| 摘要 |
PROBLEM TO BE SOLVED: To make reducible the resistance value of a coil without lowering the magnetic efficiency by increasing, at a constant ratio, the conductor width of a coil layer in the normal direction extending toward the outer periphery from the center of the coil layer, and setting the conductor width on a first normal extending from the center of the coil layer toward a portion facing a recording medium to be smaller than the conductor width on a second normal extending in the direction opposite to the first normal. SOLUTION: The conductor width of a coil layer 4, when a normal extending from the center 4h of the coil layer 4 in the direction toward the outer periphery of the coil layer 4 was measured, is set to increase, at a constant ratio, from the inner periphery side toward the outer periphery side. In addition, with respect to the conductor width of the coil layer 4 in each turn, the conductor width on a first normal 8 extending from the center 4h of the coil layer 4 toward a portion facing a recording medium is set to be smaller than the conductor width on a second normal 9 extending in the direction opposite to the first normal 8. Thus, an increase in a coil resistance value for each turn measured from the inner periphery side toward the outer periphery side of the coil layer 4 can be suppressed, and furthermore, the overall coil resistance value of the whole coil layer can be reduced.
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