusting the foot 62. The left and right sides have threaded holes for securing the side handle 63 assembly, hinge 14, power interface assembly 64, and lock assembly 5.

[0038] The present invention not only provides a low-remanence medical magnetic shielding box device through optimized mechanical structure design, but also enhances market competitiveness by adding inner and outer decorative layers and decorative strips. Specifically, the box body 1 is provided with a first exterior layer group, comprising a first interior decorative layer 17 and an exterior decorative layer 18, respectively disposed on the inside and outside of the first shielding layer group, and a decorative strip 19 disposed at the opening of the box body 1. The first interior decorative layer 17 is formed from a bent and welded aluminum plate. A base load-bearing frame 60, made of titanium alloy, is provided on the bottom side of the first interior decorative layer 17. The base load-bearing frame 60 is secured to the first aluminum-magnesium alloy shielding plate 13 along with the first inner permalloy shielding plate 11 via load-bearing frame spacers 61. The door body 2 is provided with a second exterior layer group, comprising a second decorative layer 24, a nameplate cover 25, and a door handle 26, disposed on the outside of the door body 2. The lock assembly 5, the nameplate cover 25, and the door handle 26 are secured to the door body 2 via fasteners. A skeleton 65 is provided on each of the five surfaces of the magnetic shielding box 1 for fixing the first outer permalloy shielding plate 12 to the first aluminum-magnesium alloy shielding plate 13 and the upper and lower covers of the first outer decorative layer. Both the upper and lower covers of the first outer decorative layer are provided with light-permeable and air-permeable devices and the seams are provided at the rear and bottom, and are locked to each other with bolts.

[0039] A demagnetization method for a medical magnetic shielding box comprises the following steps:

[0040] Step 1: Use the above structure to wind the degaussing coil 3;

[0041] Step 2: Connect the degaussing coil 3 to the 7796 power supply, insert a 5-ohm high-power resistor in series with the outside of the degaussing coil 3, and connect the output signal of the control circuit to the input of the power supply. The control circuit of this embodiment mainly consists of DSP28335 and DA chip MAX5719. DSP28335 is connected to the host computer via JTAG to control the DA chip to output signals to the 7796 power supply.

[0042] Step 3: Set the demagnetization current parameters on the host computer to a linear decay sine waveform with a frequency of 10Hz, a maximum current peak-to-peak value of 10A, and a 50-cycle current. The current waveform expression is I = (5-t) 5sin(20πt). The demagnetization current waveform is shown in the figure below. Figure 6 As shown;

[0043] Step 4: The control circuit outputs a corresponding demagnetization signal to the power supply, so that the power supply passes a demagnetization current to the demagnetization coil 3 to complete the demagnetization process.

Claims

1. A medical magnetic shielding box, comprising a box body (1) made of box panels with an opening on one side, and a door body (2) connected to the box body (1) for opening and closing the opening, wherein a first shielding layer plate group and a second shielding layer plate group for providing a magnetic shielding function are respectively provided in the box panels and the door body (2), characterized in that: The first shielding plate group comprises a first inner Permalloy shielding plate (11), a first outer Permalloy shielding plate (12), and a first aluminum-magnesium alloy shielding plate (13) disposed between the first and second shielding plate groups; the second shielding plate group comprises a second inner Permalloy shielding plate (21), a second outer Permalloy shielding plate (22), and a second aluminum-magnesium alloy shielding plate (23) disposed between the first and second shielding plate groups; and demagnetization coils (3) are disposed around the inner and outer sides of the first shielding plate group; Four degaussing coils (3) are provided, and the four degaussing coils (3) have the same shape. Each of the degaussing coils (3) is an annular U-shaped structure. The outer rings of the four annular U-shaped degaussing coils (3) are attached to the outside of the first outer Permalloy shielding plate (12), and the inner rings of the four annular U-shaped degaussing coils (3) are attached to the outside of the first inner Permalloy shielding plate (11), and partially pass through the entire first shielding layer plate group.

2. The medical magnetic shielding box according to claim 1, characterized in that: Two of the four degaussing coils (3) form a group, and two groups of degaussing coils (3) are respectively surrounded outside the first shielding layer plate group in a diagonal form.

3. The medical magnetic shielding box according to claim 2, characterized in that: The box plate used to make the box body (1) includes an upper side plate (71), a left side plate (72), a lower side plate (73), a right side plate (74) and a rear side plate (75); the upper side plate (71), the left side plate (72), the lower side plate (73), the right side plate (74) and the rear side plate (75) are sequentially connected to form a box body (1) with a front opening; the upper side plate (71), the left side plate (72), the lower side plate (73), the right side plate (74) and the rear side plate (75) are all provided with the first shielding layer plate group; the first shielding layer plate group in the upper side plate (71) and the lower side plate (73) is provided with a winding hole (14); four annular U-shaped demagnetization coils (3) pass through the winding hole (14) and surround the inner and outer sides of the first shielding layer plate group.

4. The medical magnetic shielding box according to claim 3, characterized in that: Four winding holes (14) are respectively provided on the first shielding layer plate group in the upper side plate (71) and the lower side plate (73). The four winding holes (14) are distributed around the center of the box plate where they are located and are located on the diagonal line of the box plate.

5. The medical magnetic shielding box according to claim 4, characterized in that: Each of the degaussing coils (3) comprises an outer coil segment located outside the first shielding layer plate group, an inner coil segment located inside the first shielding layer plate group, and a connecting coil segment passing through the winding hole (14) and connecting the inner and outer coil segments; the outer coil segment comprises a first outer coil segment (31) whose two end points are respectively located at a winding hole (14) of the upper plate (71) and a vertex of the upper plate (71) closest to the winding hole (14) of the upper plate; a second outer coil segment (32) whose two end points are respectively located at a vertex of the upper plate (71) closest to the winding hole (14) of the upper plate and a vertex of the lower plate (73) closest to the vertex of the upper plate; and a third outer coil segment (33) whose two end points are respectively located at a vertex of the lower plate (73) closest to the vertex of the winding hole (14) of the lower plate; the inner coil segment comprises a first outer coil segment (31) whose two end points are respectively located at a winding hole (14) of the upper plate and a vertex of the upper plate closest to the vertex of the lower plate. A first inner coil segment (34) is located at a winding hole (14) of the upper side plate (71) and a vertex of the upper side plate (71) closest to the winding hole (14) of the upper side plate, and two end points are located at the vertex of the upper side plate (71) closest to the winding hole (14) of the upper side plate and a second inner coil segment (35) is located at the vertex of the lower side plate (73) closest to the vertex of the upper side plate (71), and two end points are located at the vertex of the lower side plate (73) closest to the vertex of the upper side plate (71). The third inner coil segment (36) of the vertex of the lower side plate (73) and the winding hole (14) of the lower side plate closest to the vertex of the lower side plate (73); the connecting coil segment includes a first connecting coil segment (37) passing through the first shielding layer plate group in the upper side plate (71) through the winding hole (14) of the upper side plate (71), and a second connecting coil segment (38) passing through the first shielding layer plate group in the lower side plate (73) through the winding hole (14) of the lower side plate (73).

6. The medical magnetic shielding box according to claim 5, characterized in that: The thicknesses of the first inner Permalloy shielding plate (11) and the first outer Permalloy shielding plate (12) are 1.5 mm and 1 mm respectively. The first inner Permalloy shielding plate (11) and the first outer Permalloy shielding plate (12) are both bent at the opening of the box body (1) to form a stepped groove (15), so that they can be respectively sealed with the second inner Permalloy shielding plate (21) and the outer Permalloy shielding plate (22) and form surface contact.

7. The medical magnetic shielding box according to claim 6, characterized in that: The second inner Permalloy shielding plate (21) and the second outer Permalloy shielding plate (22) are leveled with the second aluminum-magnesium alloy shielding plate (23) by means of short spacers (27) and long spacers (28) and then fixed to the door body (2) by means of fasteners.

8. The medical magnetic shielding box according to claim 7, characterized in that: The box plate of the box body (1) is provided with a first appearance layer group, the first appearance layer group includes a first inner decorative layer (17) and a first outer decorative layer (18) respectively provided inside and outside the first shielding layer group, and a decorative strip (19) provided at the opening of the box body (1); the bottom side of the first inner decorative layer (17) is provided with a base load-bearing frame (60), the base load-bearing frame (60) is fixed to the first aluminum-magnesium alloy shielding plate (13) together with the first inner Permalloy shielding plate (11) through a load-bearing frame partition column (61); the door body (2) is provided with a second appearance layer group, the second appearance layer group includes a second decorative layer (24) provided on the outside of the door body (2), a nameplate cover (25) and a door handle (26), and the nameplate cover (25) and the door handle (26) are fixed to the door body (2) through fasteners.

9. A demagnetization method for a medical magnetic shielding box, characterized in that: The following steps are involved: Step 1, using the structure described in claim 3 to wind the degaussing coil (3); Step 2: Connect the degaussing coil (3) to a power supply, connect a high-power resistor in series to the outside of the degaussing coil (3), and connect the output signal of the control circuit to the input end of the power supply; Step 3: Set the demagnetization current parameters on the host computer to a linear decay sine waveform with a frequency of 10 Hz, a maximum current peak-to-peak value of 10 A, and a 50-cycle current. The current waveform expression is: ; Step 4: Outputting a corresponding demagnetization signal to the power supply through the control circuit, so that the power supply passes a demagnetization current to the demagnetization coil (3) to complete the demagnetization process.

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