Patent ID: 6529003
Filing Date: 2003-03-04
Classification: G01R,Y10T

Abstract:
A gradient coil system comprising:a plurality of pairs of conductive windings disposed on generally the same plane and being defined on one side and on another side, each of said pair of windings being formed of a conductive material and of a straight portion and a semi-circular portion on said one side and of a straight portion and a semi-circular portion on said other side, said semi-circular portions being arranged on each of said one side and said other side so as to have a smallest radius for a first semi-circular portion and gradually expanding in radius to a largest radius for an n-th semi-circular portion with said straight portion connecting ends of a corresponding semi-circular portion, said pair of windings being symmetrically disposed with their respective straight portions being adjacent and parallel to each other, wherein an axis dividing said semi-circular portions into two equal parts is defined as an x-axis; and wherein on said one side and on said other side, a straight portion is connected on one side to a semi-circular portion having said smallest radius and another end thereof is connected on said one side to a next semi-circular portion having a next larger radius, and so on in a repeated manner, with one end of said semi-circular portion having said smallest radius acting as one terminal and an end of another straight portion being connected to a semi-circular portion having the largest radius on the one side being connected to an end of a semi-circular portion having the smallest radius on the other side, with a straight por- being connected to an end of a semi-circular portion having the next largest radius on the other side, and so on in a repeated manner, with an end of said semi-circular portion having the largest radius on the other side being connected to an end of a straight portion with the other end thereof being an outlet terminal; and means for passing electric current in the same direction through all of the straight portions on both the one side and the other side and in an opposite direction through said semi-circular portions on both the one side and the other side, with said current being applied to said one terminal and then to the semi-circular portion having the smallest radius on the one side, eventually to the semi-circular portion of the largest radius on the one side, then directly to the semi-circular portion of the smallest radius on the other side, and eventually to the semi-circular portion having the largest radius on the other side, and then directly to the outlet terminal, so that an x-axis electric current distribution is generated which is basically expressed by a continuous function that does not lie in both positive and negative polarities simultaneously.