摘要:
A disk device, track positioning method, and method for generating a position error signal in which the occurrence of a wrong correction operation can be prevented by creating an appropriate PES without using a burst pattern having a defect, and reassign sectors can be decreased by decreasing defective sectors thereby to reduce the performance degradation is disclosed. In the disk device and track positioning method, the defect of a burst pattern read out from a disk is detected, and if a defect is detected in the burst pattern, a data value corresponding to the sum data of the burst pattern pair having the defect detected is obtained by measuring the maximum amplitude value of the burst pattern pairing with the burst pattern having the defect detected, and a PES is created according to the amplitude of the burst pattern having the defect detected and the maximum amplitude value.
摘要:
A distance measuring device having an improved control performance in a compact body by simplifying a structure for scanning a laser beam and a method of controlling the scanning. The device has a mirror for scanning an emitted laser beam, an axis around which the mirror is swung, a permanent magnet which swings along with the mirror, a core disposed opposite to the permanent magnet, a coil provided in the periphery of the core, a Hall element for detecting a swing angle of the mirror, and a circuit for controlling swing motion with a signal derived from a swing waveform formed in a predetermined shape in order to control a current in the coil, and a control signal formed by a controlled variable calculated from a deviation between a predetermined position of the mirror and a detected position.
摘要:
Tilt values between heads in a disk drive apparatus are previously measured. The measured values are stored in a head switch compensation table. In a head switch operation, a track nearest to the present position of a head to be used after a head switch operation is selected as a target track for the head to be used. A head switch compensation table is stored in a disk. The head switch compensation table stores tilt values represented by a number of tracks which corresponds to a relative deviation between heads. For example, if the table contains data showing that a tilt value between head 1 and head 2 is +1 track, then when heads are switched from head 1 to head 2, a target track for head 2 is selected by adding this value +1 to the current track address on which head 1 is positioned. By this method, head 2 can be positioned on the nearest track by a short time seek operation and can continue a sequential read or write operation.