Electricity: magnetically operated switches – magnets – and electr – Magnets and electromagnets – Magnet structure or material
Reexamination Certificate
2005-01-04
2005-01-04
Barrera, Ramon M. (Department: 2832)
Electricity: magnetically operated switches, magnets, and electr
Magnets and electromagnets
Magnet structure or material
C324S320000
Reexamination Certificate
active
06838966
ABSTRACT:
The object of the present invention is to minimize the residual magnetic induction in a circular pole piece included in a magnetic circuit for magnetic resonance imaging. A circular pole piece is divided into two portions, that is, a center portion and a marginal portion. A soft magnetic material that exhibits a high permeability (for example, 10000 or more) with a relatively small external magnetic field (for example, ranging from 20 A/m to 60 A/m) applied thereto is adopted as a soft magnetic material to be made into a center-portion laminate block. A soft magnetic material that exhibits a high permeability (for example, 6000 or more) with a relatively large external magnetic field (for example, ranging from 50 A/m to 150 A/m) applied thereto is adopted as a soft magnetic material to be made into a marginal-portion laminate block103b. Consequently, since the residual magnetic induction in the circular pole piece can be minimized, the degradation in image quality attributable to a residual magnetic induction can be prevented.
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Armstrong Teasdale LLP
Barrera Ramon M.
GE Medical Systems Global Technology Company LLC
Horton Esq. Carl B.
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