| 摘要 |
<p>A permanent magnet structure (10) includes a generally U-shaped frame made of a magnetic material and a pair of opposite polarity magnet members (22, 24) mounted on the opposed surfaces of the legs of the U. The connecting element (20) of the U which connects the legs (16, 18) is disposed at a sufficient distance from the magnets so that the resulting magnetic field passes substantially entirely between the magnets and through the arms and so that no substantially eddy currents are induced in the connecting element during imaging. Between the connecting element and the magnets, there is disposed a non-conductive, non-magnetic separating member (28) which contacts the two arms and tends to keep them apart. The separating member is so positioned relative to the connecting member (20) and the magnets (22, 24) that effects of the force between the two magnets and the force produced by the magnetic field passing through the arms and connecting element are counterbalanced. This results in a structure which is mechanically stable.</p> |
