| 摘要 |
A carriage retention device for use in a head disk assembly of a disk drive which reads or writes data to or from a disk with a head. The disk has a landing area where the head rests when not in use. The carriage supports the head and positions it relative to the disk. The carriage is movable to position the head over the data tracks of the disk and in the head landing area. A coil mounted on the carriage is used in conjunction with a stationary magnet assembly adjacent to the coil to electromagnetically position the carriage. The magnet assembly produces a non-uniform magnetic field having a region with a low gradient of flux density and a region with a higher gradient of flux density. A ferrous metal body, such as a steel ball, is mounted on the carriage so that it is positioned within the region with the low gradient of flux density when the carriage positions the head over the data track of the disk and within the region with the higher gradient of flux density when the head carriage positions the landing area. The magnet assembly exerts force on the ferrous metal body sufficient to move the carriage toward the parked position when no current flows in the coil and to hold the carriage in the parked position during spin up or when the head disk assembly is being moved. |
