JPH02186093A - Window for magnetic shielded room - Google Patents

Abstract

PURPOSE:To magnetically shield a window surface and view the inside if necessary by installing the window by arranging two transparent plates, keeping an interval, and by charging the vacant part between the transparent plates with the magnetic fluid and allowing said fluid to be discharged if necessary. CONSTITUTION:A window 4 is constituted by installing two transparent plates 4a and 4b in double form, keeping an interval, and an inflow port 9 and a discharge port 10 are formed in the vacant part 6 between the both transparent plates 4a and 4b. Then, the inflow port 9 is allowed to communicate to a magnetic fluid tank through a hose 14 and a pump, and the discharge port 10 is allowed to communicate to the magnetic fluid tank through a hose 14 and a vacuum device. The inside of the hollow part 6 is charged with the magnetic fluid 8 from the inflow port 9, and the window 4 surface is magnetically shielded, and if necessary, the magnetic fluid 7 is discharged from the discharge port 10, and the inside is viewed through the window 4.

Description

Detailed Description of the Invention "Industrial Application Field" The present invention is directed to a magnetically shielded room that prevents the leakage of magnetic fields to the outside from a room in which a strong magnetic field generator such as a magnetic resonance diagnostic instrument (MHI) is installed. This invention relates to a window for a magnetically shielded room in which a window is provided to see through the interior of the room and the window is magnetically shielded.

"Prior Art" Recently, hospitals have begun to install magnetic resonance diagnostic equipment (hereinafter referred to as MHI), but in addition to patients with pacemakers, there are also devices such as computers that are adversely affected by magnetism. There are many devices available. Therefore, in the room where the MHI is installed, a magnetic shield A made of ferromagnetic material such as pure iron is installed on four or six sides of the room, as shown in Figure 3, in order to prevent leakage magnetic fields from leaking to the outside.

Radio wave shields B are installed on six sides of the room to block the influence of external radio waves.

The room in which the MHI is installed is provided with windows and entrances and exits for viewing the inside from the outside, but if there is a gap in the area where these are provided, the effectiveness of both shields will be significantly reduced. Therefore, the gaps in the room where the MHI etc. are installed are completely welded, completely soldered, etc. to eliminate gaps for magnetic and radio wave leakage. In addition, the openings such as the entrance and exit of the room are also equipped with radio wave shielding such as stainless steel plates, shielding glass, and finger contacts.

However, with regard to magnetic shielding, the magnetic material used as the material is heavy and opaque, so it cannot be applied to window portions that require transparency. The size of the window is
Width 1000+nm, height 800m to see through the interior of the room
Although it is desirable to have a diameter of about 100 m, the current situation is to make windows as small as possible in order to reduce the leakage magnetic field from the windows.

``Problems to be Solved by the Invention'' In conventional MRI rooms, it is not possible to provide a magnetic shield to the window, and in that case, a large amount of magnetic field leaks from the window portion. In other words, as shown in Fig. 3, when L and ST (terrace) MHIs are installed, the 5 area is a controlled area where base manufacturer wearers are prohibited from entering and serves as a guideline for combinator installation.
The G (Gaussian) line was thick (spreading) from the window, which caused many management problems.In addition, if we tried to keep the leakage magnetic field small by placing the window as far away from the MHI as possible and using distance attenuation, the room area would become large. Problems arise in architectural planning due to constraints on the position of windows.Furthermore, large distortions occur in the magnetic field distribution in the MRI room, making it difficult to adjust using shim coils to avoid distortions in MHI images.

In order to suppress the generation of a strong magnetic field from the MHI, it is possible to cut off the power supplied to the MHI except during inspections, but the currently mainstream superconducting type MHI uses a superconducting electromagnet and generates a persistent current. It was in full operation for 24 hours to allow the flow of MHI, and it was not possible to suppress the magnetic field generated from the MHI.

Therefore, an object of the present invention is to apply an effective magnetic shield to the internal see-through window of a magnetically shielded room, and to reduce (suppress) the leakage of the magnetic field to the outside.

"Means for Solving the Problem" The window for a magnetically shielded room of the present invention is constructed by doubly arranging two transparent plates with an interval between them, and The structure is such that magnetic fluid can be filled or discharged as appropriate.

In order to fill the hollow portion between both transparent plates with magnetic fluid, the inlet of the hollow portion is communicated with a magnetic fluid supply device via piping. In order to effectively discharge the magnetic fluid within the hollow portion, the discharge port of the hollow portion may be communicated with the magnetic fluid tank via a vacuum device. In addition, in order to reliably prevent magnetic field leakage around the periphery of the window, the magnetic shielding material provided on the wall of the magnetically shielded room should be extended into the hollow space to ensure magnetic continuity with the magnetic fluid inside the hollow space. That's fine.

In addition, magnetic fluid is a particle size of 10a to 200a in water, mineral oil, etc.
It is a colloidal solution in which human (Angstrom) magnetic particles are dispersed, and because it is a fine particle, its holding power is small, and if the magnetic permeability is increased by adjusting the composition, it becomes suitable as a magnetic shielding material.

"Operation" In the magnetic shielding window of the above means, when the window is to be magnetically shielded, the magnetic fluid supply device is operated to fill the hollow space between both transparent plates with magnetic fluid. By this filling, the window surface is covered with magnetic fluid, and the window surface is magnetically shielded.

In this case, the magnetic fluid is dark brown and opaque, making it impossible to see through the window.

When looking through the inside through the breath, the inside can be seen through the double transparent plates by opening the outlet in the hollow between the two transparent plates and discharging the magnetic fluid. Note that if magnetic fluid adheres to the transparent plate, visibility will be impaired, so if the vacuum device is operated to suck out the adhered magnetic fluid, the interior becomes easier to see.

"Example" An embodiment of the present invention will be explained with reference to FIG. 1.2.

In a room where a device that generates a strong magnetic field, such as a magnetic resonance diagnostic instrument (MHI), is installed, a wall material 1, for example a magnetic shielding material 2 made of pure iron plate, is installed on the surrounding wall from the outside to the inside.
, a radio wave shield wall 3 made of copper foil or the like is provided.

A window 4 is provided in the chamber by opening the peripheral wall in order to see through the interior, and this window 4 is attached to the opening in the peripheral wall via a stainless steel frame 5. In the window 4, two transparent plates 4a and 4b are arranged doubly with an interval between them, and the periphery of the two transparent plates, that is, the end face of the window is also connected by a transparent plate made of the same material as above.
A hollow portion 6 surrounded by a transparent plate in the middle is filled with a magnetic fluid 7. The transparent plates 4a and 4b are made of, for example, shield steel (SUS304) having radio wave shielding performance.
) 8 sandwiched in the center, but it may also be formed by sandwiching a radio wave shielding material between transparent synthetic resin plates. In order to improve the magnetic shielding of the peripheral edge of the window, the magnetic shielding material 2 of the peripheral wall is extended and projected into the hollow part 6 all around, and the magnetic shielding material 2 and the magnetic fluid 7 are magnetically connected in the hollow part 6. It is designed to be continuous.

Note that the portion of the magnetic shielding material 2 penetrating the transparent plate at the end face forming the hollow portion 6 is sealed with a sealing material.

An inlet 9 for flowing the magnetic fluid is provided in the upper part of the hollow portion 6, that is, an upper end face of the transparent plate, and an outlet IO is similarly provided in the lower end face. The inlet 9 is an injection hose 1 having an electromagnetic on-off valve 12 and a pump 13 in the middle.
The hollow part 6 can be filled with magnetic fluid by opening the electromagnetic on-off valve 12 and closing the on-off valve I7 on the discharge side, which will be described later, to drive the pump 13. ing. Note that the inlet 9 is sealed so that there is no gap between it and the injection hose 14. In addition, the electromagnetic on-off valve 12 and the pump 13 are
It is controlled by a microcomputer 16.

The discharge port lO of the hollow part 6 is communicated with the magnetic fluid tank 15 via a discharge hose 19 having an electromagnetic on-off valve 17 and a vacuum device 18 in the middle, and the electromagnetic on-off valve 12 is closed and the electromagnetic on-off valve 17 is opened. By driving the vacuum device 18 with
All the magnetic fluid in the hollow part 6 can be attracted. It is also possible to provide an openable and closable air vent hole in the upper part of the hollow part 6, so that the magnetic fluid can be discharged 7 by its own weight, although not completely, without driving the vacuum device.

In addition, in the part of the discharge port 10, it and the discharge hose 14 are connected.
It is sealed so that there are no gaps between the two. Further, the electromagnetic on-off valve (2) and the vacuum device 18 are controlled by the microcomputer 16.

"Effects of the Invention" When the magnetically shielded room window of the present invention is applied to an MRI room, etc., the hollow part of the window can be filled with magnetic fluid during main examinations that require magnetic shielding, or when indoor fluoroscopy is not required. By doing so, the leakage magnetic field from the window can be greatly reduced. When it is necessary to see through the room, by discharging the magnetic fluid in the hollow part of the window, it can easily function as a viewing window, and the discharged magnetic The fluid can be used again.

In addition, by preventing magnetic field leakage, it is possible to keep the 5G line around the magnetically shielded room small, reducing the control area and increasing the flexibility of installing computers.It also increases the freedom of setting window positions, making architectural planning easier. Become. Furthermore, by preventing magnetic field leakage from the window, there is no need to greatly attenuate the magnetic field over distance, so the area of the MRI room can be kept small, and the magnetic field distortion in the room is also small, making it easy to adjust using shim coils. .

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a window portion for a magnetically shielded room according to the present invention, Fig. 2 is an explanatory diagram showing the supply and discharge route of magnetic fluid in the present invention, and Fig. 3 is an explanatory diagram showing the magnetic field state of a conventional magnetically shielded room. It is a diagram.

Claims (3)

[Claims] (1) In the window of the magnetically shielded room where the strong magnetic field generator will be installed, the window should be separated by two transparent plates with an interval between them.
An inlet and an outlet are provided in the hollow part between both transparent plates, and the inlet is communicated with a magnetic fluid supply source via piping, and the inlet and outlet are arranged in the hollow part between both transparent plates as appropriate. A window for a magnetically shielded room, characterized in that it can be filled with or discharged from a magnetic fluid. (2) Claim 1 characterized in that the discharge port in the hollow space between both transparent plates is communicated with the magnetic fluid tank via a vacuum device.
Windows for magnetically shielded rooms as described in . (3) The magnetic shield material provided on the wall of the magnetic shield room is extended and protruded into the hollow space between both transparent plates, so that it can have magnetic continuity with the magnetic fluid inside the hollow space. The window for a magnetically shielded room according to claim 1 or 2.