JP2007167265A - Magnetic induction system and magnetic field modulation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic induction system capable of modulating an induced magnetic field without using a coil or power supply for generating an alternating-current magnetic field. <P>SOLUTION: The magnetic induction system comprises a magnetic field generating part for generating a certain magnetic field for inducing a member to be induced and a magnetic field modulation device disposed in the periphery of the magnetic field generating part. The magnetic field modulation device selectively achieves a state to shield the magnetic field generated by the magnetic field generating part, a state to shield a part of the magnetic field, and a state not to shield the magnetic field. The magnetic field formed with the magnetic field generated by the magnetic field generating part is modulated by the operation of the magnetic field modulation device. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a magnetic induction system that induces a guided member using magnetism, and a magnetic field modulation device used in the system.

In a magnetic induction system in which a guided member can be guided by a magnetic field, control by adding a modulated AC magnetic field to the induced magnetic field generated for guiding the guided member causes vibration to the guided member. Since it can be added, it is considered useful in terms of assisting guidance by reducing the contact resistance between the guided member and the inside of the object (Patent Document 1). In addition, it has been studied to accurately detect the position and direction of the guided member by using the induced magnetic field and the alternating magnetic field together.
JP-A-4-22326

However, the above-described magnetic induction system requires a device for generating an induction magnetic field and an alternating magnetic field, respectively, which increases costs and enlarges the system. In particular, when coils are respectively used for generating an induction magnetic field and an AC magnetic field, a power source for supplying current to both coils is required. Furthermore, when a modulation current is supplied to a coil having a large inductance, it is necessary to increase the capacity and control capability of the power source that supplies the coil current, which increases the system cost and size and increases the power consumption. there were.

  In order to solve the above-described problems, a magnetic induction system according to the present invention includes a magnetic field generator that generates a constant magnetic field for guiding a guided member, and a magnetic field generator that is disposed around the magnetic field generator. A magnetic field modulation device that selectively realizes a magnetic field shielding state, a partial shielding state, and a non-shielding state, and a magnetic field formed by the magnetic field generated by the magnetic field generation unit by the operation of the magnetic field modulation device It is characterized by modulating.

  The magnetic field modulation device includes a filling container filled with a magnetic fluid and an adjusting mechanism for adjusting the amount of the magnetic fluid filled in the filling container, and the filling container is filled by the operation of the adjusting mechanism. By adjusting the amount of the magnetic fluid, it is possible to selectively realize a state in which the magnetic field generated by the magnetic field generator is shielded, a state in which it is partially shielded, and a state in which it is not shielded.

  The magnetic field modulation device includes a magnetic field modulation member having a magnetic part and a nonmagnetic part, and a relative position changing member that changes a relative positional relationship between the magnetic part and the nonmagnetic part of the magnetic field modulation member and the magnetic field generation part, With the operation of the relative position changing member, it is possible to selectively realize a state where the magnetic field generated by the magnetic field generation unit is shielded, a state where it is partially shielded, and a state where it is not shielded.

  The magnetic field modulation device includes a magnetic shield member having a magnetic body whose magnetic characteristics change with temperature, and a temperature adjustment member that adjusts the temperature of the magnetic shield member, and the magnetic characteristics of the magnetic body are adjusted by the operation of the temperature adjustment member. And a state where the magnetic field generated by the magnetic field generator is shielded, a partly shielded state, and a state where the magnetic field is not shielded can be selectively realized.

  The magnetic body of the magnetic shield member is a superconductor. By changing the temperature of the magnetic shield member by the operation of the temperature adjustment member, the superconductor state and non-superconductor state of the magnetic body are selectively realized, thereby generating a magnetic field. A state in which the magnetic field generated by the part is shielded, a partly shielded state, and a state in which the magnetic field is not shielded can be selectively realized.

  The magnetic field generation unit may include a coil and a power source that supplies a current for generating a constant magnetic field for inducing the guided member to the coil.

  A magnetic field modulation device according to the present invention is disposed around a magnetic field generation unit that generates a constant magnetic field for guiding a guided member, and shields the magnetic field generated by the magnetic field generation unit, partially shields the state, And the magnetic field formed by the magnetic field which the magnetic field generation | occurrence | production part generate | occur | produced by selectively implement | achieving the state which is not shielded is characterized by the above-mentioned.

  According to the present invention, even if it is necessary to supply a current to a magnetic field generating member having a large inductance by providing a magnetic induction system that does not require the use of a power supply that supplies a current for generating an alternating magnetic field. Thus, it is possible to provide a magnetic induction system that can reduce costs and reduce the size of the system.

Hereinafter, embodiments according to the present invention will be described in detail with reference to the drawings.
First Embodiment (FIGS. 1 and 2)
1st Embodiment implement | achieves the magnetic field modulation apparatus which comprises the magnetic induction system which concerns on this invention by fluctuating the filling amount of a magnetic fluid. As shown in FIG. 1, the magnetic guidance system according to the first embodiment includes a magnetic field generation unit 10 and a magnetic field modulation device 30.

  The magnetic field generating unit 10 includes a closed magnetic circuit type coil 11 having a magnetic material (for example, magnets such as pure iron, iron alloy, platinum magnet, rare earth magnet, and metal magnet) inserted therein, and supplies current to the coil 11. Power supply 12 (FIG. 2). The operation of the power supply 12 is controlled by the control unit 20. An input unit 25 is connected to the control unit 20, and by operating the input unit 25, an amount of current corresponding to the magnitude of the magnetic field desired by the operator flows through the coil 11 to form a constant magnetic field. . The magnetic field generation unit 10 can be configured not to use the coil 11 and the power source 12 by using a permanent magnet, thereby reducing the size and cost of the system. Examples of permanent magnets include neodymium magnets (rare earth magnets mainly composed of neodymium, iron and boron), rare earth magnets other than neodymium magnets (for example, rare earth magnets containing samarium), and magnets other than these (for example, pure iron) , Iron alloys, platinum magnets, terbium / dysprosium / iron alloys, ferrites, alnicos, cobalt ferrites).

  The magnetic field modulation device 30 includes a magnetic fluid filling container 31 and a magnetic fluid tank 32. The magnetic fluid filling container 31 is made of a non-magnetic material (for example, non-magnetic stainless steel or titanium alloy), and has a hollow, substantially rectangular parallelepiped shape that accommodates the magnetic field generator 10 therein. The surface constituting the magnetic fluid filling container 31 is formed with a filling space 31a communicating with each other so that the magnetic fluid can be filled therein. The magnetic fluid tank 32 is a hollow, substantially rectangular parallelepiped container in which the magnetic fluid 80 is stored.

  The filling space 31a of the magnetic fluid filling container 31 and the magnetic fluid tank 32 are connected to each other by three flow pipes 61, 62, 63, and the filling space 31a is filled with a desired amount of the magnetic fluid 80 in the magnetic fluid tank 32. Or a desired amount of the magnetic fluid 80 can be discharged from the filling space 31a and returned to the magnetic fluid tank 32. In other words, the magnetic fluid filling container 31 is magnetized by the flow pipe 61 for injecting and filling the magnetic fluid into the magnetic fluid filling container 31 through the electromagnetic valve 41 and the pump 51 arranged in order from the magnetic fluid filling container 31 side. A fluid tank 32 is connected. The magnetic fluid filling container 31 is a flow pipe 62 for discharging the magnetic fluid from the magnetic fluid filling container 31 via the flow sensor 72, the pump 52, and the electromagnetic valve 42 arranged in this order from the magnetic fluid filling container 31 side. Thus, the magnetic fluid tank 32 is connected. Further, the magnetic fluid filling container 31 is configured to exhaust air in a pipe from the magnetic fluid filling container 31 to the magnetic fluid tank 32 via a flow sensor 73 and an electromagnetic valve 43 that are sequentially arranged from the magnetic fluid filling container 31 side. In addition, the magnetic fluid tank 32 is connected to the magnetic fluid tank 32 by a flow pipe 63 for discharging the magnetic fluid 80 overflowing from the filling space 31 a to the magnetic fluid tank 32. The magnetic fluid tank 32 includes an air vent port 32a. In addition, the above piping is comprised by welding, or bolt and nut tightening via an O ring or a metal gasket. The electromagnetic valves 41 to 43, the pumps 51 and 52, the flow sensors 72 and 73, and the magnetic fluid tank 32 constitute an adjustment mechanism that adjusts the amount of the magnetic fluid 80 filled in the magnetic fluid filling container 31. The solenoid valves 41 to 43, the pumps 51 and 52, and the flow rate sensors 72 and 73 are connected to the control unit 20, respectively. The control unit 20 is connected to the input unit 25, and the magnetic field modulation device 30 performs an operation desired by the operator by operating the input unit 25. A pneumatic valve can be used in place of the electromagnetic valves 41 to 43.

  The magnetic fluid 80 may be, for example, a material in which ferromagnetic fine particles whose surface is covered with a surfactant are stably dispersed in a solvent at a high concentration (for example, about 50%). As the ferromagnetic fine particles, for example, magnetite or manganese-zinc composite ferrite, or a metal magnetic colloid containing cobalt, iron, or nickel can be used. As the surfactant, for example, a long-chain unsaturated fatty acid such as oleic acid can be used. Further, as the solvent, for example, water, hydrocarbon oil, or fluorine oil can be used.

  Subsequently, the operation of the magnetic induction system according to the first embodiment will be described. The injection and filling of the magnetic fluid 80 from the magnetic fluid tank 32 in which the magnetic fluid 80 is stored in advance into the magnetic fluid filling container 31 are performed as follows. First, the electromagnetic valve 41 and the electromagnetic valve 43 are opened with the electromagnetic valve 42 closed. As a result, the magnetic fluid filling container 31 and the magnetic fluid tank 32 are in communication with each other through the flow pipes 61 and 63. Here, when the pump 51 is operated to suck the magnetic fluid 80 in the magnetic fluid tank 32, the magnetic fluid 80 is injected from the magnetic fluid tank 32 into the magnetic fluid filling container 31 through the flow pipe 61. When the magnetic fluid filling container 31 is completely filled with the magnetic fluid 80, excess magnetic fluid 80 starts to be discharged through the flow pipe 63. When the flow sensor 73 detects that the magnetic fluid 80 is flowing through the flow pipe 63, the electromagnetic valve 41 and the electromagnetic valve 43 are closed and the pump 51 is stopped under the control of the control unit 20. Injection of the magnetic fluid 80 into the magnetic fluid filling container 31 is stopped.

  On the other hand, the operation of discharging the magnetic fluid 80 from the magnetic fluid filling container 31 is performed as follows. First, the electromagnetic valve 43 and the electromagnetic valve 42 are opened, and the magnetic fluid filling container 31 and the magnetic fluid tank 32 are in communication with each other through the flow pipe 62 and the flow pipe 63. Subsequently, by operating the pump 52, the magnetic fluid 80 in the magnetic fluid filling container 31 is sucked and discharged to the magnetic fluid tank 32. When all the magnetic fluid 80 is discharged from the magnetic fluid filling container 31 to the magnetic fluid tank 32, the magnetic fluid 80 does not flow through the flow pipe 62. When the flow sensor 72 detects that the magnetic fluid 80 does not flow through the flow pipe 62, the pump 52 is stopped, the electromagnetic valve 43 and the electromagnetic valve 42 are closed, and the magnetic fluid filling container 31 is controlled by the control of the control unit 20. The magnetic fluid 80 is discharged from the magnetic fluid tank 32 to the magnetic fluid tank 32.

  The magnetic field (magnetic field) generated by the magnetic field generator 10 can be reduced or modulated by the above injection, filling, and discharging operations. That is, in a state where the magnetic fluid filling container 31 is filled with the magnetic fluid 80, the magnetic fluid 80 functions as a magnetic shield (shielding), so that the magnetic field generated by the magnetic field generation unit 10 (the outside of the magnetic fluid filling container 31). The magnetic field acting on the guided member (for example, a magnetic anchor, an endoscope provided with a magnetic body) disposed in the position decreases. On the other hand, if the magnetic fluid 80 in the magnetic fluid filling container 31 is discharged and the amount thereof is reduced, the effect of the magnetic shield is reduced, so that the amount of reduction of the magnetic field generated by the magnetic field generator 10 is small. Thus, when all the magnetic fluid 80 in the magnetic fluid filling container 31 is discharged, the magnetic field generated by the magnetic field generator 10 does not decrease and reaches the outside of the magnetic fluid filling container 31.

  By adjusting the amount of the magnetic fluid 80 in the magnetic fluid filling container 31 in this way, a state where the magnetic field generated by the magnetic field generator 10 is shielded (a state where it is completely shielded) and a state where only a part is shielded. , And a state of not shielding (a state of not shielding at all) can be selectively realized. Therefore, the magnetic field generated by the magnetic field generator 10 can be reduced by a desired amount, and the operation of filling the magnetic fluid filling container 31 with the magnetic fluid 80 and the operation of discharging from the magnetic fluid filling container 31 are performed at regular intervals. By doing so, it is possible to modulate the main magnetic field for magnetic induction generated by the magnetic field generator 10.

As a modification of the first embodiment, the magnetic fluid filling container 31 may be formed of a flexible member such as rubber. In this case, the magnetic fluid is filled with a magnetic fluid in a part of the magnetic fluid filling container 31, and the magnetic fluid filling container 31 is subjected to a state in which a pressure is applied from the outside and a state in which the pressure is released in a constant cycle. By changing the shape of the filling container 31 at a constant period, the main magnetic field for magnetic induction generated by the magnetic field generator 10 can be modulated.
Second Embodiment (FIGS. 3 and 4)
2nd Embodiment implement | achieved the magnetic field modulation apparatus which comprises the magnetic induction system which concerns on this invention by moving the magnetic field modulation sheet (magnetic field modulation member) 140 provided with a magnetic material sheet part and a nonmagnetic material sheet part It is. As shown in FIG. 3, the magnetic guidance system according to the second embodiment includes a magnetic field generation unit 10 and a magnetic field modulation device 130. The magnetic field generation unit 10 is the same as that in the first embodiment, and a duplicate description is omitted.

  The magnetic field modulation device 130 includes a magnetic field modulation sheet 140, a guide roller 151, and a guide roller 152. The magnetic field modulation sheet 140 is a substantially rectangular sheet, and both ends in the longitudinal direction are wound around the guide roller 151 and the guide roller 152, and a portion extended between the guide roller 151 and the guide roller 152 is a coil. 11 are arranged so as to face the 11 magnetic pole surfaces 11a. The magnetic field modulation sheet 140 includes a magnetic sheet part (magnetic part) 141 and a non-magnetic sheet part (non-magnetic part) 142 coupled at a boundary line 145 at the center in the longitudinal direction. The width of the magnetic field modulation sheet 140 is preferably larger than the width of the magnetic pole surface 11a, and the lengths of the magnetic sheet portion 141 and the nonmagnetic material sheet portion 142 in the longitudinal direction of the magnetic field modulation sheet 140 are also longer than the length of the magnetic pole surface 11a. Larger is preferred.

  The magnetic field modulation sheet 140 has a plurality of longitudinal center boundary lines 145 in the longitudinal direction, and the magnetic sheet portion (magnetic portion) 141 and the non-magnetic sheet portion even when the sheet is moved in a certain direction. (Non-magnetic portions) 142 may alternately appear on the front surface of the magnetic pole surface 11a.

  The magnetic field modulation sheet 140 is formed by applying or spraying a resin or liquid in which a magnetic material is melted on half of a substantially rectangular nonmagnetic sheet (for example, plastic or cloth), and then drying the applied part. The magnetic sheet portion 141 is used, and the other portions are non-magnetic sheet portions 142. Examples of the magnetic material used in the magnetic sheet portion 141 include soft magnetic composite ferrite such as manganese-zinc-based, and soft magnetism such as Fe-Si-B-Nb-Cu and Fe-Co-Si-B-Nb-Cu. There are amorphous or Fe-Ni alloys such as permalloy.

  The magnetic field modulation sheet 140 is a flexible non-magnetic sheet (e.g. plastic, e.g., a thin strip including a magnetic material and a thin strip made of a non-magnetic material (e.g. plastic, rubber) instead of the above-described configuration. A rubber (cloth) may be laminated with an adhesive (for example, an epoxy adhesive). In addition, when a magnetic sheet portion is formed by laminating thin strips containing such a magnetic material, the electrical resistance in the thickness direction can be increased, and loss due to eddy current can be reduced. This thin body can be manufactured by machining if the magnetic material is a metal (for example, permalloy), and if it is amorphous or ferrite, it can be integrally molded by dispersing in a high concentration in a solvent (for example, plastic or rubber material). it can. Furthermore, the magnetic field modulation sheet 140 can be configured by alternately arranging the magnetic material sheet portions 141 and the nonmagnetic material sheet portions 142 along the longitudinal direction of the magnetic field modulation sheet 140. According to this configuration, it is possible to perform modulation with a constant period by moving the magnetic field modulation sheet 140 in one direction at a constant speed.

  The guide roller 151 and the guide roller 152 are rotationally driven by a motor 161 and a motor 162, respectively. The operations of the motor 161 and the motor 162 are controlled by the control unit 120. The control unit 120 outputs a control signal so as to rotate with respect to the motor 161 or the motor 162 in accordance with the operation of the input unit 125. By such control, the magnetic field modulation sheet 140 can move in the longitudinal direction. That is, the relative positional relationship between the magnetic field modulation sheet 140 and the magnetic pole surface 11a of the coil 11 can be changed. Therefore, a portion desired by the operator in the magnetic field modulation sheet 140 is disposed at a position facing the magnetic pole surface 11a.

  By moving the magnetic field modulation sheet 140 having the above configuration in the longitudinal direction, the magnetic field generated by the magnetic field generation unit 10 can be reduced or modulated. In other words, in the state where the magnetic sheet portion 141 is arranged to face the magnetic pole surface 11a, the magnetic sheet portion 141 functions as a magnetic shield, so that the magnetic field generated by the magnetic field generator 10 (magnetic field modulation with respect to the coil 11). The magnetic field acting on the guided member arranged outside the sheet 140 is reduced. On the other hand, when the non-magnetic sheet portion 142 is disposed at a position facing the magnetic pole surface 11a by moving the magnetic field modulation sheet 140, the magnetic field generated by the magnetic field generation unit 10 does not decrease and the magnetic field modulation sheet 140 is reduced. To the outside.

  In this manner, by moving the magnetic field modulation sheet 140, the magnetic field generated by the magnetic field generation unit 10 can be reduced by a desired amount, and the operation of causing the magnetic sheet unit 141 to face the magnetic pole surface 11a and nonmagnetic By performing the operation of causing the body sheet portion 142 to face the magnetic pole surface 11a at a constant period, the main magnetic field for magnetic induction generated by the magnetic field generating unit 10 can be modulated.

  As a modification of the second embodiment, instead of the magnetic field modulation sheet 140, a disk-shaped member divided into a magnetic part and a non-magnetic part can be used, and the magnetic field can be modulated by rotating this.

As another modified example of the second embodiment, by using a thick laminated silicon steel sheet instead of the magnetic field modulation sheet 140, by repeating the operation of making this opposed to the magnetic pole surface 11a and the operation of removing it, more It is also possible to modulate the magnetic field with a greater shielding effect.
<Third Embodiment> (FIGS. 5 and 6)
In the third embodiment, the magnetic field modulation device constituting the magnetic induction system according to the present invention is realized by using a coil whose magnetic characteristics change with temperature. As shown in FIG. 5, the magnetic guidance system according to the third embodiment includes a magnetic field generation unit 210 and a magnetic field modulation device 230.

The magnetic field generator 210 includes a superconducting coil (superconductor) (for example, NbTi, Nb ₃ Sn) 211 whose electric resistance becomes zero when the temperature is lower than a certain temperature, and a power supply 212 that supplies current to the superconducting coil 211 (FIG. 6). And comprising. The operation of the power supply 212 is controlled by the control unit 220. An input unit 225 is connected to the control unit 220, and by operating the input unit 225, an amount of current corresponding to the magnitude of the magnetic field desired by the operator can be supplied to the superconducting coil 211. A magnetic field corresponding to the amount is formed. The magnetic field generator 210 may be a superconducting bulk permanent magnet (for example, a superconducting bulk permanent magnet made of a compound of bismuth, strontium, calcium, and copper) instead of the superconducting coil 211 and the power source 212.

  The magnetic field modulation device 230 includes a vacuum container 231, a heater (temperature adjustment member) 240, a shield container (magnetic shield member) 232, and a refrigerator 250. The vacuum vessel 231 is a hollow vessel made of a material (for example, non-magnetic stainless steel, aluminum, titanium, FRP (fiber reinforced plastic)) that can keep the inside in a vacuum insulation state, and the magnetic field generator 210 is inside. Be contained. The magnetic field generator 210 is housed in the vacuum container 231 in a state of being housed in the shield container 232 in order to prevent heat from entering from the outside due to heat radiation. The shield container 232 is a hollow container made of a material (for example, a compound of yttrium, barium, copper, and oxygen) that exhibits superconducting characteristics at a temperature higher than that of the superconducting coil 211. The heater 240 is fixed to the outer surface of the upper surface. Yes. A power source 242 is connected to the heater 240 via a conductive wire 241, and the temperature of the heater 240 can be controlled by the amount of current supplied from the power source 242. The power source 242 is connected to the control unit 220, and the amount of current supplied to the heater 240 can be controlled by operating the input unit. If the power supplied to the heater 240 is smaller than the refrigerating capacity of the refrigerator 250 and the total heat capacity of the shield container 232 is sufficiently large, the superconducting coil 211 can be kept in a superconducting state permanently. it can.

  The refrigerator 250 includes a motor unit 251, a cylinder 252 extending from the motor unit 251, a first stage 253 fixed to the tip of the cylinder 252, a cylinder 254 further extending from the first stage 253, and fixed to the tip of the cylinder 254. And a second stage 255 to which the superconducting coil 211 is fixed. The second stage 255 is accommodated in the shield container 232 and can cool the superconducting coil 211 to realize a superconducting state. The conducting wire 241 is a current introducing terminal made of a high-temperature superconductor (for example, a compound of yttrium, barium, copper, and oxygen). This is preferable because the amount of heat entering the coil 211 can be reduced and heat generation by the conductive wire 241 can be avoided.

  In the magnetic induction system according to the third embodiment, the shield container 232 maintains the superconducting state in a state where no current is supplied to the heater 240. At this time, the magnetic field generated by the magnetic field generation unit 210 (the magnetic field that acts on the guided member disposed outside the surface 231 a close to the heater 240 among the surfaces constituting the vacuum container 231) is reduced by the shield container 232. . On the other hand, when a pulse current is applied to the heater 240 to such an extent that a part of the shield container 232 momentarily loses the superconducting state, the magnetic field acting on the outside from the magnetic field generator 210 increases instantaneously.

  By adjusting the amount of current supplied to the heater 240 in this way, the magnetic field generated by the magnetic field generator 210 can be reduced by a desired amount, and the supply and stop of the current to the heater 240 are performed at a constant period. As a result, the main magnetic field for magnetic induction generated by the magnetic field generator 210 can be modulated.

  The shield container 232 can be configured to be separated into a magnetic shield and a radiation shield.

Although the present invention has been described with reference to the above embodiment, the present invention is not limited to the above embodiment, and can be improved or changed within the scope of the purpose of the improvement or the idea of the present invention.

It is a figure which shows the structure of the magnetic guidance system which concerns on 1st Embodiment of this invention. It is a block diagram which shows the structure of the control system of the magnetic induction system which concerns on 1st Embodiment of this invention. (A) is a bottom view which shows the structure of the magnetic guidance system which concerns on 2nd Embodiment of this invention, (b) is a side view of (a). It is a block diagram which shows the structure of the control system of the magnetic induction system which concerns on 2nd Embodiment of this invention. It is a figure which shows the structure of the magnetic guidance system which concerns on 3rd Embodiment of this invention. It is a block diagram which shows the structure of the control system of the magnetic induction system which concerns on 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Magnetic field generation part 11 Coil 12 Power supply 30 Magnetic field modulation apparatus 31 Magnetic fluid filling container (filling container)
80 Magnetic fluid 130 Magnetic field modulation device 140 Magnetic field modulation sheet (magnetic field modulation member)
141 Magnetic sheet part (magnetic part)
142 Non-magnetic sheet part (non-magnetic part)
210 Magnetic field generator 230 Magnetic field modulator 232 Shield container (magnetic shield member)
240 Heater (temperature adjustment member)

Claims (7)

A magnetic field generator for generating a constant magnetic field for guiding the guided member;
A magnetic field modulation device that is arranged around the magnetic field generation unit and selectively realizes a state in which the magnetic field generated by the magnetic field generation unit is shielded, a state in which the magnetic field generation unit is shielded, and a state in which the magnetic field generation unit is not shielded.
A magnetic induction system that modulates a magnetic field formed by the magnetic field generated by the magnetic field generator by the operation of the magnetic field modulator. The magnetic field modulation device includes a filling container filled with a magnetic fluid, and an adjustment mechanism for adjusting the amount of the magnetic fluid filled in the filling container, and the filling container is operated by the operation of the adjustment mechanism. 2. The magnetism according to claim 1, wherein the amount of the magnetic fluid filled in the magnetic field is adjusted to selectively realize a state in which the magnetic field generated by the magnetic field generator is shielded, a partly shielded state, and a state in which the magnetic field is not shielded. Guidance system. The magnetic field modulation device includes a magnetic field modulation member having a magnetic part and a nonmagnetic part, and a relative position changing member that changes a relative positional relationship between the magnetic part and the nonmagnetic part of the magnetic field modulation member and the magnetic field generation part. 2. The magnetism according to claim 1, wherein a state in which the magnetic field generated by the magnetic field generator is shielded, a partly shielded state, and a state in which it is not shielded are selectively realized by the operation of the relative position changing member. Guidance system. The magnetic field modulation device includes a magnetic shield member having a magnetic body whose magnetic characteristics change according to temperature, and a temperature adjustment member that adjusts the temperature of the magnetic shield member, and the magnetic body is operated by the operation of the temperature adjustment member. The magnetic induction system according to claim 1, wherein the magnetic characteristics of the magnetic field control unit are controlled to selectively realize a state in which the magnetic field generated by the magnetic field generator is shielded, a partly shielded state, and a state in which it is not shielded. The magnetic body of the magnetic shield member is a superconductor, and the superconducting state and non-superconducting state of the magnetic body are selectively realized by changing the temperature of the magnetic shield member by the operation of the temperature adjusting member. 5. The magnetic induction system according to claim 4, wherein a magnetic field generated by the magnetic field generation unit is selectively realized in a state of shielding, partially shielding, and not shielding. The said magnetic field generation | occurrence | production part is provided with a coil and the power supply which supplies the electric current for generating a fixed magnetic field for inducing a to-be-induced member with respect to the said coil. The described magnetic induction system. It is arranged around the magnetic field generator that generates a constant magnetic field for guiding the guided member,
Modulating the magnetic field formed by the magnetic field generated by the magnetic field generation unit by selectively realizing a state where the magnetic field generated by the magnetic field generation unit is shielded, partially shielded, and not shielded. A magnetic field modulation device.

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