Disc drive unit

摘要

There is provided a disk drive unit which is capable of making control corresponding to contaminant and defect by discriminating the contaminant (dust, scratch) on the disk surface from the defect on the recording plane. In a pull-in signal PI corresponding to reflected light from a disk, a defect detecting signal corresponding to a signal whose level change is relatively quick corresponding to the defect of the recording plane and a contaminant detecting signal which corresponds to a signal whose level change is relatively slow corresponding to the contaminant on the disk surface are generated. When the defect detecting signal is at low level for example, a system controller retries a recording operation or increases laser light when the contaminant detecting signal is at low level. A quantity of output light of a laser diode is controlled so that a product of output light of a laser diode and reflected light from the disk amounts to a predetermined level. <IMAGE>