Magnetic head positioner for a magnetic disk apparatus minimizing thermal offtrack

摘要

A magnetic head positioner for a magnetic disk apparatus has an arm holder rotatably supported on a shaft by a plurality of bearings. The arm holder provides a plurality of arms carrying magnetic heads for writing and reading data at tip ends thereof. A first cylindrical sleeve is interposed between the bearings and the arm holder and fixed to the outer peripheral surface of the bearings. The first cylindrical sleeve is also made of a material having a linear expansion coefficient substantially the same as that of the shaft. A pair of second cylindrical sleeves are interposed between the bearings and the arm holder and fixed to the first cylindrical sleeve at one end portion thereof and to the inner peripheral surface of the arm holder at the other end portion thereof. The pair of second cylindrical sleeves are also made of a material having substantially the same linear expansion coefficient substantially as that of the arm holder. Thermal offtracking of the magnetic heads with respect to the disk is thus minimized.