JP2923575B

• Main Author: INOE JUJI
• Format: Patent
• Language: English
• Published: 26.07.1999
• Edition: 6
• Subjects: BASIC ELECTRIC ELEMENTS; DIAGNOSIS; ELECTRICITY; HUMAN NECESSITIES; HYGIENE; IDENTIFICATION; INDUCTANCES; INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIRCHEMICAL OR PHYSICAL PROPERTIES; MAGNETS; MEASURING; MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES; MEDICAL OR VETERINARY SCIENCE; PHYSICS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES; SURGERY; TESTING; TRANSFORMERS

PURPOSE:To decrease the deterioration of a gradient gain ratio and the deterioration of relative linearity of a gradient magnetic field by forming a current path so that magnitude of a circular arc direction component of current density is proportional to (cos theta), when an angle looked at from the center axis of a cylinder is set as theta, based on a symmetry axis of the current path as a reference, and also, 0<n<1. CONSTITUTION:A current path 3 of a printed board 2 for forming a curved shape coil 1 is formed so as to satisfy the following conditions. (1) The current path 3 is a spiral shape being symmetrical to a symmetry axis P. (2) The printed board 2 is curved to a 1/2 shape of a cylinder in which width Lc of the printed board 2 is half peripheral length, and when an angle looking at the curved shape coil 1 from the center axis of a cylinder is set as theta, based on a symmetry axis P of the current path as a reference, and also, 0<n<1, magnitude of a circular are direction component of current density is proportional to (cos theta). Therefore, comparing with a conventional curved shape coil, the circular arc direction component of current density becomes large as theta approaches + or -pi/2. Also, by an increase in this current density, a deterioration portion of a characteristic is compensated.