LARGE CAPACITY DISK DRIVE DEVICE, ITS PHOTODETECTING SIGNAL COMPENSATING METHOD AND SEEK POSITION DETECTOR

PROBLEM TO BE SOLVED: To avoid degradation in seek position detecting precision of a large capacity disk drive caused by medium defect. SOLUTION: The device is provided with a laser light source 1 which emits laser light beams, a light receiving element 4m which receives reflected beams of laser light beams being irradiated over plural tracks of a disk and outputs signals M, a light receiving element 4a which detects reflected light beams from the disk and outputs signals A that draw sine curves by the rotation of the disk, a light receiving element 4b which detects reflected light beams from the disk and outputs signals B having a phase that is deviated 90 deg. from the phase of the signals A, and a circuit 7 which generates seek position detecting signals from the signals A and B. When a temporary reduction in signal levels is detected in the signals M caused by medium defect of the disk, the signals A are amplified by a compensating circuit 6 for a prescribed time width after a time t1 from the detection time and the signals B are amplified for a prescribed time width after a time t2 from the detection time.