Static structures (e.g. – buildings) – Combined
Reexamination Certificate
1999-05-06
2001-01-09
Chilcot, Richard (Department: 3635)
Static structures (e.g., buildings)
Combined
C052S207000, C052S784100, C174S034000, C174S034000, C049S477100
Reexamination Certificate
active
06170203
ABSTRACT:
DESCRIPTION
This invention relates in general to a door construction for a magnetically shielded room, and more particularly to a multiple shell magnetically shielded room which includes a door having multiple sections which maintain consistent pressure around the circumference of the door frame to obtain continuity of electric and magnetic flux in the multiple shells.
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.” The sensitive instruments are used among other things for biomagnetic research and tests to measure minute magnetic fields. To obtain proper readings and results from the sensitive equipment, 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 and low frequencies is difficult to obtain, the ideal MSR includes multiple shells which have 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, remaining residual field in the MSR near the measuring instrument. 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 for providing access to the interior chamber of the MSR. 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. To obtain this stable and homogenous environment, the shielding layers or shields must be continuous or provide substantial continuity of the electric and magnetic flux in the electrically conductive and magnetically permeable shielding layers or shields. It is difficult to achieve this continuity between the door of the MSR and the surrounding walls or door frame due to the physical separation necessary to form the door.
To achieve the continuity between the door and the door frame, all air gaps must be eliminated between the outer peripheral edge of the multiple shielding layers or shields in the door and the inner edge of the door frame. Ideally, a substantial, continuous and even pressure is required between the door and the door frame. Previous MSRs have employed a single door having multiple layers. However, due to manufacturing tolerances and the size of the air gap between the multiple layers or shields, a one piece door will not guarantee the desired uniform electric and magnetic continuity between the door and the door frame or between the doors and the shielding layers or shields adjacent to the door. Moreover, conventional door hinges and conventional locking mechanisms will not provide the desired continuous contact to eliminate the air gaps between the shielding layers or shields in the door and door frame.
SUMMARY OF THE INVENTION
The present invention overcomes the above problems in providing a multiple section door construction for a multiple shell MSR having shielding layers of very high magnetic permeability and highly electrically conductive materials to attenuate magnetic and electromagnetic disturbances in the vicinity of the MSR. The door construction of the present invention includes interior and exterior sections corresponding with the interior and exterior shells of the MSR and provides consistent pressure around the perimeter of the door frame to obtain continuity of the electric and magnetic flux in the interior and exterior shells. The interior and exterior sections of the door are each pivotally attached to the door frame and are connected to each other by a synchronization assembly. The door construction of the present invention further includes a pneumatic locking system having multiple locking mechanisms for securing each section of the door to assure even pressure between each section of the door and the door frame. This eliminates air gaps between each section and the corresponding shell and provides electric and magnetic continuity in the interior and exterior shells of the MSR.
It is therefore an object of the present invention to provide a door construction for an MSR with multiple shells and high attenuation characteristics.
A further object of the present invention is to provide a door construction for an MSR which provides electric and magnetic continuity between the shielding layers or shields in the wall of the MSR which defines a door frame and the shielding layers or shields in the door of the MSR.
A still further object of the present invention is to provide a door construction for a MSR having interior and exterior electrically and magnetically isolating shells and a door having synchronized interior and exterior sections with corresponding isolating layers or shields which provide electric and magnetic continuity between the interior and exterior sections of the door and the interior and exterior shells of the MSR.
Other objects, features and advantages of the present invention will be apparent from the following detailed disclosure, taken in conjunction with the accompanying sheets of drawings, wherein like reference numerals refer to like parts.
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Statement of Urs Schlapfer, dated Oct. 18, 1999 (2 pages with Appendices A-D).
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James P.
Bell Boyd & Lloyd LLC
Chavez Patrick J.
Chilcot Richard
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