Static structures (e.g. – buildings) – Preassembled subenclosure or substructure section of unit or...
Reexamination Certificate
1999-05-06
2001-09-04
Stephan, Beth A. (Department: 3635)
Static structures (e.g., buildings)
Preassembled subenclosure or substructure section of unit or...
C052S265000, C052S268000, C052S403100, C052S480000, C052S481100
Reexamination Certificate
active
06282848
ABSTRACT:
DESCRIPTION
This invention relates in general to a magnetically shielded room, and more particularly to a floor, ceiling and wall construction for a magnetically shielded room which improves the attenuation characteristics of the magnetically shielded room, decreases deterioration of the attenuation characteristics caused by vibration and normal use of the room and reduces vibration interaction between the parent building and the magnetically shielded room.
BACKGROUND OF THE INVENTION
A magnetically shielded room, commonly referred to as an “MSR”, is used to magnetically and electromagnetically isolate sensitive instruments and equipment such as highly sensitive biomagnetic detectors, measuring instruments and super conductive quantum interference devices, commonly referred to as “SQUIDs.” Some of these sensitive instruments are used for biomagnetic research and tests to measure minute magnetic fields. To obtain proper readings and results from the sensitive instruments, the environment for conducting these tests must be extremely magnetically quiet. The MSR provides a magnetically and electromagnetically isolated environment for using this equipment by attenuating stray magnetic fields and other magnetic disturbances created or generated by the earth's magnetic field, power lines, current carrying conductors and moving metal masses such as trains, automobiles, elevators and other large metal objects in the vicinity of the MSR. Except for the power lines which create 50/60 hertz frequencies, the above mentioned influences create low or very low frequencies which often approach DC or zero. The earth's magnetic field is in fact a DC field. Since magnetic and electromagnetic shielding of DC to high frequencies is somewhat difficult to obtain, the ideal MSR includes multiple shielding layers or shields of very high magnetic permeability and highly electrically conductive materials capable of attenuating these various frequencies.
The MSR must also provide a stable and homogeneous environment for the small, if any, residual field in the MSR near the sensitive instruments. To achieve this stable and homogeneous environment, the MSR is preferably a six sided cube having a floor, a ceiling, four walls and a door in one of the walls. In the ideal MSR, the floor, ceiling, walls and door have multiple magnetic and electromagnetic shielding layers or shields to obtain high attenuation characteristics and to produce the desired stable and homogeneous environment in the interior chamber of the MSR.
An MSR may lose its attenuation, stability and homogenous characteristics due to vibration from the earth or parent building, the pressure or weight of the sensitive instruments on the weight bearing floor in the MSR and the normal use of the MSR including people walking on the weight bearing floor in the room. Such vibration, pressure, weight and use of the MSR can cause the shielding layers or shields to lose part of their attenuation properties which alter the readings from the sensitive instrument in the MSR, and ultimately the results of the biomagnetic or other research or tests. The ideal MSR room thereby compensates for the weight of the sensitive instrument by separating the weight bearing floor from the shielding layers or shields, and dampens the vibration caused by use of the room as well as from the earth and the parent building.
The use of multiple shielding layers or shields in an MSR creates additional problems, such as electric conductivity or magnetic coupling between the shielding layers or shields. Such electric conductivity may be eliminated by a dielectric separation between the shields, and such magnetic coupling may be substantially reduced by the appropriate separation or spacing of the independent shielding layers or shields with non-magnetically permeable material. In an ideal MSR, at one or more levels, at least one electrically conductive shielding layer or shield is thereby magnetically decoupled and electrically isolated from at least one magnetically permeable shielding layer or shield.
SUMMARY OF THE INVENTION
The present invention overcomes the above problems in providing an improved floor, ceiling and wall construction for a MSR having multiple shielding layers or shields of very high magnetic permeability and highly electrically conductive materials to attenuate magnetic and electromagnetic disturbances in the vicinity of the MSR. The floor construction of the present invention electrically insulates the MSR from the parent building and dampens exterior and interior vibrations including vibration in the weight bearing floor caused by the weight of the sensitive instruments or normal use of the MSR to provide a stable and homogeneous environment in the MSR. The floor, ceiling and wall construction of the present invention further provides desired magnetic decoupling and a dielectric separation between certain electrically conductive and magnetically permeable shielding layers or shields.
The floor construction of the present invention enables the weight bearing floor to rest independent from the shielding layers or shields on a plurality of uniformly distributed separators, columns or stands extending through the shielding layers or shields and supporting the weight bearing floor. Each separator, column or stand includes an interior section, a spacer and an exterior section, which includes a vibration pad that rests on the substrate of the parent building which support the components of the MSR. The vibration pad electrically insulates the MSR from the parent building, directly dampens vibration in the weight bearing floor transmitted through the separators, columns or stands to the vibration pad and further dampens and thus avoids the transmission of building vibration and resonance to the MSR. The floor construction of the present invention therefore provides a double action vibration dampening system which eliminates deterioration of the attenuation characteristics of the shielding layers or shields resulting from pressure or weight on the weight bearing floor and reduces vibration interaction between the parent building and the MSR.
The MSR of the present invention includes an exterior shell surrounding an interior shell. The shells are supported by a plurality of floor separators, columns or stands ceiling separators and wall separators. The exterior shell includes inner and outer shielding layers or shields. The outer shield is a highly conductive non-magnetically permeable material and the inner shield is a highly magnetically permeable material. The interior shell includes inner and outer shields. The outer shield is a highly conductive non-magnetically permeable material and the inner shield is a highly magnetically permeable material. The inner and outer shields of the interior shell are magnetically decoupled and dielectrically separated by a non-conductive insulating layer and non-conductive insulating sleeves and rings. The exterior and interior shells are magnetically decoupled and dielectrically separated by non-conductive separators, sleeves and rings and an air gap or separation between the shells. The exterior and interior shells thereby co-act to attenuate the stray magnetic fields and disturbances created by the earth's magnetic field, power lines, current carrying conductors and moving metal masses near the MSR and create an extremely magnetically quiet environment in the MSR.
It is therefore an object of the present invention to provide a MSR with high attenuation characteristics.
A further object of the present invention is to provide a MSR with a stable and homogeneous environment.
Another object of the present invention is to provide an MSR which dampens external vibration from the parent building and surrounding environment and dampens internal vibration which occurs during the normal use of the MSR.
A still further object of the present invention is to provide an MSR with interior and exterior magnetically decoupled and dielectrically separated shells having very high magnetic permeability and electrically highly conduc
Bell Boyd & Lloyd LLC
Glessner Brian E.
Imedco AG
Stephan Beth A.
LandOfFree
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