Patent ID: 7154707

Claim:
A thin film magnetic head, comprising: a thin film coil generating a magnetic flux; an insulating layer electrically separating the thin film coil from its surroundings; a pole layer including a first pole layer portion and a second pole layer portion, and emitting the magnetic flux generated in the thin film coil toward the recording medium, the first pole layer portion extending from a recording-medium-facing surface to face a recording medium moving in a predetermined direction of medium movement to a direction away from the recording-medium-facing surface and having an uniform width determining a recording track width, the second pole layer portion being connected to the rear of the first pole layer portion and having a larger width than that of the first pole layer portion; and a return pole layer being disposed on a medium-outgoing side of the pole layer in the direction of medium movement so as to face the pole layer with a gap layer in between on a side closer to the recording-medium-facing surface and connected to the pole layer in a back gap on a side farther from the recording-medium-facing surface, the return pole layer returning the magnetic flux emitted from the pole layer to magnetize the recording medium, wherein a width of the first pole layer portion in the pole layer is W 1 (μm), and a distance between the recording-medium-facing surface and a widening position where the width of the pole layer expands from the first pole layer portion to the second pole layer portion is NH (μm), and a distance between the recording-medium-facing surface and the forefront end position of the insulating layer is TH (μm), the distance NH is within a range of NH≦W 1 +0.05 μm, and a distance ratio NH/TH is within a range of 0.5<NH/TH<1.6.